{ "mode": "info", "parameter": "coreutils", "section": "", "url": "https://www.chedong.com/phpMan.php/info/coreutils/json", "generated": "2026-07-30T03:28:42Z", "sections": { "File: coreutils.info, Node: Top, Next: Introduction, Up: (dir)": { "content": "", "subsections": [] }, "GNU Coreutils": { "content": "", "subsections": [] }, "This manual documents version 8.32 of the GNU core utilities, including": { "content": "the standard programs for text and file manipulation.\n\nCopyright (C) 1994-2020 Free Software Foundation, Inc.\n\nPermission is granted to copy, distribute and/or modify this\ndocument under the terms of the GNU Free Documentation License,\nVersion 1.3 or any later version published by the Free Software\nFoundation; with no Invariant Sections, with no Front-Cover Texts,\nand with no Back-Cover Texts. A copy of the license is included in\nthe section entitled \"GNU Free Documentation License\".\n\n* Menu:\n\n* Introduction:: Caveats, overview, and authors\n* Common options:: Common options\n* Output of entire files:: cat tac nl od base32 base64 basenc\n* Formatting file contents:: fmt pr fold\n* Output of parts of files:: head tail split csplit\n* Summarizing files:: wc sum cksum b2sum md5sum sha1sum sha2\n* Operating on sorted files:: sort shuf uniq comm ptx tsort\n* Operating on fields:: cut paste join\n* Operating on characters:: tr expand unexpand\n* Directory listing:: ls dir vdir dircolors\n* Basic operations:: cp dd install mv rm shred\n* Special file types:: mkdir rmdir unlink mkfifo mknod ln link readlink\n* Changing file attributes:: chgrp chmod chown touch\n* Disk usage:: df du stat sync truncate\n* Printing text:: echo printf yes\n* Conditions:: false true test expr\n* Redirection:: tee\n* File name manipulation:: dirname basename pathchk mktemp realpath\n* Working context:: pwd stty printenv tty\n* User information:: id logname whoami groups users who\n* System context:: date arch nproc uname hostname hostid uptime\n* SELinux context:: chcon runcon\n* Modified command invocation:: chroot env nice nohup stdbuf timeout\n* Process control:: kill\n* Delaying:: sleep\n* Numeric operations:: factor numfmt seq\n* File permissions:: Access modes\n* File timestamps:: File timestamp issues\n* Date input formats:: Specifying date strings\n* Version sort ordering:: Details on version-sort algorithm\n* Opening the software toolbox:: The software tools philosophy\n* GNU Free Documentation License:: Copying and sharing this manual\n* Concept index:: General index\n\n-- The Detailed Node Listing --\n", "subsections": [] }, "Common Options": { "content": "* Exit status:: Indicating program success or failure\n* Backup options:: Backup options\n* Block size:: Block size\n* Floating point:: Floating point number representation\n* Signal specifications:: Specifying signals\n* Disambiguating names and IDs:: chgrp, chown, chroot, id: user and group syntax\n* Random sources:: Sources of random data\n* Target directory:: Target directory\n* Trailing slashes:: Trailing slashes\n* Traversing symlinks:: Traversing symlinks to directories\n* Treating / specially:: Treating / specially\n* Standards conformance:: Standards conformance\n* Multi-call invocation:: Multi-call program invocation\n", "subsections": [] }, "Output of entire files": { "content": "* cat invocation:: Concatenate and write files\n* tac invocation:: Concatenate and write files in reverse\n* nl invocation:: Number lines and write files\n* od invocation:: Write files in octal or other formats\n* base32 invocation:: Transform data into printable data\n* base64 invocation:: Transform data into printable data\n* basenc invocation:: Transform data into printable data\n", "subsections": [] }, "Formatting file contents": { "content": "* fmt invocation:: Reformat paragraph text\n* pr invocation:: Paginate or columnate files for printing\n* fold invocation:: Wrap input lines to fit in specified width\n", "subsections": [] }, "Output of parts of files": { "content": "* head invocation:: Output the first part of files\n* tail invocation:: Output the last part of files\n* split invocation:: Split a file into fixed-size pieces\n* csplit invocation:: Split a file into context-determined pieces\n", "subsections": [] }, "Summarizing files": { "content": "* wc invocation:: Print newline, word, and byte counts\n* sum invocation:: Print checksum and block counts\n* cksum invocation:: Print CRC checksum and byte counts\n* b2sum invocation:: Print or check BLAKE2 digests\n* md5sum invocation:: Print or check MD5 digests\n* sha1sum invocation:: Print or check SHA-1 digests\n* sha2 utilities:: Print or check SHA-2 digests\n", "subsections": [] }, "Operating on sorted files": { "content": "* sort invocation:: Sort text files\n* shuf invocation:: Shuffle text files\n* uniq invocation:: Uniquify files\n* comm invocation:: Compare two sorted files line by line\n* ptx invocation:: Produce a permuted index of file contents\n* tsort invocation:: Topological sort\n\n'ptx': Produce permuted indexes\n\n* General options in ptx:: Options which affect general program behavior\n* Charset selection in ptx:: Underlying character set considerations\n* Input processing in ptx:: Input fields, contexts, and keyword selection\n* Output formatting in ptx:: Types of output format, and sizing the fields\n* Compatibility in ptx:: The GNU extensions to 'ptx'\n", "subsections": [] }, "Operating on fields": { "content": "* cut invocation:: Print selected parts of lines\n* paste invocation:: Merge lines of files\n* join invocation:: Join lines on a common field\n", "subsections": [] }, "Operating on characters": { "content": "* tr invocation:: Translate, squeeze, and/or delete characters\n* expand invocation:: Convert tabs to spaces\n* unexpand invocation:: Convert spaces to tabs\n\n'tr': Translate, squeeze, and/or delete characters\n\n* Character sets:: Specifying sets of characters\n* Translating:: Changing one set of characters to another\n* Squeezing and deleting:: Removing characters\n", "subsections": [] }, "Directory listing": { "content": "* ls invocation:: List directory contents\n* dir invocation:: Briefly list directory contents\n* vdir invocation:: Verbosely list directory contents\n* dircolors invocation:: Color setup for 'ls'\n\n'ls': List directory contents\n\n* Which files are listed:: Which files are listed\n* What information is listed:: What information is listed\n* Sorting the output:: Sorting the output\n* General output formatting:: General output formatting\n* Formatting the file names:: Formatting the file names\n", "subsections": [] }, "Basic operations": { "content": "* cp invocation:: Copy files and directories\n* dd invocation:: Convert and copy a file\n* install invocation:: Copy files and set attributes\n* mv invocation:: Move (rename) files\n* rm invocation:: Remove files or directories\n* shred invocation:: Remove files more securely\n", "subsections": [] }, "Special file types": { "content": "* link invocation:: Make a hard link via the link syscall\n* ln invocation:: Make links between files\n* mkdir invocation:: Make directories\n* mkfifo invocation:: Make FIFOs (named pipes)\n* mknod invocation:: Make block or character special files\n* readlink invocation:: Print value of a symlink or canonical file name\n* rmdir invocation:: Remove empty directories\n* unlink invocation:: Remove files via unlink syscall\n", "subsections": [] }, "Changing file attributes": { "content": "* chown invocation:: Change file owner and group\n* chgrp invocation:: Change group ownership\n* chmod invocation:: Change access permissions\n* touch invocation:: Change file timestamps\n", "subsections": [] }, "Disk usage": { "content": "* df invocation:: Report file system disk space usage\n* du invocation:: Estimate file space usage\n* stat invocation:: Report file or file system status\n* sync invocation:: Synchronize cached writes to persistent storage\n* truncate invocation:: Shrink or extend the size of a file\n", "subsections": [] }, "Printing text": { "content": "* echo invocation:: Print a line of text\n* printf invocation:: Format and print data\n* yes invocation:: Print a string until interrupted\n", "subsections": [] }, "Conditions": { "content": "* false invocation:: Do nothing, unsuccessfully\n* true invocation:: Do nothing, successfully\n* test invocation:: Check file types and compare values\n* expr invocation:: Evaluate expressions\n\n'test': Check file types and compare values\n\n* File type tests:: File type tests\n* Access permission tests:: Access permission tests\n* File characteristic tests:: File characteristic tests\n* String tests:: String tests\n* Numeric tests:: Numeric tests\n\n'expr': Evaluate expression\n\n* String expressions:: + : match substr index length\n* Numeric expressions:: + - * / %\n* Relations for expr:: | & < <= = == != >= >\n* Examples of expr:: Examples of using 'expr'\n", "subsections": [] }, "Redirection": { "content": "* tee invocation:: Redirect output to multiple files or processes\n", "subsections": [] }, "File name manipulation": { "content": "* basename invocation:: Strip directory and suffix from a file name\n* dirname invocation:: Strip last file name component\n* pathchk invocation:: Check file name validity and portability\n* mktemp invocation:: Create temporary file or directory\n* realpath invocation:: Print resolved file names\n", "subsections": [] }, "Working context": { "content": "* pwd invocation:: Print working directory\n* stty invocation:: Print or change terminal characteristics\n* printenv invocation:: Print all or some environment variables\n* tty invocation:: Print file name of terminal on standard input\n\n'stty': Print or change terminal characteristics\n\n* Control:: Control settings\n* Input:: Input settings\n* Output:: Output settings\n* Local:: Local settings\n* Combination:: Combination settings\n* Characters:: Special characters\n* Special:: Special settings\n", "subsections": [] }, "User information": { "content": "* id invocation:: Print user identity\n* logname invocation:: Print current login name\n* whoami invocation:: Print effective user ID\n* groups invocation:: Print group names a user is in\n* users invocation:: Print login names of users currently logged in\n* who invocation:: Print who is currently logged in\n", "subsections": [] }, "System context": { "content": "* arch invocation:: Print machine hardware name\n* date invocation:: Print or set system date and time\n* nproc invocation:: Print the number of processors\n* uname invocation:: Print system information\n* hostname invocation:: Print or set system name\n* hostid invocation:: Print numeric host identifier\n* uptime invocation:: Print system uptime and load\n\n'date': Print or set system date and time\n\n* Time conversion specifiers:: %[HIklMNpPrRsSTXzZ]\n* Date conversion specifiers:: %[aAbBcCdDeFgGhjmuUVwWxyY]\n* Literal conversion specifiers:: %[%nt]\n* Padding and other flags:: Pad with zeros, spaces, etc.\n* Setting the time:: Changing the system clock\n* Options for date:: Instead of the current time\n* Date input formats:: Specifying date strings\n* Examples of date:: Examples\n\nSELinux context\n\n* chcon invocation:: Change SELinux context of file\n* runcon invocation:: Run a command in specified SELinux context\n", "subsections": [] }, "Modified command invocation": { "content": "* chroot invocation:: Run a command with a different root directory\n* env invocation:: Run a command in a modified environment\n* nice invocation:: Run a command with modified niceness\n* nohup invocation:: Run a command immune to hangups\n* stdbuf invocation:: Run a command with modified I/O buffering\n* timeout invocation:: Run a command with a time limit\n", "subsections": [] }, "Process control": { "content": "* kill invocation:: Sending a signal to processes.\n", "subsections": [] }, "Delaying": { "content": "* sleep invocation:: Delay for a specified time\n", "subsections": [] }, "Numeric operations": { "content": "* factor invocation:: Print prime factors\n* numfmt invocation:: Reformat numbers\n* seq invocation:: Print numeric sequences\n\n", "subsections": [] }, "File timestamps": { "content": "* File timestamps:: File timestamp issues\n", "subsections": [] }, "File permissions": { "content": "* Mode Structure:: Structure of file mode bits\n* Symbolic Modes:: Mnemonic representation of file mode bits\n* Numeric Modes:: File mode bits as octal numbers\n* Directory Setuid and Setgid:: Set-user-ID and set-group-ID on directories\n", "subsections": [] }, "Date input formats": { "content": "* General date syntax:: Common rules\n* Calendar date items:: 19 Dec 1994\n* Time of day items:: 9:20pm\n* Time zone items:: EST, PDT, UTC, ...\n* Combined date and time of day items:: 1972-09-24T20:02:00,000000-0500\n* Day of week items:: Monday and others\n* Relative items in date strings:: next tuesday, 2 years ago\n* Pure numbers in date strings:: 19931219, 1440\n* Seconds since the Epoch:: @1078100502\n* Specifying time zone rules:: TZ=\"America/NewYork\", TZ=\"UTC0\"\n* Authors of parsedatetime:: Bellovin, Eggert, Salz, Berets, et al.\n", "subsections": [] }, "Version sorting order": { "content": "* Version sort overview::\n* Implementation Details::\n* Differences from the official Debian Algorithm::\n* Advanced Topics::\n", "subsections": [] }, "Opening the software toolbox": { "content": "* Toolbox introduction:: Toolbox introduction\n* I/O redirection:: I/O redirection\n* The who command:: The 'who' command\n* The cut command:: The 'cut' command\n* The sort command:: The 'sort' command\n* The uniq command:: The 'uniq' command\n* Putting the tools together:: Putting the tools together\n", "subsections": [] }, "Copying This Manual": { "content": "* GNU Free Documentation License:: Copying and sharing this manual\n\n", "subsections": [] }, "File: coreutils.info, Node: Introduction, Next: Common options, Prev: Top, Up: Top": { "content": "", "subsections": [] }, "1 Introduction": { "content": "", "subsections": [] }, "This manual is a work in progress: many sections make no attempt to": { "content": "explain basic concepts in a way suitable for novices. Thus, if you are\ninterested, please get involved in improving this manual. The entire\nGNU community will benefit.\n\nThe GNU utilities documented here are mostly compatible with the\nPOSIX standard.\n\nPlease report bugs to . Include the version\nnumber, machine architecture, input files, and any other information\nneeded to reproduce the bug: your input, what you expected, what you\ngot, and why it is wrong.\n\nIf you have a problem with 'sort' or 'date', try using the '--debug'\noption, as it can can often help find and fix problems without having to\nwait for an answer to a bug report. If the debug output does not\nsuffice to fix the problem on your own, please compress and attach it to\nthe rest of your bug report.\n\nAlthough diffs are welcome, please include a description of the\nproblem as well, since this is sometimes difficult to infer. *Note\n(gcc)Bugs::.\n\nThis manual was originally derived from the Unix man pages in the\ndistributions, which were written by David MacKenzie and updated by Jim", "subsections": [] }, "Meyering. What you are reading now is the authoritative documentation": { "content": "for these utilities; the man pages are no longer being maintained. The\noriginal 'fmt' man page was written by Ross Paterson. Franc,ois Pinard\ndid the initial conversion to Texinfo format. Karl Berry did the\nindexing, some reorganization, and editing of the results. Brian", "subsections": [] }, "Youmans of the Free Software Foundation office staff combined the": { "content": "manuals for textutils, fileutils, and sh-utils to produce the present\nomnibus manual. Richard Stallman contributed his usual invaluable\ninsights to the overall process.\n", "subsections": [] }, "File: coreutils.info, Node: Common options, Next: Output of entire files, Prev: Introduction, Up: Top": { "content": "", "subsections": [] }, "2 Common options": { "content": "", "subsections": [] }, "Certain options are available in all of these programs. Rather than": { "content": "writing identical descriptions for each of the programs, they are\ndescribed here. (In fact, every GNU program accepts (or should accept)\nthese options.)\n\nNormally options and operands can appear in any order, and programs\nact as if all the options appear before any operands. For example,\n'sort -r passwd -t :' acts like 'sort -r -t : passwd', since ':' is an\noption-argument of '-t'. However, if the 'POSIXLYCORRECT' environment\nvariable is set, options must appear before operands, unless otherwise\nspecified for a particular command.\n\nA few programs can usefully have trailing operands with leading '-'.", "subsections": [] }, "With such a program, options must precede operands even if": { "content": "'POSIXLYCORRECT' is not set, and this fact is noted in the program\ndescription. For example, the 'env' command's options must appear\nbefore its operands, since in some cases the operands specify a command\nthat itself contains options.\n\nMost programs that accept long options recognize unambiguous\nabbreviations of those options. For example, 'rmdir\n--ignore-fail-on-non-empty' can be invoked as 'rmdir --ignore-fail' or\neven 'rmdir --i'. Ambiguous options, such as 'ls --h', are identified\nas such.\n\nSome of these programs recognize the '--help' and '--version' options\nonly when one of them is the sole command line argument. For these\nprograms, abbreviations of the long options are not always recognized.\n\n'--help'\nPrint a usage message listing all available options, then exit\nsuccessfully.\n\n'--version'\nPrint the version number, then exit successfully.\n\n'--'\nDelimit the option list. Later arguments, if any, are treated as\noperands even if they begin with '-'. For example, 'sort -- -r'\nreads from the file named '-r'.\n\nA single '-' operand is not really an option, though it looks like\none. It stands for a file operand, and some tools treat it as standard\ninput, or as standard output if that is clear from the context. For\nexample, 'sort -' reads from standard input, and is equivalent to plain\n'sort'. Unless otherwise specified, a '-' can appear as any operand\nthat requires a file name.\n\n* Menu:\n\n* Exit status:: Indicating program success or failure.\n* Backup options:: -b -S, in some programs.\n* Block size:: BLOCKSIZE and -block-size, in some programs.\n* Floating point:: Floating point number representation.\n* Signal specifications:: Specifying signals using the -signal option.\n* Disambiguating names and IDs:: chgrp, chown, chroot, id: user and group syntax\n* Random sources:: -random-source, in some programs.\n* Target directory:: Specifying a target directory, in some programs.\n* Trailing slashes:: -strip-trailing-slashes, in some programs.\n* Traversing symlinks:: -H, -L, or -P, in some programs.\n* Treating / specially:: -preserve-root and -no-preserve-root.\n* Special built-in utilities:: 'break', ':', ...\n* Standards conformance:: Conformance to the POSIX standard.\n* Multi-call invocation:: Multi-call program invocation.\n", "subsections": [] }, "File: coreutils.info, Node: Exit status, Next: Backup options, Up: Common options": { "content": "", "subsections": [ { "name": "2.1 Exit status", "content": "Nearly every command invocation yields an integral \"exit status\" that\ncan be used to change how other commands work. For the vast majority of\ncommands, an exit status of zero indicates success. Failure is\nindicated by a nonzero value--typically '1', though it may differ on\nunusual platforms as POSIX requires only that it be nonzero.\n\nHowever, some of the programs documented here do produce other exit\nstatus values and a few associate different meanings with the values '0'\nand '1'. Here are some of the exceptions: 'chroot', 'env', 'expr',\n'nice', 'nohup', 'numfmt', 'printenv', 'sort', 'stdbuf', 'test',\n'timeout', 'tty'.\n" } ] }, "File: coreutils.info, Node: Backup options, Next: Block size, Prev: Exit status, Up: Common options": { "content": "", "subsections": [ { "name": "2.2 Backup options", "content": "" } ] }, "Some GNU programs (at least 'cp', 'install', 'ln', and 'mv') optionally": { "content": "make backups of files before writing new versions. These options\ncontrol the details of these backups. The options are also briefly\nmentioned in the descriptions of the particular programs.\n\n'-b'\n'--backup[=METHOD]'\nMake a backup of each file that would otherwise be overwritten or\nremoved. Without this option, the original versions are destroyed.\nUse METHOD to determine the type of backups to make. When this\noption is used but METHOD is not specified, then the value of the\n'VERSIONCONTROL' environment variable is used. And if\n'VERSIONCONTROL' is not set, the default backup type is\n'existing'.\n\nNote that the short form of this option, '-b' does not accept any\nargument. Using '-b' is equivalent to using '--backup=existing'.\n\nThis option corresponds to the Emacs variable 'version-control';\nthe values for METHOD are the same as those used in Emacs. This\noption also accepts more descriptive names. The valid METHODs are\n(unique abbreviations are accepted):\n\n'none'\n'off'\nNever make backups.\n\n'numbered'\n't'\nAlways make numbered backups.\n\n'existing'\n'nil'\nMake numbered backups of files that already have them, simple\nbackups of the others.\n\n'simple'\n'never'\nAlways make simple backups. Please note 'never' is not to be\nconfused with 'none'.\n\n'-S SUFFIX'\n'--suffix=SUFFIX'\nAppend SUFFIX to each backup file made with '-b'. If this option\nis not specified, the value of the 'SIMPLEBACKUPSUFFIX'\nenvironment variable is used. And if 'SIMPLEBACKUPSUFFIX' is not\nset, the default is '~', just as in Emacs.\n", "subsections": [] }, "File: coreutils.info, Node: Block size, Next: Floating point, Prev: Backup options, Up: Common options": { "content": "", "subsections": [ { "name": "2.3 Block size", "content": "" } ] }, "Some GNU programs (at least 'df', 'du', and 'ls') display sizes in": { "content": "\"blocks\". You can adjust the block size and method of display to make\nsizes easier to read. The block size used for display is independent of\nany file system block size. Fractional block counts are rounded up to\nthe nearest integer.\n\nThe default block size is chosen by examining the following\nenvironment variables in turn; the first one that is set determines the\nblock size.\n\n'DFBLOCKSIZE'\nThis specifies the default block size for the 'df' command.\nSimilarly, 'DUBLOCKSIZE' specifies the default for 'du' and\n'LSBLOCKSIZE' for 'ls'.\n\n'BLOCKSIZE'\nThis specifies the default block size for all three commands, if\nthe above command-specific environment variables are not set.\n\n'BLOCKSIZE'\nThis specifies the default block size for all values that are\nnormally printed as blocks, if neither 'BLOCKSIZE' nor the above\ncommand-specific environment variables are set. Unlike the other\nenvironment variables, 'BLOCKSIZE' does not affect values that are\nnormally printed as byte counts, e.g., the file sizes contained in\n'ls -l' output.\n\n'POSIXLYCORRECT'\nIf neither 'COMMANDBLOCKSIZE', nor 'BLOCKSIZE', nor 'BLOCKSIZE'\nis set, but this variable is set, the block size defaults to 512.\n\nIf none of the above environment variables are set, the block size\ncurrently defaults to 1024 bytes in most contexts, but this number may\nchange in the future. For 'ls' file sizes, the block size defaults to 1\nbyte.\n\nA block size specification can be a positive integer specifying the\nnumber of bytes per block, or it can be 'human-readable' or 'si' to\nselect a human-readable format. Integers may be followed by suffixes\nthat are upward compatible with the SI prefixes\n(http://www.bipm.org/en/publications/si-brochure/chapter3.html) for\ndecimal multiples and with the ISO/IEC 80000-13 (formerly IEC 60027-2)\nprefixes (https://physics.nist.gov/cuu/Units/binary.html) for binary\nmultiples.\n\nWith human-readable formats, output sizes are followed by a size\nletter such as 'M' for megabytes. 'BLOCKSIZE=human-readable' uses\npowers of 1024; 'M' stands for 1,048,576 bytes. 'BLOCKSIZE=si' is\nsimilar, but uses powers of 1000 and appends 'B'; 'MB' stands for\n1,000,000 bytes.\n\nA block size specification preceded by ''' causes output sizes to be\ndisplayed with thousands separators. The 'LCNUMERIC' locale specifies\nthe thousands separator and grouping. For example, in an American\nEnglish locale, '--block-size=\"'1kB\"' would cause a size of 1234000\nbytes to be displayed as '1,234'. In the default C locale, there is no\nthousands separator so a leading ''' has no effect.\n\nAn integer block size can be followed by a suffix to specify a\nmultiple of that size. A bare size letter, or one followed by 'iB',\nspecifies a multiple using powers of 1024. A size letter followed by\n'B' specifies powers of 1000 instead. For example, '1M' and '1MiB' are\nequivalent to '1048576', whereas '1MB' is equivalent to '1000000'.\n\nA plain suffix without a preceding integer acts as if '1' were\nprepended, except that it causes a size indication to be appended to the\noutput. For example, '--block-size=\"kB\"' displays 3000 as '3kB'.\n\nThe following suffixes are defined. Large sizes like '1Y' may be\nrejected by your computer due to limitations of its arithmetic.\n\n'kB'\nkilobyte: 10^3 = 1000.\n'k'\n'K'\n'KiB'\nkibibyte: 2^{10} = 1024. 'K' is special: the SI prefix is 'k' and\nthe ISO/IEC 80000-13 prefix is 'Ki', but tradition and POSIX use\n'k' to mean 'KiB'.\n'MB'\nmegabyte: 10^6 = 1,000,000.\n'M'\n'MiB'\nmebibyte: 2^{20} = 1,048,576.\n'GB'\ngigabyte: 10^9 = 1,000,000,000.\n'G'\n'GiB'\ngibibyte: 2^{30} = 1,073,741,824.\n'TB'\nterabyte: 10^{12} = 1,000,000,000,000.\n'T'\n'TiB'\ntebibyte: 2^{40} = 1,099,511,627,776.\n'PB'\npetabyte: 10^{15} = 1,000,000,000,000,000.\n'P'\n'PiB'\npebibyte: 2^{50} = 1,125,899,906,842,624.\n'EB'\nexabyte: 10^{18} = 1,000,000,000,000,000,000.\n'E'\n'EiB'\nexbibyte: 2^{60} = 1,152,921,504,606,846,976.\n'ZB'\nzettabyte: 10^{21} = 1,000,000,000,000,000,000,000\n'Z'\n'ZiB'\n2^{70} = 1,180,591,620,717,411,303,424.\n'YB'\nyottabyte: 10^{24} = 1,000,000,000,000,000,000,000,000.\n'Y'\n'YiB'\n2^{80} = 1,208,925,819,614,629,174,706,176.\n\nBlock size defaults can be overridden by an explicit\n'--block-size=SIZE' option. The '-k' option is equivalent to\n'--block-size=1K', which is the default unless the 'POSIXLYCORRECT'\nenvironment variable is set. The '-h' or '--human-readable' option is\nequivalent to '--block-size=human-readable'. The '--si' option is\nequivalent to '--block-size=si'. Note for 'ls' the '-k' option does not\ncontrol the display of the apparent file sizes, whereas the\n'--block-size' option does.\n", "subsections": [] }, "File: coreutils.info, Node: Floating point, Next: Signal specifications, Prev: Block size, Up: Common options": { "content": "", "subsections": [ { "name": "2.4 Floating point numbers", "content": "" } ] }, "Commands that accept or produce floating point numbers employ the": { "content": "floating point representation of the underlying system, and suffer from\nrounding error, overflow, and similar floating-point issues. Almost all\nmodern systems use IEEE-754 floating point, and it is typically portable\nto assume IEEE-754 behavior these days. IEEE-754 has positive and\nnegative infinity, distinguishes positive from negative zero, and uses\nspecial values called NaNs to represent invalid computations such as\ndividing zero by itself. For more information, please see David", "subsections": [] }, "Goldberg's paper What Every Computer Scientist Should Know About": { "content": "", "subsections": [] }, "Floating-Point Arithmetic": { "content": "(https://docs.oracle.com/cd/E19957-01/806-3568/ncggoldberg.html).\n\nCommands that accept floating point numbers as options, operands or\ninput use the standard C functions 'strtod' and 'strtold' to convert\nfrom text to floating point numbers. These floating point numbers\ntherefore can use scientific notation like '1.0e-34' and '-10e100'.", "subsections": [] }, "Commands that parse floating point also understand case-insensitive": { "content": "'inf', 'infinity', and 'NaN', although whether such values are useful\ndepends on the command in question. Modern C implementations also\naccept hexadecimal floating point numbers such as '-0x.ep-3', which\nstands for -14/16 times 2^-3, which equals -0.109375. *Note\n(libc)Parsing of Floats::.\n\nNormally the 'LCNUMERIC' locale determines the decimal-point\ncharacter. However, some commands' descriptions specify that they\naccept numbers in either the current or the C locale; for example, they\ntreat '3.14' like '3,14' if the current locale uses comma as a decimal\npoint.\n", "subsections": [] }, "File: coreutils.info, Node: Signal specifications, Next: Disambiguating names and IDs, Prev: Floating point, Up: Common options": { "content": "", "subsections": [ { "name": "2.5 Signal specifications", "content": "A SIGNAL may be a signal name like 'HUP', or a signal number like '1',\nor an exit status of a process terminated by the signal. A signal name\ncan be given in canonical form or prefixed by 'SIG'. The case of the\nletters is ignored. The following signal names and numbers are\nsupported on all POSIX compliant systems:\n\n'HUP'\n1. Hangup.\n'INT'\n2. Terminal interrupt.\n'QUIT'\n3. Terminal quit.\n'ABRT'\n6. Process abort.\n'KILL'\n9. Kill (cannot be caught or ignored).\n'ALRM'\n14. Alarm Clock.\n'TERM'\n15. Termination.\n" } ] }, "Other supported signal names have system-dependent corresponding": { "content": "numbers. All systems conforming to POSIX 1003.1-2001 also support the\nfollowing signals:\n\n'BUS'\nAccess to an undefined portion of a memory object.\n'CHLD'\nChild process terminated, stopped, or continued.\n'CONT'\nContinue executing, if stopped.\n'FPE'\nErroneous arithmetic operation.\n'ILL'\nIllegal Instruction.\n'PIPE'\nWrite on a pipe with no one to read it.\n'SEGV'\nInvalid memory reference.\n'STOP'\nStop executing (cannot be caught or ignored).\n'TSTP'\nTerminal stop.\n'TTIN'\nBackground process attempting read.\n'TTOU'\nBackground process attempting write.\n'URG'\nHigh bandwidth data is available at a socket.\n'USR1'\nUser-defined signal 1.\n'USR2'\nUser-defined signal 2.\n\nPOSIX 1003.1-2001 systems that support the XSI extension also support\nthe following signals:\n\n'POLL'\nPollable event.\n'PROF'\nProfiling timer expired.\n'SYS'\nBad system call.\n'TRAP'\nTrace/breakpoint trap.\n'VTALRM'\nVirtual timer expired.\n'XCPU'\nCPU time limit exceeded.\n'XFSZ'\nFile size limit exceeded.\n\nPOSIX 1003.1-2001 systems that support the XRT extension also support at\nleast eight real-time signals called 'RTMIN', 'RTMIN+1', ..., 'RTMAX-1',\n'RTMAX'.\n", "subsections": [] }, "File: coreutils.info, Node: Disambiguating names and IDs, Next: Random sources, Prev: Signal specifications, Up: Common options": { "content": "", "subsections": [ { "name": "2.6 chown, chgrp, chroot, id: Disambiguating user names and IDs", "content": "" } ] }, "Since the USER and GROUP arguments to these commands may be specified as": { "content": "names or numeric IDs, there is an apparent ambiguity. What if a user or\ngroup name is a string of digits? (1) Should the command interpret\nit as a user name or as an ID? POSIX requires that these commands first\nattempt to resolve the specified string as a name, and only once that\nfails, then try to interpret it as an ID. This is troublesome when you\nwant to specify a numeric ID, say 42, and it must work even in a\npathological situation where '42' is a user name that maps to some other\nuser ID, say 1000. Simply invoking 'chown 42 F', will set 'F's owner ID\nto 1000--not what you intended.\n\nGNU 'chown', 'chgrp', 'chroot', and 'id' provide a way to work around\nthis, that at the same time may result in a significant performance\nimprovement by eliminating a database look-up. Simply precede each\nnumeric user ID and/or group ID with a '+', in order to force its\ninterpretation as an integer:\n\nchown +42 F\nchgrp +$numericgroupid another-file\nchown +0:+0 /\n\nThe name look-up process is skipped for each '+'-prefixed string,\nbecause a string containing '+' is never a valid user or group name.", "subsections": [] }, "This syntax is accepted on most common Unix systems, but not on Solaris": { "content": "10.\n\n---------- Footnotes ----------\n\n(1) Using a number as a user name is common in some environments.\n", "subsections": [] }, "File: coreutils.info, Node: Random sources, Next: Target directory, Prev: Disambiguating names and IDs, Up: Common options": { "content": "", "subsections": [ { "name": "2.7 Sources of random data", "content": "" } ] }, "The 'shuf', 'shred', and 'sort' commands sometimes need random data to": { "content": "do their work. For example, 'sort -R' must choose a hash function at\nrandom, and it needs random data to make this selection.\n\nBy default these commands use an internal pseudo-random generator\ninitialized by a small amount of entropy, but can be directed to use an\nexternal source with the '--random-source=FILE' option. An error is\nreported if FILE does not contain enough bytes.\n\nFor example, the device file '/dev/urandom' could be used as the\nsource of random data. Typically, this device gathers environmental\nnoise from device drivers and other sources into an entropy pool, and\nuses the pool to generate random bits. If the pool is short of data,\nthe device reuses the internal pool to produce more bits, using a\ncryptographically secure pseudo-random number generator. But be aware\nthat this device is not designed for bulk random data generation and is\nrelatively slow.\n\n'/dev/urandom' suffices for most practical uses, but applications\nrequiring high-value or long-term protection of private data may require\nan alternate data source like '/dev/random' or '/dev/arandom'. The set\nof available sources depends on your operating system.\n\nTo reproduce the results of an earlier invocation of a command, you\ncan save some random data into a file and then use that file as the\nrandom source in earlier and later invocations of the command. Rather\nthan depending on a file, one can generate a reproducible arbitrary\namount of pseudo-random data given a seed value, using for example:\n\ngetseededrandom()\n{\nseed=\"$1\"\nopenssl enc -aes-256-ctr -pass pass:\"$seed\" -nosalt \\\n/dev/null\n}\n\nshuf -i1-100 --random-source=<(getseededrandom 42)\n", "subsections": [] }, "File: coreutils.info, Node: Target directory, Next: Trailing slashes, Prev: Random sources, Up: Common options": { "content": "", "subsections": [ { "name": "2.8 Target directory", "content": "" } ] }, "The 'cp', 'install', 'ln', and 'mv' commands normally treat the last": { "content": "operand specially when it is a directory or a symbolic link to a\ndirectory. For example, 'cp source dest' is equivalent to 'cp source\ndest/source' if 'dest' is a directory. Sometimes this behavior is not\nexactly what is wanted, so these commands support the following options\nto allow more fine-grained control:\n\n'-T'\n'--no-target-directory'\nDo not treat the last operand specially when it is a directory or a\nsymbolic link to a directory. This can help avoid race conditions\nin programs that operate in a shared area. For example, when the\ncommand 'mv /tmp/source /tmp/dest' succeeds, there is no guarantee\nthat '/tmp/source' was renamed to '/tmp/dest': it could have been\nrenamed to '/tmp/dest/source' instead, if some other process\ncreated '/tmp/dest' as a directory. However, if 'mv -T /tmp/source\n/tmp/dest' succeeds, there is no question that '/tmp/source' was\nrenamed to '/tmp/dest'.\n\nIn the opposite situation, where you want the last operand to be\ntreated as a directory and want a diagnostic otherwise, you can use\nthe '--target-directory' ('-t') option.\n\n'-t DIRECTORY'\n'--target-directory=DIRECTORY'\nUse DIRECTORY as the directory component of each destination file\nname.\n\nThe interface for most programs is that after processing options\nand a finite (possibly zero) number of fixed-position arguments,\nthe remaining argument list is either expected to be empty, or is a\nlist of items (usually files) that will all be handled identically.\nThe 'xargs' program is designed to work well with this convention.\n\nThe commands in the 'mv'-family are unusual in that they take a\nvariable number of arguments with a special case at the end\n(namely, the target directory). This makes it nontrivial to\nperform some operations, e.g., \"move all files from here to ../d/\",\nbecause 'mv * ../d/' might exhaust the argument space, and 'ls |\nxargs ...' doesn't have a clean way to specify an extra final\nargument for each invocation of the subject command. (It can be\ndone by going through a shell command, but that requires more human\nlabor and brain power than it should.)\n\nThe '--target-directory' ('-t') option allows the 'cp', 'install',\n'ln', and 'mv' programs to be used conveniently with 'xargs'. For\nexample, you can move the files from the current directory to a\nsibling directory, 'd' like this:\n\nls | xargs mv -t ../d --\n\nHowever, this doesn't move files whose names begin with '.'. If\nyou use the GNU 'find' program, you can move those files too, with\nthis command:\n\nfind . -mindepth 1 -maxdepth 1 \\\n| xargs mv -t ../d\n\nBut both of the above approaches fail if there are no files in the\ncurrent directory, or if any file has a name containing a blank or\nsome other special characters. The following example removes those\nlimitations and requires both GNU 'find' and GNU 'xargs':\n\nfind . -mindepth 1 -maxdepth 1 -print0 \\\n| xargs --null --no-run-if-empty \\\nmv -t ../d\n", "subsections": [] }, "The '--target-directory' ('-t') and '--no-target-directory' ('-T')": { "content": "options cannot be combined.\n", "subsections": [] }, "File: coreutils.info, Node: Trailing slashes, Next: Traversing symlinks, Prev: Target directory, Up: Common options": { "content": "", "subsections": [ { "name": "2.9 Trailing slashes", "content": "" } ] }, "Some GNU programs (at least 'cp' and 'mv') allow you to remove any": { "content": "trailing slashes from each SOURCE argument before operating on it. The\n'--strip-trailing-slashes' option enables this behavior.\n\nThis is useful when a SOURCE argument may have a trailing slash and\nspecify a symbolic link to a directory. This scenario is in fact rather\ncommon because some shells can automatically append a trailing slash\nwhen performing file name completion on such symbolic links. Without\nthis option, 'mv', for example, (via the system's rename function) must\ninterpret a trailing slash as a request to dereference the symbolic link\nand so must rename the indirectly referenced directory and not the\nsymbolic link. Although it may seem surprising that such behavior be\nthe default, it is required by POSIX and is consistent with other parts\nof that standard.\n", "subsections": [] }, "File: coreutils.info, Node: Traversing symlinks, Next: Treating / specially, Prev: Trailing slashes, Up: Common options": { "content": "", "subsections": [ { "name": "2.10 Traversing symlinks", "content": "" } ] }, "The following options modify how 'chown' and 'chgrp' traverse a": { "content": "hierarchy when the '--recursive' ('-R') option is also specified. If\nmore than one of the following options is specified, only the final one\ntakes effect. These options specify whether processing a symbolic link\nto a directory entails operating on just the symbolic link or on all\nfiles in the hierarchy rooted at that directory.\n\nThese options are independent of '--dereference' and\n'--no-dereference' ('-h'), which control whether to modify a symlink or\nits referent.\n\n'-H'\nIf '--recursive' ('-R') is specified and a command line argument is\na symbolic link to a directory, traverse it.\n\n'-L'\nIn a recursive traversal, traverse every symbolic link to a\ndirectory that is encountered.\n\n'-P'\nDo not traverse any symbolic links. This is the default if none of\n'-H', '-L', or '-P' is specified.\n", "subsections": [] }, "File: coreutils.info, Node: Treating / specially, Next: Special built-in utilities, Prev: Traversing symlinks, Up: Common options": { "content": "", "subsections": [ { "name": "2.11 Treating '/' specially", "content": "" } ] }, "Certain commands can operate destructively on entire hierarchies. For": { "content": "example, if a user with appropriate privileges mistakenly runs 'rm -rf /\ntmp/junk', that may remove all files on the entire system. Since there\nare so few legitimate uses for such a command, GNU 'rm' normally\ndeclines to operate on any directory that resolves to '/'. If you\nreally want to try to remove all the files on your system, you can use\nthe '--no-preserve-root' option, but the default behavior, specified by\nthe '--preserve-root' option, is safer for most purposes.\n\nThe commands 'chgrp', 'chmod' and 'chown' can also operate\ndestructively on entire hierarchies, so they too support these options.", "subsections": [] }, "Although, unlike 'rm', they don't actually unlink files, these commands": { "content": "are arguably more dangerous when operating recursively on '/', since\nthey often work much more quickly, and hence damage more files before an\nalert user can interrupt them. Tradition and POSIX require these\ncommands to operate recursively on '/', so they default to\n'--no-preserve-root', but using the '--preserve-root' option makes them\nsafer for most purposes. For convenience you can specify\n'--preserve-root' in an alias or in a shell function.\n\nNote that the '--preserve-root' option also ensures that 'chgrp' and\n'chown' do not modify '/' even when dereferencing a symlink pointing to\n'/'.\n", "subsections": [] }, "File: coreutils.info, Node: Special built-in utilities, Next: Standards conformance, Prev: Treating / specially, Up: Common options": { "content": "", "subsections": [ { "name": "2.12 Special built-in utilities", "content": "" } ] }, "Some programs like 'nice' can invoke other programs; for example, the": { "content": "command 'nice cat file' invokes the program 'cat' by executing the\ncommand 'cat file'. However, \"special built-in utilities\" like 'exit'\ncannot be invoked this way. For example, the command 'nice exit' does\nnot have a well-defined behavior: it may generate an error message\ninstead of exiting.\n\nHere is a list of the special built-in utilities that are\nstandardized by POSIX 1003.1-2004.\n\n. : break continue eval exec exit export readonly return set shift\ntimes trap unset\n\nFor example, because '.', ':', and 'exec' are special, the commands\n'nice . foo.sh', 'nice :', and 'nice exec pwd' do not work as you might\nexpect.\n\nMany shells extend this list. For example, Bash has several extra\nspecial built-in utilities like 'history', and 'suspend', and with Bash\nthe command 'nice suspend' generates an error message instead of\nsuspending.\n", "subsections": [] }, "File: coreutils.info, Node: Standards conformance, Next: Multi-call invocation, Prev: Special built-in utilities, Up: Common options": { "content": "", "subsections": [ { "name": "2.13 Standards conformance", "content": "" } ] }, "In a few cases, the GNU utilities' default behavior is incompatible with": { "content": "the POSIX standard. To suppress these incompatibilities, define the\n'POSIXLYCORRECT' environment variable. Unless you are checking for\nPOSIX conformance, you probably do not need to define 'POSIXLYCORRECT'.\n\nNewer versions of POSIX are occasionally incompatible with older\nversions. For example, older versions of POSIX required the command\n'sort +1' to sort based on the second and succeeding fields in each\ninput line, but in POSIX 1003.1-2001 the same command is required to\nsort the file named '+1', and you must instead use the command 'sort -k\n2' to get the field-based sort. To complicate things further, POSIX\n1003.1-2008 allows an implementation to have either the old or the new\nbehavior.\n\nThe GNU utilities normally conform to the version of POSIX that is\nstandard for your system. To cause them to conform to a different\nversion of POSIX, define the 'POSIX2VERSION' environment variable to a\nvalue of the form YYYYMM specifying the year and month the standard was\nadopted. Three values are currently supported for 'POSIX2VERSION':\n'199209' stands for POSIX 1003.2-1992, '200112' stands for POSIX\n1003.1-2001, and '200809' stands for POSIX 1003.1-2008. For example, if\nyou have a POSIX 1003.1-2001 system but are running software containing\ntraditional usage like 'sort +1' or 'tail +10', you can work around the\ncompatibility problems by setting 'POSIX2VERSION=200809' in your\nenvironment.\n", "subsections": [] }, "File: coreutils.info, Node: Multi-call invocation, Prev: Standards conformance, Up: Common options": { "content": "", "subsections": [ { "name": "2.14 'coreutils': Multi-call program", "content": "" } ] }, "The 'coreutils' command invokes an individual utility, either implicitly": { "content": "selected by the last component of the name used to invoke 'coreutils',\nor explicitly with the '--coreutils-prog' option. Synopsis:\n\ncoreutils --coreutils-prog=PROGRAM ...\n\nThe 'coreutils' command is not installed by default, so portable\nscripts should not rely on its existence.\n", "subsections": [] }, "File: coreutils.info, Node: Output of entire files, Next: Formatting file contents, Prev: Common options, Up: Top": { "content": "", "subsections": [] }, "3 Output of entire files": { "content": "", "subsections": [] }, "These commands read and write entire files, possibly transforming them": { "content": "in some way.\n\n* Menu:\n\n* cat invocation:: Concatenate and write files.\n* tac invocation:: Concatenate and write files in reverse.\n* nl invocation:: Number lines and write files.\n* od invocation:: Write files in octal or other formats.\n* base32 invocation:: Transform data into printable data.\n* base64 invocation:: Transform data into printable data.\n* basenc invocation:: Transform data into printable data.\n", "subsections": [] }, "File: coreutils.info, Node: cat invocation, Next: tac invocation, Up: Output of entire files": { "content": "", "subsections": [ { "name": "3.1 'cat': Concatenate and write files", "content": "'cat' copies each FILE ('-' means standard input), or standard input if\nnone are given, to standard output. Synopsis:\n\ncat [OPTION] [FILE]...\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-A'\n'--show-all'\nEquivalent to '-vET'.\n\n'-b'\n'--number-nonblank'\nNumber all nonempty output lines, starting with 1.\n\n'-e'\nEquivalent to '-vE'.\n\n'-E'\n'--show-ends'\nDisplay a '$' after the end of each line.\n\n'-n'\n'--number'\nNumber all output lines, starting with 1. This option is ignored\nif '-b' is in effect.\n\n'-s'\n'--squeeze-blank'\nSuppress repeated adjacent blank lines; output just one empty line\ninstead of several.\n\n'-t'\nEquivalent to '-vT'.\n\n'-T'\n'--show-tabs'\nDisplay TAB characters as '^I'.\n\n'-u'\nIgnored; for POSIX compatibility.\n\n'-v'\n'--show-nonprinting'\nDisplay control characters except for LFD and TAB using '^'\nnotation and precede characters that have the high bit set with\n'M-'.\n\nOn systems like MS-DOS that distinguish between text and binary\nfiles, 'cat' normally reads and writes in binary mode. However, 'cat'\nreads in text mode if one of the options '-bensAE' is used or if 'cat'\nis reading from standard input and standard input is a terminal." } ] }, "Similarly, 'cat' writes in text mode if one of the options '-bensAE' is": { "content": "used or if standard output is a terminal.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nExamples:\n\n# Output f's contents, then standard input, then g's contents.\ncat f - g\n\n# Copy standard input to standard output.\ncat\n", "subsections": [] }, "File: coreutils.info, Node: tac invocation, Next: nl invocation, Prev: cat invocation, Up: Output of entire files": { "content": "", "subsections": [ { "name": "3.2 'tac': Concatenate and write files in reverse", "content": "'tac' copies each FILE ('-' means standard input), or standard input if\nnone are given, to standard output, reversing the records (lines by\ndefault) in each separately. Synopsis:\n\ntac [OPTION]... [FILE]...\n\n\"Records\" are separated by instances of a string (newline by\ndefault). By default, this separator string is attached to the end of\nthe record that it follows in the file.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-b'\n'--before'\nThe separator is attached to the beginning of the record that it\nprecedes in the file.\n\n'-r'\n'--regex'\nTreat the separator string as a regular expression.\n\n'-s SEPARATOR'\n'--separator=SEPARATOR'\nUse SEPARATOR as the record separator, instead of newline. Note an\nempty SEPARATOR is treated as a zero byte. I.e., input and output\nitems are delimited with ASCII NUL.\n\nOn systems like MS-DOS that distinguish between text and binary\nfiles, 'tac' reads and writes in binary mode.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nExample:\n\n# Reverse a file character by character.\ntac -r -s 'x\\|[^x]'\n" } ] }, "File: coreutils.info, Node: nl invocation, Next: od invocation, Prev: tac invocation, Up: Output of entire files": { "content": "", "subsections": [ { "name": "3.3 'nl': Number lines and write files", "content": "'nl' writes each FILE ('-' means standard input), or standard input if\nnone are given, to standard output, with line numbers added to some or\nall of the lines. Synopsis:\n\nnl [OPTION]... [FILE]...\n\n'nl' decomposes its input into (logical) page sections; by default,\nthe line number is reset to 1 at each logical page section. 'nl' treats\nall of the input files as a single document; it does not reset line\nnumbers or logical pages between files.\n\nA logical page consists of three sections: header, body, and footer." } ] }, "Any of the sections can be empty. Each can be numbered in a different": { "content": "style from the others.\n\nThe beginnings of the sections of logical pages are indicated in the\ninput file by a line containing exactly one of these delimiter strings:\n\n'\\:\\:\\:'\nstart of header;\n'\\:\\:'\nstart of body;\n'\\:'\nstart of footer.\n\nThe two characters from which these strings are made can be changed\nfrom '\\' and ':' via options (see below), but the pattern and length of\neach string cannot be changed.\n\nA section delimiter is replaced by an empty line on output. Any text\nthat comes before the first section delimiter string in the input file\nis considered to be part of a body section, so 'nl' treats a file that\ncontains no section delimiters as a single body section.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-b STYLE'\n'--body-numbering=STYLE'\nSelect the numbering style for lines in the body section of each\nlogical page. When a line is not numbered, the current line number\nis not incremented, but the line number separator character is\nstill prepended to the line. The styles are:\n\n'a'\nnumber all lines,\n't'\nnumber only nonempty lines (default for body),\n'n'\ndo not number lines (default for header and footer),\n'pBRE'\nnumber only lines that contain a match for the basic regular\nexpression BRE. *Note Regular Expressions: (grep)Regular\nExpressions.\n\n'-d CD'\n'--section-delimiter=CD'\nSet the section delimiter characters to CD; default is '\\:'. If\nonly C is given, the second remains ':'. (Remember to protect '\\'\nor other metacharacters from shell expansion with quotes or extra\nbackslashes.)\n\n'-f STYLE'\n'--footer-numbering=STYLE'\nAnalogous to '--body-numbering'.\n\n'-h STYLE'\n'--header-numbering=STYLE'\nAnalogous to '--body-numbering'.\n\n'-i NUMBER'\n'--line-increment=NUMBER'\nIncrement line numbers by NUMBER (default 1).\n\n'-l NUMBER'\n'--join-blank-lines=NUMBER'\nConsider NUMBER (default 1) consecutive empty lines to be one\nlogical line for numbering, and only number the last one. Where\nfewer than NUMBER consecutive empty lines occur, do not number\nthem. An empty line is one that contains no characters, not even\nspaces or tabs.\n\n'-n FORMAT'\n'--number-format=FORMAT'\nSelect the line numbering format (default is 'rn'):\n\n'ln'\nleft justified, no leading zeros;\n'rn'\nright justified, no leading zeros;\n'rz'\nright justified, leading zeros.\n\n'-p'\n'--no-renumber'\nDo not reset the line number at the start of a logical page.\n\n'-s STRING'\n'--number-separator=STRING'\nSeparate the line number from the text line in the output with\nSTRING (default is the TAB character).\n\n'-v NUMBER'\n'--starting-line-number=NUMBER'\nSet the initial line number on each logical page to NUMBER (default\n1).\n\n'-w NUMBER'\n'--number-width=NUMBER'\nUse NUMBER characters for line numbers (default 6).\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: od invocation, Next: base32 invocation, Prev: nl invocation, Up: Output of entire files": { "content": "", "subsections": [ { "name": "3.4 'od': Write files in octal or other formats", "content": "'od' writes an unambiguous representation of each FILE ('-' means\nstandard input), or standard input if none are given. Synopses:\n\nod [OPTION]... [FILE]...\nod [-abcdfilosx]... [FILE] [[+]OFFSET[.][b]]\nod [OPTION]... --traditional [FILE] [[+]OFFSET[.][b] [[+]LABEL[.][b]]]\n\nEach line of output consists of the offset in the input, followed by\ngroups of data from the file. By default, 'od' prints the offset in\noctal, and each group of file data is a C 'short int''s worth of input\nprinted as a single octal number.\n\nIf OFFSET is given, it specifies how many input bytes to skip before\nformatting and writing. By default, it is interpreted as an octal\nnumber, but the optional trailing decimal point causes it to be\ninterpreted as decimal. If no decimal is specified and the offset\nbegins with '0x' or '0X' it is interpreted as a hexadecimal number. If\nthere is a trailing 'b', the number of bytes skipped will be OFFSET\nmultiplied by 512.\n\nIf a command is of both the first and second forms, the second form\nis assumed if the last operand begins with '+' or (if there are two\noperands) a digit. For example, in 'od foo 10' and 'od +10' the '10' is\nan offset, whereas in 'od 10' the '10' is a file name.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-A RADIX'\n'--address-radix=RADIX'\nSelect the base in which file offsets are printed. RADIX can be\none of the following:\n\n'd'\ndecimal;\n'o'\noctal;\n'x'\nhexadecimal;\n'n'\nnone (do not print offsets).\n\nThe default is octal.\n\n'--endian=ORDER'\nReorder input bytes, to handle inputs with differing byte orders,\nor to provide consistent output independent of the endian\nconvention of the current system. Swapping is performed according\nto the specified '--type' size and endian ORDER, which can be\n'little' or 'big'.\n\n'-j BYTES'\n'--skip-bytes=BYTES'\nSkip BYTES input bytes before formatting and writing. If BYTES\nbegins with '0x' or '0X', it is interpreted in hexadecimal;\notherwise, if it begins with '0', in octal; otherwise, in decimal.\nBYTES may be, or may be an integer optionally followed by, one of\nthe following multiplicative suffixes:\n'b' => 512 (\"blocks\")\n'KB' => 1000 (KiloBytes)\n'K' => 1024 (KibiBytes)\n'MB' => 1000*1000 (MegaBytes)\n'M' => 1024*1024 (MebiBytes)\n'GB' => 1000*1000*1000 (GigaBytes)\n'G' => 1024*1024*1024 (GibiBytes)\nand so on for 'T', 'P', 'E', 'Z', and 'Y'. Binary prefixes can be\nused, too: 'KiB'='K', 'MiB'='M', and so on.\n\n'-N BYTES'\n'--read-bytes=BYTES'\nOutput at most BYTES bytes of the input. Prefixes and suffixes on\n'bytes' are interpreted as for the '-j' option.\n\n'-S BYTES'\n'--strings[=BYTES]'\nInstead of the normal output, output only \"string constants\": at\nleast BYTES consecutive ASCII graphic characters, followed by a\nzero byte (ASCII NUL). Prefixes and suffixes on BYTES are\ninterpreted as for the '-j' option.\n\nIf BYTES is omitted with '--strings', the default is 3.\n\n'-t TYPE'\n'--format=TYPE'\nSelect the format in which to output the file data. TYPE is a\nstring of one or more of the below type indicator characters. If\nyou include more than one type indicator character in a single TYPE\nstring, or use this option more than once, 'od' writes one copy of\neach output line using each of the data types that you specified,\nin the order that you specified.\n\nAdding a trailing \"z\" to any type specification appends a display\nof the single byte character representation of the printable\ncharacters to the output line generated by the type specification.\n\n'a'\nnamed character, ignoring high-order bit\n'c'\nprintable single byte character, C backslash escape or a 3\ndigit octal sequence\n'd'\nsigned decimal\n'f'\nfloating point (*note Floating point::)\n'o'\noctal\n'u'\nunsigned decimal\n'x'\nhexadecimal\n\nThe type 'a' outputs things like 'sp' for space, 'nl' for newline,\nand 'nul' for a zero byte. Only the least significant seven bits\nof each byte is used; the high-order bit is ignored. Type 'c'\noutputs ' ', '\\n', and '\\0', respectively.\n\nExcept for types 'a' and 'c', you can specify the number of bytes\nto use in interpreting each number in the given data type by\nfollowing the type indicator character with a decimal integer.\nAlternately, you can specify the size of one of the C compiler's\nbuilt-in data types by following the type indicator character with\none of the following characters. For integers ('d', 'o', 'u',\n'x'):\n\n'C'\nchar\n'S'\nshort\n'I'\nint\n'L'\nlong\n\nFor floating point ('f'):\n\nF\nfloat\nD\ndouble\nL\nlong double\n\n'-v'\n'--output-duplicates'\nOutput consecutive lines that are identical. By default, when two\nor more consecutive output lines would be identical, 'od' outputs\nonly the first line, and puts just an asterisk on the following\nline to indicate the elision.\n\n'-w[N]'\n'--width[=N]'\nDump 'n' input bytes per output line. This must be a multiple of\nthe least common multiple of the sizes associated with the\nspecified output types.\n\nIf this option is not given at all, the default is 16. If N is\nomitted, the default is 32.\n\nThe next several options are shorthands for format specifications.\nGNU 'od' accepts any combination of shorthands and format specification\noptions. These options accumulate.\n\n'-a'\nOutput as named characters. Equivalent to '-t a'.\n\n'-b'\nOutput as octal bytes. Equivalent to '-t o1'.\n\n'-c'\nOutput as printable single byte characters, C backslash escapes or\n3 digit octal sequences. Equivalent to '-t c'.\n\n'-d'\nOutput as unsigned decimal two-byte units. Equivalent to '-t u2'.\n\n'-f'\nOutput as floats. Equivalent to '-t fF'.\n\n'-i'\nOutput as decimal ints. Equivalent to '-t dI'.\n\n'-l'\nOutput as decimal long ints. Equivalent to '-t dL'.\n\n'-o'\nOutput as octal two-byte units. Equivalent to '-t o2'.\n\n'-s'\nOutput as decimal two-byte units. Equivalent to '-t d2'.\n\n'-x'\nOutput as hexadecimal two-byte units. Equivalent to '-t x2'.\n\n'--traditional'\nRecognize the non-option label argument that traditional 'od'\naccepted. The following syntax:\n\nod --traditional [FILE] [[+]OFFSET[.][b] [[+]LABEL[.][b]]]\n\ncan be used to specify at most one file and optional arguments\nspecifying an offset and a pseudo-start address, LABEL. The LABEL\nargument is interpreted just like OFFSET, but it specifies an\ninitial pseudo-address. The pseudo-addresses are displayed in\nparentheses following any normal address.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: base32 invocation, Next: base64 invocation, Prev: od invocation, Up: Output of entire files": { "content": "", "subsections": [ { "name": "3.5 'base32': Transform data into printable data", "content": "'base32' transforms data read from a file, or standard input, into (or\nfrom) base32 encoded form. The base32 encoded form uses printable ASCII\ncharacters to represent binary data. The usage and options of this\ncommand are precisely the same as for 'base64'. *Note base64\ninvocation::.\n" } ] }, "File: coreutils.info, Node: base64 invocation, Next: basenc invocation, Prev: base32 invocation, Up: Output of entire files": { "content": "", "subsections": [ { "name": "3.6 'base64': Transform data into printable data", "content": "'base64' transforms data read from a file, or standard input, into (or\nfrom) base64 encoded form. The base64 encoded form uses printable ASCII\ncharacters to represent binary data. Synopses:\n\nbase64 [OPTION]... [FILE]\nbase64 --decode [OPTION]... [FILE]\n\nThe base64 encoding expands data to roughly 133% of the original.\nThe base32 encoding expands data to roughly 160% of the original. The\nformat conforms to RFC 4648 (https://tools.ietf.org/search/rfc4648).\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-w COLS'\n'--wrap=COLS'\nDuring encoding, wrap lines after COLS characters. This must be a\npositive number.\n\nThe default is to wrap after 76 characters. Use the value 0 to\ndisable line wrapping altogether.\n\n'-d'\n'--decode'\nChange the mode of operation, from the default of encoding data, to\ndecoding data. Input is expected to be base64 encoded data, and\nthe output will be the original data.\n\n'-i'\n'--ignore-garbage'\nWhen decoding, newlines are always accepted. During decoding,\nignore unrecognized bytes, to permit distorted data to be decoded.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: basenc invocation, Prev: base64 invocation, Up: Output of entire files": { "content": "", "subsections": [ { "name": "3.7 'basenc': Transform data into printable data", "content": "'basenc' transforms data read from a file, or standard input, into (or\nfrom) various common encoding forms. The encoded form uses printable\nASCII characters to represent binary data.\n\nSynopses:\n\nbasenc ENCODING [OPTION]... [FILE]\nbasenc ENCODING --decode [OPTION]... [FILE]\n\nThe ENCODING argument is required. If FILE is omitted, reads input\nfrom stdin. The '-w/--wrap','-i/--ignore-garbage', '-d/--decode'\noptions of this command are precisely the same as for 'base64'. *Note\nbase64 invocation::.\n\nSupported ENCODINGs are:\n\n'--base64'\nEncode into (or decode from with '-d/--decode') base64 form. The\nformat conforms to RFC 4648#4\n(https://tools.ietf.org/search/rfc4648#section-4). Equivalent to\nthe 'base64' command.\n\n'--base64url'\nEncode into (or decode from with '-d/--decode') file-and-url-safe\nbase64 form (using '' and '-' instead of '+' and '/'). The format\nconforms to RFC 4648#5\n(https://tools.ietf.org/search/rfc4648#section-5).\n\n'--base32'\nEncode into (or decode from with '-d/--decode') base32 form. The\nencoded data uses the 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567='\ncharacters. The format conforms to RFC 4648#6\n(https://tools.ietf.org/search/rfc4648#section-6). Equivalent to\nthe 'base32' command.\n\n'--base32hex'\nEncode into (or decode from with '-d/--decode') Extended Hex\nAlphabet base32 form. The encoded data uses the\n'0123456789ABCDEFGHIJKLMNOPQRSTUV=' characters. The format\nconforms to RFC 4648#7\n(https://tools.ietf.org/search/rfc4648#section-7).\n\n'--base16'\nEncode into (or decode from with '-d/--decode') base16\n(hexadecimal) form. The encoded data uses the '0123456789ABCDEF'\ncharacters. The format conforms to RFC 4648#8\n(https://tools.ietf.org/search/rfc4648#section-8).\n\n'--base2lsbf'\nEncode into (or decode from with '-d/--decode') binary string form\n('0' and '1') with the least significant bit of every byte first.\n\n'--base2msbf'\nEncode into (or decode from with '-d/--decode') binary string form\n('0' and '1') with the most significant bit of every byte first.\n\n'--z85'\nEncode into (or decode from with '-d/--decode') Z85 form (a\nmodified Ascii85 form). The encoded data uses the\n'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTU VWXYZ.-:+=^!/*?&<>()[]{}@%$#'.\ncharacters. The format conforms to ZeroMQ spec:32/Z85\n(https://rfc.zeromq.org/spec:32/Z85/).\n\nWhen encoding with '--z85', input length must be a multiple of 4;\nwhen decoding with '--z85', input length must be a multiple of 5.\n\nEncoding/decoding examples:\n\n$ printf '\\376\\117\\202' | basenc --base64\n/k+C\n\n$ printf '\\376\\117\\202' | basenc --base64url\nk-C\n\n$ printf '\\376\\117\\202' | basenc --base32\n7ZHYE===\n\n$ printf '\\376\\117\\202' | basenc --base32hex\nVP7O4===\n\n$ printf '\\376\\117\\202' | basenc --base16\nFE4F82\n\n$ printf '\\376\\117\\202' | basenc --base2lsbf\n011111111111001001000001\n\n$ printf '\\376\\117\\202' | basenc --base2msbf\n111111100100111110000010\n\n$ printf '\\376\\117\\202\\000' | basenc --z85\n@.FaC\n\n$ printf 01010100 | basenc --base2msbf --decode\nT\n\n$ printf 01010100 | basenc --base2lsbf --decode\n*\n" } ] }, "File: coreutils.info, Node: Formatting file contents, Next: Output of parts of files, Prev: Output of entire files, Up: Top": { "content": "", "subsections": [] }, "4 Formatting file contents": { "content": "These commands reformat the contents of files.\n\n* Menu:\n\n* fmt invocation:: Reformat paragraph text.\n* pr invocation:: Paginate or columnate files for printing.\n* fold invocation:: Wrap input lines to fit in specified width.\n", "subsections": [] }, "File: coreutils.info, Node: fmt invocation, Next: pr invocation, Up: Formatting file contents": { "content": "", "subsections": [ { "name": "4.1 'fmt': Reformat paragraph text", "content": "'fmt' fills and joins lines to produce output lines of (at most) a given\nnumber of characters (75 by default). Synopsis:\n\nfmt [OPTION]... [FILE]...\n\n'fmt' reads from the specified FILE arguments (or standard input if\nnone are given), and writes to standard output.\n\nBy default, blank lines, spaces between words, and indentation are\npreserved in the output; successive input lines with different\nindentation are not joined; tabs are expanded on input and introduced on\noutput.\n\n'fmt' prefers breaking lines at the end of a sentence, and tries to\navoid line breaks after the first word of a sentence or before the last\nword of a sentence. A \"sentence break\" is defined as either the end of\na paragraph or a word ending in any of '.?!', followed by two spaces or\nend of line, ignoring any intervening parentheses or quotes. Like TeX,\n'fmt' reads entire \"paragraphs\" before choosing line breaks; the\nalgorithm is a variant of that given by Donald E. Knuth and Michael F.\nPlass in \"Breaking Paragraphs Into Lines\", 'Software--Practice &\nExperience' 11, 11 (November 1981), 1119-1184.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-c'\n'--crown-margin'\n\"Crown margin\" mode: preserve the indentation of the first two\nlines within a paragraph, and align the left margin of each\nsubsequent line with that of the second line.\n\n'-t'\n'--tagged-paragraph'\n\"Tagged paragraph\" mode: like crown margin mode, except that if\nindentation of the first line of a paragraph is the same as the\nindentation of the second, the first line is treated as a one-line\nparagraph.\n\n'-s'\n'--split-only'\nSplit lines only. Do not join short lines to form longer ones.\nThis prevents sample lines of code, and other such \"formatted\" text\nfrom being unduly combined.\n\n'-u'\n'--uniform-spacing'\nUniform spacing. Reduce spacing between words to one space, and\nspacing between sentences to two spaces.\n\n'-WIDTH'\n'-w WIDTH'\n'--width=WIDTH'\nFill output lines up to WIDTH characters (default 75 or GOAL plus\n10, if GOAL is provided).\n\n'-g GOAL'\n'--goal=GOAL'\n'fmt' initially tries to make lines GOAL characters wide. By\ndefault, this is 7% shorter than WIDTH.\n\n'-p PREFIX'\n'--prefix=PREFIX'\nOnly lines beginning with PREFIX (possibly preceded by whitespace)\nare subject to formatting. The prefix and any preceding whitespace\nare stripped for the formatting and then re-attached to each\nformatted output line. One use is to format certain kinds of\nprogram comments, while leaving the code unchanged.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: pr invocation, Next: fold invocation, Prev: fmt invocation, Up: Formatting file contents": { "content": "", "subsections": [ { "name": "4.2 'pr': Paginate or columnate files for printing", "content": "'pr' writes each FILE ('-' means standard input), or standard input if\nnone are given, to standard output, paginating and optionally outputting\nin multicolumn format; optionally merges all FILEs, printing all in\nparallel, one per column. Synopsis:\n\npr [OPTION]... [FILE]...\n\nBy default, a 5-line header is printed at each page: two blank lines;\na line with the date, the file name, and the page count; and two more\nblank lines. A footer of five blank lines is also printed. The default\nPAGELENGTH is 66 lines. The default number of text lines is therefore\n56. The text line of the header takes the form 'DATE STRING PAGE', with\nspaces inserted around STRING so that the line takes up the full\nPAGEWIDTH. Here, DATE is the date (see the '-D' or '--date-format'\noption for details), STRING is the centered header string, and PAGE\nidentifies the page number. The 'LCMESSAGES' locale category affects\nthe spelling of PAGE; in the default C locale, it is 'Page NUMBER' where\nNUMBER is the decimal page number.\n\nForm feeds in the input cause page breaks in the output. Multiple\nform feeds produce empty pages.\n\nColumns are of equal width, separated by an optional string (default\nis 'space'). For multicolumn output, lines will always be truncated to\nPAGEWIDTH (default 72), unless you use the '-J' option. For single\ncolumn output no line truncation occurs by default. Use '-W' option to\ntruncate lines in that case.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'+FIRSTPAGE[:LASTPAGE]'\n'--pages=FIRSTPAGE[:LASTPAGE]'\nBegin printing with page FIRSTPAGE and stop with LASTPAGE.\nMissing ':LASTPAGE' implies end of file. While estimating the\nnumber of skipped pages each form feed in the input file results in\na new page. Page counting with and without '+FIRSTPAGE' is\nidentical. By default, counting starts with the first page of\ninput file (not first page printed). Line numbering may be altered\nby '-N' option.\n\n'-COLUMN'\n'--columns=COLUMN'\nWith each single FILE, produce COLUMN columns of output (default is\n1) and print columns down, unless '-a' is used. The column width\nis automatically decreased as COLUMN increases; unless you use the\n'-W/-w' option to increase PAGEWIDTH as well. This option might\nwell cause some lines to be truncated. The number of lines in the\ncolumns on each page are balanced. The options '-e' and '-i' are\non for multiple text-column output. Together with '-J' option\ncolumn alignment and line truncation is turned off. Lines of full\nlength are joined in a free field format and '-S' option may set\nfield separators. '-COLUMN' may not be used with '-m' option.\n\n'-a'\n'--across'\nWith each single FILE, print columns across rather than down. The\n'-COLUMN' option must be given with COLUMN greater than one. If a\nline is too long to fit in a column, it is truncated.\n\n'-c'\n'--show-control-chars'\nPrint control characters using hat notation (e.g., '^G'); print\nother nonprinting characters in octal backslash notation. By\ndefault, nonprinting characters are not changed.\n\n'-d'\n'--double-space'\nDouble space the output.\n\n'-D FORMAT'\n'--date-format=FORMAT'\nFormat header dates using FORMAT, using the same conventions as for\nthe command 'date +FORMAT'. *Note date invocation::. Except for\ndirectives, which start with '%', characters in FORMAT are printed\nunchanged. You can use this option to specify an arbitrary string\nin place of the header date, e.g., '--date-format=\"Monday\nmorning\"'.\n\nThe default date format is '%Y-%m-%d %H:%M' (for example,\n'2001-12-04 23:59'); but if the 'POSIXLYCORRECT' environment\nvariable is set and the 'LCTIME' locale category specifies the\nPOSIX locale, the default is '%b %e %H:%M %Y' (for example, 'Dec 4\n23:59 2001'.\n\nTimestamps are listed according to the time zone rules specified by\nthe 'TZ' environment variable, or by the system default rules if\n'TZ' is not set. *Note Specifying the Time Zone with 'TZ':\n(libc)TZ Variable.\n\n'-e[IN-TABCHAR[IN-TABWIDTH]]'\n'--expand-tabs[=IN-TABCHAR[IN-TABWIDTH]]'\nExpand TABs to spaces on input. Optional argument IN-TABCHAR is\nthe input tab character (default is the TAB character). Second\noptional argument IN-TABWIDTH is the input tab character's width\n(default is 8).\n\n'-f'\n'-F'\n'--form-feed'\nUse a form feed instead of newlines to separate output pages. This\ndoes not alter the default page length of 66 lines.\n\n'-h HEADER'\n'--header=HEADER'\nReplace the file name in the header with the centered string\nHEADER. When using the shell, HEADER should be quoted and should\nbe separated from '-h' by a space.\n\n'-i[OUT-TABCHAR[OUT-TABWIDTH]]'\n'--output-tabs[=OUT-TABCHAR[OUT-TABWIDTH]]'\nReplace spaces with TABs on output. Optional argument OUT-TABCHAR\nis the output tab character (default is the TAB character). Second\noptional argument OUT-TABWIDTH is the output tab character's width\n(default is 8).\n\n'-J'\n'--join-lines'\nMerge lines of full length. Used together with the column options\n'-COLUMN', '-a -COLUMN' or '-m'. Turns off '-W/-w' line\ntruncation; no column alignment used; may be used with\n'--sep-string[=STRING]'. '-J' has been introduced (together with\n'-W' and '--sep-string') to disentangle the old (POSIX-compliant)\noptions '-w' and '-s' along with the three column options.\n\n'-l PAGELENGTH'\n'--length=PAGELENGTH'\nSet the page length to PAGELENGTH (default 66) lines, including\nthe lines of the header [and the footer]. If PAGELENGTH is less\nthan or equal to 10, the header and footer are omitted, as if the\n'-t' option had been given.\n\n'-m'\n'--merge'\nMerge and print all FILEs in parallel, one in each column. If a\nline is too long to fit in a column, it is truncated, unless the\n'-J' option is used. '--sep-string[=STRING]' may be used. Empty\npages in some FILEs (form feeds set) produce empty columns, still\nmarked by STRING. The result is a continuous line numbering and\ncolumn marking throughout the whole merged file. Completely empty\nmerged pages show no separators or line numbers. The default\nheader becomes 'DATE PAGE' with spaces inserted in the middle; this\nmay be used with the '-h' or '--header' option to fill up the\nmiddle blank part.\n\n'-n[NUMBER-SEPARATOR[DIGITS]]'\n'--number-lines[=NUMBER-SEPARATOR[DIGITS]]'\nProvide DIGITS digit line numbering (default for DIGITS is 5).\nWith multicolumn output the number occupies the first DIGITS column\npositions of each text column or only each line of '-m' output.\nWith single column output the number precedes each line just as\n'-m' does. Default counting of the line numbers starts with the\nfirst line of the input file (not the first line printed, compare\nthe '--page' option and '-N' option). Optional argument\nNUMBER-SEPARATOR is the character appended to the line number to\nseparate it from the text followed. The default separator is the\nTAB character. In a strict sense a TAB is always printed with\nsingle column output only. The TAB width varies with the TAB\nposition, e.g., with the left MARGIN specified by '-o' option.\nWith multicolumn output priority is given to 'equal width of output\ncolumns' (a POSIX specification). The TAB width is fixed to the\nvalue of the first column and does not change with different values\nof left MARGIN. That means a fixed number of spaces is always\nprinted in the place of the NUMBER-SEPARATOR TAB. The tabification\ndepends upon the output position.\n\n'-N LINENUMBER'\n'--first-line-number=LINENUMBER'\nStart line counting with the number LINENUMBER at first line of\nfirst page printed (in most cases not the first line of the input\nfile).\n\n'-o MARGIN'\n'--indent=MARGIN'\nIndent each line with a margin MARGIN spaces wide (default is\nzero). The total page width is the size of the margin plus the\nPAGEWIDTH set with the '-W/-w' option. A limited overflow may\noccur with numbered single column output (compare '-n' option).\n\n'-r'\n'--no-file-warnings'\nDo not print a warning message when an argument FILE cannot be\nopened. (The exit status will still be nonzero, however.)\n\n'-s[CHAR]'\n'--separator[=CHAR]'\nSeparate columns by a single character CHAR. The default for CHAR\nis the TAB character without '-w' and 'no character' with '-w'.\nWithout '-s' the default separator 'space' is set. '-s[char]'\nturns off line truncation of all three column options\n('-COLUMN'|'-a -COLUMN'|'-m') unless '-w' is set. This is a\nPOSIX-compliant formulation.\n\n'-S[STRING]'\n'--sep-string[=STRING]'\nUse STRING to separate output columns. The '-S' option doesn't\naffect the '-W/-w' option, unlike the '-s' option which does. It\ndoes not affect line truncation or column alignment. Without '-S',\nand with '-J', 'pr' uses the default output separator, TAB.\nWithout '-S' or '-J', 'pr' uses a 'space' (same as '-S\" \"'). If no\n'STRING' argument is specified, '\"\"' is assumed.\n\n'-t'\n'--omit-header'\nDo not print the usual header [and footer] on each page, and do not\nfill out the bottom of pages (with blank lines or a form feed). No\npage structure is produced, but form feeds set in the input files\nare retained. The predefined pagination is not changed. '-t' or\n'-T' may be useful together with other options; e.g.: '-t -e4',\nexpand TAB characters in the input file to 4 spaces but don't make\nany other changes. Use of '-t' overrides '-h'.\n\n'-T'\n'--omit-pagination'\nDo not print header [and footer]. In addition eliminate all form\nfeeds set in the input files.\n\n'-v'\n'--show-nonprinting'\nPrint nonprinting characters in octal backslash notation.\n\n'-w PAGEWIDTH'\n'--width=PAGEWIDTH'\nSet page width to PAGEWIDTH characters for multiple text-column\noutput only (default for PAGEWIDTH is 72). The specified\nPAGEWIDTH is rounded down so that columns have equal width.\n'-s[CHAR]' turns off the default page width and any line truncation\nand column alignment. Lines of full length are merged, regardless\nof the column options set. No PAGEWIDTH setting is possible with\nsingle column output. A POSIX-compliant formulation.\n\n'-W PAGEWIDTH'\n'--pagewidth=PAGEWIDTH'\nSet the page width to PAGEWIDTH characters, honored with and\nwithout a column option. With a column option, the specified\nPAGEWIDTH is rounded down so that columns have equal width. Text\nlines are truncated, unless '-J' is used. Together with one of the\nthree column options ('-COLUMN', '-a -COLUMN' or '-m') column\nalignment is always used. The separator options '-S' or '-s' don't\ndisable the '-W' option. Default is 72 characters. Without '-W\nPAGEWIDTH' and without any of the column options NO line\ntruncation is used (defined to keep downward compatibility and to\nmeet most frequent tasks). That's equivalent to '-W 72 -J'. The\nheader line is never truncated.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: fold invocation, Prev: pr invocation, Up: Formatting file contents": { "content": "", "subsections": [ { "name": "4.3 'fold': Wrap input lines to fit in specified width", "content": "'fold' writes each FILE ('-' means standard input), or standard input if\nnone are given, to standard output, breaking long lines. Synopsis:\n\nfold [OPTION]... [FILE]...\n\nBy default, 'fold' breaks lines wider than 80 columns. The output is\nsplit into as many lines as necessary.\n\n'fold' counts screen columns by default; thus, a tab may count more\nthan one column, backspace decreases the column count, and carriage\nreturn sets the column to zero.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-b'\n'--bytes'\nCount bytes rather than columns, so that tabs, backspaces, and\ncarriage returns are each counted as taking up one column, just\nlike other characters.\n\n'-s'\n'--spaces'\nBreak at word boundaries: the line is broken after the last blank\nbefore the maximum line length. If the line contains no such\nblanks, the line is broken at the maximum line length as usual.\n\n'-w WIDTH'\n'--width=WIDTH'\nUse a maximum line length of WIDTH columns instead of 80.\n\nFor compatibility 'fold' supports an obsolete option syntax\n'-WIDTH'. New scripts should use '-w WIDTH' instead.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: Output of parts of files, Next: Summarizing files, Prev: Formatting file contents, Up: Top": { "content": "", "subsections": [] }, "5 Output of parts of files": { "content": "These commands output pieces of the input.\n\n* Menu:\n\n* head invocation:: Output the first part of files.\n* tail invocation:: Output the last part of files.\n* split invocation:: Split a file into pieces.\n* csplit invocation:: Split a file into context-determined pieces.\n", "subsections": [] }, "File: coreutils.info, Node: head invocation, Next: tail invocation, Up: Output of parts of files": { "content": "", "subsections": [ { "name": "5.1 'head': Output the first part of files", "content": "'head' prints the first part (10 lines by default) of each FILE; it\nreads from standard input if no files are given or when given a FILE of\n'-'. Synopsis:\n\nhead [OPTION]... [FILE]...\n\nIf more than one FILE is specified, 'head' prints a one-line header\nconsisting of:\n\n==> FILE NAME <==\n\nbefore the output for each FILE.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-c [-]NUM'\n'--bytes=[-]NUM'\nPrint the first NUM bytes, instead of initial lines. However, if\nNUM is prefixed with a '-', print all but the last NUM bytes of\neach file. NUM may be, or may be an integer optionally followed\nby, one of the following multiplicative suffixes:\n'b' => 512 (\"blocks\")\n'KB' => 1000 (KiloBytes)\n'K' => 1024 (KibiBytes)\n'MB' => 1000*1000 (MegaBytes)\n'M' => 1024*1024 (MebiBytes)\n'GB' => 1000*1000*1000 (GigaBytes)\n'G' => 1024*1024*1024 (GibiBytes)\nand so on for 'T', 'P', 'E', 'Z', and 'Y'. Binary prefixes can be\nused, too: 'KiB'='K', 'MiB'='M', and so on.\n\n'-n [-]NUM'\n'--lines=[-]NUM'\nOutput the first NUM lines. However, if NUM is prefixed with a\n'-', print all but the last NUM lines of each file. Size\nmultiplier suffixes are the same as with the '-c' option.\n\n'-q'\n'--quiet'\n'--silent'\nNever print file name headers.\n\n'-v'\n'--verbose'\nAlways print file name headers.\n\n'-z'\n'--zero-terminated'\nDelimit items with a zero byte rather than a newline (ASCII LF).\nI.e., treat input as items separated by ASCII NUL and terminate\noutput items with ASCII NUL. This option can be useful in\nconjunction with 'perl -0' or 'find -print0' and 'xargs -0' which\ndo the same in order to reliably handle arbitrary file names (even\nthose containing blanks or other special characters).\n\nFor compatibility 'head' also supports an obsolete option syntax\n'-[NUM][bkm][cqv]', which is recognized only if it is specified first.\nNUM is a decimal number optionally followed by a size letter ('b', 'k',\n'm') as in '-c', or 'l' to mean count by lines, or other option letters\n('cqv'). Scripts intended for standard hosts should use '-c NUM' or '-n\nNUM' instead. If your script must also run on hosts that support only\nthe obsolete syntax, it is usually simpler to avoid 'head', e.g., by\nusing 'sed 5q' instead of 'head -5'.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: tail invocation, Next: split invocation, Prev: head invocation, Up: Output of parts of files": { "content": "", "subsections": [ { "name": "5.2 'tail': Output the last part of files", "content": "'tail' prints the last part (10 lines by default) of each FILE; it reads\nfrom standard input if no files are given or when given a FILE of '-'.\nSynopsis:\n\ntail [OPTION]... [FILE]...\n\nIf more than one FILE is specified, 'tail' prints a one-line header\nbefore the output for each FILE, consisting of:\n\n==> FILE NAME <==\n\nFor further processing of tail output, it can be useful to convert\nthe file headers to line prefixes, which can be done like:\n\ntail ... |\nawk '\n/^==> .* <==$/ {prefix=substr($0,5,length-8)\":\"; next}\n{print prefix$0}\n' | ...\n\nGNU 'tail' can output any amount of data (some other versions of\n'tail' cannot). It also has no '-r' option (print in reverse), since\nreversing a file is really a different job from printing the end of a\nfile; BSD 'tail' (which is the one with '-r') can only reverse files\nthat are at most as large as its buffer, which is typically 32 KiB. A\nmore reliable and versatile way to reverse files is the GNU 'tac'\ncommand.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-c [+]NUM'\n'--bytes=[+]NUM'\nOutput the last NUM bytes, instead of final lines. However, if NUM\nis prefixed with a '+', start printing with byte NUM from the start\nof each file, instead of from the end. NUM may be, or may be an\ninteger optionally followed by, one of the following multiplicative\nsuffixes:\n'b' => 512 (\"blocks\")\n'KB' => 1000 (KiloBytes)\n'K' => 1024 (KibiBytes)\n'MB' => 1000*1000 (MegaBytes)\n'M' => 1024*1024 (MebiBytes)\n'GB' => 1000*1000*1000 (GigaBytes)\n'G' => 1024*1024*1024 (GibiBytes)\nand so on for 'T', 'P', 'E', 'Z', and 'Y'. Binary prefixes can be\nused, too: 'KiB'='K', 'MiB'='M', and so on.\n\n'-f'\n'--follow[=HOW]'\nLoop forever trying to read more characters at the end of the file,\npresumably because the file is growing. If more than one file is\ngiven, 'tail' prints a header whenever it gets output from a\ndifferent file, to indicate which file that output is from.\n\nThere are two ways to specify how you'd like to track files with\nthis option, but that difference is noticeable only when a followed\nfile is removed or renamed. If you'd like to continue to track the\nend of a growing file even after it has been unlinked, use\n'--follow=descriptor'. This is the default behavior, but it is not\nuseful if you're tracking a log file that may be rotated (removed\nor renamed, then reopened). In that case, use '--follow=name' to\ntrack the named file, perhaps by reopening it periodically to see\nif it has been removed and recreated by some other program. Note\nthat the inotify-based implementation handles this case without the\nneed for any periodic reopening.\n\nNo matter which method you use, if the tracked file is determined\nto have shrunk, 'tail' prints a message saying the file has been\ntruncated and resumes tracking from the start of the file, assuming\nit has been truncated to 0, which is the usual truncation operation\nfor log files.\n\nWhen a file is removed, 'tail''s behavior depends on whether it is\nfollowing the name or the descriptor. When following by name, tail\ncan detect that a file has been removed and gives a message to that\neffect, and if '--retry' has been specified it will continue\nchecking periodically to see if the file reappears. When following\na descriptor, tail does not detect that the file has been unlinked\nor renamed and issues no message; even though the file may no\nlonger be accessible via its original name, it may still be\ngrowing.\n\nThe option values 'descriptor' and 'name' may be specified only\nwith the long form of the option, not with '-f'.\n\nThe '-f' option is ignored if no FILE operand is specified and\nstandard input is a FIFO or a pipe. Likewise, the '-f' option has\nno effect for any operand specified as '-', when standard input is\na FIFO or a pipe.\n\nWith kernel inotify support, output is triggered by file changes\nand is generally very prompt. Otherwise, 'tail' sleeps for one\nsecond between checks-- use '--sleep-interval=N' to change that\ndefault--which can make the output appear slightly less responsive\nor bursty. When using tail without inotify support, you can make\nit more responsive by using a sub-second sleep interval, e.g., via\nan alias like this:\n\nalias tail='tail -s.1'\n\n'-F'\nThis option is the same as '--follow=name --retry'. That is, tail\nwill attempt to reopen a file when it is removed. Should this\nfail, tail will keep trying until it becomes accessible again.\n\n'--max-unchanged-stats=N'\nWhen tailing a file by name, if there have been N (default n=5)\nconsecutive iterations for which the file has not changed, then\n'open'/'fstat' the file to determine if that file name is still\nassociated with the same device/inode-number pair as before. When\nfollowing a log file that is rotated, this is approximately the\nnumber of seconds between when tail prints the last pre-rotation\nlines and when it prints the lines that have accumulated in the new\nlog file. This option is meaningful only when polling (i.e.,\nwithout inotify) and when following by name.\n\n'-n [+]NUM'\n'--lines=[+]'\nOutput the last NUM lines. However, if NUM is prefixed with a '+',\nstart printing with line NUM from the start of each file, instead\nof from the end. Size multiplier suffixes are the same as with the\n'-c' option.\n\n'--pid=PID'\nWhen following by name or by descriptor, you may specify the\nprocess ID, PID, of the sole writer of all FILE arguments. Then,\nshortly after that process terminates, tail will also terminate.\nThis will work properly only if the writer and the tailing process\nare running on the same machine. For example, to save the output\nof a build in a file and to watch the file grow, if you invoke\n'make' and 'tail' like this then the tail process will stop when\nyour build completes. Without this option, you would have had to\nkill the 'tail -f' process yourself.\n\n$ make >& makerr & tail --pid=$! -f makerr\n\nIf you specify a PID that is not in use or that does not correspond\nto the process that is writing to the tailed files, then 'tail' may\nterminate long before any FILEs stop growing or it may not\nterminate until long after the real writer has terminated. Note\nthat '--pid' cannot be supported on some systems; 'tail' will print\na warning if this is the case.\n\n'-q'\n'--quiet'\n'--silent'\nNever print file name headers.\n\n'--retry'\nIndefinitely try to open the specified file. This option is useful\nmainly when following (and otherwise issues a warning).\n\nWhen following by file descriptor (i.e., with\n'--follow=descriptor'), this option only affects the initial open\nof the file, as after a successful open, 'tail' will start\nfollowing the file descriptor.\n\nWhen following by name (i.e., with '--follow=name'), 'tail'\ninfinitely retries to re-open the given files until killed.\n\nWithout this option, when 'tail' encounters a file that doesn't\nexist or is otherwise inaccessible, it reports that fact and never\nchecks it again.\n\n'-s NUMBER'\n'--sleep-interval=NUMBER'\nChange the number of seconds to wait between iterations (the\ndefault is 1.0). During one iteration, every specified file is\nchecked to see if it has changed size. When 'tail' uses inotify,\nthis polling-related option is usually ignored. However, if you\nalso specify '--pid=P', 'tail' checks whether process P is alive at\nleast every NUMBER seconds. The NUMBER must be non-negative and\ncan be a floating-point number in either the current or the C\nlocale. *Note Floating point::.\n\n'-v'\n'--verbose'\nAlways print file name headers.\n\n'-z'\n'--zero-terminated'\nDelimit items with a zero byte rather than a newline (ASCII LF).\nI.e., treat input as items separated by ASCII NUL and terminate\noutput items with ASCII NUL. This option can be useful in\nconjunction with 'perl -0' or 'find -print0' and 'xargs -0' which\ndo the same in order to reliably handle arbitrary file names (even\nthose containing blanks or other special characters).\n\nFor compatibility 'tail' also supports an obsolete usage 'tail\n-[NUM][bcl][f] [FILE]', which is recognized only if it does not conflict\nwith the usage described above. This obsolete form uses exactly one\noption and at most one file. In the option, NUM is an optional decimal\nnumber optionally followed by a size letter ('b', 'c', 'l') to mean\ncount by 512-byte blocks, bytes, or lines, optionally followed by 'f'\nwhich has the same meaning as '-f'.\n\nOn systems not conforming to POSIX 1003.1-2001, the leading '-' can\nbe replaced by '+' in the traditional option syntax with the same\nmeaning as in counts, and on obsolete systems predating POSIX\n1003.1-2001 traditional usage overrides normal usage when the two\nconflict. This behavior can be controlled with the 'POSIX2VERSION'\nenvironment variable (*note Standards conformance::).\n\nScripts intended for use on standard hosts should avoid traditional\nsyntax and should use '-c NUM[b]', '-n NUM', and/or '-f' instead. If\nyour script must also run on hosts that support only the traditional\nsyntax, you can often rewrite it to avoid problematic usages, e.g., by\nusing 'sed -n '$p'' rather than 'tail -1'. If that's not possible, the\nscript can use a test like 'if tail -c +1 /dev/null 2>&1;\nthen ...' to decide which syntax to use.\n\nEven if your script assumes the standard behavior, you should still\nbeware usages whose behaviors differ depending on the POSIX version." } ] }, "For example, avoid 'tail - main.c', since it might be interpreted as": { "content": "either 'tail main.c' or as 'tail -- - main.c'; avoid 'tail -c 4', since\nit might mean either 'tail -c4' or 'tail -c 10 4'; and avoid 'tail +4',\nsince it might mean either 'tail ./+4' or 'tail -n +4'.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: split invocation, Next: csplit invocation, Prev: tail invocation, Up: Output of parts of files": { "content": "", "subsections": [ { "name": "5.3 'split': Split a file into pieces.", "content": "'split' creates output files containing consecutive or interleaved\nsections of INPUT (standard input if none is given or INPUT is '-').\nSynopsis:\n\nsplit [OPTION] [INPUT [PREFIX]]\n\nBy default, 'split' puts 1000 lines of INPUT (or whatever is left\nover for the last section), into each output file.\n\nThe output files' names consist of PREFIX ('x' by default) followed\nby a group of characters ('aa', 'ab', ... by default), such that\nconcatenating the output files in traditional sorted order by file name\nproduces the original input file (except '-nr/N'). By default split\nwill initially create files with two generated suffix characters, and\nwill increase this width by two when the next most significant position\nreaches the last character. ('yz', 'zaaa', 'zaab', ...). In this way\nan arbitrary number of output files are supported, which sort as\ndescribed above, even in the presence of an '--additional-suffix'\noption. If the '-a' option is specified and the output file names are\nexhausted, 'split' reports an error without deleting the output files\nthat it did create.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-l LINES'\n'--lines=LINES'\nPut LINES lines of INPUT into each output file. If '--separator'\nis specified, then LINES determines the number of records.\n\nFor compatibility 'split' also supports an obsolete option syntax\n'-LINES'. New scripts should use '-l LINES' instead.\n\n'-b SIZE'\n'--bytes=SIZE'\nPut SIZE bytes of INPUT into each output file. SIZE may be, or may\nbe an integer optionally followed by, one of the following\nmultiplicative suffixes:\n'b' => 512 (\"blocks\")\n'KB' => 1000 (KiloBytes)\n'K' => 1024 (KibiBytes)\n'MB' => 1000*1000 (MegaBytes)\n'M' => 1024*1024 (MebiBytes)\n'GB' => 1000*1000*1000 (GigaBytes)\n'G' => 1024*1024*1024 (GibiBytes)\nand so on for 'T', 'P', 'E', 'Z', and 'Y'. Binary prefixes can be\nused, too: 'KiB'='K', 'MiB'='M', and so on.\n\n'-C SIZE'\n'--line-bytes=SIZE'\nPut into each output file as many complete lines of INPUT as\npossible without exceeding SIZE bytes. Individual lines or records\nlonger than SIZE bytes are broken into multiple files. SIZE has\nthe same format as for the '--bytes' option. If '--separator' is\nspecified, then LINES determines the number of records.\n\n'--filter=COMMAND'\nWith this option, rather than simply writing to each output file,\nwrite through a pipe to the specified shell COMMAND for each output\nfile. COMMAND should use the $FILE environment variable, which is\nset to a different output file name for each invocation of the\ncommand. For example, imagine that you have a 1TiB compressed file\nthat, if uncompressed, would be too large to reside on disk, yet\nyou must split it into individually-compressed pieces of a more\nmanageable size. To do that, you might run this command:\n\nxz -dc BIG.xz | split -b200G --filter='xz > $FILE.xz' - big-\n\nAssuming a 10:1 compression ratio, that would create about fifty\n20GiB files with names 'big-aa.xz', 'big-ab.xz', 'big-ac.xz', etc.\n\n'-n CHUNKS'\n'--number=CHUNKS'\n\nSplit INPUT to CHUNKS output files where CHUNKS may be:\n\nN generate N files based on current size of INPUT\nK/N only output Kth of N to stdout\nl/N generate N files without splitting lines or records\nl/K/N likewise but only output Kth of N to stdout\nr/N like 'l' but use round robin distribution\nr/K/N likewise but only output Kth of N to stdout\n\nAny excess bytes remaining after dividing the INPUT into N chunks,\nare assigned to the last chunk. Any excess bytes appearing after\nthe initial calculation are discarded (except when using 'r' mode).\n\nAll N files are created even if there are fewer than N lines, or\nthe INPUT is truncated.\n\nFor 'l' mode, chunks are approximately INPUT size / N. The INPUT\nis partitioned into N equal sized portions, with the last assigned\nany excess. If a line starts within a partition it is written\ncompletely to the corresponding file. Since lines or records are\nnot split even if they overlap a partition, the files written can\nbe larger or smaller than the partition size, and even empty if a\nline/record is so long as to completely overlap the partition.\n\nFor 'r' mode, the size of INPUT is irrelevant, and so can be a pipe\nfor example.\n\n'-a LENGTH'\n'--suffix-length=LENGTH'\nUse suffixes of length LENGTH. If a LENGTH of 0 is specified, this\nis the same as if (any previous) '-a' was not specified, and thus\nenables the default behavior, which starts the suffix length at 2,\nand unless '-n' or '--numeric-suffixes=FROM' is specified, will\nauto increase the length by 2 as required.\n\n'-d'\n'--numeric-suffixes[=FROM]'\nUse digits in suffixes rather than lower-case letters. The\nnumerical suffix counts from FROM if specified, 0 otherwise.\n\nFROM is supported with the long form option, and is used to either\nset the initial suffix for a single run, or to set the suffix\noffset for independently split inputs, and consequently the auto\nsuffix length expansion described above is disabled. Therefore you\nmay also want to use option '-a' to allow suffixes beyond '99'.\nNote if option '--number' is specified and the number of files is\nless than FROM, a single run is assumed and the minimum suffix\nlength required is automatically determined.\n\n'-x'\n'--hex-suffixes[=FROM]'\nLike '--numeric-suffixes', but use hexadecimal numbers (in lower\ncase).\n\n'--additional-suffix=SUFFIX'\nAppend an additional SUFFIX to output file names. SUFFIX must not\ncontain slash.\n\n'-e'\n'--elide-empty-files'\nSuppress the generation of zero-length output files. This can\nhappen with the '--number' option if a file is (truncated to be)\nshorter than the number requested, or if a line is so long as to\ncompletely span a chunk. The output file sequence numbers, always\nrun consecutively even when this option is specified.\n\n'-t SEPARATOR'\n'--separator=SEPARATOR'\nUse character SEPARATOR as the record separator instead of the\ndefault newline character (ASCII LF). To specify ASCII NUL as the\nseparator, use the two-character string '\\0', e.g., 'split -t\n'\\0''.\n\n'-u'\n'--unbuffered'\nImmediately copy input to output in '--number r/...' mode, which is\na much slower mode of operation.\n\n'--verbose'\nWrite a diagnostic just before each output file is opened.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nHere are a few examples to illustrate how the '--number' ('-n')\noption works:\n\nNotice how, by default, one line may be split onto two or more:\n\n$ seq -w 6 10 > k; split -n3 k; head xa?\n==> xaa <==\n06\n07\n==> xab <==\n\n08\n0\n==> xac <==\n9\n10\n\nUse the \"l/\" modifier to suppress that:\n\n$ seq -w 6 10 > k; split -nl/3 k; head xa?\n==> xaa <==\n06\n07\n\n==> xab <==\n08\n09\n\n==> xac <==\n10\n\nUse the \"r/\" modifier to distribute lines in a round-robin fashion:\n\n$ seq -w 6 10 > k; split -nr/3 k; head xa?\n==> xaa <==\n06\n09\n\n==> xab <==\n07\n10\n\n==> xac <==\n08\n\nYou can also extract just the Kth chunk. This extracts and prints\njust the 7th \"chunk\" of 33:\n\n$ seq 100 > k; split -nl/7/33 k\n20\n21\n22\n" } ] }, "File: coreutils.info, Node: csplit invocation, Prev: split invocation, Up: Output of parts of files": { "content": "", "subsections": [ { "name": "5.4 'csplit': Split a file into context-determined pieces", "content": "'csplit' creates zero or more output files containing sections of INPUT\n(standard input if INPUT is '-'). Synopsis:\n\ncsplit [OPTION]... INPUT PATTERN...\n\nThe contents of the output files are determined by the PATTERN\narguments, as detailed below. An error occurs if a PATTERN argument\nrefers to a nonexistent line of the input file (e.g., if no remaining\nline matches a given regular expression). After every PATTERN has been\nmatched, any remaining input is copied into one last output file.\n\nBy default, 'csplit' prints the number of bytes written to each\noutput file after it has been created.\n\nThe types of pattern arguments are:\n\n'N'\nCreate an output file containing the input up to but not including\nline N (a positive integer). If followed by a repeat count, also\ncreate an output file containing the next N lines of the input file\nonce for each repeat.\n\n'/REGEXP/[OFFSET]'\nCreate an output file containing the current line up to (but not\nincluding) the next line of the input file that contains a match\nfor REGEXP. The optional OFFSET is an integer. If it is given,\nthe input up to (but not including) the matching line plus or minus\nOFFSET is put into the output file, and the line after that begins\nthe next section of input. Note lines within a negative offset of\na regexp pattern are not matched in subsequent regexp patterns.\n\n'%REGEXP%[OFFSET]'\nLike the previous type, except that it does not create an output\nfile, so that section of the input file is effectively ignored.\n\n'{REPEAT-COUNT}'\nRepeat the previous pattern REPEAT-COUNT additional times. The\nREPEAT-COUNT can either be a positive integer or an asterisk,\nmeaning repeat as many times as necessary until the input is\nexhausted.\n\nThe output files' names consist of a prefix ('xx' by default)\nfollowed by a suffix. By default, the suffix is an ascending sequence\nof two-digit decimal numbers from '00' to '99'. In any case,\nconcatenating the output files in sorted order by file name produces the\noriginal input file, excluding portions skipped with a %REGEXP% pattern\nor the '--suppress-matched' option.\n\nBy default, if 'csplit' encounters an error or receives a hangup,\ninterrupt, quit, or terminate signal, it removes any output files that\nit has created so far before it exits.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-f PREFIX'\n'--prefix=PREFIX'\nUse PREFIX as the output file name prefix.\n\n'-b FORMAT'\n'--suffix-format=FORMAT'\nUse FORMAT as the output file name suffix. When this option is\nspecified, the suffix string must include exactly one\n'printf(3)'-style conversion specification, possibly including\nformat specification flags, a field width, a precision\nspecifications, or all of these kinds of modifiers. The format\nletter must convert a binary unsigned integer argument to readable\nform. The format letters 'd' and 'i' are aliases for 'u', and the\n'u', 'o', 'x', and 'X' conversions are allowed. The entire FORMAT\nis given (with the current output file number) to 'sprintf(3)' to\nform the file name suffixes for each of the individual output files\nin turn. If this option is used, the '--digits' option is ignored.\n\n'-n DIGITS'\n'--digits=DIGITS'\nUse output file names containing numbers that are DIGITS digits\nlong instead of the default 2.\n\n'-k'\n'--keep-files'\nDo not remove output files when errors are encountered.\n\n'--suppress-matched'\nDo not output lines matching the specified PATTERN. I.e., suppress\nthe boundary line from the start of the second and subsequent\nsplits.\n\n'-z'\n'--elide-empty-files'\nSuppress the generation of zero-length output files. (In cases\nwhere the section delimiters of the input file are supposed to mark\nthe first lines of each of the sections, the first output file will\ngenerally be a zero-length file unless you use this option.) The\noutput file sequence numbers always run consecutively starting from\n0, even when this option is specified.\n\n'-s'\n'-q'\n'--silent'\n'--quiet'\nDo not print counts of output file sizes.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nHere is an example of its usage. First, create an empty directory\nfor the exercise, and cd into it:\n\n$ mkdir d && cd d\n\nNow, split the sequence of 1..14 on lines that end with 0 or 5:\n\n$ seq 14 | csplit - '/[05]$/' '{*}'\n8\n10\n15\n\nEach number printed above is the size of an output file that csplit\nhas just created. List the names of those output files:\n\n$ ls\nxx00 xx01 xx02\n\nUse 'head' to show their contents:\n\n$ head xx*\n==> xx00 <==\n1\n2\n3\n4\n\n==> xx01 <==\n5\n6\n7\n8\n9\n\n==> xx02 <==\n10\n11\n12\n13\n14\n\nExample of splitting input by empty lines:\n\n$ csplit --suppress-matched INPUT.TXT '/^$/' '{*}'\n" } ] }, "File: coreutils.info, Node: Summarizing files, Next: Operating on sorted files, Prev: Output of parts of files, Up: Top": { "content": "", "subsections": [] }, "6 Summarizing files": { "content": "", "subsections": [] }, "These commands generate just a few numbers representing entire contents": { "content": "of files.\n\n* Menu:\n\n* wc invocation:: Print newline, word, and byte counts.\n* sum invocation:: Print checksum and block counts.\n* cksum invocation:: Print CRC checksum and byte counts.\n* b2sum invocation:: Print or check BLAKE2 digests.\n* md5sum invocation:: Print or check MD5 digests.\n* sha1sum invocation:: Print or check SHA-1 digests.\n* sha2 utilities:: Print or check SHA-2 digests.\n", "subsections": [] }, "File: coreutils.info, Node: wc invocation, Next: sum invocation, Up: Summarizing files": { "content": "", "subsections": [ { "name": "6.1 'wc': Print newline, word, and byte counts", "content": "'wc' counts the number of bytes, characters, whitespace-separated words,\nand newlines in each given FILE, or standard input if none are given or\nfor a FILE of '-'. Synopsis:\n\nwc [OPTION]... [FILE]...\n\n'wc' prints one line of counts for each file, and if the file was\ngiven as an argument, it prints the file name following the counts. If\nmore than one FILE is given, 'wc' prints a final line containing the\ncumulative counts, with the file name 'total'. The counts are printed\nin this order: newlines, words, characters, bytes, maximum line length." } ] }, "Each count is printed right-justified in a field with at least one space": { "content": "between fields so that the numbers and file names normally line up\nnicely in columns. The width of the count fields varies depending on\nthe inputs, so you should not depend on a particular field width.", "subsections": [] }, "However, as a GNU extension, if only one count is printed, it is": { "content": "guaranteed to be printed without leading spaces.\n\nBy default, 'wc' prints three counts: the newline, words, and byte\ncounts. Options can specify that only certain counts be printed.", "subsections": [] }, "Options do not undo others previously given, so": { "content": "wc --bytes --words\n\nprints both the byte counts and the word counts.\n\nWith the '--max-line-length' option, 'wc' prints the length of the\nlongest line per file, and if there is more than one file it prints the\nmaximum (not the sum) of those lengths. The line lengths here are\nmeasured in screen columns, according to the current locale and assuming\ntab positions in every 8th column.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-c'\n'--bytes'\nPrint only the byte counts.\n\n'-m'\n'--chars'\nPrint only the character counts.\n\n'-w'\n'--words'\nPrint only the word counts.\n\n'-l'\n'--lines'\nPrint only the newline counts.\n\n'-L'\n'--max-line-length'\nPrint only the maximum display widths. Tabs are set at every 8th\ncolumn. Display widths of wide characters are considered.\nNon-printable characters are given 0 width.\n\n'--files0-from=FILE'\nDisallow processing files named on the command line, and instead\nprocess those named in file FILE; each name being terminated by a\nzero byte (ASCII NUL). This is useful when the list of file names\nis so long that it may exceed a command line length limitation. In\nsuch cases, running 'wc' via 'xargs' is undesirable because it\nsplits the list into pieces and makes 'wc' print a total for each\nsublist rather than for the entire list. One way to produce a list\nof ASCII NUL terminated file names is with GNU 'find', using its\n'-print0' predicate. If FILE is '-' then the ASCII NUL terminated\nfile names are read from standard input.\n\nFor example, to find the length of the longest line in any '.c' or\n'.h' file in the current hierarchy, do this:\n\nfind . -name '*.[ch]' -print0 |\nwc -L --files0-from=- | tail -n1\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: sum invocation, Next: cksum invocation, Prev: wc invocation, Up: Summarizing files": { "content": "", "subsections": [ { "name": "6.2 'sum': Print checksum and block counts", "content": "'sum' computes a 16-bit checksum for each given FILE, or standard input\nif none are given or for a FILE of '-'. Synopsis:\n\nsum [OPTION]... [FILE]...\n\n'sum' prints the checksum for each FILE followed by the number of\nblocks in the file (rounded up). If more than one FILE is given, file\nnames are also printed (by default). (With the '--sysv' option,\ncorresponding file names are printed when there is at least one file\nargument.)\n\nBy default, GNU 'sum' computes checksums using an algorithm\ncompatible with BSD 'sum' and prints file sizes in units of 1024-byte\nblocks.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-r'\nUse the default (BSD compatible) algorithm. This option is\nincluded for compatibility with the System V 'sum'. Unless '-s'\nwas also given, it has no effect.\n\n'-s'\n'--sysv'\nCompute checksums using an algorithm compatible with System V\n'sum''s default, and print file sizes in units of 512-byte blocks.\n\n'sum' is provided for compatibility; the 'cksum' program (see next\nsection) is preferable in new applications.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: cksum invocation, Next: b2sum invocation, Prev: sum invocation, Up: Summarizing files": { "content": "", "subsections": [ { "name": "6.3 'cksum': Print CRC checksum and byte counts", "content": "'cksum' computes a cyclic redundancy check (CRC) checksum for each given\nFILE, or standard input if none are given or for a FILE of '-'.\nSynopsis:\n\ncksum [OPTION]... [FILE]...\n\n'cksum' prints the CRC checksum for each file along with the number\nof bytes in the file, and the file name unless no arguments were given.\n\n'cksum' is typically used to ensure that files transferred by\nunreliable means (e.g., netnews) have not been corrupted, by comparing\nthe 'cksum' output for the received files with the 'cksum' output for\nthe original files (typically given in the distribution).\n\nThe CRC algorithm is specified by the POSIX standard. It is not\ncompatible with the BSD or System V 'sum' algorithms (see the previous\nsection); it is more robust.\n\nThe only options are '--help' and '--version'. *Note Common\noptions::.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: b2sum invocation, Next: md5sum invocation, Prev: cksum invocation, Up: Summarizing files": { "content": "", "subsections": [ { "name": "6.4 'b2sum': Print or check BLAKE2 digests", "content": "'b2sum' computes a 512-bit checksum for each specified FILE. The same\nusage and options as the 'md5sum' command are supported. *Note md5sum\ninvocation::. In addition 'b2sum' supports the following options.\n\n'-l'\n'--length'\nChange (shorten) the default digest length. This is specified in\nbits and thus must be a multiple of 8. This option is ignored when\n'--check' is specified, as the length is automatically determined\nwhen checking.\n" } ] }, "File: coreutils.info, Node: md5sum invocation, Next: sha1sum invocation, Prev: b2sum invocation, Up: Summarizing files": { "content": "", "subsections": [ { "name": "6.5 'md5sum': Print or check MD5 digests", "content": "'md5sum' computes a 128-bit checksum (or \"fingerprint\" or\n\"message-digest\") for each specified FILE.\n\nNote: The MD5 digest is more reliable than a simple CRC (provided by\nthe 'cksum' command) for detecting accidental file corruption, as the\nchances of accidentally having two files with identical MD5 are\nvanishingly small. However, it should not be considered secure against\nmalicious tampering: although finding a file with a given MD5\nfingerprint is considered infeasible at the moment, it is known how to\nmodify certain files, including digital certificates, so that they\nappear valid when signed with an MD5 digest. For more secure hashes,\nconsider using SHA-2, or the newer 'b2sum' command. *Note sha2\nutilities::. *Note b2sum invocation::.\n\nIf a FILE is specified as '-' or if no files are given 'md5sum'\ncomputes the checksum for the standard input. 'md5sum' can also\ndetermine whether a file and checksum are consistent. Synopsis:\n\nmd5sum [OPTION]... [FILE]...\n\nFor each FILE, 'md5sum' outputs by default, the MD5 checksum, a\nspace, a flag indicating binary or text input mode, and the file name.\nBinary mode is indicated with '*', text mode with ' ' (space). Binary\nmode is the default on systems where it's significant, otherwise text\nmode is the default. Without '--zero', if FILE contains a backslash or\nnewline, the line is started with a backslash, and each problematic\ncharacter in the file name is escaped with a backslash, making the\noutput unambiguous even in the presence of arbitrary file names. If\nFILE is omitted or specified as '-', standard input is read.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-b'\n'--binary'\nTreat each input file as binary, by reading it in binary mode and\noutputting a '*' flag. This is the inverse of '--text'. On\nsystems like GNU that do not distinguish between binary and text\nfiles, this option merely flags each input mode as binary: the MD5\nchecksum is unaffected. This option is the default on systems like\nMS-DOS that distinguish between binary and text files, except for\nreading standard input when standard input is a terminal.\n\n'-c'\n'--check'\nRead file names and checksum information (not data) from each FILE\n(or from stdin if no FILE was specified) and report whether the\nchecksums match the contents of the named files. The input to this\nmode of 'md5sum' is usually the output of a prior,\nchecksum-generating run of 'md5sum'. Three input formats are\nsupported. Either the default output format described above, the\n'--tag' output format, or the BSD reversed mode format which is\nsimilar to the default mode, but doesn't use a character to\ndistinguish binary and text modes. Output with '--zero' enabled is\nnot supported by '--check'.\n\nFor each such line, 'md5sum' reads the named file and computes its\nMD5 checksum. Then, if the computed message digest does not match\nthe one on the line with the file name, the file is noted as having\nfailed the test. Otherwise, the file passes the test. By default,\nfor each valid line, one line is written to standard output\nindicating whether the named file passed the test. After all\nchecks have been performed, if there were any failures, a warning\nis issued to standard error. Use the '--status' option to inhibit\nthat output. If any listed file cannot be opened or read, if any\nvalid line has an MD5 checksum inconsistent with the associated\nfile, or if no valid line is found, 'md5sum' exits with nonzero\nstatus. Otherwise, it exits successfully.\n\n'--ignore-missing'\nThis option is useful only when verifying checksums. When\nverifying checksums, don't fail or report any status for missing\nfiles. This is useful when verifying a subset of downloaded files\ngiven a larger list of checksums.\n\n'--quiet'\nThis option is useful only when verifying checksums. When\nverifying checksums, don't generate an 'OK' message per\nsuccessfully checked file. Files that fail the verification are\nreported in the default one-line-per-file format. If there is any\nchecksum mismatch, print a warning summarizing the failures to\nstandard error.\n\n'--status'\nThis option is useful only when verifying checksums. When\nverifying checksums, don't generate the default one-line-per-file\ndiagnostic and don't output the warning summarizing any failures.\nFailures to open or read a file still evoke individual diagnostics\nto standard error. If all listed files are readable and are\nconsistent with the associated MD5 checksums, exit successfully.\nOtherwise exit with a status code indicating there was a failure.\n\n'--tag'\nOutput BSD style checksums, which indicate the checksum algorithm\nused. As a GNU extension, if '--zero' is not used, file names with\nproblematic characters are escaped as described above, with the\nsame escaping indicator of '\\' at the start of the line, being\nused. The '--tag' option implies binary mode, and is disallowed\nwith '--text' mode as supporting that would unnecessarily\ncomplicate the output format, while providing little benefit.\n\n'-t'\n'--text'\nTreat each input file as text, by reading it in text mode and\noutputting a ' ' flag. This is the inverse of '--binary'. This\noption is the default on systems like GNU that do not distinguish\nbetween binary and text files. On other systems, it is the default\nfor reading standard input when standard input is a terminal. This\nmode is never defaulted to if '--tag' is used.\n\n'-w'\n'--warn'\nWhen verifying checksums, warn about improperly formatted MD5\nchecksum lines. This option is useful only if all but a few lines\nin the checked input are valid.\n\n'--strict'\nWhen verifying checksums, if one or more input line is invalid,\nexit nonzero after all warnings have been issued.\n\n'-z'\n'--zero'\nOutput a zero byte (ASCII NUL) at the end of each line, rather than\na newline. This option enables other programs to parse the output\neven when that output would contain data with embedded newlines.\nAlso file name escaping is not used.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: sha1sum invocation, Next: sha2 utilities, Prev: md5sum invocation, Up: Summarizing files": { "content": "", "subsections": [ { "name": "6.6 'sha1sum': Print or check SHA-1 digests", "content": "'sha1sum' computes a 160-bit checksum for each specified FILE. The\nusage and options of this command are precisely the same as for\n'md5sum'. *Note md5sum invocation::.\n\nNote: The SHA-1 digest is more reliable than a simple CRC (provided\nby the 'cksum' command) for detecting accidental file corruption, as the\nchances of accidentally having two files with identical SHA-1 are\nvanishingly small. However, it should not be considered secure against\nmalicious tampering: although finding a file with a given SHA-1\nfingerprint is considered infeasible at the moment, it is known how to\nmodify certain files, including digital certificates, so that they\nappear valid when signed with an SHA-1 digest. For more secure hashes,\nconsider using SHA-2, or the newer 'b2sum' command. *Note sha2\nutilities::. *Note b2sum invocation::.\n" } ] }, "File: coreutils.info, Node: sha2 utilities, Prev: sha1sum invocation, Up: Summarizing files": { "content": "", "subsections": [ { "name": "6.7 sha2 utilities: Print or check SHA-2 digests", "content": "" } ] }, "The commands 'sha224sum', 'sha256sum', 'sha384sum' and 'sha512sum'": { "content": "compute checksums of various lengths (respectively 224, 256, 384 and 512\nbits), collectively known as the SHA-2 hashes. The usage and options of\nthese commands are precisely the same as for 'md5sum' and 'sha1sum'.\n*Note md5sum invocation::.\n", "subsections": [] }, "File: coreutils.info, Node: Operating on sorted files, Next: Operating on fields, Prev: Summarizing files, Up: Top": { "content": "", "subsections": [] }, "7 Operating on sorted files": { "content": "These commands work with (or produce) sorted files.\n\n* Menu:\n\n* sort invocation:: Sort text files.\n* shuf invocation:: Shuffle text files.\n* uniq invocation:: Uniquify files.\n* comm invocation:: Compare two sorted files line by line.\n* ptx invocation:: Produce a permuted index of file contents.\n* tsort invocation:: Topological sort.\n", "subsections": [] }, "File: coreutils.info, Node: sort invocation, Next: shuf invocation, Up: Operating on sorted files": { "content": "", "subsections": [ { "name": "7.1 'sort': Sort text files", "content": "'sort' sorts, merges, or compares all the lines from the given files, or\nstandard input if none are given or for a FILE of '-'. By default,\n'sort' writes the results to standard output. Synopsis:\n\nsort [OPTION]... [FILE]...\n\nMany options affect how 'sort' compares lines; if the results are\nunexpected, try the '--debug' option to see what happened. A pair of\nlines is compared as follows: 'sort' compares each pair of fields (see\n'--key'), in the order specified on the command line, according to the\nassociated ordering options, until a difference is found or no fields\nare left. If no key fields are specified, 'sort' uses a default key of\nthe entire line. Finally, as a last resort when all keys compare equal,\n'sort' compares entire lines as if no ordering options other than\n'--reverse' ('-r') were specified. The '--stable' ('-s') option\ndisables this \"last-resort comparison\" so that lines in which all fields\ncompare equal are left in their original relative order. The '--unique'\n('-u') option also disables the last-resort comparison.\n\nUnless otherwise specified, all comparisons use the character\ncollating sequence specified by the 'LCCOLLATE' locale.(1) A line's\ntrailing newline is not part of the line for comparison purposes. If\nthe final byte of an input file is not a newline, GNU 'sort' silently\nsupplies one. GNU 'sort' (as specified for all GNU utilities) has no\nlimit on input line length or restrictions on bytes allowed within\nlines.\n\n'sort' has three modes of operation: sort (the default), merge, and\ncheck for sortedness. The following options change the operation mode:\n\n'-c'\n'--check'\n'--check=diagnose-first'\nCheck whether the given file is already sorted: if it is not all\nsorted, print a diagnostic containing the first out-of-order line\nand exit with a status of 1. Otherwise, exit successfully. At\nmost one input file can be given.\n\n'-C'\n'--check=quiet'\n'--check=silent'\nExit successfully if the given file is already sorted, and exit\nwith status 1 otherwise. At most one input file can be given.\nThis is like '-c', except it does not print a diagnostic.\n\n'-m'\n'--merge'\nMerge the given files by sorting them as a group. Each input file\nmust always be individually sorted. It always works to sort\ninstead of merge; merging is provided because it is faster, in the\ncase where it works.\n\nExit status:\n\n0 if no error occurred\n1 if invoked with '-c' or '-C' and the input is not sorted\n2 if an error occurred\n\nIf the environment variable 'TMPDIR' is set, 'sort' uses its value as\nthe directory for temporary files instead of '/tmp'. The\n'--temporary-directory' ('-T') option in turn overrides the environment\nvariable.\n\nThe following options affect the ordering of output lines. They may\nbe specified globally or as part of a specific key field. If no key\nfields are specified, global options apply to comparison of entire\nlines; otherwise the global options are inherited by key fields that do\nnot specify any special options of their own. In pre-POSIX versions of\n'sort', global options affect only later key fields, so portable shell\nscripts should specify global options first.\n\n'-b'\n'--ignore-leading-blanks'\nIgnore leading blanks when finding sort keys in each line. By\ndefault a blank is a space or a tab, but the 'LCCTYPE' locale can\nchange this. Note blanks may be ignored by your locale's collating\nrules, but without this option they will be significant for\ncharacter positions specified in keys with the '-k' option.\n\n'-d'\n'--dictionary-order'\nSort in \"phone directory\" order: ignore all characters except\nletters, digits and blanks when sorting. By default letters and\ndigits are those of ASCII and a blank is a space or a tab, but the\n'LCCTYPE' locale can change this.\n\n'-f'\n'--ignore-case'\nFold lowercase characters into the equivalent uppercase characters\nwhen comparing so that, for example, 'b' and 'B' sort as equal.\nThe 'LCCTYPE' locale determines character types. When used with\n'--unique' those lower case equivalent lines are thrown away.\n(There is currently no way to throw away the upper case equivalent\ninstead. (Any '--reverse' given would only affect the final\nresult, after the throwing away.))\n\n'-g'\n'--general-numeric-sort'\n'--sort=general-numeric'\nSort numerically, converting a prefix of each line to a long\ndouble-precision floating point number. *Note Floating point::.\nDo not report overflow, underflow, or conversion errors. Use the\nfollowing collating sequence:\n\n* Lines that do not start with numbers (all considered to be\nequal).\n* NaNs (\"Not a Number\" values, in IEEE floating point\narithmetic) in a consistent but machine-dependent order.\n* Minus infinity.\n* Finite numbers in ascending numeric order (with -0 and +0\nequal).\n* Plus infinity.\n\nUse this option only if there is no alternative; it is much slower\nthan '--numeric-sort' ('-n') and it can lose information when\nconverting to floating point.\n\n'-h'\n'--human-numeric-sort'\n'--sort=human-numeric'\nSort numerically, first by numeric sign (negative, zero, or\npositive); then by SI suffix (either empty, or 'k' or 'K', or one\nof 'MGTPEZY', in that order; *note Block size::); and finally by\nnumeric value. For example, '1023M' sorts before '1G' because 'M'\n(mega) precedes 'G' (giga) as an SI suffix. This option sorts\nvalues that are consistently scaled to the nearest suffix,\nregardless of whether suffixes denote powers of 1000 or 1024, and\nit therefore sorts the output of any single invocation of the 'df',\n'du', or 'ls' commands that are invoked with their\n'--human-readable' or '--si' options. The syntax for numbers is\nthe same as for the '--numeric-sort' option; the SI suffix must\nimmediately follow the number. Note also the 'numfmt' command,\nwhich can be used to reformat numbers to human format after the\nsort, thus often allowing sort to operate on more accurate numbers.\n\n'-i'\n'--ignore-nonprinting'\nIgnore nonprinting characters. The 'LCCTYPE' locale determines\ncharacter types. This option has no effect if the stronger\n'--dictionary-order' ('-d') option is also given.\n\n'-M'\n'--month-sort'\n'--sort=month'\nAn initial string, consisting of any amount of blanks, followed by\na month name abbreviation, is folded to UPPER case and compared in\nthe order 'JAN' < 'FEB' < ... < 'DEC'. Invalid names compare low\nto valid names. The 'LCTIME' locale category determines the month\nspellings. By default a blank is a space or a tab, but the\n'LCCTYPE' locale can change this.\n\n'-n'\n'--numeric-sort'\n'--sort=numeric'\nSort numerically. The number begins each line and consists of\noptional blanks, an optional '-' sign, and zero or more digits\npossibly separated by thousands separators, optionally followed by\na decimal-point character and zero or more digits. An empty number\nis treated as '0'. The 'LCNUMERIC' locale specifies the\ndecimal-point character and thousands separator. By default a\nblank is a space or a tab, but the 'LCCTYPE' locale can change\nthis.\n\nComparison is exact; there is no rounding error.\n\nNeither a leading '+' nor exponential notation is recognized. To\ncompare such strings numerically, use the '--general-numeric-sort'\n('-g') option.\n\n'-V'\n'--version-sort'\nSort by version name and number. It behaves like a standard sort,\nexcept that each sequence of decimal digits is treated numerically\nas an index/version number. (*Note Version sort ordering::.)\n\n'-r'\n'--reverse'\nReverse the result of comparison, so that lines with greater key\nvalues appear earlier in the output instead of later.\n\n'-R'\n'--random-sort'\n'--sort=random'\nSort by hashing the input keys and then sorting the hash values.\nChoose the hash function at random, ensuring that it is free of\ncollisions so that differing keys have differing hash values. This\nis like a random permutation of the inputs (*note shuf\ninvocation::), except that keys with the same value sort together.\n\nIf multiple random sort fields are specified, the same random hash\nfunction is used for all fields. To use different random hash\nfunctions for different fields, you can invoke 'sort' more than\nonce.\n\nThe choice of hash function is affected by the '--random-source'\noption.\n\nOther options are:\n\n'--compress-program=PROG'\nCompress any temporary files with the program PROG.\n\nWith no arguments, PROG must compress standard input to standard\noutput, and when given the '-d' option it must decompress standard\ninput to standard output.\n\nTerminate with an error if PROG exits with nonzero status.\n\nWhite space and the backslash character should not appear in PROG;\nthey are reserved for future use.\n\n'--files0-from=FILE'\nDisallow processing files named on the command line, and instead\nprocess those named in file FILE; each name being terminated by a\nzero byte (ASCII NUL). This is useful when the list of file names\nis so long that it may exceed a command line length limitation. In\nsuch cases, running 'sort' via 'xargs' is undesirable because it\nsplits the list into pieces and makes 'sort' print sorted output\nfor each sublist rather than for the entire list. One way to\nproduce a list of ASCII NUL terminated file names is with GNU\n'find', using its '-print0' predicate. If FILE is '-' then the\nASCII NUL terminated file names are read from standard input.\n\n'-k POS1[,POS2]'\n'--key=POS1[,POS2]'\nSpecify a sort field that consists of the part of the line between\nPOS1 and POS2 (or the end of the line, if POS2 is omitted),\ninclusive.\n\nIn its simplest form POS specifies a field number (starting with\n1), with fields being separated by runs of blank characters, and by\ndefault those blanks being included in the comparison at the start\nof each field. To adjust the handling of blank characters see the\n'-b' and '-t' options.\n\nMore generally, each POS has the form 'F[.C][OPTS]', where F is the\nnumber of the field to use, and C is the number of the first\ncharacter from the beginning of the field. Fields and character\npositions are numbered starting with 1; a character position of\nzero in POS2 indicates the field's last character. If '.C' is\nomitted from POS1, it defaults to 1 (the beginning of the field);\nif omitted from POS2, it defaults to 0 (the end of the field).\nOPTS are ordering options, allowing individual keys to be sorted\naccording to different rules; see below for details. Keys can span\nmultiple fields.\n\nExample: To sort on the second field, use '--key=2,2' ('-k 2,2').\nSee below for more notes on keys and more examples. See also the\n'--debug' option to help determine the part of the line being used\nin the sort.\n\n'--debug'\nHighlight the portion of each line used for sorting. Also issue\nwarnings about questionable usage to stderr.\n\n'--batch-size=NMERGE'\nMerge at most NMERGE inputs at once.\n\nWhen 'sort' has to merge more than NMERGE inputs, it merges them in\ngroups of NMERGE, saving the result in a temporary file, which is\nthen used as an input in a subsequent merge.\n\nA large value of NMERGE may improve merge performance and decrease\ntemporary storage utilization at the expense of increased memory\nusage and I/O. Conversely a small value of NMERGE may reduce\nmemory requirements and I/O at the expense of temporary storage\nconsumption and merge performance.\n\nThe value of NMERGE must be at least 2. The default value is\ncurrently 16, but this is implementation-dependent and may change\nin the future.\n\nThe value of NMERGE may be bounded by a resource limit for open\nfile descriptors. The commands 'ulimit -n' or 'getconf OPENMAX'\nmay display limits for your systems; these limits may be modified\nfurther if your program already has some files open, or if the\noperating system has other limits on the number of open files. If\nthe value of NMERGE exceeds the resource limit, 'sort' silently\nuses a smaller value.\n\n'-o OUTPUT-FILE'\n'--output=OUTPUT-FILE'\nWrite output to OUTPUT-FILE instead of standard output. Normally,\n'sort' reads all input before opening OUTPUT-FILE, so you can sort\na file in place by using commands like 'sort -o F F' and 'cat F |\nsort -o F'. However, it is often safer to output to an\notherwise-unused file, as data may be lost if the system crashes or\n'sort' encounters an I/O or other serious error while a file is\nbeing sorted in place. Also, 'sort' with '--merge' ('-m') can open\nthe output file before reading all input, so a command like 'cat F\n| sort -m -o F - G' is not safe as 'sort' might start writing 'F'\nbefore 'cat' is done reading it.\n\nOn newer systems, '-o' cannot appear after an input file if\n'POSIXLYCORRECT' is set, e.g., 'sort F -o F'. Portable scripts\nshould specify '-o OUTPUT-FILE' before any input files.\n\n'--random-source=FILE'\nUse FILE as a source of random data used to determine which random\nhash function to use with the '-R' option. *Note Random sources::.\n\n'-s'\n'--stable'\n\nMake 'sort' stable by disabling its last-resort comparison. This\noption has no effect if no fields or global ordering options other\nthan '--reverse' ('-r') are specified.\n\n'-S SIZE'\n'--buffer-size=SIZE'\nUse a main-memory sort buffer of the given SIZE. By default, SIZE\nis in units of 1024 bytes. Appending '%' causes SIZE to be\ninterpreted as a percentage of physical memory. Appending 'K'\nmultiplies SIZE by 1024 (the default), 'M' by 1,048,576, 'G' by\n1,073,741,824, and so on for 'T', 'P', 'E', 'Z', and 'Y'.\nAppending 'b' causes SIZE to be interpreted as a byte count, with\nno multiplication.\n\nThis option can improve the performance of 'sort' by causing it to\nstart with a larger or smaller sort buffer than the default.\nHowever, this option affects only the initial buffer size. The\nbuffer grows beyond SIZE if 'sort' encounters input lines larger\nthan SIZE.\n\n'-t SEPARATOR'\n'--field-separator=SEPARATOR'\nUse character SEPARATOR as the field separator when finding the\nsort keys in each line. By default, fields are separated by the\nempty string between a non-blank character and a blank character.\nBy default a blank is a space or a tab, but the 'LCCTYPE' locale\ncan change this.\n\nThat is, given the input line ' foo bar', 'sort' breaks it into\nfields ' foo' and ' bar'. The field separator is not considered to\nbe part of either the field preceding or the field following, so\nwith 'sort -t \" \"' the same input line has three fields: an empty\nfield, 'foo', and 'bar'. However, fields that extend to the end of\nthe line, as '-k 2', or fields consisting of a range, as '-k 2,3',\nretain the field separators present between the endpoints of the\nrange.\n\nTo specify ASCII NUL as the field separator, use the two-character\nstring '\\0', e.g., 'sort -t '\\0''.\n\n'-T TEMPDIR'\n'--temporary-directory=TEMPDIR'\nUse directory TEMPDIR to store temporary files, overriding the\n'TMPDIR' environment variable. If this option is given more than\nonce, temporary files are stored in all the directories given. If\nyou have a large sort or merge that is I/O-bound, you can often\nimprove performance by using this option to specify directories on\ndifferent disks and controllers.\n\n'--parallel=N'\nSet the number of sorts run in parallel to N. By default, N is set\nto the number of available processors, but limited to 8, as there\nare diminishing performance gains after that. Note also that using\nN threads increases the memory usage by a factor of log N. Also\nsee *note nproc invocation::.\n\n'-u'\n'--unique'\n\nNormally, output only the first of a sequence of lines that compare\nequal. For the '--check' ('-c' or '-C') option, check that no pair\nof consecutive lines compares equal.\n\nThis option also disables the default last-resort comparison.\n\nThe commands 'sort -u' and 'sort | uniq' are equivalent, but this\nequivalence does not extend to arbitrary 'sort' options. For\nexample, 'sort -n -u' inspects only the value of the initial\nnumeric string when checking for uniqueness, whereas 'sort -n |\nuniq' inspects the entire line. *Note uniq invocation::.\n\n'-z'\n'--zero-terminated'\nDelimit items with a zero byte rather than a newline (ASCII LF).\nI.e., treat input as items separated by ASCII NUL and terminate\noutput items with ASCII NUL. This option can be useful in\nconjunction with 'perl -0' or 'find -print0' and 'xargs -0' which\ndo the same in order to reliably handle arbitrary file names (even\nthose containing blanks or other special characters).\n\nHistorical (BSD and System V) implementations of 'sort' have differed\nin their interpretation of some options, particularly '-b', '-f', and\n'-n'. GNU sort follows the POSIX behavior, which is usually (but not\nalways!) like the System V behavior. According to POSIX, '-n' no\nlonger implies '-b'. For consistency, '-M' has been changed in the same\nway. This may affect the meaning of character positions in field\nspecifications in obscure cases. The only fix is to add an explicit\n'-b'.\n\nA position in a sort field specified with '-k' may have any of the\noption letters 'MbdfghinRrV' appended to it, in which case no global\nordering options are inherited by that particular field. The '-b'\noption may be independently attached to either or both of the start and\nend positions of a field specification, and if it is inherited from the\nglobal options it will be attached to both. If input lines can contain\nleading or adjacent blanks and '-t' is not used, then '-k' is typically\ncombined with '-b' or an option that implicitly ignores leading blanks\n('Mghn') as otherwise the varying numbers of leading blanks in fields\ncan cause confusing results.\n\nIf the start position in a sort field specifier falls after the end\nof the line or after the end field, the field is empty. If the '-b'\noption was specified, the '.C' part of a field specification is counted\nfrom the first nonblank character of the field.\n\nOn systems not conforming to POSIX 1003.1-2001, 'sort' supports a\ntraditional origin-zero syntax '+POS1 [-POS2]' for specifying sort keys.\nThe traditional command 'sort +A.X -B.Y' is equivalent to 'sort -k\nA+1.X+1,B' if Y is '0' or absent, otherwise it is equivalent to 'sort -k\nA+1.X+1,B+1.Y'.\n\nThis traditional behavior can be controlled with the\n'POSIX2VERSION' environment variable (*note Standards conformance::);\nit can also be enabled when 'POSIXLYCORRECT' is not set by using the\ntraditional syntax with '-POS2' present.\n\nScripts intended for use on standard hosts should avoid traditional\nsyntax and should use '-k' instead. For example, avoid 'sort +2', since\nit might be interpreted as either 'sort ./+2' or 'sort -k 3'. If your\nscript must also run on hosts that support only the traditional syntax,\nit can use a test like 'if sort -k 1 /dev/null 2>&1; then\n...' to decide which syntax to use.\n\nHere are some examples to illustrate various combinations of options.\n\n* Sort in descending (reverse) numeric order.\n\nsort -n -r\n\n* Run no more than 4 sorts concurrently, using a buffer size of 10M.\n\nsort --parallel=4 -S 10M\n\n* Sort alphabetically, omitting the first and second fields and the\nblanks at the start of the third field. This uses a single key\ncomposed of the characters beginning at the start of the first\nnonblank character in field three and extending to the end of each\nline.\n\nsort -k 3b\n\n* Sort numerically on the second field and resolve ties by sorting\nalphabetically on the third and fourth characters of field five.\nUse ':' as the field delimiter.\n\nsort -t : -k 2,2n -k 5.3,5.4\n\nNote that if you had written '-k 2n' instead of '-k 2,2n' 'sort'\nwould have used all characters beginning in the second field and\nextending to the end of the line as the primary numeric key. For\nthe large majority of applications, treating keys spanning more\nthan one field as numeric will not do what you expect.\n\nAlso note that the 'n' modifier was applied to the field-end\nspecifier for the first key. It would have been equivalent to\nspecify '-k 2n,2' or '-k 2n,2n'. All modifiers except 'b' apply to\nthe associated field, regardless of whether the modifier\ncharacter is attached to the field-start and/or the field-end part\nof the key specifier.\n\n* Sort the password file on the fifth field and ignore any leading\nblanks. Sort lines with equal values in field five on the numeric\nuser ID in field three. Fields are separated by ':'.\n\nsort -t : -k 5b,5 -k 3,3n /etc/passwd\nsort -t : -n -k 5b,5 -k 3,3 /etc/passwd\nsort -t : -b -k 5,5 -k 3,3n /etc/passwd\n\nThese three commands have equivalent effect. The first specifies\nthat the first key's start position ignores leading blanks and the\nsecond key is sorted numerically. The other two commands rely on\nglobal options being inherited by sort keys that lack modifiers.\nThe inheritance works in this case because '-k 5b,5b' and '-k 5b,5'\nare equivalent, as the location of a field-end lacking a '.C'\ncharacter position is not affected by whether initial blanks are\nskipped.\n\n* Sort a set of log files, primarily by IPv4 address and secondarily\nby timestamp. If two lines' primary and secondary keys are\nidentical, output the lines in the same order that they were input.\nThe log files contain lines that look like this:\n\n4.150.156.3 - - [01/Apr/2004:06:31:51 +0000] message 1\n211.24.3.231 - - [24/Apr/2004:20:17:39 +0000] message 2\n\nFields are separated by exactly one space. Sort IPv4 addresses\nlexicographically, e.g., 212.61.52.2 sorts before 212.129.233.201\nbecause 61 is less than 129.\n\nsort -s -t ' ' -k 4.9n -k 4.5M -k 4.2n -k 4.14,4.21 file*.log |\nsort -s -t '.' -k 1,1n -k 2,2n -k 3,3n -k 4,4n\n\nThis example cannot be done with a single 'sort' invocation, since\nIPv4 address components are separated by '.' while dates come just\nafter a space. So it is broken down into two invocations of\n'sort': the first sorts by timestamp and the second by IPv4\naddress. The timestamp is sorted by year, then month, then day,\nand finally by hour-minute-second field, using '-k' to isolate each\nfield. Except for hour-minute-second there's no need to specify\nthe end of each key field, since the 'n' and 'M' modifiers sort\nbased on leading prefixes that cannot cross field boundaries. The\nIPv4 addresses are sorted lexicographically. The second sort uses\n'-s' so that ties in the primary key are broken by the secondary\nkey; the first sort uses '-s' so that the combination of the two\nsorts is stable.\n\n* Generate a tags file in case-insensitive sorted order.\n\nfind src -type f -print0 | sort -z -f | xargs -0 etags --append\n\nThe use of '-print0', '-z', and '-0' in this case means that file\nnames that contain blanks or other special characters are not\nbroken up by the sort operation.\n\n* Use the common DSU, Decorate Sort Undecorate idiom to sort lines\naccording to their length.\n\nawk '{print length, $0}' /etc/passwd | sort -n | cut -f2- -d' '\n\nIn general this technique can be used to sort data that the 'sort'\ncommand does not support, or is inefficient at, sorting directly.\n\n* Shuffle a list of directories, but preserve the order of files\nwithin each directory. For instance, one could use this to\ngenerate a music playlist in which albums are shuffled but the\nsongs of each album are played in order.\n\nls */* | sort -t / -k 1,1R -k 2,2\n\n---------- Footnotes ----------\n\n(1) If you use a non-POSIX locale (e.g., by setting 'LCALL' to\n'enUS'), then 'sort' may produce output that is sorted differently than\nyou're accustomed to. In that case, set the 'LCALL' environment\nvariable to 'C'. Note that setting only 'LCCOLLATE' has two problems." } ] }, "First, it is ineffective if 'LCALL' is also set. Second, it has": { "content": "undefined behavior if 'LCCTYPE' (or 'LANG', if 'LCCTYPE' is unset) is\nset to an incompatible value. For example, you get undefined behavior\nif 'LCCTYPE' is 'jaJP.PCK' but 'LCCOLLATE' is 'enUS.UTF-8'.\n", "subsections": [] }, "File: coreutils.info, Node: shuf invocation, Next: uniq invocation, Prev: sort invocation, Up: Operating on sorted files": { "content": "", "subsections": [ { "name": "7.2 'shuf': Shuffling text", "content": "'shuf' shuffles its input by outputting a random permutation of its\ninput lines. Each output permutation is equally likely. Synopses:\n\nshuf [OPTION]... [FILE]\nshuf -e [OPTION]... [ARG]...\nshuf -i LO-HI [OPTION]...\n\n'shuf' has three modes of operation that affect where it obtains its\ninput lines. By default, it reads lines from standard input. The\nfollowing options change the operation mode:\n\n'-e'\n'--echo'\nTreat each command-line operand as an input line.\n\n'-i LO-HI'\n'--input-range=LO-HI'\nAct as if input came from a file containing the range of unsigned\ndecimal integers LO...HI, one per line.\n\n'shuf''s other options can affect its behavior in all operation\nmodes:\n\n'-n COUNT'\n'--head-count=COUNT'\nOutput at most COUNT lines. By default, all input lines are\noutput.\n\n'-o OUTPUT-FILE'\n'--output=OUTPUT-FILE'\nWrite output to OUTPUT-FILE instead of standard output. 'shuf'\nreads all input before opening OUTPUT-FILE, so you can safely\nshuffle a file in place by using commands like 'shuf -o F file1\n$ printf '%s\\n' b c d e f g > file2\n$ comm --total -123 file1 file2\n1 2 4 total\n\nThis option is a GNU extension. Portable scripts should use 'wc'\nto get the totals, e.g. for the above example files:\n\n$ comm -23 file1 file2 | wc -l # number of lines only in file1\n1\n$ comm -13 file1 file2 | wc -l # number of lines only in file2\n2\n$ comm -12 file1 file2 | wc -l # number of lines common to both files\n4\n\n'-z'\n'--zero-terminated'\nDelimit items with a zero byte rather than a newline (ASCII LF).\nI.e., treat input as items separated by ASCII NUL and terminate\noutput items with ASCII NUL. This option can be useful in\nconjunction with 'perl -0' or 'find -print0' and 'xargs -0' which\ndo the same in order to reliably handle arbitrary file names (even\nthose containing blanks or other special characters).\n", "subsections": [] }, "File: coreutils.info, Node: ptx invocation, Next: tsort invocation, Prev: comm invocation, Up: Operating on sorted files": { "content": "", "subsections": [ { "name": "7.5 'ptx': Produce permuted indexes", "content": "'ptx' reads a text file and essentially produces a permuted index, with\neach keyword in its context. The calling sketch is either one of:\n\nptx [OPTION ...] [FILE ...]\nptx -G [OPTION ...] [INPUT [OUTPUT]]\n\nThe '-G' (or its equivalent: '--traditional') option disables all GNU\nextensions and reverts to traditional mode, thus introducing some\nlimitations and changing several of the program's default option values." } ] }, "When '-G' is not specified, GNU extensions are always enabled. GNU": { "content": "extensions to 'ptx' are documented wherever appropriate in this\ndocument. *Note Compatibility in ptx::, for the full list.\n\nIndividual options are explained in the following sections.\n\nWhen GNU extensions are enabled, there may be zero, one or several\nFILEs after the options. If there is no FILE, the program reads the\nstandard input. If there is one or several FILEs, they give the name of\ninput files which are all read in turn, as if all the input files were\nconcatenated. However, there is a full contextual break between each\nfile and, when automatic referencing is requested, file names and line\nnumbers refer to individual text input files. In all cases, the program\noutputs the permuted index to the standard output.\n\nWhen GNU extensions are not enabled, that is, when the program\noperates in traditional mode, there may be zero, one or two parameters\nbesides the options. If there are no parameters, the program reads the\nstandard input and outputs the permuted index to the standard output.", "subsections": [] }, "If there is only one parameter, it names the text INPUT to be read": { "content": "instead of the standard input. If two parameters are given, they give\nrespectively the name of the INPUT file to read and the name of the\nOUTPUT file to produce. Be very careful to note that, in this case,\nthe contents of file given by the second parameter is destroyed. This\nbehavior is dictated by System V 'ptx' compatibility; GNU Standards\nnormally discourage output parameters not introduced by an option.\n\nNote that for any file named as the value of an option or as an\ninput text file, a single dash '-' may be used, in which case standard\ninput is assumed. However, it would not make sense to use this\nconvention more than once per program invocation.\n\n* Menu:\n\n* General options in ptx:: Options which affect general program behavior.\n* Charset selection in ptx:: Underlying character set considerations.\n* Input processing in ptx:: Input fields, contexts, and keyword selection.\n* Output formatting in ptx:: Types of output format, and sizing the fields.\n* Compatibility in ptx::\n", "subsections": [] }, "File: coreutils.info, Node: General options in ptx, Next: Charset selection in ptx, Up: ptx invocation": { "content": "'-G'\n'--traditional'\nAs already explained, this option disables all GNU extensions to\n'ptx' and switches to traditional mode.\n\n'--help'\nPrint a short help on standard output, then exit without further\nprocessing.\n\n'--version'\nPrint the program version on standard output, then exit without\nfurther processing.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: Charset selection in ptx, Next: Input processing in ptx, Prev: General options in ptx, Up: ptx invocation": { "content": "", "subsections": [] }, "As it is set up now, the program assumes that the input file is coded": { "content": "using 8-bit ISO 8859-1 code, also known as Latin-1 character set,\nunless it is compiled for MS-DOS, in which case it uses the character\nset of the IBM-PC. (GNU 'ptx' is not known to work on smaller MS-DOS\nmachines anymore.) Compared to 7-bit ASCII, the set of characters which\nare letters is different; this alters the behavior of regular expression\nmatching. Thus, the default regular expression for a keyword allows\nforeign or diacriticized letters. Keyword sorting, however, is still\ncrude; it obeys the underlying character set ordering quite blindly.\n\n'-f'\n'--ignore-case'\nFold lower case letters to upper case for sorting.\n", "subsections": [] }, "File: coreutils.info, Node: Input processing in ptx, Next: Output formatting in ptx, Prev: Charset selection in ptx, Up: ptx invocation": { "content": "'-b FILE'\n'--break-file=FILE'\n\nThis option provides an alternative (to '-W') method of describing\nwhich characters make up words. It introduces the name of a file\nwhich contains a list of characters which cannot be part of one\nword; this file is called the \"Break file\". Any character which is\nnot part of the Break file is a word constituent. If both options\n'-b' and '-W' are specified, then '-W' has precedence and '-b' is\nignored.\n\nWhen GNU extensions are enabled, the only way to avoid newline as a\nbreak character is to write all the break characters in the file\nwith no newline at all, not even at the end of the file. When GNU\nextensions are disabled, spaces, tabs and newlines are always\nconsidered as break characters even if not included in the Break\nfile.\n\n'-i FILE'\n'--ignore-file=FILE'\n\nThe file associated with this option contains a list of words which\nwill never be taken as keywords in concordance output. It is\ncalled the \"Ignore file\". The file contains exactly one word in\neach line; the end of line separation of words is not subject to\nthe value of the '-S' option.\n\n'-o FILE'\n'--only-file=FILE'\n\nThe file associated with this option contains a list of words which\nwill be retained in concordance output; any word not mentioned in\nthis file is ignored. The file is called the \"Only file\". The\nfile contains exactly one word in each line; the end of line\nseparation of words is not subject to the value of the '-S' option.\n\nThere is no default for the Only file. When both an Only file and\nan Ignore file are specified, a word is considered a keyword only\nif it is listed in the Only file and not in the Ignore file.\n\n'-r'\n'--references'\n\nOn each input line, the leading sequence of non-white space\ncharacters will be taken to be a reference that has the purpose of\nidentifying this input line in the resulting permuted index. *Note\nOutput formatting in ptx::, for more information about reference\nproduction. Using this option changes the default value for option\n'-S'.\n\nUsing this option, the program does not try very hard to remove\nreferences from contexts in output, but it succeeds in doing so\nwhen the context ends exactly at the newline. If option '-r' is\nused with '-S' default value, or when GNU extensions are disabled,\nthis condition is always met and references are completely excluded\nfrom the output contexts.\n\n'-S REGEXP'\n'--sentence-regexp=REGEXP'\n\nThis option selects which regular expression will describe the end\nof a line or the end of a sentence. In fact, this regular\nexpression is not the only distinction between end of lines or end\nof sentences, and input line boundaries have no special\nsignificance outside this option. By default, when GNU extensions\nare enabled and if '-r' option is not used, end of sentences are\nused. In this case, this REGEX is imported from GNU Emacs:\n\n[.?!][]\\\"')}]*\\\\($\\\\|\\t\\\\| \\\\)[ \\t\\n]*\n\nWhenever GNU extensions are disabled or if '-r' option is used, end\nof lines are used; in this case, the default REGEXP is just:\n\n\\n\n\nUsing an empty REGEXP is equivalent to completely disabling end of\nline or end of sentence recognition. In this case, the whole file\nis considered to be a single big line or sentence. The user might\nwant to disallow all truncation flag generation as well, through\noption '-F \"\"'. *Note Syntax of Regular Expressions:\n(emacs)Regexps.\n\nWhen the keywords happen to be near the beginning of the input line\nor sentence, this often creates an unused area at the beginning of\nthe output context line; when the keywords happen to be near the\nend of the input line or sentence, this often creates an unused\narea at the end of the output context line. The program tries to\nfill those unused areas by wrapping around context in them; the\ntail of the input line or sentence is used to fill the unused area\non the left of the output line; the head of the input line or\nsentence is used to fill the unused area on the right of the output\nline.\n\nAs a matter of convenience to the user, many usual backslashed\nescape sequences from the C language are recognized and converted\nto the corresponding characters by 'ptx' itself.\n\n'-W REGEXP'\n'--word-regexp=REGEXP'\n\nThis option selects which regular expression will describe each\nkeyword. By default, if GNU extensions are enabled, a word is a\nsequence of letters; the REGEXP used is '\\w+'. When GNU extensions\nare disabled, a word is by default anything which ends with a\nspace, a tab or a newline; the REGEXP used is '[^ \\t\\n]+'.\n\nAn empty REGEXP is equivalent to not using this option. *Note\nSyntax of Regular Expressions: (emacs)Regexps.\n\nAs a matter of convenience to the user, many usual backslashed\nescape sequences, as found in the C language, are recognized and\nconverted to the corresponding characters by 'ptx' itself.\n", "subsections": [] }, "File: coreutils.info, Node: Output formatting in ptx, Next: Compatibility in ptx, Prev: Input processing in ptx, Up: ptx invocation": { "content": "", "subsections": [] }, "Output format is mainly controlled by the '-O' and '-T' options": { "content": "described in the table below. When neither '-O' nor '-T' are selected,\nand if GNU extensions are enabled, the program chooses an output format\nsuitable for a dumb terminal. Each keyword occurrence is output to the\ncenter of one line, surrounded by its left and right contexts. Each\nfield is properly justified, so the concordance output can be readily\nobserved. As a special feature, if automatic references are selected by\noption '-A' and are output before the left context, that is, if option\n'-R' is not selected, then a colon is added after the reference; this\nnicely interfaces with GNU Emacs 'next-error' processing. In this\ndefault output format, each white space character, like newline and tab,\nis merely changed to exactly one space, with no special attempt to\ncompress consecutive spaces. This might change in the future. Except\nfor those white space characters, every other character of the\nunderlying set of 256 characters is transmitted verbatim.\n\nOutput format is further controlled by the following options.\n\n'-g NUMBER'\n'--gap-size=NUMBER'\n\nSelect the size of the minimum white space gap between the fields\non the output line.\n\n'-w NUMBER'\n'--width=NUMBER'\n\nSelect the maximum output width of each final line. If references\nare used, they are included or excluded from the maximum output\nwidth depending on the value of option '-R'. If this option is not\nselected, that is, when references are output before the left\ncontext, the maximum output width takes into account the maximum\nlength of all references. If this option is selected, that is,\nwhen references are output after the right context, the maximum\noutput width does not take into account the space taken by\nreferences, nor the gap that precedes them.\n\n'-A'\n'--auto-reference'\n\nSelect automatic references. Each input line will have an\nautomatic reference made up of the file name and the line ordinal,\nwith a single colon between them. However, the file name will be\nempty when standard input is being read. If both '-A' and '-r' are\nselected, then the input reference is still read and skipped, but\nthe automatic reference is used at output time, overriding the\ninput reference.\n\n'-R'\n'--right-side-refs'\n\nIn the default output format, when option '-R' is not used, any\nreferences produced by the effect of options '-r' or '-A' are\nplaced to the far right of output lines, after the right context.\nWith default output format, when the '-R' option is specified,\nreferences are rather placed at the beginning of each output line,\nbefore the left context. For any other output format, option '-R'\nis ignored, with one exception: with '-R' the width of references\nis not taken into account in total output width given by '-w'.\n\nThis option is automatically selected whenever GNU extensions are\ndisabled.\n\n'-F STRING'\n'--flag-truncation=STRING'\n\nThis option will request that any truncation in the output be\nreported using the string STRING. Most output fields theoretically\nextend towards the beginning or the end of the current line, or\ncurrent sentence, as selected with option '-S'. But there is a\nmaximum allowed output line width, changeable through option '-w',\nwhich is further divided into space for various output fields.\nWhen a field has to be truncated because it cannot extend beyond\nthe beginning or the end of the current line to fit in, then a\ntruncation occurs. By default, the string used is a single slash,\nas in '-F /'.\n\nSTRING may have more than one character, as in '-F ...'. Also, in\nthe particular case when STRING is empty ('-F \"\"'), truncation\nflagging is disabled, and no truncation marks are appended in this\ncase.\n\nAs a matter of convenience to the user, many usual backslashed\nescape sequences, as found in the C language, are recognized and\nconverted to the corresponding characters by 'ptx' itself.\n\n'-M STRING'\n'--macro-name=STRING'\n\nSelect another STRING to be used instead of 'xx', while generating\noutput suitable for 'nroff', 'troff' or TeX.\n\n'-O'\n'--format=roff'\n\nChoose an output format suitable for 'nroff' or 'troff' processing.\nEach output line will look like:\n\n.xx \"TAIL\" \"BEFORE\" \"KEYWORDANDAFTER\" \"HEAD\" \"REF\"\n\nso it will be possible to write a '.xx' roff macro to take care of\nthe output typesetting. This is the default output format when GNU\nextensions are disabled. Option '-M' can be used to change 'xx' to\nanother macro name.\n\nIn this output format, each non-graphical character, like newline\nand tab, is merely changed to exactly one space, with no special\nattempt to compress consecutive spaces. Each quote character '\"'\nis doubled so it will be correctly processed by 'nroff' or 'troff'.\n\n'-T'\n'--format=tex'\n\nChoose an output format suitable for TeX processing. Each output\nline will look like:\n\n\\xx {TAIL}{BEFORE}{KEYWORD}{AFTER}{HEAD}{REF}\n\nso it will be possible to write a '\\xx' definition to take care of\nthe output typesetting. Note that when references are not being\nproduced, that is, neither option '-A' nor option '-r' is selected,\nthe last parameter of each '\\xx' call is inhibited. Option '-M'\ncan be used to change 'xx' to another macro name.\n\nIn this output format, some special characters, like '$', '%', '&',\n'#' and '' are automatically protected with a backslash. Curly\nbrackets '{', '}' are protected with a backslash and a pair of\ndollar signs (to force mathematical mode). The backslash itself\nproduces the sequence '\\backslash{}'. Circumflex and tilde\ndiacritical marks produce the sequence '^\\{ }' and '~\\{ }'\nrespectively. Other diacriticized characters of the underlying\ncharacter set produce an appropriate TeX sequence as far as\npossible. The other non-graphical characters, like newline and\ntab, and all other characters which are not part of ASCII, are\nmerely changed to exactly one space, with no special attempt to\ncompress consecutive spaces. Let me know how to improve this\nspecial character processing for TeX.\n", "subsections": [] }, "File: coreutils.info, Node: Compatibility in ptx, Prev: Output formatting in ptx, Up: ptx invocation": { "content": "", "subsections": [] }, "This version of 'ptx' contains a few features which do not exist in": { "content": "", "subsections": [] }, "System V 'ptx'. These extra features are suppressed by using the '-G'": { "content": "command line option, unless overridden by other command line options.", "subsections": [] }, "Some GNU extensions cannot be recovered by overriding, so the simple": { "content": "rule is to avoid '-G' if you care about GNU extensions. Here are the\ndifferences between this program and System V 'ptx'.\n\n* This program can read many input files at once, it always writes\nthe resulting concordance on standard output. On the other hand,\nSystem V 'ptx' reads only one file and sends the result to standard\noutput or, if a second FILE parameter is given on the command, to\nthat FILE.\n\nHaving output parameters not introduced by options is a dangerous\npractice which GNU avoids as far as possible. So, for using 'ptx'\nportably between GNU and System V, you should always use it with a\nsingle input file, and always expect the result on standard output.\nYou might also want to automatically configure in a '-G' option to\n'ptx' calls in products using 'ptx', if the configurator finds that\nthe installed 'ptx' accepts '-G'.\n\n* The only options available in System V 'ptx' are options '-b',\n'-f', '-g', '-i', '-o', '-r', '-t' and '-w'. All other options are\nGNU extensions and are not repeated in this enumeration. Moreover,\nsome options have a slightly different meaning when GNU extensions\nare enabled, as explained below.\n\n* By default, concordance output is not formatted for 'troff' or\n'nroff'. It is rather formatted for a dumb terminal. 'troff' or\n'nroff' output may still be selected through option '-O'.\n\n* Unless '-R' option is used, the maximum reference width is\nsubtracted from the total output line width. With GNU extensions\ndisabled, width of references is not taken into account in the\noutput line width computations.\n\n* All 256 bytes, even ASCII NUL bytes, are always read and processed\nfrom input file with no adverse effect, even if GNU extensions are\ndisabled. However, System V 'ptx' does not accept 8-bit\ncharacters, a few control characters are rejected, and the tilde\n'~' is also rejected.\n\n* Input line length is only limited by available memory, even if GNU\nextensions are disabled. However, System V 'ptx' processes only\nthe first 200 characters in each line.\n\n* The break (non-word) characters default to be every character\nexcept all letters of the underlying character set, diacriticized\nor not. When GNU extensions are disabled, the break characters\ndefault to space, tab and newline only.\n\n* The program makes better use of output line width. If GNU\nextensions are disabled, the program rather tries to imitate System\nV 'ptx', but still, there are some slight disposition glitches this\nprogram does not completely reproduce.\n\n* The user can specify both an Ignore file and an Only file. This is\nnot allowed with System V 'ptx'.\n", "subsections": [] }, "File: coreutils.info, Node: tsort invocation, Prev: ptx invocation, Up: Operating on sorted files": { "content": "", "subsections": [ { "name": "7.6 'tsort': Topological sort", "content": "'tsort' performs a topological sort on the given FILE, or standard input\nif no input file is given or for a FILE of '-'. For more details and\nsome history, see *note tsort background::. Synopsis:\n\ntsort [OPTION] [FILE]\n\n'tsort' reads its input as pairs of strings, separated by blanks,\nindicating a partial ordering. The output is a total ordering that\ncorresponds to the given partial ordering.\n\nFor example\n\ntsort < file1.sorted\n$ sort -k 1b,1 file2 > file2.sorted\n$ join file1.sorted file2.sorted > file3\n\nNormally, the sort order is that of the collating sequence specified\nby the 'LCCOLLATE' locale. Unless the '-t' option is given, the sort\ncomparison ignores blanks at the start of the join field, as in 'sort\n-b'. If the '--ignore-case' option is given, the sort comparison\nignores the case of characters in the join field, as in 'sort -f':\n\n$ sort -k 1bf,1 file1 > file1.sorted\n$ sort -k 1bf,1 file2 > file2.sorted\n$ join --ignore-case file1.sorted file2.sorted > file3\n\nThe 'sort' and 'join' commands should use consistent locales and\noptions if the output of 'sort' is fed to 'join'. You can use a command\nlike 'sort -k 1b,1' to sort a file on its default join field, but if you\nselect a non-default locale, join field, separator, or comparison\noptions, then you should do so consistently between 'join' and 'sort'.\n", "subsections": [] }, "To avoid any locale-related issues, it is recommended to use the 'C'": { "content": "locale for both commands:\n\n$ LCALL=C sort -k 1b,1 file1 > file1.sorted\n$ LCALL=C sort -k 1b,1 file2 > file2.sorted\n$ LCALL=C join file1.sorted file2.sorted > file3\n", "subsections": [] }, "File: coreutils.info, Node: Working with fields, Next: Paired and unpaired lines, Prev: Sorting files for join, Up: join invocation": { "content": "", "subsections": [] }, "Use '-1','-2' to set the key fields for each of the input files. Ensure": { "content": "the preceding 'sort' commands operated on the same fields.\n", "subsections": [] }, "The following example joins two files, using the values from seventh": { "content": "field of the first file and the third field of the second file:\n\n$ sort -k 7b,7 file1 > file1.sorted\n$ sort -k 3b,3 file2 > file2.sorted\n$ join -1 7 -2 3 file1.sorted file2.sorted > file3\n\nIf the field number is the same for both files, use '-j':\n\n$ sort -k4b,4 file1 > file1.sorted\n$ sort -k4b,4 file2 > file2.sorted\n$ join -j4 file1.sorted file2.sorted > file3\n", "subsections": [] }, "Both 'sort' and 'join' operate of whitespace-delimited fields. To": { "content": "specify a different delimiter, use '-t' in both:\n\n$ sort -t, -k3b,3 file1 > file1.sorted\n$ sort -t, -k3b,3 file2 > file2.sorted\n$ join -t, -j3 file1.sorted file2.sorted > file3\n\nTo specify a tab (ASCII 0x09) character instead of whitespace, use (1):\n\n$ sort -t$'\\t' -k3b,3 file1 > file1.sorted\n$ sort -t$'\\t' -k3b,3 file2 > file2.sorted\n$ join -t$'\\t' -j3 file1.sorted file2.sorted > file3\n", "subsections": [] }, "If 'join -t ''' is specified then the whole line is considered which": { "content": "matches the default operation of sort:\n\n$ sort file1 > file1.sorted\n$ sort file2 > file2.sorted\n$ join -t '' file1.sorted file2.sorted > file3\n\n---------- Footnotes ----------\n\n(1) the '$'\\t'' is supported in most modern shells. For older\nshells, use a literal tab\n", "subsections": [] }, "File: coreutils.info, Node: Paired and unpaired lines, Next: Header lines, Prev: Working with fields, Up: join invocation": { "content": "", "subsections": [] }, "In this section the 'sort' commands are omitted for brevity. Sorting": { "content": "the files before joining is still required.\n\n'join''s default behavior is to print only lines common to both input\nfiles. Use '-a' and '-v' to print unpairable lines from one or both\nfiles.\n\nAll examples below use the following two (pre-sorted) input files:\n\n$ cat file1 $ cat file2\na 1 a A\nb 2 c C\n", "subsections": [] }, "Command Outcome": { "content": "--------------------------------------------------------------------------\n$ join file1 file2 common lines (intersection)\na 1 A\n$ join -a 1 file1 file2 common lines and unpaired lines\na 1 A from the first file\nb 2\n$ join -a 2 file1 file2 common lines and unpaired lines\na 1 A from the second file\nc C\n$ join -a 1 -a 2 file1 file2 all lines (paired and unpaired)\na 1 A from both files (union).\nb 2 see note below regarding '-o\nc C auto'.\n\n$ join -v 1 file1 file2 unpaired lines from the first file\nb 2 (difference)\n\n$ join -v 2 file1 file2 unpaired lines from the second\nc C file (difference)\n\n$ join -v 1 -v 2 file1 file2 unpaired lines from both files,\nb 2 omitting common lines (symmetric\nc C difference).\n\n\nThe '-o auto -e X' options are useful when dealing with unpaired lines.", "subsections": [] }, "The following example prints all lines (common and unpaired) from both": { "content": "files. Without '-o auto' it is not easy to discern which fields\noriginate from which file:\n\n$ join -a 1 -a 2 file1 file2\na 1 A\nb 2\nc C\n\n$ join -o auto -e X -a 1 -a 2 file1 file2\na 1 A\nb 2 X\nc X C\n\nIf the input has no unpairable lines, a GNU extension is available;\nthe sort order can be any order that considers two fields to be equal if\nand only if the sort comparison described above considers them to be\nequal. For example:\n\n$ cat file1\na a1\nc c1\nb b1\n\n$ cat file2\na a2\nc c2\nb b2\n\n$ join file1 file2\na a1 a2\nc c1 c2\nb b1 b2\n", "subsections": [] }, "File: coreutils.info, Node: Header lines, Next: Set operations, Prev: Paired and unpaired lines, Up: join invocation": { "content": "", "subsections": [] }, "The '--header' option can be used when the files to join have a header": { "content": "line which is not sorted:\n\n$ cat file1\nName Age\nAlice 25\nCharlie 34\n\n$ cat file2\nName Country\nAlice France\nBob Spain\n\n$ join --header -o auto -e NA -a1 -a2 file1 file2\nName Age Country\nAlice 25 France\nBob NA Spain\nCharlie 34 NA\n\nTo sort a file with a header line, use GNU 'sed -u'. The following\nexample sort the files but keeps the first line of each file in place:\n\n$ ( sed -u 1q ; sort -k2b,2 ) < file1 > file1.sorted\n$ ( sed -u 1q ; sort -k2b,2 ) < file2 > file2.sorted\n$ join --header -o auto -e NA -a1 -a2 file1.sorted file2.sorted > file3\n", "subsections": [] }, "File: coreutils.info, Node: Set operations, Prev: Header lines, Up: join invocation": { "content": "", "subsections": [] }, "Combine 'sort', 'uniq' and 'join' to perform the equivalent of set": { "content": "operations on files:\n\n'sort -u file1 file2' Union of unsorted files\n\n'sort file1 file2 | uniq -d' Intersection of unsorted files\n\n'sort file1 file1 file2 | uniq -u' Difference of unsorted files\n\n'sort file1 file2 | uniq -u' Symmetric Difference of unsorted\nfiles\n\n'join -t '' -a1 -a2 file1 file2' Union of sorted files\n\n'join -t '' file1 file2' Intersection of sorted files\n\n'join -t '' -v2 file1 file2' Difference of sorted files\n\n'join -t '' -v1 -v2 file1 file2' Symmetric Difference of sorted\nfiles\n\n\nAll examples above operate on entire lines and not on specific\nfields: 'sort' without '-k' and 'join -t ''' both consider entire lines\nas the key.\n", "subsections": [] }, "File: coreutils.info, Node: Operating on characters, Next: Directory listing, Prev: Operating on fields, Up: Top": { "content": "", "subsections": [] }, "9 Operating on characters": { "content": "These commands operate on individual characters.\n\n* Menu:\n\n* tr invocation:: Translate, squeeze, and/or delete characters.\n* expand invocation:: Convert tabs to spaces.\n* unexpand invocation:: Convert spaces to tabs.\n", "subsections": [] }, "File: coreutils.info, Node: tr invocation, Next: expand invocation, Up: Operating on characters": { "content": "", "subsections": [ { "name": "9.1 'tr': Translate, squeeze, and/or delete characters", "content": "Synopsis:\n\ntr [OPTION]... SET1 [SET2]\n\n'tr' copies standard input to standard output, performing one of the\nfollowing operations:\n\n* translate, and optionally squeeze repeated characters in the\nresult,\n* squeeze repeated characters,\n* delete characters,\n* delete characters, then squeeze repeated characters from the\nresult.\n\nThe SET1 and (if given) SET2 arguments define ordered sets of\ncharacters, referred to below as SET1 and SET2. These sets are the\ncharacters of the input that 'tr' operates on. The '--complement'\n('-c', '-C') option replaces SET1 with its complement (all of the\ncharacters that are not in SET1).\n\nCurrently 'tr' fully supports only single-byte characters." } ] }, "Eventually it will support multibyte characters; when it does, the '-C'": { "content": "option will cause it to complement the set of characters, whereas '-c'\nwill cause it to complement the set of values. This distinction will\nmatter only when some values are not characters, and this is possible\nonly in locales using multibyte encodings when the input contains\nencoding errors.\n\nThe program accepts the '--help' and '--version' options. *Note\nCommon options::. Options must precede operands.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\n* Menu:\n\n* Character sets:: Specifying sets of characters.\n* Translating:: Changing one set of characters to another.\n* Squeezing and deleting:: Removing characters.\n", "subsections": [] }, "File: coreutils.info, Node: Character sets, Next: Translating, Up: tr invocation": { "content": "", "subsections": [] }, "The format of the SET1 and SET2 arguments resembles the format of": { "content": "regular expressions; however, they are not regular expressions, only\nlists of characters. Most characters simply represent themselves in\nthese strings, but the strings can contain the shorthands listed below,\nfor convenience. Some of them can be used only in SET1 or SET2, as\nnoted below.\n", "subsections": [] }, "Backslash escapes": { "content": "The following backslash escape sequences are recognized:\n\n'\\a'\nControl-G.\n'\\b'\nControl-H.\n'\\f'\nControl-L.\n'\\n'\nControl-J.\n'\\r'\nControl-M.\n'\\t'\nControl-I.\n'\\v'\nControl-K.\n'\\OOO'\nThe 8-bit character with the value given by OOO, which is 1 to\n3 octal digits. Note that '\\400' is interpreted as the\ntwo-byte sequence, '\\040' '0'.\n'\\\\'\nA backslash.\n\nWhile a backslash followed by a character not listed above is\ninterpreted as that character, the backslash also effectively\nremoves any special significance, so it is useful to escape '[',\n']', '*', and '-'.\n", "subsections": [] }, "Ranges": { "content": "The notation 'M-N' expands to all of the characters from M through\nN, in ascending order. M should collate before N; if it doesn't,\nan error results. As an example, '0-9' is the same as\n'0123456789'.\n\nGNU 'tr' does not support the System V syntax that uses square\nbrackets to enclose ranges. Translations specified in that format\nsometimes work as expected, since the brackets are often\ntransliterated to themselves. However, they should be avoided\nbecause they sometimes behave unexpectedly. For example, 'tr -d\n'[0-9]'' deletes brackets as well as digits.\n\nMany historically common and even accepted uses of ranges are not\nportable. For example, on EBCDIC hosts using the 'A-Z' range will\nnot do what most would expect because 'A' through 'Z' are not\ncontiguous as they are in ASCII. If you can rely on a POSIX\ncompliant version of 'tr', then the best way to work around this is\nto use character classes (see below). Otherwise, it is most\nportable (and most ugly) to enumerate the members of the ranges.\n", "subsections": [] }, "Repeated characters": { "content": "The notation '[C*N]' in SET2 expands to N copies of character C.\nThus, '[y*6]' is the same as 'yyyyyy'. The notation '[C*]' in\nSTRING2 expands to as many copies of C as are needed to make SET2\nas long as SET1. If N begins with '0', it is interpreted in octal,\notherwise in decimal.\n", "subsections": [] }, "Character classes": { "content": "The notation '[:CLASS:]' expands to all of the characters in the\n(predefined) class CLASS. The characters expand in no particular\norder, except for the 'upper' and 'lower' classes, which expand in\nascending order. When the '--delete' ('-d') and\n'--squeeze-repeats' ('-s') options are both given, any character\nclass can be used in SET2. Otherwise, only the character classes\n'lower' and 'upper' are accepted in SET2, and then only if the\ncorresponding character class ('upper' and 'lower', respectively)\nis specified in the same relative position in SET1. Doing this\nspecifies case conversion. The class names are given below; an\nerror results when an invalid class name is given.\n\n'alnum'\nLetters and digits.\n'alpha'\nLetters.\n'blank'\nHorizontal whitespace.\n'cntrl'\nControl characters.\n'digit'\nDigits.\n'graph'\nPrintable characters, not including space.\n'lower'\nLowercase letters.\n'print'\nPrintable characters, including space.\n'punct'\nPunctuation characters.\n'space'\nHorizontal or vertical whitespace.\n'upper'\nUppercase letters.\n'xdigit'\nHexadecimal digits.\n", "subsections": [] }, "Equivalence classes": { "content": "The syntax '[=C=]' expands to all of the characters that are\nequivalent to C, in no particular order. Equivalence classes are a\nrelatively recent invention intended to support non-English\nalphabets. But there seems to be no standard way to define them or\ndetermine their contents. Therefore, they are not fully\nimplemented in GNU 'tr'; each character's equivalence class\nconsists only of that character, which is of no particular use.\n", "subsections": [] }, "File: coreutils.info, Node: Translating, Next: Squeezing and deleting, Prev: Character sets, Up: tr invocation": { "content": "'tr' performs translation when SET1 and SET2 are both given and the\n'--delete' ('-d') option is not given. 'tr' translates each character\nof its input that is in SET1 to the corresponding character in SET2.", "subsections": [] }, "Characters not in SET1 are passed through unchanged. When a character": { "content": "appears more than once in SET1 and the corresponding characters in SET2\nare not all the same, only the final one is used. For example, these\ntwo commands are equivalent:\n\ntr aaa xyz\ntr a z\n\nA common use of 'tr' is to convert lowercase characters to uppercase.\nThis can be done in many ways. Here are three of them:\n\ntr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ\ntr a-z A-Z\ntr '[:lower:]' '[:upper:]'\n\nBut note that using ranges like 'a-z' above is not portable.\n\nWhen 'tr' is performing translation, SET1 and SET2 typically have the\nsame length. If SET1 is shorter than SET2, the extra characters at the\nend of SET2 are ignored.\n\nOn the other hand, making SET1 longer than SET2 is not portable;\nPOSIX says that the result is undefined. In this situation, BSD 'tr'\npads SET2 to the length of SET1 by repeating the last character of SET2\nas many times as necessary. System V 'tr' truncates SET1 to the length\nof SET2.\n\nBy default, GNU 'tr' handles this case like BSD 'tr'. When the\n'--truncate-set1' ('-t') option is given, GNU 'tr' handles this case\nlike the System V 'tr' instead. This option is ignored for operations\nother than translation.\n\nActing like System V 'tr' in this case breaks the relatively common\nBSD idiom:\n\ntr -cs A-Za-z0-9 '\\012'\n\nbecause it converts only zero bytes (the first element in the complement\nof SET1), rather than all non-alphanumerics, to newlines.\n", "subsections": [] }, "By the way, the above idiom is not portable because it uses ranges, and": { "content": "it assumes that the octal code for newline is 012. Assuming a POSIX\ncompliant 'tr', here is a better way to write it:\n\ntr -cs '[:alnum:]' '[\\n*]'\n", "subsections": [] }, "File: coreutils.info, Node: Squeezing and deleting, Prev: Translating, Up: tr invocation": { "content": "", "subsections": [] }, "When given just the '--delete' ('-d') option, 'tr' removes any input": { "content": "characters that are in SET1.\n\nWhen given just the '--squeeze-repeats' ('-s') option and not\ntranslating, 'tr' replaces each input sequence of a repeated character\nthat is in SET1 with a single occurrence of that character.\n\nWhen given both '--delete' and '--squeeze-repeats', 'tr' first\nperforms any deletions using SET1, then squeezes repeats from any\nremaining characters using SET2.\n\nThe '--squeeze-repeats' option may also be used when translating, in\nwhich case 'tr' first performs translation, then squeezes repeats from\nany remaining characters using SET2.\n\nHere are some examples to illustrate various combinations of options:\n\n* Remove all zero bytes:\n\ntr -d '\\0'\n\n* Put all words on lines by themselves. This converts all\nnon-alphanumeric characters to newlines, then squeezes each string\nof repeated newlines into a single newline:\n\ntr -cs '[:alnum:]' '[\\n*]'\n\n* Convert each sequence of repeated newlines to a single newline.\nI.e., delete blank lines:\n\ntr -s '\\n'\n\n* Find doubled occurrences of words in a document. For example,\npeople often write \"the the\" with the repeated words separated by a\nnewline. The Bourne shell script below works first by converting\neach sequence of punctuation and blank characters to a single\nnewline. That puts each \"word\" on a line by itself. Next it maps\nall uppercase characters to lower case, and finally it runs 'uniq'\nwith the '-d' option to print out only the words that were\nrepeated.\n\n#!/bin/sh\ncat -- \"$@\" \\\n| tr -s '[:punct:][:blank:]' '[\\n*]' \\\n| tr '[:upper:]' '[:lower:]' \\\n| uniq -d\n\n* Deleting a small set of characters is usually straightforward. For\nexample, to remove all 'a's, 'x's, and 'M's you would do this:\n\ntr -d axM\n\nHowever, when '-' is one of those characters, it can be tricky\nbecause '-' has special meanings. Performing the same task as\nabove but also removing all '-' characters, we might try 'tr -d\n-axM', but that would fail because 'tr' would try to interpret '-a'\nas a command-line option. Alternatively, we could try putting the\nhyphen inside the string, 'tr -d a-xM', but that wouldn't work\neither because it would make 'tr' interpret 'a-x' as the range of\ncharacters 'a'...'x' rather than the three. One way to solve the\nproblem is to put the hyphen at the end of the list of characters:\n\ntr -d axM-\n\nOr you can use '--' to terminate option processing:\n\ntr -d -- -axM\n\nMore generally, use the character class notation '[=c=]' with '-'\n(or any other character) in place of the 'c':\n\ntr -d '[=-=]axM'\n\nNote how single quotes are used in the above example to protect the\nsquare brackets from interpretation by a shell.\n", "subsections": [] }, "File: coreutils.info, Node: expand invocation, Next: unexpand invocation, Prev: tr invocation, Up: Operating on characters": { "content": "", "subsections": [ { "name": "9.2 'expand': Convert tabs to spaces", "content": "'expand' writes the contents of each given FILE, or standard input if\nnone are given or for a FILE of '-', to standard output, with tab\ncharacters converted to the appropriate number of spaces. Synopsis:\n\nexpand [OPTION]... [FILE]...\n\nBy default, 'expand' converts all tabs to spaces. It preserves\nbackspace characters in the output; they decrement the column count for\ntab calculations. The default action is equivalent to '-t 8' (set tabs\nevery 8 columns).\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-t TAB1[,TAB2]...'\n'--tabs=TAB1[,TAB2]...'\nIf only one tab stop is given, set the tabs TAB1 spaces apart\n(default is 8). Otherwise, set the tabs at columns TAB1, TAB2, ...\n(numbered from 0), and replace any tabs beyond the last tab stop\ngiven with single spaces. Tab stops can be separated by blanks as\nwell as by commas.\n\nAs a GNU extension the last TAB specified can be prefixed with a\n'/' to indicate a tab size to use for remaining positions. For\nexample, '--tabs=2,4,/8' will set tab stops at position 2 and 4,\nand every multiple of 8 after that.\n\nAlso the last TAB specified can be prefixed with a '+' to indicate\na tab size to use for remaining positions, offset from the final\nexplicitly specified tab stop. For example, to ignore the 1\ncharacter gutter present in diff output, one can specify a 1\ncharacter offset using '--tabs=1,+8', which will set tab stops at\npositions 1,9,17,...\n\nFor compatibility, GNU 'expand' also accepts the obsolete option\nsyntax, '-T1[,T2]...'. New scripts should use '-t T1[,T2]...'\ninstead.\n\n'-i'\n'--initial'\nOnly convert initial tabs (those that precede all non-space or\nnon-tab characters) on each line to spaces.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: unexpand invocation, Prev: expand invocation, Up: Operating on characters": { "content": "", "subsections": [ { "name": "9.3 'unexpand': Convert spaces to tabs", "content": "'unexpand' writes the contents of each given FILE, or standard input if\nnone are given or for a FILE of '-', to standard output, converting\nblanks at the beginning of each line into as many tab characters as\nneeded. In the default POSIX locale, a \"blank\" is a space or a tab;\nother locales may specify additional blank characters. Synopsis:\n\nunexpand [OPTION]... [FILE]...\n\nBy default, 'unexpand' converts only initial blanks (those that\nprecede all non-blank characters) on each line. It preserves backspace\ncharacters in the output; they decrement the column count for tab\ncalculations. By default, tabs are set at every 8th column.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-t TAB1[,TAB2]...'\n'--tabs=TAB1[,TAB2]...'\nIf only one tab stop is given, set the tabs TAB1 columns apart\ninstead of the default 8. Otherwise, set the tabs at columns TAB1,\nTAB2, ... (numbered from 0), and leave blanks beyond the tab stops\ngiven unchanged. Tab stops can be separated by blanks as well as\nby commas.\n\nAs a GNU extension the last TAB specified can be prefixed with a\n'/' to indicate a tab size to use for remaining positions. For\nexample, '--tabs=2,4,/8' will set tab stops at position 2 and 4,\nand every multiple of 8 after that.\n\nAlso the last TAB specified can be prefixed with a '+' to indicate\na tab size to use for remaining positions, offset from the final\nexplicitly specified tab stop. For example, to ignore the 1\ncharacter gutter present in diff output, one can specify a 1\ncharacter offset using '--tabs=1,+8', which will set tab stops at\npositions 1,9,17,...\n\nThis option implies the '-a' option.\n\nFor compatibility, GNU 'unexpand' supports the obsolete option\nsyntax, '-TAB1[,TAB2]...', where tab stops must be separated by\ncommas. (Unlike '-t', this obsolete option does not imply '-a'.)\nNew scripts should use '--first-only -t TAB1[,TAB2]...' instead.\n\n'-a'\n'--all'\nAlso convert all sequences of two or more blanks just before a tab\nstop, even if they occur after non-blank characters in a line.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: Directory listing, Next: Basic operations, Prev: Operating on characters, Up: Top": { "content": "", "subsections": [] }, "10 Directory listing": { "content": "", "subsections": [] }, "This chapter describes the 'ls' command and its variants 'dir' and": { "content": "'vdir', which list information about files.\n\n* Menu:\n\n* ls invocation:: List directory contents.\n* dir invocation:: Briefly ls.\n* vdir invocation:: Verbosely ls.\n* dircolors invocation:: Color setup for ls, etc.\n", "subsections": [] }, "File: coreutils.info, Node: ls invocation, Next: dir invocation, Up: Directory listing": { "content": "", "subsections": [ { "name": "10.1 'ls': List directory contents", "content": "" } ] }, "The 'ls' program lists information about files (of any type, including": { "content": "directories). Options and file arguments can be intermixed arbitrarily,\nas usual.\n\nFor non-option command-line arguments that are directories, by\ndefault 'ls' lists the contents of directories, not recursively, and\nomitting files with names beginning with '.'. For other non-option\narguments, by default 'ls' lists just the file name. If no non-option\nargument is specified, 'ls' operates on the current directory, acting as\nif it had been invoked with a single argument of '.'.\n\nBy default, the output is sorted alphabetically, according to the\nlocale settings in effect.(1) If standard output is a terminal, the\noutput is in columns (sorted vertically) and control characters are\noutput as question marks; otherwise, the output is listed one per line\nand control characters are output as-is.\n\nBecause 'ls' is such a fundamental program, it has accumulated many\noptions over the years. They are described in the subsections below;\nwithin each section, options are listed alphabetically (ignoring case).", "subsections": [] }, "The division of options into the subsections is not absolute, since some": { "content": "options affect more than one aspect of 'ls''s operation.\n\nExit status:\n\n0 success\n1 minor problems (e.g., failure to access a file or directory not\nspecified as a command line argument. This happens when listing a\ndirectory in which entries are actively being removed or renamed.)\n2 serious trouble (e.g., memory exhausted, invalid option, failure\nto access a file or directory specified as a command line argument\nor a directory loop)\n\nAlso see *note Common options::.\n\n* Menu:\n\n* Which files are listed::\n* What information is listed::\n* Sorting the output::\n* General output formatting::\n* Formatting file timestamps::\n* Formatting the file names::\n\n---------- Footnotes ----------\n\n(1) If you use a non-POSIX locale (e.g., by setting 'LCALL' to\n'enUS'), then 'ls' may produce output that is sorted differently than\nyou're accustomed to. In that case, set the 'LCALL' environment\nvariable to 'C'.\n", "subsections": [] }, "File: coreutils.info, Node: Which files are listed, Next: What information is listed, Up: ls invocation": { "content": "", "subsections": [] }, "These options determine which files 'ls' lists information for. By": { "content": "default, 'ls' lists files and the contents of any directories on the\ncommand line, except that in directories it ignores files whose names\nstart with '.'.\n\n'-a'\n'--all'\nIn directories, do not ignore file names that start with '.'.\n\n'-A'\n'--almost-all'\nIn directories, do not ignore all file names that start with '.';\nignore only '.' and '..'. The '--all' ('-a') option overrides this\noption.\n\n'-B'\n'--ignore-backups'\nIn directories, ignore files that end with '~'. This option is\nequivalent to '--ignore='*~' --ignore='.*~''.\n\n'-d'\n'--directory'\nList just the names of directories, as with other types of files,\nrather than listing their contents. Do not follow symbolic links\nlisted on the command line unless the '--dereference-command-line'\n('-H'), '--dereference' ('-L'), or\n'--dereference-command-line-symlink-to-dir' options are specified.\n\n'-H'\n'--dereference-command-line'\nIf a command line argument specifies a symbolic link, show\ninformation for the file the link references rather than for the\nlink itself.\n\n'--dereference-command-line-symlink-to-dir'\nDo not dereference symbolic links, with one exception: if a command\nline argument specifies a symbolic link that refers to a directory,\nshow information for that directory rather than for the link\nitself. This is the default behavior when no other\ndereferencing-related option has been specified ('--classify'\n('-F'), '--directory' ('-d'), ('-l'), '--dereference' ('-L'), or\n'--dereference-command-line' ('-H')).\n\n'--group-directories-first'\nGroup all the directories before the files and then sort the\ndirectories and the files separately using the selected sort key\n(see -sort option). That is, this option specifies a primary sort\nkey, and the -sort option specifies a secondary key. However, any\nuse of '--sort=none' ('-U') disables this option altogether.\n\n'--hide=PATTERN'\nIn directories, ignore files whose names match the shell pattern\nPATTERN, unless the '--all' ('-a') or '--almost-all' ('-A') is also\ngiven. This option acts like '--ignore=PATTERN' except that it has\nno effect if '--all' ('-a') or '--almost-all' ('-A') is also given.\n\nThis option can be useful in shell aliases. For example, if 'lx'\nis an alias for 'ls --hide='*~'' and 'ly' is an alias for 'ls\n--ignore='*~'', then the command 'lx -A' lists the file 'README~'\neven though 'ly -A' would not.\n\n'-I PATTERN'\n'--ignore=PATTERN'\nIn directories, ignore files whose names match the shell pattern\n(not regular expression) PATTERN. As in the shell, an initial '.'\nin a file name does not match a wildcard at the start of PATTERN.\nSometimes it is useful to give this option several times. For\nexample,\n\n$ ls --ignore='.??*' --ignore='.[^.]' --ignore='#*'\n\nThe first option ignores names of length 3 or more that start with\n'.', the second ignores all two-character names that start with '.'\nexcept '..', and the third ignores names that start with '#'.\n\n'-L'\n'--dereference'\nWhen showing file information for a symbolic link, show information\nfor the file the link references rather than the link itself.\nHowever, even with this option, 'ls' still prints the name of the\nlink itself, not the name of the file that the link points to.\n\n'-R'\n'--recursive'\nList the contents of all directories recursively.\n", "subsections": [] }, "File: coreutils.info, Node: What information is listed, Next: Sorting the output, Prev: Which files are listed, Up: ls invocation": { "content": "", "subsections": [] }, "These options affect the information that 'ls' displays. By default,": { "content": "only file names are shown.\n\n'--author'\nList each file's author when producing long format directory\nlistings. In GNU/Hurd, file authors can differ from their owners,\nbut in other operating systems the two are the same.\n\n'-D'\n'--dired'\nWith the long listing ('-l') format, print an additional line after\nthe main output:\n\n//DIRED// BEG1 END1 BEG2 END2 ...\n\nThe BEGN and ENDN are unsigned integers that record the byte\nposition of the beginning and end of each file name in the output.\nThis makes it easy for Emacs to find the names, even when they\ncontain unusual characters such as space or newline, without fancy\nsearching.\n\nIf directories are being listed recursively ('-R'), output a\nsimilar line with offsets for each subdirectory name:\n\n//SUBDIRED// BEG1 END1 ...\n\nFinally, output a line of the form:\n\n//DIRED-OPTIONS// --quoting-style=WORD\n\nwhere WORD is the quoting style (*note Formatting the file\nnames::).\n\nHere is an actual example:\n\n$ mkdir -p a/sub/deeper a/sub2\n$ touch a/f1 a/f2\n$ touch a/sub/deeper/file\n$ ls -gloRF --dired a\na:\ntotal 8\n-rw-r--r-- 1 0 Jun 10 12:27 f1\n-rw-r--r-- 1 0 Jun 10 12:27 f2\ndrwxr-xr-x 3 4096 Jun 10 12:27 sub/\ndrwxr-xr-x 2 4096 Jun 10 12:27 sub2/\n\na/sub:\ntotal 4\ndrwxr-xr-x 2 4096 Jun 10 12:27 deeper/\n\na/sub/deeper:\ntotal 0\n-rw-r--r-- 1 0 Jun 10 12:27 file\n\na/sub2:\ntotal 0\n//DIRED// 48 50 84 86 120 123 158 162 217 223 282 286\n//SUBDIRED// 2 3 167 172 228 240 290 296\n//DIRED-OPTIONS// --quoting-style=literal\n\nNote that the pairs of offsets on the '//DIRED//' line above\ndelimit these names: 'f1', 'f2', 'sub', 'sub2', 'deeper', 'file'.\nThe offsets on the '//SUBDIRED//' line delimit the following\ndirectory names: 'a', 'a/sub', 'a/sub/deeper', 'a/sub2'.\n\nHere is an example of how to extract the fifth entry name,\n'deeper', corresponding to the pair of offsets, 222 and 228:\n\n$ ls -gloRF --dired a > out\n$ dd bs=1 skip=222 count=6 < out 2>/dev/null; echo\ndeeper\n\nNote that although the listing above includes a trailing slash for\nthe 'deeper' entry, the offsets select the name without the\ntrailing slash. However, if you invoke 'ls' with '--dired' along\nwith an option like '--escape' (aka '-b') and operate on a file\nwhose name contains special characters, notice that the backslash\nis included:\n\n$ touch 'a b'\n$ ls -blog --dired 'a b'\n-rw-r--r-- 1 0 Jun 10 12:28 a\\ b\n//DIRED// 30 34\n//DIRED-OPTIONS// --quoting-style=escape\n\nIf you use a quoting style that adds quote marks (e.g.,\n'--quoting-style=c'), then the offsets include the quote marks. So\nbeware that the user may select the quoting style via the\nenvironment variable 'QUOTINGSTYLE'. Hence, applications using\n'--dired' should either specify an explicit\n'--quoting-style=literal' option (aka '-N' or '--literal') on the\ncommand line, or else be prepared to parse the escaped names.\n\n'--full-time'\nProduce long format directory listings, and list times in full. It\nis equivalent to using '--format=long' with '--time-style=full-iso'\n(*note Formatting file timestamps::).\n\n'-g'\nProduce long format directory listings, but don't display owner\ninformation.\n\n'-G'\n'--no-group'\nInhibit display of group information in a long format directory\nlisting. (This is the default in some non-GNU versions of 'ls', so\nwe provide this option for compatibility.)\n\n'-h'\n'--human-readable'\nAppend a size letter to each size, such as 'M' for mebibytes.\nPowers of 1024 are used, not 1000; 'M' stands for 1,048,576 bytes.\nThis option is equivalent to '--block-size=human-readable'. Use\nthe '--si' option if you prefer powers of 1000.\n\n'-i'\n'--inode'\nPrint the inode number (also called the file serial number and\nindex number) of each file to the left of the file name. (This\nnumber uniquely identifies each file within a particular file\nsystem.)\n\n'-l'\n'--format=long'\n'--format=verbose'\nIn addition to the name of each file, print the file type, file\nmode bits, number of hard links, owner name, group name, size, and\ntimestamp (*note Formatting file timestamps::), normally the\nmodification timestamp (the mtime, *note File timestamps::). If\nthe owner or group name cannot be determined, print the owner or\ngroup ID instead, right-justified as a cue that it is a number\nrather than a textual name. Print question marks for other\ninformation that cannot be determined.\n\nNormally the size is printed as a byte count without punctuation,\nbut this can be overridden (*note Block size::). For example, '-h'\nprints an abbreviated, human-readable count, and\n'--block-size=\"'1\"' prints a byte count with the thousands\nseparator of the current locale.\n\nFor each directory that is listed, preface the files with a line\n'total BLOCKS', where BLOCKS is the total disk allocation for all\nfiles in that directory. The block size currently defaults to 1024\nbytes, but this can be overridden (*note Block size::). The BLOCKS\ncomputed counts each hard link separately; this is arguably a\ndeficiency.\n\nThe file type is one of the following characters:\n\n'-'\nregular file\n'b'\nblock special file\n'c'\ncharacter special file\n'C'\nhigh performance (\"contiguous data\") file\n'd'\ndirectory\n'D'\ndoor (Solaris 2.5 and up)\n'l'\nsymbolic link\n'M'\noff-line (\"migrated\") file (Cray DMF)\n'n'\nnetwork special file (HP-UX)\n'p'\nFIFO (named pipe)\n'P'\nport (Solaris 10 and up)\n's'\nsocket\n'?'\nsome other file type\n\nThe file mode bits listed are similar to symbolic mode\nspecifications (*note Symbolic Modes::). But 'ls' combines\nmultiple bits into the third character of each set of permissions\nas follows:\n\n's'\nIf the set-user-ID or set-group-ID bit and the corresponding\nexecutable bit are both set.\n\n'S'\nIf the set-user-ID or set-group-ID bit is set but the\ncorresponding executable bit is not set.\n\n't'\nIf the restricted deletion flag or sticky bit, and the\nother-executable bit, are both set. The restricted deletion\nflag is another name for the sticky bit. *Note Mode\nStructure::.\n\n'T'\nIf the restricted deletion flag or sticky bit is set but the\nother-executable bit is not set.\n\n'x'\nIf the executable bit is set and none of the above apply.\n\n'-'\nOtherwise.\n\nFollowing the file mode bits is a single character that specifies\nwhether an alternate access method such as an access control list\napplies to the file. When the character following the file mode\nbits is a space, there is no alternate access method. When it is a\nprinting character, then there is such a method.\n\nGNU 'ls' uses a '.' character to indicate a file with a security\ncontext, but no other alternate access method.\n\nA file with any other combination of alternate access methods is\nmarked with a '+' character.\n\n'-n'\n'--numeric-uid-gid'\nProduce long format directory listings, but display right-justified\nnumeric user and group IDs instead of left-justified owner and\ngroup names.\n\n'-o'\nProduce long format directory listings, but don't display group\ninformation. It is equivalent to using '--format=long' with\n'--no-group' .\n\n'-s'\n'--size'\nPrint the disk allocation of each file to the left of the file\nname. This is the amount of disk space used by the file, which is\nusually a bit more than the file's size, but it can be less if the\nfile has holes.\n\nNormally the disk allocation is printed in units of 1024 bytes, but\nthis can be overridden (*note Block size::).\n\nFor files that are NFS-mounted from an HP-UX system to a BSD\nsystem, this option reports sizes that are half the correct values.\nOn HP-UX systems, it reports sizes that are twice the correct\nvalues for files that are NFS-mounted from BSD systems. This is\ndue to a flaw in HP-UX; it also affects the HP-UX 'ls' program.\n\n'--si'\nAppend an SI-style abbreviation to each size, such as 'M' for\nmegabytes. Powers of 1000 are used, not 1024; 'M' stands for\n1,000,000 bytes. This option is equivalent to '--block-size=si'.\nUse the '-h' or '--human-readable' option if you prefer powers of\n1024.\n\n'-Z'\n'--context'\nDisplay the SELinux security context or '?' if none is found. When\nused with the '-l' option, print the security context to the left\nof the size column.\n", "subsections": [] }, "File: coreutils.info, Node: Sorting the output, Next: General output formatting, Prev: What information is listed, Up: ls invocation": { "content": "", "subsections": [] }, "These options change the order in which 'ls' sorts the information it": { "content": "outputs. By default, sorting is done by character code (e.g., ASCII\norder).\n\n'-c'\n'--time=ctime'\n'--time=status'\nIf the long listing format (e.g., '-l', '-o') is being used, print\nthe status change timestamp (the ctime) instead of the mtime. When\nexplicitly sorting by time ('--sort=time' or '-t') or when not\nusing a long listing format, sort according to the ctime. *Note\nFile timestamps::.\n\n'-f'\nPrimarily, like '-U'--do not sort; list the files in whatever order\nthey are stored in the directory. But also enable '-a' (list all\nfiles) and disable '-l', '--color', and '-s' (if they were\nspecified before the '-f').\n\n'-r'\n'--reverse'\nReverse whatever the sorting method is--e.g., list files in reverse\nalphabetical order, youngest first, smallest first, or whatever.\n\n'-S'\n'--sort=size'\nSort by file size, largest first.\n\n'-t'\n'--sort=time'\nSort by modification timestamp (mtime) by default, newest first.\nThe timestamp to order by can be changed with the '--time' option.\n*Note File timestamps::.\n\n'-u'\n'--time=atime'\n'--time=access'\n'--time=use'\nIf the long listing format (e.g., '--format=long') is being used,\nprint the last access timestamp (the atime). When explicitly\nsorting by time ('--sort=time' or '-t') or when not using a long\nlisting format, sort according to the atime. *Note File\ntimestamps::.\n\n'--time=birth'\n'--time=creation'\nIf the long listing format (e.g., '--format=long') is being used,\nprint the file creation timestamp if available. When explicitly\nsorting by time ('--sort=time' or '-t') or when not using a long\nlisting format, sort according to the birth time. *Note File\ntimestamps::.\n\n'-U'\n'--sort=none'\nDo not sort; list the files in whatever order they are stored in\nthe directory. (Do not do any of the other unrelated things that\n'-f' does.) This is especially useful when listing very large\ndirectories, since not doing any sorting can be noticeably faster.\n\n'-v'\n'--sort=version'\nSort by version name and number, lowest first. It behaves like a\ndefault sort, except that each sequence of decimal digits is\ntreated numerically as an index/version number. (*Note Version\nsort ordering::.)\n\n'-X'\n'--sort=extension'\nSort directory contents alphabetically by file extension\n(characters after the last '.'); files with no extension are sorted\nfirst.\n", "subsections": [] }, "File: coreutils.info, Node: General output formatting, Next: Formatting file timestamps, Prev: Sorting the output, Up: ls invocation": { "content": "These options affect the appearance of the overall output.\n\n'-1'\n'--format=single-column'\nList one file per line. This is the default for 'ls' when standard\noutput is not a terminal. See also the '-b' and '-q' options to\nsuppress direct output of newline characters within a file name.\n\n'-C'\n'--format=vertical'\nList files in columns, sorted vertically. This is the default for\n'ls' if standard output is a terminal. It is always the default\nfor the 'dir' program. GNU 'ls' uses variable width columns to\ndisplay as many files as possible in the fewest lines.\n\n'--color [=WHEN]'\nSpecify whether to use color for distinguishing file types. WHEN\nmay be omitted, or one of:\n* none - Do not use color at all. This is the default.\n* auto - Only use color if standard output is a terminal.\n* always - Always use color.\nSpecifying '--color' and no WHEN is equivalent to '--color=always'.\nIf piping a colorized listing through a pager like 'less', use the\n'-R' option to pass the color codes to the terminal.\n\nNote that using the '--color' option may incur a noticeable\nperformance penalty when run in a directory with very many entries,\nbecause the default settings require that 'ls' 'stat' every single\nfile it lists. However, if you would like most of the file-type\ncoloring but can live without the other coloring options (e.g.,\nexecutable, orphan, sticky, other-writable, capability), use\n'dircolors' to set the 'LSCOLORS' environment variable like this,\neval $(dircolors -p | perl -pe \\\n's/^((CAP|S[ET]|O[TR]|M|E)\\w+).*/$1 00/' | dircolors -)\nand on a 'dirent.dtype'-capable file system, 'ls' will perform\nonly one 'stat' call per command line argument.\n\n'-F'\n'--classify'\n'--indicator-style=classify'\nAppend a character to each file name indicating the file type.\nAlso, for regular files that are executable, append '*'. The file\ntype indicators are '/' for directories, '@' for symbolic links,\n'|' for FIFOs, '=' for sockets, '>' for doors, and nothing for\nregular files. Do not follow symbolic links listed on the command\nline unless the '--dereference-command-line' ('-H'),\n'--dereference' ('-L'), or\n'--dereference-command-line-symlink-to-dir' options are specified.\n\n'--file-type'\n'--indicator-style=file-type'\nAppend a character to each file name indicating the file type.\nThis is like '-F', except that executables are not marked.\n\n'--hyperlink [=WHEN]'\nOutput codes recognized by some terminals to link to files using\nthe 'file://' URI format. WHEN may be omitted, or one of:\n* none - Do not use hyperlinks at all. This is the default.\n* auto - Only use hyperlinks if standard output is a terminal.\n* always - Always use hyperlinks.\nSpecifying '--hyperlink' and no WHEN is equivalent to\n'--hyperlink=always'.\n\n'--indicator-style=WORD'\nAppend a character indicator with style WORD to entry names, as\nfollows:\n\n'none'\nDo not append any character indicator; this is the default.\n'slash'\nAppend '/' for directories. This is the same as the '-p'\noption.\n'file-type'\nAppend '/' for directories, '@' for symbolic links, '|' for\nFIFOs, '=' for sockets, and nothing for regular files. This\nis the same as the '--file-type' option.\n'classify'\nAppend '*' for executable regular files, otherwise behave as\nfor 'file-type'. This is the same as the '-F' or '--classify'\noption.\n\n'-k'\n'--kibibytes'\nSet the default block size to its normal value of 1024 bytes,\noverriding any contrary specification in environment variables\n(*note Block size::). If '--block-size', '-h', '--human-readable',\nor '--si' options are used, they take precedence over '-k' or\n'--kibibytes' even if '-k' or '--kibibytes' is placed after the\nother options.\n\nThe '-k' or '--kibibytes' option affects the per-directory block\ncount written by the '-l' and similar options, and the size written\nby the '-s' or '--size' option. It does not affect the file size\nwritten by '-l'.\n\n'-m'\n'--format=commas'\nList files horizontally, with as many as will fit on each line,\nseparated by ', ' (a comma and a space).\n\n'-p'\n'--indicator-style=slash'\nAppend a '/' to directory names.\n\n'-x'\n'--format=across'\n'--format=horizontal'\nList the files in columns, sorted horizontally.\n\n'-T COLS'\n'--tabsize=COLS'\nAssume that each tab stop is COLS columns wide. The default is 8.\n'ls' uses tabs where possible in the output, for efficiency. If\nCOLS is zero, do not use tabs at all.\n\nSome terminal emulators might not properly align columns to the\nright of a TAB following a non-ASCII byte. You can avoid that\nissue by using the '-T0' option or put 'TABSIZE=0' in your\nenvironment, to tell 'ls' to align using spaces, not tabs.\n\n'-w COLS'\n'--width=COLS'\nAssume the screen is COLS columns wide. The default is taken from\nthe terminal settings if possible; otherwise the environment\nvariable 'COLUMNS' is used if it is set; otherwise the default is\n80. With a COLS value of '0', there is no limit on the length of\nthe output line, and that single output line will be delimited with\nspaces, not tabs.\n", "subsections": [] }, "File: coreutils.info, Node: Formatting file timestamps, Next: Formatting the file names, Prev: General output formatting, Up: ls invocation": { "content": "", "subsections": [] }, "By default, file timestamps are listed in abbreviated form, using a date": { "content": "like 'Mar 30 2002' for non-recent timestamps, and a date-without-year\nand time like 'Mar 30 23:45' for recent timestamps. This format can\nchange depending on the current locale as detailed below.\n\nA timestamp is considered to be \"recent\" if it is less than six\nmonths old, and is not dated in the future. If a timestamp dated today\nis not listed in recent form, the timestamp is in the future, which\nmeans you probably have clock skew problems which may break programs\nlike 'make' that rely on file timestamps. *Note File timestamps::.\n\nTimestamps are listed according to the time zone rules specified by\nthe 'TZ' environment variable, or by the system default rules if 'TZ' is\nnot set. *Note Specifying the Time Zone with 'TZ': (libc)TZ Variable.\n\nThe following option changes how file timestamps are printed.\n\n'--time-style=STYLE'\nList timestamps in style STYLE. The STYLE should be one of the\nfollowing:\n\n'+FORMAT'\nList timestamps using FORMAT, where FORMAT is interpreted like\nthe format argument of 'date' (*note date invocation::). For\nexample, '--time-style=\"+%Y-%m-%d %H:%M:%S\"' causes 'ls' to\nlist timestamps like '2002-03-30 23:45:56'. As with 'date',\nFORMAT's interpretation is affected by the 'LCTIME' locale\ncategory.\n\nIf FORMAT contains two format strings separated by a newline,\nthe former is used for non-recent files and the latter for\nrecent files; if you want output columns to line up, you may\nneed to insert spaces in one of the two formats.\n\n'full-iso'\nList timestamps in full using ISO 8601-like date, time, and\ntime zone components with nanosecond precision, e.g.,\n'2002-03-30 23:45:56.477817180 -0700'. This style is\nequivalent to '+%Y-%m-%d %H:%M:%S.%N %z'.\n\nThis is useful because the time output includes all the\ninformation that is available from the operating system. For\nexample, this can help explain 'make''s behavior, since GNU\n'make' uses the full timestamp to determine whether a file is\nout of date.\n\n'long-iso'\nList ISO 8601 date and time components with minute precision,\ne.g., '2002-03-30 23:45'. These timestamps are shorter than\n'full-iso' timestamps, and are usually good enough for\neveryday work. This style is equivalent to '+%Y-%m-%d %H:%M'.\n\n'iso'\nList ISO 8601 dates for non-recent timestamps (e.g.,\n'2002-03-30 '), and ISO 8601-like month, day, hour, and minute\nfor recent timestamps (e.g., '03-30 23:45'). These timestamps\nare uglier than 'long-iso' timestamps, but they carry nearly\nthe same information in a smaller space and their brevity\nhelps 'ls' output fit within traditional 80-column output\nlines. The following two 'ls' invocations are equivalent:\n\nnewline='\n'\nls -l --time-style=\"+%Y-%m-%d $newline%m-%d %H:%M\"\nls -l --time-style=\"iso\"\n\n'locale'\nList timestamps in a locale-dependent form. For example, a\nFinnish locale might list non-recent timestamps like 'maalis\n30 2002' and recent timestamps like 'maalis 30 23:45'.\nLocale-dependent timestamps typically consume more space than\n'iso' timestamps and are harder for programs to parse because\nlocale conventions vary so widely, but they are easier for\nmany people to read.\n\nThe 'LCTIME' locale category specifies the timestamp format.\nThe default POSIX locale uses timestamps like 'Mar 30 2002'\nand 'Mar 30 23:45'; in this locale, the following two 'ls'\ninvocations are equivalent:\n\nnewline='\n'\nls -l --time-style=\"+%b %e %Y$newline%b %e %H:%M\"\nls -l --time-style=\"locale\"\n\nOther locales behave differently. For example, in a German\nlocale, '--time-style=\"locale\"' might be equivalent to\n'--time-style=\"+%e. %b %Y $newline%e. %b %H:%M\"' and might\ngenerate timestamps like '30. Ma\"r 2002 ' and '30. Ma\"r 23:45'.\n\n'posix-STYLE'\nList POSIX-locale timestamps if the 'LCTIME' locale category\nis POSIX, STYLE timestamps otherwise. For example, the\n'posix-long-iso' style lists timestamps like 'Mar 30 2002'\nand 'Mar 30 23:45' when in the POSIX locale, and like\n'2002-03-30 23:45' otherwise.\n\nYou can specify the default value of the '--time-style' option with\nthe environment variable 'TIMESTYLE'; if 'TIMESTYLE' is not set the\ndefault style is 'locale'. GNU Emacs 21.3 and later use the '--dired'\noption and therefore can parse any date format, but if you are using", "subsections": [] }, "Emacs 21.1 or 21.2 and specify a non-POSIX locale you may need to set": { "content": "'TIMESTYLE=\"posix-long-iso\"'.\n\nTo avoid certain denial-of-service attacks, timestamps that would be\nlonger than 1000 bytes may be treated as errors.\n", "subsections": [] }, "File: coreutils.info, Node: Formatting the file names, Prev: Formatting file timestamps, Up: ls invocation": { "content": "These options change how file names themselves are printed.\n\n'-b'\n'--escape'\n'--quoting-style=escape'\nQuote nongraphic characters in file names using alphabetic and\noctal backslash sequences like those used in C.\n\n'-N'\n'--literal'\n'--quoting-style=literal'\nDo not quote file names. However, with 'ls' nongraphic characters\nare still printed as question marks if the output is a terminal and\nyou do not specify the '--show-control-chars' option.\n\n'-q'\n'--hide-control-chars'\nPrint question marks instead of nongraphic characters in file\nnames. This is the default if the output is a terminal and the\nprogram is 'ls'.\n\n'-Q'\n'--quote-name'\n'--quoting-style=c'\nEnclose file names in double quotes and quote nongraphic characters\nas in C.\n\n'--quoting-style=WORD'\nUse style WORD to quote file names and other strings that may\ncontain arbitrary characters. The WORD should be one of the\nfollowing:\n\n'literal'\nOutput strings as-is; this is the same as the '-N' or\n'--literal' option.\n'shell'\nQuote strings for the shell if they contain shell\nmetacharacters or would cause ambiguous output. The quoting\nis suitable for POSIX-compatible shells like 'bash', but it\ndoes not always work for incompatible shells like 'csh'.\n'shell-always'\nQuote strings for the shell, even if they would normally not\nrequire quoting.\n'shell-escape'\nLike 'shell', but also quoting non-printable characters using\nthe POSIX proposed '$''' syntax suitable for most shells.\n'shell-escape-always'\nLike 'shell-escape', but quote strings even if they would\nnormally not require quoting.\n'c'\nQuote strings as for C character string literals, including\nthe surrounding double-quote characters; this is the same as\nthe '-Q' or '--quote-name' option.\n'escape'\nQuote strings as for C character string literals, except omit\nthe surrounding double-quote characters; this is the same as\nthe '-b' or '--escape' option.\n'clocale'\nQuote strings as for C character string literals, except use\nsurrounding quotation marks appropriate for the locale.\n'locale'\nQuote strings as for C character string literals, except use\nsurrounding quotation marks appropriate for the locale, and\nquote 'like this' instead of \"like this\" in the default C\nlocale. This looks nicer on many displays.\n\nYou can specify the default value of the '--quoting-style' option\nwith the environment variable 'QUOTINGSTYLE'. If that environment\nvariable is not set, the default value is 'shell-escape' when the\noutput is a terminal, and 'literal' otherwise.\n\n'--show-control-chars'\nPrint nongraphic characters as-is in file names. This is the\ndefault unless the output is a terminal and the program is 'ls'.\n", "subsections": [] }, "File: coreutils.info, Node: dir invocation, Next: vdir invocation, Prev: ls invocation, Up: Directory listing": { "content": "", "subsections": [ { "name": "10.2 'dir': Briefly list directory contents", "content": "'dir' is equivalent to 'ls -C -b'; that is, by default files are listed\nin columns, sorted vertically, and special characters are represented by\nbackslash escape sequences.\n\n*Note 'ls': ls invocation.\n" } ] }, "File: coreutils.info, Node: vdir invocation, Next: dircolors invocation, Prev: dir invocation, Up: Directory listing": { "content": "", "subsections": [ { "name": "10.3 'vdir': Verbosely list directory contents", "content": "'vdir' is equivalent to 'ls -l -b'; that is, by default files are listed\nin long format and special characters are represented by backslash\nescape sequences.\n\n*Note 'ls': ls invocation.\n" } ] }, "File: coreutils.info, Node: dircolors invocation, Prev: vdir invocation, Up: Directory listing": { "content": "", "subsections": [ { "name": "10.4 'dircolors': Color setup for 'ls'", "content": "'dircolors' outputs a sequence of shell commands to set up the terminal\nfor color output from 'ls' (and 'dir', etc.). Typical usage:\n\neval \"$(dircolors [OPTION]... [FILE])\"\n\nIf FILE is specified, 'dircolors' reads it to determine which colors\nto use for which file types and extensions. Otherwise, a precompiled\ndatabase is used. For details on the format of these files, run\n'dircolors --print-database'.\n\nTo make 'dircolors' read a '~/.dircolors' file if it exists, you can\nput the following lines in your '~/.bashrc' (or adapt them to your\nfavorite shell):\n\nd=.dircolors\ntest -r $d && eval \"$(dircolors $d)\"\n\nThe output is a shell command to set the 'LSCOLORS' environment\nvariable. You can specify the shell syntax to use on the command line,\nor 'dircolors' will guess it from the value of the 'SHELL' environment\nvariable.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-b'\n'--sh'\n'--bourne-shell'\nOutput Bourne shell commands. This is the default if the 'SHELL'\nenvironment variable is set and does not end with 'csh' or 'tcsh'.\n\n'-c'\n'--csh'\n'--c-shell'\nOutput C shell commands. This is the default if 'SHELL' ends with\n'csh' or 'tcsh'.\n\n'-p'\n'--print-database'\nPrint the (compiled-in) default color configuration database. This\noutput is itself a valid configuration file, and is fairly\ndescriptive of the possibilities.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: Basic operations, Next: Special file types, Prev: Directory listing, Up: Top": { "content": "", "subsections": [] }, "11 Basic operations": { "content": "This chapter describes the commands for basic file manipulation:\ncopying, moving (renaming), and deleting (removing).\n\n* Menu:\n\n* cp invocation:: Copy files.\n* dd invocation:: Convert and copy a file.\n* install invocation:: Copy files and set attributes.\n* mv invocation:: Move (rename) files.\n* rm invocation:: Remove files or directories.\n* shred invocation:: Remove files more securely.\n", "subsections": [] }, "File: coreutils.info, Node: cp invocation, Next: dd invocation, Up: Basic operations": { "content": "", "subsections": [ { "name": "11.1 'cp': Copy files and directories", "content": "'cp' copies files (or, optionally, directories). The copy is completely\nindependent of the original. You can either copy one file to another,\nor copy arbitrarily many files to a destination directory. Synopses:\n\ncp [OPTION]... [-T] SOURCE DEST\ncp [OPTION]... SOURCE... DIRECTORY\ncp [OPTION]... -t DIRECTORY SOURCE...\n\n* If two file names are given, 'cp' copies the first file to the\nsecond.\n\n* If the '--target-directory' ('-t') option is given, or failing that\nif the last file is a directory and the '--no-target-directory'\n('-T') option is not given, 'cp' copies each SOURCE file to the\nspecified directory, using the SOURCEs' names.\n\nGenerally, files are written just as they are read. For exceptions,\nsee the '--sparse' option below.\n\nBy default, 'cp' does not copy directories. However, the '-R', '-a',\nand '-r' options cause 'cp' to copy recursively by descending into\nsource directories and copying files to corresponding destination\ndirectories.\n\nWhen copying from a symbolic link, 'cp' normally follows the link\nonly when not copying recursively or when '--link' ('-l') is used. This\ndefault can be overridden with the '--archive' ('-a'), '-d',\n'--dereference' ('-L'), '--no-dereference' ('-P'), and '-H' options. If\nmore than one of these options is specified, the last one silently\noverrides the others.\n\nWhen copying to a symbolic link, 'cp' follows the link only when it\nrefers to an existing regular file. However, when copying to a dangling\nsymbolic link, 'cp' refuses by default, and fails with a diagnostic,\nsince the operation is inherently dangerous. This behavior is contrary\nto historical practice and to POSIX. Set 'POSIXLYCORRECT' to make 'cp'\nattempt to create the target of a dangling destination symlink, in spite\nof the possible risk. Also, when an option like '--backup' or '--link'\nacts to rename or remove the destination before copying, 'cp' renames or\nremoves the symbolic link rather than the file it points to.\n\nBy default, 'cp' copies the contents of special files only when not\ncopying recursively. This default can be overridden with the\n'--copy-contents' option.\n\n'cp' generally refuses to copy a file onto itself, with the following\nexception: if '--force --backup' is specified with SOURCE and DEST\nidentical, and referring to a regular file, 'cp' will make a backup\nfile, either regular or numbered, as specified in the usual ways (*note" } ] }, "Backup options::). This is useful when you simply want to make a backup": { "content": "of an existing file before changing it.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-a'\n'--archive'\nPreserve as much as possible of the structure and attributes of the\noriginal files in the copy (but do not attempt to preserve internal\ndirectory structure; i.e., 'ls -U' may list the entries in a copied\ndirectory in a different order). Try to preserve SELinux security\ncontext and extended attributes (xattr), but ignore any failure to\ndo that and print no corresponding diagnostic. Equivalent to '-dR\n--preserve=all' with the reduced diagnostics.\n\n'--attributes-only'\nCopy only the specified attributes of the source file to the\ndestination. If the destination already exists, do not alter its\ncontents. See the '--preserve' option for controlling which\nattributes to copy.\n\n'-b'\n'--backup[=METHOD]'\n*Note Backup options::. Make a backup of each file that would\notherwise be overwritten or removed. As a special case, 'cp' makes\na backup of SOURCE when the force and backup options are given and\nSOURCE and DEST are the same name for an existing, regular file.\nOne useful application of this combination of options is this tiny\nBourne shell script:\n\n#!/bin/sh\n# Usage: backup FILE...\n# Create a GNU-style backup of each listed FILE.\nfail=0\nfor i; do\ncp --backup --force --preserve=all -- \"$i\" \"$i\" || fail=1\ndone\nexit $fail\n\n'--copy-contents'\nIf copying recursively, copy the contents of any special files\n(e.g., FIFOs and device files) as if they were regular files. This\nmeans trying to read the data in each source file and writing it to\nthe destination. It is usually a mistake to use this option, as it\nnormally has undesirable effects on special files like FIFOs and\nthe ones typically found in the '/dev' directory. In most cases,\n'cp -R --copy-contents' will hang indefinitely trying to read from\nFIFOs and special files like '/dev/console', and it will fill up\nyour destination disk if you use it to copy '/dev/zero'. This\noption has no effect unless copying recursively, and it does not\naffect the copying of symbolic links.\n\n'-d'\nCopy symbolic links as symbolic links rather than copying the files\nthat they point to, and preserve hard links between source files in\nthe copies. Equivalent to '--no-dereference --preserve=links'.\n\n'-f'\n'--force'\nWhen copying without this option and an existing destination file\ncannot be opened for writing, the copy fails. However, with\n'--force', when a destination file cannot be opened, 'cp' then\ntries to recreate the file by first removing it. Note '--force'\nalone will not remove dangling symlinks. When this option is\ncombined with '--link' ('-l') or '--symbolic-link' ('-s'), the\ndestination link is replaced, and unless '--backup' ('-b') is also\ngiven there is no brief moment when the destination does not exist.\nAlso see the description of '--remove-destination'.\n\nThis option is independent of the '--interactive' or '-i' option:\nneither cancels the effect of the other.\n\nThis option is ignored when the '--no-clobber' or '-n' option is\nalso used.\n\n'-H'\nIf a command line argument specifies a symbolic link, then copy the\nfile it points to rather than the symbolic link itself. However,\ncopy (preserving its nature) any symbolic link that is encountered\nvia recursive traversal.\n\n'-i'\n'--interactive'\nWhen copying a file other than a directory, prompt whether to\noverwrite an existing destination file. The '-i' option overrides\na previous '-n' option.\n\n'-l'\n'--link'\nMake hard links instead of copies of non-directories.\n\n'-L'\n'--dereference'\nFollow symbolic links when copying from them. With this option,\n'cp' cannot create a symbolic link. For example, a symlink (to\nregular file) in the source tree will be copied to a regular file\nin the destination tree.\n\n'-n'\n'--no-clobber'\nDo not overwrite an existing file; silently do nothing instead.\nThis option overrides a previous '-i' option. This option is\nmutually exclusive with '-b' or '--backup' option.\n\n'-P'\n'--no-dereference'\nCopy symbolic links as symbolic links rather than copying the files\nthat they point to. This option affects only symbolic links in the\nsource; symbolic links in the destination are always followed if\npossible.\n\n'-p'\n'--preserve[=ATTRIBUTELIST]'\nPreserve the specified attributes of the original files. If\nspecified, the ATTRIBUTELIST must be a comma-separated list of one\nor more of the following strings:\n\n'mode'\nPreserve the file mode bits and access control lists.\n'ownership'\nPreserve the owner and group. On most modern systems, only\nusers with appropriate privileges may change the owner of a\nfile, and ordinary users may preserve the group ownership of a\nfile only if they happen to be a member of the desired group.\n'timestamps'\nPreserve the times of last access and last modification, when\npossible. On older systems, it is not possible to preserve\nthese attributes when the affected file is a symbolic link.\nHowever, many systems now provide the 'utimensat' function,\nwhich makes it possible even for symbolic links.\n'links'\nPreserve in the destination files any links between\ncorresponding source files. Note that with '-L' or '-H', this\noption can convert symbolic links to hard links. For example,\n$ mkdir c; : > a; ln -s a b; cp -aH a b c; ls -i1 c\n74161745 a\n74161745 b\nNote the inputs: 'b' is a symlink to regular file 'a', yet the\nfiles in destination directory, 'c/', are hard-linked. Since\n'-a' implies '--no-dereference' it would copy the symlink, but\nthe later '-H' tells 'cp' to dereference the command line\narguments where it then sees two files with the same inode\nnumber. Then the '--preserve=links' option also implied by\n'-a' will preserve the perceived hard link.\n\nHere is a similar example that exercises 'cp''s '-L' option:\n$ mkdir b c; (cd b; : > a; ln -s a b); cp -aL b c; ls -i1 c/b\n74163295 a\n74163295 b\n\n'context'\nPreserve SELinux security context of the file, or fail with\nfull diagnostics.\n'xattr'\nPreserve extended attributes of the file, or fail with full\ndiagnostics. If 'cp' is built without xattr support, ignore\nthis option. If SELinux context, ACLs or Capabilities are\nimplemented using xattrs, they are preserved implicitly by\nthis option as well, i.e., even without specifying\n'--preserve=mode' or '--preserve=context'.\n'all'\nPreserve all file attributes. Equivalent to specifying all of\nthe above, but with the difference that failure to preserve\nSELinux security context or extended attributes does not\nchange 'cp''s exit status. In contrast to '-a', all but\n'Operation not supported' warnings are output.\n\nUsing '--preserve' with no ATTRIBUTELIST is equivalent to\n'--preserve=mode,ownership,timestamps'.\n\nIn the absence of this option, the permissions of existing\ndestination files are unchanged. Each new file is created with the\nmode of the corresponding source file minus the set-user-ID,\nset-group-ID, and sticky bits as the create mode; the operating\nsystem then applies either the umask or a default ACL, possibly\nresulting in a more restrictive file mode. *Note File\npermissions::.\n\n'--no-preserve=ATTRIBUTELIST'\nDo not preserve the specified attributes. The ATTRIBUTELIST has\nthe same form as for '--preserve'.\n\n'--parents'\nForm the name of each destination file by appending to the target\ndirectory a slash and the specified name of the source file. The\nlast argument given to 'cp' must be the name of an existing\ndirectory. For example, the command:\n\ncp --parents a/b/c existingdir\n\ncopies the file 'a/b/c' to 'existingdir/a/b/c', creating any\nmissing intermediate directories.\n\n'-R'\n'-r'\n'--recursive'\nCopy directories recursively. By default, do not follow symbolic\nlinks in the source unless used together with the '--link' ('-l')\noption; see the '--archive' ('-a'), '-d', '--dereference' ('-L'),\n'--no-dereference' ('-P'), and '-H' options. Special files are\ncopied by creating a destination file of the same type as the\nsource; see the '--copy-contents' option. It is not portable to\nuse '-r' to copy symbolic links or special files. On some non-GNU\nsystems, '-r' implies the equivalent of '-L' and '--copy-contents'\nfor historical reasons. Also, it is not portable to use '-R' to\ncopy symbolic links unless you also specify '-P', as POSIX allows\nimplementations that dereference symbolic links by default.\n\n'--reflink[=WHEN]'\nPerform a lightweight, copy-on-write (COW) copy, if supported by\nthe file system. Once it has succeeded, beware that the source and\ndestination files share the same disk data blocks as long as they\nremain unmodified. Thus, if a disk I/O error affects data blocks\nof one of the files, the other suffers the same fate.\n\nThe WHEN value can be one of the following:\n\n'always'\nThe default behavior: if the copy-on-write operation is not\nsupported then report the failure for each file and exit with\na failure status.\n\n'auto'\nIf the copy-on-write operation is not supported then fall back\nto the standard copy behavior.\n\n'never'\nDisable copy-on-write operation and use the standard copy\nbehavior.\n\nThis option is overridden by the '--link', '--symbolic-link' and\n'--attributes-only' options, thus allowing it to be used to\nconfigure the default data copying behavior for 'cp'. For example,\nwith the following alias, 'cp' will use the minimum amount of space\nsupported by the file system.\n\nalias cp='cp --reflink=auto --sparse=always'\n\n'--remove-destination'\nRemove each existing destination file before attempting to open it\n(contrast with '-f' above).\n\n'--sparse=WHEN'\nA \"sparse file\" contains \"holes\"--a sequence of zero bytes that does\nnot occupy any physical disk blocks; the 'read' system call reads\nthese as zeros. This can both save considerable disk space and\nincrease speed, since many binary files contain lots of consecutive\nzero bytes. By default, 'cp' detects holes in input source files\nvia a crude heuristic and makes the corresponding output file\nsparse as well. Only regular files may be sparse.\n\nThe WHEN value can be one of the following:\n\n'auto'\nThe default behavior: if the input file is sparse, attempt to\nmake the output file sparse, too. However, if an output file\nexists but refers to a non-regular file, then do not attempt\nto make it sparse.\n\n'always'\nFor each sufficiently long sequence of zero bytes in the input\nfile, attempt to create a corresponding hole in the output\nfile, even if the input file does not appear to be sparse.\nThis is useful when the input file resides on a file system\nthat does not support sparse files (for example, 'efs' file\nsystems in SGI IRIX 5.3 and earlier), but the output file is\non a type of file system that does support them. Holes may be\ncreated only in regular files, so if the destination file is\nof some other type, 'cp' does not even try to make it sparse.\n\n'never'\nNever make the output file sparse. This is useful in creating\na file for use with the 'mkswap' command, since such a file\nmust not have any holes.\n\n'--strip-trailing-slashes'\nRemove any trailing slashes from each SOURCE argument. *Note\nTrailing slashes::.\n\n'-s'\n'--symbolic-link'\nMake symbolic links instead of copies of non-directories. All\nsource file names must be absolute (starting with '/') unless the\ndestination files are in the current directory. This option merely\nresults in an error message on systems that do not support symbolic\nlinks.\n\n'-S SUFFIX'\n'--suffix=SUFFIX'\nAppend SUFFIX to each backup file made with '-b'. *Note Backup\noptions::.\n\n'-t DIRECTORY'\n'--target-directory=DIRECTORY'\nSpecify the destination DIRECTORY. *Note Target directory::.\n\n'-T'\n'--no-target-directory'\nDo not treat the last operand specially when it is a directory or a\nsymbolic link to a directory. *Note Target directory::.\n\n'-u'\n'--update'\nDo not copy a non-directory that has an existing destination with\nthe same or newer modification timestamp. If timestamps are being\npreserved, the comparison is to the source timestamp truncated to\nthe resolutions of the destination file system and of the system\ncalls used to update timestamps; this avoids duplicate work if\nseveral 'cp -pu' commands are executed with the same source and\ndestination. This option is ignored if the '-n' or '--no-clobber'\noption is also specified. Also, if '--preserve=links' is also\nspecified (like with 'cp -au' for example), that will take\nprecedence; consequently, depending on the order that files are\nprocessed from the source, newer files in the destination may be\nreplaced, to mirror hard links in the source.\n\n'-v'\n'--verbose'\nPrint the name of each file before copying it.\n\n'-x'\n'--one-file-system'\nSkip subdirectories that are on different file systems from the one\nthat the copy started on. However, mount point directories are\ncopied.\n\n'-Z'\n'--context[=CONTEXT]'\nWithout a specified CONTEXT, adjust the SELinux security context\naccording to the system default type for destination files,\nsimilarly to the 'restorecon' command. The long form of this\noption with a specific context specified, will set the context for\nnewly created files only. With a specified context, if both\nSELinux and SMACK are disabled, a warning is issued. This option\nis mutually exclusive with the '--preserve=context' option, and\noverrides the '--preserve=all' and '-a' options.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: dd invocation, Next: install invocation, Prev: cp invocation, Up: Basic operations": { "content": "", "subsections": [ { "name": "11.2 'dd': Convert and copy a file", "content": "'dd' copies a file (from standard input to standard output, by default)\nwith a changeable I/O block size, while optionally performing\nconversions on it. Synopses:\n\ndd [OPERAND]...\ndd OPTION\n\nThe only options are '--help' and '--version'. *Note Common\noptions::. 'dd' accepts the following operands, whose syntax was\ninspired by the DD (data definition) statement of OS/360 JCL.\n\n'if=FILE'\nRead from FILE instead of standard input.\n\n'of=FILE'\nWrite to FILE instead of standard output. Unless 'conv=notrunc' is\ngiven, 'dd' truncates FILE to zero bytes (or the size specified\nwith 'seek=').\n\n'ibs=BYTES'\nSet the input block size to BYTES. This makes 'dd' read BYTES per\nblock. The default is 512 bytes.\n\n'obs=BYTES'\nSet the output block size to BYTES. This makes 'dd' write BYTES\nper block. The default is 512 bytes.\n\n'bs=BYTES'\nSet both input and output block sizes to BYTES. This makes 'dd'\nread and write BYTES per block, overriding any 'ibs' and 'obs'\nsettings. In addition, if no data-transforming 'conv' operand is\nspecified, input is copied to the output as soon as it's read, even\nif it is smaller than the block size.\n\n'cbs=BYTES'\nSet the conversion block size to BYTES. When converting\nvariable-length records to fixed-length ones ('conv=block') or the\nreverse ('conv=unblock'), use BYTES as the fixed record length.\n\n'skip=N'\nSkip N 'ibs'-byte blocks in the input file before copying. If\n'iflag=skipbytes' is specified, N is interpreted as a byte count\nrather than a block count.\n\n'seek=N'\nSkip N 'obs'-byte blocks in the output file before copying. if\n'oflag=seekbytes' is specified, N is interpreted as a byte count\nrather than a block count.\n\n'count=N'\nCopy N 'ibs'-byte blocks from the input file, instead of everything\nuntil the end of the file. if 'iflag=countbytes' is specified, N\nis interpreted as a byte count rather than a block count. Note if\nthe input may return short reads as could be the case when reading\nfrom a pipe for example, 'iflag=fullblock' will ensure that\n'count=' corresponds to complete input blocks rather than the\ntraditional POSIX specified behavior of counting input read\noperations.\n\n'status=LEVEL'\nSpecify the amount of information printed. If this operand is\ngiven multiple times, the last one takes precedence. The LEVEL\nvalue can be one of the following:\n\n'none'\nDo not print any informational or warning messages to stderr.\nError messages are output as normal.\n\n'noxfer'\nDo not print the final transfer rate and volume statistics\nthat normally make up the last status line.\n\n'progress'\nPrint the transfer rate and volume statistics on stderr, when\nprocessing each input block. Statistics are output on a\nsingle line at most once every second, but updates can be\ndelayed when waiting on I/O.\n\nTransfer information is normally output to stderr upon receipt of\nthe 'INFO' signal or when 'dd' exits, and defaults to the following\nform in the C locale:\n\n7287+1 records in\n116608+0 records out\n59703296 bytes (60 MB, 57 MiB) copied, 0.0427974 s, 1.4 GB/s\n\nThe notation 'W+P' stands for W whole blocks and P partial blocks.\nA partial block occurs when a read or write operation succeeds but\ntransfers less data than the block size. An additional line like\n'1 truncated record' or '10 truncated records' is output after the\n'records out' line if 'conv=block' processing truncated one or more\ninput records.\n\n'conv=CONVERSION[,CONVERSION]...'\nConvert the file as specified by the CONVERSION argument(s). (No\nspaces around any comma(s).)\n\nConversions:\n\n'ascii'\nConvert EBCDIC to ASCII, using the conversion table specified\nby POSIX. This provides a 1:1 translation for all 256 bytes.\nThis implies 'conv=unblock'; input is converted to ASCII\nbefore trailing spaces are deleted.\n\n'ebcdic'\nConvert ASCII to EBCDIC. This is the inverse of the 'ascii'\nconversion. This implies 'conv=block'; trailing spaces are\nadded before being converted to EBCDIC.\n\n'ibm'\nThis acts like 'conv=ebcdic', except it uses the alternate\nconversion table specified by POSIX. This is not a 1:1\ntranslation, but reflects common historical practice for '~',\n'[', and ']'.\n\nThe 'ascii', 'ebcdic', and 'ibm' conversions are mutually\nexclusive. If you use any of these conversions, you should\nalso use the 'cbs=' operand.\n\n'block'\nFor each line in the input, output 'cbs' bytes, replacing the\ninput newline with a space and truncating or padding input\nlines with spaces as necessary.\n\n'unblock'\nRemove any trailing spaces in each 'cbs'-sized input block,\nand append a newline.\n\nThe 'block' and 'unblock' conversions are mutually exclusive.\n\n'lcase'\nChange uppercase letters to lowercase.\n\n'ucase'\nChange lowercase letters to uppercase.\n\nThe 'lcase' and 'ucase' conversions are mutually exclusive.\n\n'sparse'\nTry to seek rather than write NUL output blocks. On a file\nsystem that supports sparse files, this will create sparse\noutput when extending the output file. Be careful when using\nthis conversion in conjunction with 'conv=notrunc' or\n'oflag=append'. With 'conv=notrunc', existing data in the\noutput file corresponding to NUL blocks from the input, will\nbe untouched. With 'oflag=append' the seeks performed will be\nineffective. Similarly, when the output is a device rather\nthan a file, NUL input blocks are not copied, and therefore\nthis conversion is most useful with virtual or pre zeroed\ndevices.\n\n'swab'\nSwap every pair of input bytes. GNU 'dd', unlike others,\nworks when an odd number of bytes are read--the last byte is\nsimply copied (since there is nothing to swap it with).\n\n'sync'\nPad every input block to size of 'ibs' with trailing zero\nbytes. When used with 'block' or 'unblock', pad with spaces\ninstead of zero bytes.\n\nThe following \"conversions\" are really file flags and don't affect\ninternal processing:\n\n'excl'\nFail if the output file already exists; 'dd' must create the\noutput file itself.\n\n'nocreat'\nDo not create the output file; the output file must already\nexist.\n\nThe 'excl' and 'nocreat' conversions are mutually exclusive.\n\n'notrunc'\nDo not truncate the output file.\n\n'noerror'\nContinue after read errors.\n\n'fdatasync'\nSynchronize output data just before finishing. This forces a\nphysical write of output data.\n\n'fsync'\nSynchronize output data and metadata just before finishing.\nThis forces a physical write of output data and metadata.\n\n'iflag=FLAG[,FLAG]...'\nAccess the input file using the flags specified by the FLAG\nargument(s). (No spaces around any comma(s).)\n\n'oflag=FLAG[,FLAG]...'\nAccess the output file using the flags specified by the FLAG\nargument(s). (No spaces around any comma(s).)\n\nHere are the flags. Not every flag is supported on every operating\nsystem.\n\n'append'\nWrite in append mode, so that even if some other process is\nwriting to this file, every 'dd' write will append to the\ncurrent contents of the file. This flag makes sense only for\noutput. If you combine this flag with the 'of=FILE' operand,\nyou should also specify 'conv=notrunc' unless you want the\noutput file to be truncated before being appended to.\n\n'cio'\nUse concurrent I/O mode for data. This mode performs direct\nI/O and drops the POSIX requirement to serialize all I/O to\nthe same file. A file cannot be opened in CIO mode and with a\nstandard open at the same time.\n\n'direct'\nUse direct I/O for data, avoiding the buffer cache. Note that\nthe kernel may impose restrictions on read or write buffer\nsizes. For example, with an ext4 destination file system and\na Linux-based kernel, using 'oflag=direct' will cause writes\nto fail with 'EINVAL' if the output buffer size is not a\nmultiple of 512.\n\n'directory'\n\nFail unless the file is a directory. Most operating systems\ndo not allow I/O to a directory, so this flag has limited\nutility.\n\n'dsync'\nUse synchronized I/O for data. For the output file, this\nforces a physical write of output data on each write. For the\ninput file, this flag can matter when reading from a remote\nfile that has been written to synchronously by some other\nprocess. Metadata (e.g., last-access and last-modified time)\nis not necessarily synchronized.\n\n'sync'\nUse synchronized I/O for both data and metadata.\n\n'nocache'\nRequest to discard the system data cache for a file. When\ncount=0 all cached data for the file is specified, otherwise\nthe cache is dropped for the processed portion of the file.\nAlso when count=0, failure to discard the cache is diagnosed\nand reflected in the exit status.\n\nNote data that is not already persisted to storage will not be\ndiscarded from cache, so note the use of the 'sync'\nconversions in the examples below, which are used to maximize\nthe effectiveness of the 'nocache' flag.\n\nHere are some usage examples:\n\n# Advise to drop cache for whole file\ndd if=ifile iflag=nocache count=0\n\n# Ensure drop cache for the whole file\ndd of=ofile oflag=nocache conv=notrunc,fdatasync count=0\n\n# Advise to drop cache for part of file\n# Note the kernel will only consider complete and\n# already persisted pages.\ndd if=ifile iflag=nocache skip=10 count=10 of=/dev/null\n\n# Stream data using just the read-ahead cache.\n# See also the 'direct' flag.\ndd if=ifile of=ofile iflag=nocache oflag=nocache,sync\n\n'nonblock'\nUse non-blocking I/O.\n\n'noatime'\nDo not update the file's access timestamp. *Note File\ntimestamps::. Some older file systems silently ignore this\nflag, so it is a good idea to test it on your files before\nrelying on it.\n\n'noctty'\nDo not assign the file to be a controlling terminal for 'dd'.\nThis has no effect when the file is not a terminal. On many\nhosts (e.g., GNU/Linux hosts), this flag has no effect at all.\n\n'nofollow'\nDo not follow symbolic links.\n\n'nolinks'\nFail if the file has multiple hard links.\n\n'binary'\nUse binary I/O. This flag has an effect only on nonstandard\nplatforms that distinguish binary from text I/O.\n\n'text'\nUse text I/O. Like 'binary', this flag has no effect on\nstandard platforms.\n\n'fullblock'\nAccumulate full blocks from input. The 'read' system call may\nreturn early if a full block is not available. When that\nhappens, continue calling 'read' to fill the remainder of the\nblock. This flag can be used only with 'iflag'. This flag is\nuseful with pipes for example as they may return short reads.\nIn that case, this flag is needed to ensure that a 'count='\nargument is interpreted as a block count rather than a count\nof read operations.\n\n'countbytes'\nInterpret the 'count=' operand as a byte count, rather than a\nblock count, which allows specifying a length that is not a\nmultiple of the I/O block size. This flag can be used only\nwith 'iflag'.\n\n'skipbytes'\nInterpret the 'skip=' operand as a byte count, rather than a\nblock count, which allows specifying an offset that is not a\nmultiple of the I/O block size. This flag can be used only\nwith 'iflag'.\n\n'seekbytes'\nInterpret the 'seek=' operand as a byte count, rather than a\nblock count, which allows specifying an offset that is not a\nmultiple of the I/O block size. This flag can be used only\nwith 'oflag'.\n\nThese flags are not supported on all systems, and 'dd' rejects\nattempts to use them when they are not supported. When reading\nfrom standard input or writing to standard output, the 'nofollow'\nand 'noctty' flags should not be specified, and the other flags\n(e.g., 'nonblock') can affect how other processes behave with the\naffected file descriptors, even after 'dd' exits.\n\nThe numeric-valued strings above (N and BYTES) can be followed by a\nmultiplier: 'b'=512, 'c'=1, 'w'=2, 'xM'=M, or any of the standard block\nsize suffixes like 'k'=1024 (*note Block size::).\n\nAny block size you specify via 'bs=', 'ibs=', 'obs=', 'cbs=' should\nnot be too large--values larger than a few megabytes are generally\nwasteful or (as in the gigabyte..exabyte case) downright\ncounterproductive or error-inducing.\n\nTo process data that is at an offset or size that is not a multiple\nof the I/O block size, you can use the 'skipbytes', 'seekbytes' and\n'countbytes' flags. Alternatively the traditional method of separate\n'dd' invocations can be used. For example, the following shell commands\ncopy data in 512 KiB blocks between a disk and a tape, but do not save\nor restore a 4 KiB label at the start of the disk:\n\ndisk=/dev/rdsk/c0t1d0s2\ntape=/dev/rmt/0\n\n# Copy all but the label from disk to tape.\n(dd bs=4k skip=1 count=0 && dd bs=512k) <$disk >$tape\n\n# Copy from tape back to disk, but leave the disk label alone.\n(dd bs=4k seek=1 count=0 && dd bs=512k) <$tape >$disk\n\nFor failing disks, other tools come with a great variety of extra\nfunctionality to ease the saving of as much data as possible before the\ndisk finally dies, e.g. GNU 'ddrescue'\n(https://www.gnu.org/software/ddrescue/). However, in some cases such a\ntool is not available or the administrator feels more comfortable with\nthe handling of 'dd'. As a simple rescue method, call 'dd' as shown in\nthe following example: the operand 'conv=noerror,sync' is used to\ncontinue after read errors and to pad out bad reads with NULs, while\n'iflag=fullblock' caters for short reads (which traditionally never\noccur on disk based devices):\n\n# Rescue data from an (unmounted!) partition of a failing disk.\ndd conv=noerror,sync iflag=fullblock /mnt/rescue.img\n\nSending an 'INFO' signal (or 'USR1' signal where that is unavailable)\nto a running 'dd' process makes it print I/O statistics to standard\nerror and then resume copying. In the example below, 'dd' is run in the\nbackground to copy 5GB of data. The 'kill' command makes it output\nintermediate I/O statistics, and when 'dd' completes normally or is\nkilled by the 'SIGINT' signal, it outputs the final statistics.\n\n# Ignore the signal so we never inadvertently terminate the dd child.\n# Note this is not needed when SIGINFO is available.\ntrap '' USR1\n\n# Run dd with the fullblock iflag to avoid short reads\n# which can be triggered by reception of signals.\ndd iflag=fullblock if=/dev/zero of=/dev/null count=5000000 bs=1000 & pid=$!\n\n# Output stats every second.\nwhile kill -s USR1 $pid 2>/dev/null; do sleep 1; done\n\nThe above script will output in the following format:\n\n3441325+0 records in\n3441325+0 records out\n3441325000 bytes (3.4 GB, 3.2 GiB) copied, 1.00036 s, 3.4 GB/s\n5000000+0 records in\n5000000+0 records out\n5000000000 bytes (5.0 GB, 4.7 GiB) copied, 1.44433 s, 3.5 GB/s\n\nThe 'status=progress' operand periodically updates the last line of\nthe transfer statistics above.\n\nOn systems lacking the 'INFO' signal 'dd' responds to the 'USR1'\nsignal instead, unless the 'POSIXLYCORRECT' environment variable is\nset.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: install invocation, Next: mv invocation, Prev: dd invocation, Up: Basic operations": { "content": "", "subsections": [ { "name": "11.3 'install': Copy files and set attributes", "content": "'install' copies files while setting their file mode bits and, if\npossible, their owner and group. Synopses:\n\ninstall [OPTION]... [-T] SOURCE DEST\ninstall [OPTION]... SOURCE... DIRECTORY\ninstall [OPTION]... -t DIRECTORY SOURCE...\ninstall [OPTION]... -d DIRECTORY...\n\n* If two file names are given, 'install' copies the first file to the\nsecond.\n\n* If the '--target-directory' ('-t') option is given, or failing that\nif the last file is a directory and the '--no-target-directory'\n('-T') option is not given, 'install' copies each SOURCE file to\nthe specified directory, using the SOURCEs' names.\n\n* If the '--directory' ('-d') option is given, 'install' creates each\nDIRECTORY and any missing parent directories. Parent directories\nare created with mode 'u=rwx,go=rx' (755), regardless of the '-m'\noption or the current umask. *Note Directory Setuid and Setgid::,\nfor how the set-user-ID and set-group-ID bits of parent directories\nare inherited.\n\n'install' is similar to 'cp', but allows you to control the\nattributes of destination files. It is typically used in Makefiles to\ncopy programs into their destination directories. It refuses to copy\nfiles onto themselves.\n\n'install' never preserves extended attributes (xattr).\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-b'\n'--backup[=METHOD]'\n*Note Backup options::. Make a backup of each file that would\notherwise be overwritten or removed.\n\n'-C'\n'--compare'\nCompare each pair of source and destination files, and if the\ndestination has identical content and any specified owner, group,\npermissions, and possibly SELinux context, then do not modify the\ndestination at all. Note this option is best used in conjunction\nwith '--user', '--group' and '--mode' options, lest 'install'\nincorrectly determines the default attributes that installed files\nwould have (as it doesn't consider setgid directories and POSIX\ndefault ACLs for example). This could result in redundant copies\nor attributes that are not reset to the correct defaults.\n\n'-c'\nIgnored; for compatibility with old Unix versions of 'install'.\n\n'-D'\nCreate any missing parent directories of DEST, then copy SOURCE to\nDEST. Explicitly specifying the '--target-directory=DIR' will\nsimilarly ensure the presence of that hierarchy before copying\nSOURCE arguments.\n\n'-d'\n'--directory'\nCreate any missing parent directories, giving them the default\nattributes. Then create each given directory, setting their owner,\ngroup and mode as given on the command line or to the defaults.\n\n'-g GROUP'\n'--group=GROUP'\nSet the group ownership of installed files or directories to GROUP.\nThe default is the process's current group. GROUP may be either a\ngroup name or a numeric group ID.\n\n'-m MODE'\n'--mode=MODE'\nSet the file mode bits for the installed file or directory to MODE,\nwhich can be either an octal number, or a symbolic mode as in\n'chmod', with 'a=' (no access allowed to anyone) as the point of\ndeparture (*note File permissions::). The default mode is\n'u=rwx,go=rx,a-s'--read, write, and execute for the owner, read and\nexecute for group and other, and with set-user-ID and set-group-ID\ndisabled. This default is not quite the same as '755', since it\ndisables instead of preserving set-user-ID and set-group-ID on\ndirectories. *Note Directory Setuid and Setgid::.\n\n'-o OWNER'\n'--owner=OWNER'\nIf 'install' has appropriate privileges (is run as root), set the\nownership of installed files or directories to OWNER. The default\nis 'root'. OWNER may be either a user name or a numeric user ID.\n\n'--preserve-context'\nPreserve the SELinux security context of files and directories.\nFailure to preserve the context in all of the files or directories\nwill result in an exit status of 1. If SELinux is disabled then\nprint a warning and ignore the option.\n\n'-p'\n'--preserve-timestamps'\nSet the time of last access and the time of last modification of\neach installed file to match those of each corresponding original\nfile. When a file is installed without this option, its last\naccess and last modification timestamps are both set to the time of\ninstallation. This option is useful if you want to use the last\nmodification timestamps of installed files to keep track of when\nthey were last built as opposed to when they were last installed.\n\n'-s'\n'--strip'\nStrip the symbol tables from installed binary executables.\n\n'--strip-program=PROGRAM'\nProgram used to strip binaries.\n\n'-S SUFFIX'\n'--suffix=SUFFIX'\nAppend SUFFIX to each backup file made with '-b'. *Note Backup\noptions::.\n\n'-t DIRECTORY'\n'--target-directory=DIRECTORY'\nSpecify the destination DIRECTORY. *Note Target directory::. Also\nspecifying the '-D' option will ensure the directory is present.\n\n'-T'\n'--no-target-directory'\nDo not treat the last operand specially when it is a directory or a\nsymbolic link to a directory. *Note Target directory::.\n\n'-v'\n'--verbose'\nPrint the name of each file before copying it.\n\n'-Z'\n'--context[=CONTEXT]'\nWithout a specified CONTEXT, adjust the SELinux security context\naccording to the system default type for destination files,\nsimilarly to the 'restorecon' command. The long form of this\noption with a specific context specified, will set the context for\nnewly created files only. With a specified context, if both\nSELinux and SMACK are disabled, a warning is issued. This option\nis mutually exclusive with the '--preserve-context' option.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: mv invocation, Next: rm invocation, Prev: install invocation, Up: Basic operations": { "content": "", "subsections": [ { "name": "11.4 'mv': Move (rename) files", "content": "'mv' moves or renames files (or directories). Synopses:\n\nmv [OPTION]... [-T] SOURCE DEST\nmv [OPTION]... SOURCE... DIRECTORY\nmv [OPTION]... -t DIRECTORY SOURCE...\n\n* If two file names are given, 'mv' moves the first file to the\nsecond.\n\n* If the '--target-directory' ('-t') option is given, or failing that\nif the last file is a directory and the '--no-target-directory'\n('-T') option is not given, 'mv' moves each SOURCE file to the\nspecified directory, using the SOURCEs' names.\n\n'mv' can move any type of file from one file system to another." } ] }, "Prior to version '4.0' of the fileutils, 'mv' could move only regular": { "content": "files between file systems. For example, now 'mv' can move an entire\ndirectory hierarchy including special device files from one partition to\nanother. It first uses some of the same code that's used by 'cp -a' to\ncopy the requested directories and files, then (assuming the copy\nsucceeded) it removes the originals. If the copy fails, then the part\nthat was copied to the destination partition is removed. If you were to\ncopy three directories from one partition to another and the copy of the\nfirst directory succeeded, but the second didn't, the first would be\nleft on the destination partition and the second and third would be left\non the original partition.\n\n'mv' always tries to copy extended attributes (xattr), which may\ninclude SELinux context, ACLs or Capabilities. Upon failure all but\n'Operation not supported' warnings are output.\n\nIf a destination file exists but is normally unwritable, standard\ninput is a terminal, and the '-f' or '--force' option is not given, 'mv'\nprompts the user for whether to replace the file. (You might own the\nfile, or have write permission on its directory.) If the response is\nnot affirmative, the file is skipped.\n\nWarning: Avoid specifying a source name with a trailing slash, when\nit might be a symlink to a directory. Otherwise, 'mv' may do something\nvery surprising, since its behavior depends on the underlying rename\nsystem call. On a system with a modern Linux-based kernel, it fails\nwith 'errno=ENOTDIR'. However, on other systems (at least FreeBSD 6.1\nand Solaris 10) it silently renames not the symlink but rather the\ndirectory referenced by the symlink. *Note Trailing slashes::.\n\nNote: 'mv' will only replace empty directories in the destination.\nConflicting populated directories are skipped with a diagnostic.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-b'\n'--backup[=METHOD]'\n*Note Backup options::. Make a backup of each file that would\notherwise be overwritten or removed.\n\n'-f'\n'--force'\nDo not prompt the user before removing a destination file. If you\nspecify more than one of the '-i', '-f', '-n' options, only the\nfinal one takes effect.\n\n'-i'\n'--interactive'\nPrompt whether to overwrite each existing destination file,\nregardless of its permissions. If the response is not affirmative,\nthe file is skipped. If you specify more than one of the '-i',\n'-f', '-n' options, only the final one takes effect.\n\n'-n'\n'--no-clobber'\nDo not overwrite an existing file; silently do nothing instead. If\nyou specify more than one of the '-i', '-f', '-n' options, only the\nfinal one takes effect. This option is mutually exclusive with\n'-b' or '--backup' option.\n\n'-u'\n'--update'\nDo not move a non-directory that has an existing destination with\nthe same or newer modification timestamp. If the move is across\nfile system boundaries, the comparison is to the source timestamp\ntruncated to the resolutions of the destination file system and of\nthe system calls used to update timestamps; this avoids duplicate\nwork if several 'mv -u' commands are executed with the same source\nand destination. This option is ignored if the '-n' or\n'--no-clobber' option is also specified.\n\n'-v'\n'--verbose'\nPrint the name of each file before moving it.\n\n'--strip-trailing-slashes'\nRemove any trailing slashes from each SOURCE argument. *Note\nTrailing slashes::.\n\n'-S SUFFIX'\n'--suffix=SUFFIX'\nAppend SUFFIX to each backup file made with '-b'. *Note Backup\noptions::.\n\n'-t DIRECTORY'\n'--target-directory=DIRECTORY'\nSpecify the destination DIRECTORY. *Note Target directory::.\n\n'-T'\n'--no-target-directory'\nDo not treat the last operand specially when it is a directory or a\nsymbolic link to a directory. *Note Target directory::.\n\n'-Z'\n'--context'\nThis option functions similarly to the 'restorecon' command, by\nadjusting the SELinux security context according to the system\ndefault type for destination files and each created directory.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: rm invocation, Next: shred invocation, Prev: mv invocation, Up: Basic operations": { "content": "", "subsections": [ { "name": "11.5 'rm': Remove files or directories", "content": "'rm' removes each given FILE. By default, it does not remove\ndirectories. Synopsis:\n\nrm [OPTION]... [FILE]...\n\nIf the '-I' or '--interactive=once' option is given, and there are\nmore than three files or the '-r', '-R', or '--recursive' are given,\nthen 'rm' prompts the user for whether to proceed with the entire\noperation. If the response is not affirmative, the entire command is\naborted.\n\nOtherwise, if a file is unwritable, standard input is a terminal, and\nthe '-f' or '--force' option is not given, or the '-i' or\n'--interactive=always' option is given, 'rm' prompts the user for\nwhether to remove the file. If the response is not affirmative, the\nfile is skipped.\n\nAny attempt to remove a file whose last file name component is '.' or\n'..' is rejected without any prompting, as mandated by POSIX.\n\nWarning: If you use 'rm' to remove a file, it is usually possible\nto recover the contents of that file. If you want more assurance that\nthe contents are unrecoverable, consider using 'shred'.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-d'\n'--dir'\nRemove the listed directories if they are empty.\n\n'-f'\n'--force'\nIgnore nonexistent files and missing operands, and never prompt the\nuser. Ignore any previous '--interactive' ('-i') option.\n\n'-i'\nPrompt whether to remove each file. If the response is not\naffirmative, the file is skipped. Ignore any previous '--force'\n('-f') option. Equivalent to '--interactive=always'.\n\n'-I'\nPrompt once whether to proceed with the command, if more than three\nfiles are named or if a recursive removal is requested. Ignore any\nprevious '--force' ('-f') option. Equivalent to\n'--interactive=once'.\n\n'--interactive [=WHEN]'\nSpecify when to issue an interactive prompt. WHEN may be omitted,\nor one of:\n* never - Do not prompt at all.\n* once - Prompt once if more than three files are named or if a\nrecursive removal is requested. Equivalent to '-I'.\n* always - Prompt for every file being removed. Equivalent to\n'-i'.\n'--interactive' with no WHEN is equivalent to\n'--interactive=always'.\n\n'--one-file-system'\nWhen removing a hierarchy recursively, skip any directory that is\non a file system different from that of the corresponding command\nline argument. This option is useful when removing a build\n\"chroot\" hierarchy, which normally contains no valuable data.\nHowever, it is not uncommon to bind-mount '/home' into such a\nhierarchy, to make it easier to use one's start-up file. The catch\nis that it's easy to forget to unmount '/home'. Then, when you use\n'rm -rf' to remove your normally throw-away chroot, that command\nwill remove everything under '/home', too. Use the\n'--one-file-system' option, and it will warn about and skip\ndirectories on other file systems. Of course, this will not save\nyour '/home' if it and your chroot happen to be on the same file\nsystem. See also '--preserve-root=all' to protect command line\narguments themselves.\n\n'--preserve-root [=all]'\nFail upon any attempt to remove the root directory, '/', when used\nwith the '--recursive' option. This is the default behavior.\n*Note Treating / specially::. When 'all' is specified, reject any\ncommand line argument that is not on the same file system as its\nparent.\n\n'--no-preserve-root'\nDo not treat '/' specially when removing recursively. This option\nis not recommended unless you really want to remove all the files\non your computer. *Note Treating / specially::.\n\n'-r'\n'-R'\n'--recursive'\nRemove the listed directories and their contents recursively.\n\n'-v'\n'--verbose'\nPrint the name of each file before removing it.\n\nOne common question is how to remove files whose names begin with a\n'-'. GNU 'rm', like every program that uses the 'getopt' function to\nparse its arguments, lets you use the '--' option to indicate that all\nfollowing arguments are non-options. To remove a file called '-f' in\nthe current directory, you could type either:\n\nrm -- -f\n\nor:\n\nrm ./-f\n\nThe Unix 'rm' program's use of a single '-' for this purpose predates\nthe development of the 'getopt' standard syntax.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: shred invocation, Prev: rm invocation, Up: Basic operations": { "content": "", "subsections": [ { "name": "11.6 'shred': Remove files more securely", "content": "'shred' overwrites devices or files, to help prevent even extensive\nforensics from recovering the data.\n\nOrdinarily when you remove a file (*note rm invocation::), its data\nand metadata are not actually destroyed. Only the file's directory\nentry is removed, and the file's storage is reclaimed only when no\nprocess has the file open and no other directory entry links to the\nfile. And even if file's data and metadata's storage space is freed for\nfurther reuse, there are undelete utilities that will attempt to\nreconstruct the file from the data in freed storage, and that can bring\nthe file back if the storage was not rewritten.\n\nOn a busy system with a nearly-full device, space can get reused in a\nfew seconds. But there is no way to know for sure. And although the\nundelete utilities and already-existing processes require insider or\nsuperuser access, you may be wary of the superuser, of processes running\non your behalf, or of attackers that can physically access the storage\ndevice. So if you have sensitive data, you may want to be sure that\nrecovery is not possible by plausible attacks like these.\n\nThe best way to remove something irretrievably is to destroy the\nmedia it's on with acid, melt it down, or the like. For cheap removable\nmedia this is often the preferred method. However, some storage devices\nare expensive or are harder to destroy, so the 'shred' utility tries to\nachieve a similar effect non-destructively, by overwriting the file with\nnon-sensitive data.\n\n*Please note* that 'shred' relies on a crucial assumption: that the\nfile system and hardware overwrite data in place. Although this is\ncommon and is the traditional way to do things, but many modern file\nsystem designs do not satisfy this assumption. Exceptions include:\n\n* Log-structured or journaled file systems, such as ext3/ext4 (in\n'data=journal' mode), Btrfs, NTFS, ReiserFS, XFS, ZFS, file systems\nsupplied with AIX and Solaris, etc., when they are configured to\njournal data.\n\n* File systems that write redundant data and carry on even if some\nwrites fail, such as RAID-based file systems.\n\n* File systems that make snapshots, such as Network Appliance's NFS\nserver.\n\n* File systems that cache in temporary locations, such as NFS version\n3 clients.\n\n* Compressed file systems.\n\nFor ext3 and ext4 file systems, 'shred' is less effective when the\nfile system is in 'data=journal' mode, which journals file data in\naddition to just metadata. In both the 'data=ordered' (default) and\n'data=writeback' modes, 'shred' works as usual. The ext3/ext4\njournaling modes can be changed by adding the 'data=something' option to\nthe mount options for a particular file system in the '/etc/fstab' file,\nas documented in the 'mount' man page ('man mount'). Alternatively, if\nyou know how large the journal is, you can shred the journal by\nshredding enough file data so that the journal cycles around and fills\nup with shredded data.\n\nIf you are not sure how your file system operates, then you should\nassume that it does not overwrite data in place, which means 'shred'\ncannot reliably operate on regular files in your file system.\n\nGenerally speaking, it is more reliable to shred a device than a\nfile, since this bypasses file system design issues mentioned above." } ] }, "However, devices are also problematic for shredding, for reasons such as": { "content": "the following:\n\n* Solid-state storage devices (SSDs) typically do wear leveling to\nprolong service life, and this means writes are distributed to\nother blocks by the hardware, so \"overwritten\" data blocks are\nstill present in the underlying device.\n\n* Most storage devices map out bad blocks invisibly to the\napplication; if the bad blocks contain sensitive data, 'shred'\nwon't be able to destroy it.\n\n* With some obsolete storage technologies, it may be possible to take\n(say) a floppy disk back to a laboratory and use a lot of sensitive\n(and expensive) equipment to look for the faint \"echoes\" of the\noriginal data underneath the overwritten data. With these older\ntechnologies, if the file has been overwritten only once, it's\nreputedly not even that hard. Luckily, this kind of data recovery\nhas become difficult, and there is no public evidence that today's\nhigher-density storage devices can be analyzed in this way.\n\nThe 'shred' command can use many overwrite passes, with data\npatterns chosen to maximize the damage they do to the old data. By\ndefault the patterns are designed for best effect on hard drives\nusing now-obsolete technology; for newer devices, a single pass\nshould suffice. For more details, see the source code and Peter\nGutmann's paper 'Secure Deletion of Data from Magnetic and\nSolid-State Memory'\n(https://www.cs.auckland.ac.nz/~pgut001/pubs/securedel.html), from\nthe proceedings of the Sixth USENIX Security Symposium (San Jose,\nCalifornia, July 22-25, 1996).\n\n'shred' makes no attempt to detect or report these problems, just as\nit makes no attempt to do anything about backups. However, since it is\nmore reliable to shred devices than files, 'shred' by default does not\ndeallocate or remove the output file. This default is more suitable for\ndevices, which typically cannot be deallocated and should not be\nremoved.\n\nFinally, consider the risk of backups and mirrors. File system\nbackups and remote mirrors may contain copies of the file that cannot be\nremoved, and that will allow a shredded file to be recovered later. So\nif you keep any data you may later want to destroy using 'shred', be\nsure that it is not backed up or mirrored.\n\nshred [OPTION]... FILE[...]\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-f'\n'--force'\nOverride file permissions if necessary to allow overwriting.\n\n'-n NUMBER'\n'--iterations=NUMBER'\nBy default, 'shred' uses 3 passes of overwrite. You can reduce\nthis to save time, or increase it if you think it's appropriate.\nAfter 25 passes all of the internal overwrite patterns will have\nbeen used at least once.\n\n'--random-source=FILE'\nUse FILE as a source of random data used to overwrite and to choose\npass ordering. *Note Random sources::.\n\n'-s BYTES'\n'--size=BYTES'\nShred the first BYTES bytes of the file. The default is to shred\nthe whole file. BYTES can be followed by a size specification like\n'K', 'M', or 'G' to specify a multiple. *Note Block size::.\n\n'-u'\n'--remove[=HOW]'\nAfter shredding a file, deallocate it (if possible) and then remove\nit. If a file has multiple links, only the named links will be\nremoved. Often the file name is less sensitive than the file data,\nin which case the optional HOW parameter, supported with the long\nform option, gives control of how to more efficiently remove each\ndirectory entry. The 'unlink' parameter will just use a standard\nunlink call, 'wipe' will also first obfuscate bytes in the name,\nand 'wipesync' will also sync each obfuscated byte in the name to\ndisk. Note 'wipesync' is the default method, but can be expensive,\nrequiring a sync for every character in every file. This can\nbecome significant with many files, or is redundant if your file\nsystem provides synchronous metadata updates.\n\n'-v'\n'--verbose'\nDisplay to standard error all status updates as sterilization\nproceeds.\n\n'-x'\n'--exact'\nBy default, 'shred' rounds the size of a regular file up to the\nnext multiple of the file system block size to fully erase the\nslack space in the last block of the file. This space may contain\nportions of the current system memory on some systems for example.\nUse '--exact' to suppress that behavior. Thus, by default if you\nshred a 10-byte regular file on a system with 512-byte blocks, the\nresulting file will be 512 bytes long. With this option, shred\ndoes not increase the apparent size of the file.\n\n'-z'\n'--zero'\nNormally, the last pass that 'shred' writes is made up of random\ndata. If this would be conspicuous on your storage device (for\nexample, because it looks like encrypted data), or you just think\nit's tidier, the '--zero' option adds an additional overwrite pass\nwith all zero bits. This is in addition to the number of passes\nspecified by the '--iterations' option.\n\nYou might use the following command to erase the file system you\ncreated on a USB flash drive. This command typically takes several\nminutes, depending on the drive's size and write speed. On modern\nstorage devices a single pass should be adequate, and will take one\nthird the time of the default three-pass approach.\n\nshred -v -n 1 /dev/sdd1\n\nSimilarly, to erase all data on a selected partition of your hard\ndisk, you could give a command like the following.\n\n# 1 pass, write pseudo-random data; 3x faster than the default\nshred -v -n1 /dev/sda5\n\nTo be on the safe side, use at least one pass that overwrites using\npseudo-random data. I.e., don't be tempted to use '-n0 --zero', in case\nsome disk controller optimizes the process of writing blocks of all\nzeros, and thereby does not clear all bytes in a block. Some SSDs may\ndo just that.\n\nA FILE of '-' denotes standard output. The intended use of this is\nto shred a removed temporary file. For example:\n\ni=$(mktemp)\nexec 3<>\"$i\"\nrm -- \"$i\"\necho \"Hello, world\" >&3\nshred - >&3\nexec 3>-\n\nHowever, the command 'shred - >file' does not shred the contents of\nFILE, since the shell truncates FILE before invoking 'shred'. Use the\ncommand 'shred file' or (if using a Bourne-compatible shell) the command\n'shred - 1<>file' instead.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: Special file types, Next: Changing file attributes, Prev: Basic operations, Up: Top": { "content": "", "subsections": [] }, "12 Special file types": { "content": "", "subsections": [] }, "This chapter describes commands which create special types of files (and": { "content": "'rmdir', which removes directories, one special file type).\n\nAlthough Unix-like operating systems have markedly fewer special file\ntypes than others, not everything can be treated only as the\nundifferentiated byte stream of \"normal files\". For example, when a\nfile is created or removed, the system must record this information,\nwhich it does in a \"directory\"--a special type of file. Although you can\nread directories as normal files, if you're curious, in order for the\nsystem to do its job it must impose a structure, a certain order, on the\nbytes of the file. Thus it is a \"special\" type of file.\n\nBesides directories, other special file types include named pipes\n(FIFOs), symbolic links, sockets, and so-called \"special files\".\n\n* Menu:\n\n* link invocation:: Make a hard link via the link syscall\n* ln invocation:: Make links between files.\n* mkdir invocation:: Make directories.\n* mkfifo invocation:: Make FIFOs (named pipes).\n* mknod invocation:: Make block or character special files.\n* readlink invocation:: Print value of a symlink or canonical file name.\n* rmdir invocation:: Remove empty directories.\n* unlink invocation:: Remove files via the unlink syscall\n", "subsections": [] }, "File: coreutils.info, Node: link invocation, Next: ln invocation, Up: Special file types": { "content": "", "subsections": [ { "name": "12.1 'link': Make a hard link via the link syscall", "content": "'link' creates a single hard link at a time. It is a minimalist\ninterface to the system-provided 'link' function. *Note (libc)Hard" } ] }, "Links::. It avoids the bells and whistles of the more commonly-used": { "content": "'ln' command (*note ln invocation::). Synopsis:\n\nlink FILENAME LINKNAME\n\nFILENAME must specify an existing file, and LINKNAME must specify a\nnonexistent entry in an existing directory. 'link' simply calls 'link\n(FILENAME, LINKNAME)' to create the link.\n\nOn a GNU system, this command acts like 'ln --directory\n--no-target-directory FILENAME LINKNAME'. However, the '--directory'\nand '--no-target-directory' options are not specified by POSIX, and the\n'link' command is more portable in practice.\n\nIf FILENAME is a symbolic link, it is unspecified whether LINKNAME\nwill be a hard link to the symbolic link or to the target of the\nsymbolic link. Use 'ln -P' or 'ln -L' to specify which behavior is\ndesired.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: ln invocation, Next: mkdir invocation, Prev: link invocation, Up: Special file types": { "content": "", "subsections": [ { "name": "12.2 'ln': Make links between files", "content": "'ln' makes links between files. By default, it makes hard links; with\nthe '-s' option, it makes symbolic (or \"soft\") links. Synopses:\n\nln [OPTION]... [-T] TARGET LINKNAME\nln [OPTION]... TARGET\nln [OPTION]... TARGET... DIRECTORY\nln [OPTION]... -t DIRECTORY TARGET...\n\n* If two file names are given, 'ln' creates a link to the first file\nfrom the second.\n\n* If one TARGET is given, 'ln' creates a link to that file in the\ncurrent directory.\n\n* If the '--target-directory' ('-t') option is given, or failing that\nif the last file is a directory and the '--no-target-directory'\n('-T') option is not given, 'ln' creates a link to each TARGET file\nin the specified directory, using the TARGETs' names.\n\nNormally 'ln' does not replace existing files. Use the '--force'\n('-f') option to replace them unconditionally, the '--interactive'\n('-i') option to replace them conditionally, and the '--backup' ('-b')\noption to rename them. Unless the '--backup' ('-b') option is used\nthere is no brief moment when the destination does not exist; this is an\nextension to POSIX.\n\nA \"hard link\" is another name for an existing file; the link and the\noriginal are indistinguishable. Technically speaking, they share the\nsame inode, and the inode contains all the information about a\nfile--indeed, it is not incorrect to say that the inode is the file." } ] }, "Most systems prohibit making a hard link to a directory; on those where": { "content": "it is allowed, only the super-user can do so (and with caution, since\ncreating a cycle will cause problems to many other utilities). Hard\nlinks cannot cross file system boundaries. (These restrictions are not\nmandated by POSIX, however.)\n\n\"Symbolic links\" (\"symlinks\" for short), on the other hand, are a\nspecial file type (which not all kernels support: System V release 3\n(and older) systems lack symlinks) in which the link file actually\nrefers to a different file, by name. When most operations (opening,\nreading, writing, and so on) are passed the symbolic link file, the\nkernel automatically \"dereferences\" the link and operates on the target\nof the link. But some operations (e.g., removing) work on the link file\nitself, rather than on its target. The owner and group of a symlink are\nnot significant to file access performed through the link, but do have\nimplications on deleting a symbolic link from a directory with the\nrestricted deletion bit set. On the GNU system, the mode of a symlink\nhas no significance and cannot be changed, but on some BSD systems, the\nmode can be changed and will affect whether the symlink will be\ntraversed in file name resolution. *Note (libc)Symbolic Links::.\n\nSymbolic links can contain arbitrary strings; a \"dangling symlink\"\noccurs when the string in the symlink does not resolve to a file. There\nare no restrictions against creating dangling symbolic links. There are\ntrade-offs to using absolute or relative symlinks. An absolute symlink\nalways points to the same file, even if the directory containing the\nlink is moved. However, if the symlink is visible from more than one\nmachine (such as on a networked file system), the file pointed to might\nnot always be the same. A relative symbolic link is resolved in\nrelation to the directory that contains the link, and is often useful in\nreferring to files on the same device without regards to what name that\ndevice is mounted on when accessed via networked machines.\n\nWhen creating a relative symlink in a different location than the\ncurrent directory, the resolution of the symlink will be different than\nthe resolution of the same string from the current directory.", "subsections": [] }, "Therefore, many users prefer to first change directories to the location": { "content": "where the relative symlink will be created, so that tab-completion or\nother file resolution will find the same target as what will be placed\nin the symlink.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-b'\n'--backup[=METHOD]'\n*Note Backup options::. Make a backup of each file that would\notherwise be overwritten or removed.\n\n'-d'\n'-F'\n'--directory'\nAllow users with appropriate privileges to attempt to make hard\nlinks to directories. However, note that this will probably fail\ndue to system restrictions, even for the super-user.\n\n'-f'\n'--force'\nRemove existing destination files.\n\n'-i'\n'--interactive'\nPrompt whether to remove existing destination files.\n\n'-L'\n'--logical'\nIf '-s' is not in effect, and the source file is a symbolic link,\ncreate the hard link to the file referred to by the symbolic link,\nrather than the symbolic link itself.\n\n'-n'\n'--no-dereference'\nDo not treat the last operand specially when it is a symbolic link\nto a directory. Instead, treat it as if it were a normal file.\n\nWhen the destination is an actual directory (not a symlink to one),\nthere is no ambiguity. The link is created in that directory. But\nwhen the specified destination is a symlink to a directory, there\nare two ways to treat the user's request. 'ln' can treat the\ndestination just as it would a normal directory and create the link\nin it. On the other hand, the destination can be viewed as a\nnon-directory--as the symlink itself. In that case, 'ln' must\ndelete or backup that symlink before creating the new link. The\ndefault is to treat a destination that is a symlink to a directory\njust like a directory.\n\nThis option is weaker than the '--no-target-directory' ('-T')\noption, so it has no effect if both options are given.\n\n'-P'\n'--physical'\nIf '-s' is not in effect, and the source file is a symbolic link,\ncreate the hard link to the symbolic link itself. On platforms\nwhere this is not supported by the kernel, this option creates a\nsymbolic link with identical contents; since symbolic link contents\ncannot be edited, any file name resolution performed through either\nlink will be the same as if a hard link had been created.\n\n'-r'\n'--relative'\nMake symbolic links relative to the link location.\n\nExample:\n\nln -srv /a/file /tmp\n'/tmp/file' -> '../a/file'\n\nRelative symbolic links are generated based on their canonicalized\ncontaining directory, and canonicalized targets. I.e., all\nsymbolic links in these file names will be resolved. *Note\nrealpath invocation::, which gives greater control over relative\nfile name generation, as demonstrated in the following example:\n\nln--relative() {\ntest \"$1\" = --no-symlinks && { nosym=$1; shift; }\ntarget=\"$1\";\ntest -d \"$2\" && link=\"$2/.\" || link=\"$2\"\nrtarget=\"$(realpath $nosym -m \"$target\" \\\n--relative-to \"$(dirname \"$link\")\")\"\nln -s -v \"$rtarget\" \"$link\"\n}\n\n'-s'\n'--symbolic'\nMake symbolic links instead of hard links. This option merely\nproduces an error message on systems that do not support symbolic\nlinks.\n\n'-S SUFFIX'\n'--suffix=SUFFIX'\nAppend SUFFIX to each backup file made with '-b'. *Note Backup\noptions::.\n\n'-t DIRECTORY'\n'--target-directory=DIRECTORY'\nSpecify the destination DIRECTORY. *Note Target directory::.\n\n'-T'\n'--no-target-directory'\nDo not treat the last operand specially when it is a directory or a\nsymbolic link to a directory. *Note Target directory::.\n\n'-v'\n'--verbose'\nPrint the name of each file after linking it successfully.\n\nIf '-L' and '-P' are both given, the last one takes precedence. If\n'-s' is also given, '-L' and '-P' are silently ignored. If neither\noption is given, then this implementation defaults to '-P' if the system\n'link' supports hard links to symbolic links (such as the GNU system),\nand '-L' if 'link' follows symbolic links (such as on BSD).\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nExamples:\n\nBad Example:\n\n# Create link ../a pointing to a in that directory.\n# Not really useful because it points to itself.\nln -s a ..\n\nBetter Example:\n\n# Change to the target before creating symlinks to avoid being confused.\ncd ..\nln -s adir/a .\n\nBad Example:\n\n# Hard coded file names don't move well.\nln -s $(pwd)/a /some/dir/\n\nBetter Example:\n\n# Relative file names survive directory moves and also\n# work across networked file systems.\nln -s afile anotherfile\nln -s ../adir/afile yetanotherfile\n", "subsections": [] }, "File: coreutils.info, Node: mkdir invocation, Next: mkfifo invocation, Prev: ln invocation, Up: Special file types": { "content": "", "subsections": [ { "name": "12.3 'mkdir': Make directories", "content": "'mkdir' creates directories with the specified names. Synopsis:\n\nmkdir [OPTION]... NAME...\n\n'mkdir' creates each directory NAME in the order given. It reports\nan error if NAME already exists, unless the '-p' option is given and\nNAME is a directory.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-m MODE'\n'--mode=MODE'\nSet the file permission bits of created directories to MODE, which\nuses the same syntax as in 'chmod' and uses 'a=rwx' (read, write\nand execute allowed for everyone) for the point of the departure.\n*Note File permissions::.\n\nNormally the directory has the desired file mode bits at the moment\nit is created. As a GNU extension, MODE may also mention special\nmode bits, but in this case there may be a temporary window during\nwhich the directory exists but its special mode bits are incorrect.\n*Note Directory Setuid and Setgid::, for how the set-user-ID and\nset-group-ID bits of directories are inherited unless overridden in\nthis way.\n\n'-p'\n'--parents'\nMake any missing parent directories for each argument, setting\ntheir file permission bits to the umask modified by 'u+wx'. Ignore\nexisting parent directories, and do not change their file\npermission bits.\n\nTo set the file permission bits of any newly-created parent\ndirectories to a value that includes 'u+wx', you can set the umask\nbefore invoking 'mkdir'. For example, if the shell command '(umask\nu=rwx,go=rx; mkdir -p P/Q)' creates the parent 'P' it sets the\nparent's permission bits to 'u=rwx,go=rx'. To set a parent's\nspecial mode bits as well, you can invoke 'chmod' after 'mkdir'.\n*Note Directory Setuid and Setgid::, for how the set-user-ID and\nset-group-ID bits of newly-created parent directories are\ninherited.\n\n'-v'\n'--verbose'\nPrint a message for each created directory. This is most useful\nwith '--parents'.\n\n'-Z'\n'--context[=CONTEXT]'\nWithout a specified CONTEXT, adjust the SELinux security context\naccording to the system default type for destination files,\nsimilarly to the 'restorecon' command. The long form of this\noption with a specific context specified, will set the context for\nnewly created files only. With a specified context, if both\nSELinux and SMACK are disabled, a warning is issued.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: mkfifo invocation, Next: mknod invocation, Prev: mkdir invocation, Up: Special file types": { "content": "", "subsections": [ { "name": "12.4 'mkfifo': Make FIFOs (named pipes)", "content": "'mkfifo' creates FIFOs (also called \"named pipes\") with the specified\nnames. Synopsis:\n\nmkfifo [OPTION] NAME...\n\nA \"FIFO\" is a special file type that permits independent processes to\ncommunicate. One process opens the FIFO file for writing, and another\nfor reading, after which data can flow as with the usual anonymous pipe\nin shells or elsewhere.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-m MODE'\n'--mode=MODE'\nSet the mode of created FIFOs to MODE, which is symbolic as in\n'chmod' and uses 'a=rw' (read and write allowed for everyone) for\nthe point of departure. MODE should specify only file permission\nbits. *Note File permissions::.\n\n'-Z'\n'--context[=CONTEXT]'\nWithout a specified CONTEXT, adjust the SELinux security context\naccording to the system default type for destination files,\nsimilarly to the 'restorecon' command. The long form of this\noption with a specific context specified, will set the context for\nnewly created files only. With a specified context, if both\nSELinux and SMACK are disabled, a warning is issued.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: mknod invocation, Next: readlink invocation, Prev: mkfifo invocation, Up: Special file types": { "content": "", "subsections": [ { "name": "12.5 'mknod': Make block or character special files", "content": "'mknod' creates a FIFO, character special file, or block special file\nwith the specified name. Synopsis:\n\nmknod [OPTION]... NAME TYPE [MAJOR MINOR]\n\nUnlike the phrase \"special file type\" above, the term \"special file\"\nhas a technical meaning on Unix: something that can generate or receive\ndata. Usually this corresponds to a physical piece of hardware, e.g., a\nprinter or a disk. (These files are typically created at\nsystem-configuration time.) The 'mknod' command is what creates files\nof this type. Such devices can be read either a character at a time or\na \"block\" (many characters) at a time, hence we say there are \"block\nspecial\" files and \"character special\" files.\n\nDue to shell aliases and built-in 'mknod' functions, using an\nunadorned 'mknod' interactively or in a script may get you different\nfunctionality than that described here. Invoke it via 'env' (i.e., 'env\nmknod ...') to avoid interference from the shell.\n\nThe arguments after NAME specify the type of file to make:\n\n'p'\nfor a FIFO\n\n'b'\nfor a block special file\n\n'c'\nfor a character special file\n\nWhen making a block or character special file, the major and minor\ndevice numbers must be given after the file type. If a major or minor\ndevice number begins with '0x' or '0X', it is interpreted as\nhexadecimal; otherwise, if it begins with '0', as octal; otherwise, as\ndecimal.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-m MODE'\n'--mode=MODE'\nSet the mode of created files to MODE, which is symbolic as in\n'chmod' and uses 'a=rw' as the point of departure. MODE should\nspecify only file permission bits. *Note File permissions::.\n\n'-Z'\n'--context[=CONTEXT]'\nWithout a specified CONTEXT, adjust the SELinux security context\naccording to the system default type for destination files,\nsimilarly to the 'restorecon' command. The long form of this\noption with a specific context specified, will set the context for\nnewly created files only. With a specified context, if both\nSELinux and SMACK are disabled, a warning is issued.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: readlink invocation, Next: rmdir invocation, Prev: mknod invocation, Up: Special file types": { "content": "", "subsections": [ { "name": "12.6 'readlink': Print value of a symlink or canonical file name", "content": "'readlink' may work in one of two supported modes:\n\n'Readlink mode'\n\n'readlink' outputs the value of the given symbolic links. If\n'readlink' is invoked with an argument other than the name of a\nsymbolic link, it produces no output and exits with a nonzero exit\ncode.\n\n'Canonicalize mode'\n\n'readlink' outputs the absolute name of the given files which\ncontain no '.', '..' components nor any repeated separators ('/')\nor symbolic links. Note the 'realpath' command is the preferred\ncommand to use for canonicalization. *Note realpath invocation::.\n\nreadlink [OPTION]... FILE...\n\nBy default, 'readlink' operates in readlink mode.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-f'\n'--canonicalize'\nActivate canonicalize mode. If any component of the file name\nexcept the last one is missing or unavailable, 'readlink' produces\nno output and exits with a nonzero exit code. A trailing slash is\nignored.\n\n'-e'\n'--canonicalize-existing'\nActivate canonicalize mode. If any component is missing or\nunavailable, 'readlink' produces no output and exits with a nonzero\nexit code. A trailing slash requires that the name resolve to a\ndirectory.\n\n'-m'\n'--canonicalize-missing'\nActivate canonicalize mode. If any component is missing or\nunavailable, 'readlink' treats it as a directory.\n\n'-n'\n'--no-newline'\nDo not print the output delimiter, when a single FILE is specified.\nPrint a warning if specified along with multiple FILEs.\n\n'-s'\n'-q'\n'--silent'\n'--quiet'\nSuppress most error messages. On by default.\n\n'-v'\n'--verbose'\nReport error messages.\n\n'-z'\n'--zero'\nOutput a zero byte (ASCII NUL) at the end of each line, rather than\na newline. This option enables other programs to parse the output\neven when that output would contain data with embedded newlines.\n\nThe 'readlink' utility first appeared in OpenBSD 2.1.\n\nThe 'realpath' command without options, operates like 'readlink' in\ncanonicalize mode.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: rmdir invocation, Next: unlink invocation, Prev: readlink invocation, Up: Special file types": { "content": "", "subsections": [ { "name": "12.7 'rmdir': Remove empty directories", "content": "'rmdir' removes empty directories. Synopsis:\n\nrmdir [OPTION]... DIRECTORY...\n\nIf any DIRECTORY argument does not refer to an existing empty\ndirectory, it is an error.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'--ignore-fail-on-non-empty'\nIgnore each failure to remove a directory that is solely because\nthe directory is non-empty.\n\n'-p'\n'--parents'\nRemove DIRECTORY, then try to remove each component of DIRECTORY.\nSo, for example, 'rmdir -p a/b/c' is similar to 'rmdir a/b/c a/b\na'. As such, it fails if any of those directories turns out not to\nbe empty. Use the '--ignore-fail-on-non-empty' option to make it\nso such a failure does not evoke a diagnostic and does not cause\n'rmdir' to exit unsuccessfully.\n\n'-v'\n'--verbose'\nGive a diagnostic for each successful removal. DIRECTORY is\nremoved.\n\n*Note rm invocation::, for how to remove non-empty directories\n(recursively).\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: unlink invocation, Prev: rmdir invocation, Up: Special file types": { "content": "", "subsections": [ { "name": "12.8 'unlink': Remove files via the unlink syscall", "content": "'unlink' deletes a single specified file name. It is a minimalist\ninterface to the system-provided 'unlink' function. *Note\n(libc)Deleting Files::. Synopsis: It avoids the bells and whistles of\nthe more commonly-used 'rm' command (*note rm invocation::).\n\nunlink FILENAME\n\nOn some systems 'unlink' can be used to delete the name of a\ndirectory. On others, it can be used that way only by a privileged\nuser. In the GNU system 'unlink' can never delete the name of a\ndirectory.\n\nThe 'unlink' command honors the '--help' and '--version' options. To\nremove a file whose name begins with '-', prefix the name with './',\ne.g., 'unlink ./--help'.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: Changing file attributes, Next: Disk usage, Prev: Special file types, Up: Top": { "content": "", "subsections": [] }, "13 Changing file attributes": { "content": "A file is not merely its contents, a name, and a file type (*note", "subsections": [] }, "Special file types::). A file also has an owner (a user ID), a group (a": { "content": "group ID), permissions (what the owner can do with the file, what people\nin the group can do, and what everyone else can do), various timestamps,\nand other information. Collectively, we call these a file's\n\"attributes\".\n\nThese commands change file attributes.\n\n* Menu:\n\n* chown invocation:: Change file owners and groups.\n* chgrp invocation:: Change file groups.\n* chmod invocation:: Change access permissions.\n* touch invocation:: Change file timestamps.\n", "subsections": [] }, "File: coreutils.info, Node: chown invocation, Next: chgrp invocation, Up: Changing file attributes": { "content": "", "subsections": [ { "name": "13.1 'chown': Change file owner and group", "content": "'chown' changes the user and/or group ownership of each given FILE to\nNEW-OWNER or to the user and group of an existing reference file.\nSynopsis:\n\nchown [OPTION]... {NEW-OWNER | --reference=REFFILE} FILE...\n\nIf used, NEW-OWNER specifies the new owner and/or group as follows\n(with no embedded white space):\n\n[OWNER] [ : [GROUP] ]\n\nSpecifically:\n" } ] }, "OWNER": { "content": "If only an OWNER (a user name or numeric user ID) is given, that\nuser is made the owner of each given file, and the files' group is\nnot changed.\n\nOWNER':'GROUP\nIf the OWNER is followed by a colon and a GROUP (a group name or\nnumeric group ID), with no spaces between them, the group ownership\nof the files is changed as well (to GROUP).\n\nOWNER':'\nIf a colon but no group name follows OWNER, that user is made the\nowner of the files and the group of the files is changed to OWNER's\nlogin group.\n\n':'GROUP\nIf the colon and following GROUP are given, but the owner is\nomitted, only the group of the files is changed; in this case,\n'chown' performs the same function as 'chgrp'.\n\n':'\nIf only a colon is given, or if NEW-OWNER is empty, neither the\nowner nor the group is changed.\n\nIf OWNER or GROUP is intended to represent a numeric user or group\nID, then you may specify it with a leading '+'. *Note Disambiguating\nnames and IDs::.\n\nSome older scripts may still use '.' in place of the ':' separator.\nPOSIX 1003.1-2001 (*note Standards conformance::) does not require\nsupport for that, but for backward compatibility GNU 'chown' supports\n'.' so long as no ambiguity results. New scripts should avoid the use\nof '.' because it is not portable, and because it has undesirable\nresults if the entire OWNER'.'GROUP happens to identify a user whose\nname contains '.'.\n\nIt is system dependent whether a user can change the group to an\narbitrary one, or the more portable behavior of being restricted to\nsetting a group of which the user is a member.\n\nThe 'chown' command sometimes clears the set-user-ID or set-group-ID\npermission bits. This behavior depends on the policy and functionality\nof the underlying 'chown' system call, which may make system-dependent\nfile mode modifications outside the control of the 'chown' command. For\nexample, the 'chown' command might not affect those bits when invoked by\na user with appropriate privileges, or when the bits signify some\nfunction other than executable permission (e.g., mandatory locking).\nWhen in doubt, check the underlying system behavior.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-c'\n'--changes'\nVerbosely describe the action for each FILE whose ownership\nactually changes.\n\n'-f'\n'--silent'\n'--quiet'\nDo not print error messages about files whose ownership cannot be\nchanged.\n\n'--from=OLD-OWNER'\nChange a FILE's ownership only if it has current attributes\nspecified by OLD-OWNER. OLD-OWNER has the same form as NEW-OWNER\ndescribed above. This option is useful primarily from a security\nstandpoint in that it narrows considerably the window of potential\nabuse. For example, to reflect a user ID numbering change for one\nuser's files without an option like this, 'root' might run\n\nfind / -owner OLDUSER -print0 | xargs -0 chown -h NEWUSER\n\nBut that is dangerous because the interval between when the 'find'\ntests the existing file's owner and when the 'chown' is actually\nrun may be quite large. One way to narrow the gap would be to\ninvoke chown for each file as it is found:\n\nfind / -owner OLDUSER -exec chown -h NEWUSER {} \\;\n\nBut that is very slow if there are many affected files. With this\noption, it is safer (the gap is narrower still) though still not\nperfect:\n\nchown -h -R --from=OLDUSER NEWUSER /\n\n'--dereference'\nDo not act on symbolic links themselves but rather on what they\npoint to. This is the default when not operating recursively.\n\nCombining this dereferencing option with the '--recursive' option\nmay create a security risk: During the traversal of the directory\ntree, an attacker may be able to introduce a symlink to an\narbitrary target; when the tool reaches that, the operation will be\nperformed on the target of that symlink, possibly allowing the\nattacker to escalate privileges.\n\n'-h'\n'--no-dereference'\nAct on symbolic links themselves instead of what they point to.\nThis mode relies on the 'lchown' system call. On systems that do\nnot provide the 'lchown' system call, 'chown' fails when a file\nspecified on the command line is a symbolic link. By default, no\ndiagnostic is issued for symbolic links encountered during a\nrecursive traversal, but see '--verbose'.\n\n'--preserve-root'\nFail upon any attempt to recursively change the root directory,\n'/'. Without '--recursive', this option has no effect. *Note\nTreating / specially::.\n\n'--no-preserve-root'\nCancel the effect of any preceding '--preserve-root' option. *Note\nTreating / specially::.\n\n'--reference=REFFILE'\nChange the user and group of each FILE to be the same as those of\nREFFILE. If REFFILE is a symbolic link, do not use the user and\ngroup of the symbolic link, but rather those of the file it refers\nto.\n\n'-v'\n'--verbose'\nOutput a diagnostic for every file processed. If a symbolic link\nis encountered during a recursive traversal on a system without the\n'lchown' system call, and '--no-dereference' is in effect, then\nissue a diagnostic saying neither the symbolic link nor its\nreferent is being changed.\n\n'-R'\n'--recursive'\nRecursively change ownership of directories and their contents.\n\n'-H'\nIf '--recursive' ('-R') is specified and a command line argument is\na symbolic link to a directory, traverse it. *Note Traversing\nsymlinks::.\n\n'-L'\nIn a recursive traversal, traverse every symbolic link to a\ndirectory that is encountered.\n\nCombining this dereferencing option with the '--recursive' option\nmay create a security risk: During the traversal of the directory\ntree, an attacker may be able to introduce a symlink to an\narbitrary target; when the tool reaches that, the operation will be\nperformed on the target of that symlink, possibly allowing the\nattacker to escalate privileges.\n\n*Note Traversing symlinks::.\n\n'-P'\nDo not traverse any symbolic links. This is the default if none of\n'-H', '-L', or '-P' is specified. *Note Traversing symlinks::.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nExamples:\n\n# Change the owner of /u to \"root\".\nchown root /u\n\n# Likewise, but also change its group to \"staff\".\nchown root:staff /u\n\n# Change the owner of /u and subfiles to \"root\".\nchown -hR root /u\n", "subsections": [] }, "File: coreutils.info, Node: chgrp invocation, Next: chmod invocation, Prev: chown invocation, Up: Changing file attributes": { "content": "", "subsections": [ { "name": "13.2 'chgrp': Change group ownership", "content": "'chgrp' changes the group ownership of each given FILE to GROUP (which\ncan be either a group name or a numeric group ID) or to the group of an\nexisting reference file. *Note chown invocation::. Synopsis:\n\nchgrp [OPTION]... {GROUP | --reference=REFFILE} FILE...\n\nIf GROUP is intended to represent a numeric group ID, then you may\nspecify it with a leading '+'. *Note Disambiguating names and IDs::.\n\nIt is system dependent whether a user can change the group to an\narbitrary one, or the more portable behavior of being restricted to\nsetting a group of which the user is a member.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-c'\n'--changes'\nVerbosely describe the action for each FILE whose group actually\nchanges.\n\n'-f'\n'--silent'\n'--quiet'\nDo not print error messages about files whose group cannot be\nchanged.\n\n'--dereference'\nDo not act on symbolic links themselves but rather on what they\npoint to. This is the default when not operating recursively.\n\nCombining this dereferencing option with the '--recursive' option\nmay create a security risk: During the traversal of the directory\ntree, an attacker may be able to introduce a symlink to an\narbitrary target; when the tool reaches that, the operation will be\nperformed on the target of that symlink, possibly allowing the\nattacker to escalate privileges.\n\n'-h'\n'--no-dereference'\nAct on symbolic links themselves instead of what they point to.\nThis mode relies on the 'lchown' system call. On systems that do\nnot provide the 'lchown' system call, 'chgrp' fails when a file\nspecified on the command line is a symbolic link. By default, no\ndiagnostic is issued for symbolic links encountered during a\nrecursive traversal, but see '--verbose'.\n\n'--preserve-root'\nFail upon any attempt to recursively change the root directory,\n'/'. Without '--recursive', this option has no effect. *Note\nTreating / specially::.\n\n'--no-preserve-root'\nCancel the effect of any preceding '--preserve-root' option. *Note\nTreating / specially::.\n\n'--reference=REFFILE'\nChange the group of each FILE to be the same as that of REFFILE.\nIf REFFILE is a symbolic link, do not use the group of the\nsymbolic link, but rather that of the file it refers to.\n\n'-v'\n'--verbose'\nOutput a diagnostic for every file processed. If a symbolic link\nis encountered during a recursive traversal on a system without the\n'lchown' system call, and '--no-dereference' is in effect, then\nissue a diagnostic saying neither the symbolic link nor its\nreferent is being changed.\n\n'-R'\n'--recursive'\nRecursively change the group ownership of directories and their\ncontents.\n\n'-H'\nIf '--recursive' ('-R') is specified and a command line argument is\na symbolic link to a directory, traverse it. *Note Traversing\nsymlinks::.\n\n'-L'\nIn a recursive traversal, traverse every symbolic link to a\ndirectory that is encountered.\n\nCombining this dereferencing option with the '--recursive' option\nmay create a security risk: During the traversal of the directory\ntree, an attacker may be able to introduce a symlink to an\narbitrary target; when the tool reaches that, the operation will be\nperformed on the target of that symlink, possibly allowing the\nattacker to escalate privileges.\n\n*Note Traversing symlinks::.\n\n'-P'\nDo not traverse any symbolic links. This is the default if none of\n'-H', '-L', or '-P' is specified. *Note Traversing symlinks::.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nExamples:\n\n# Change the group of /u to \"staff\".\nchgrp staff /u\n\n# Change the group of /u and subfiles to \"staff\".\nchgrp -hR staff /u\n" } ] }, "File: coreutils.info, Node: chmod invocation, Next: touch invocation, Prev: chgrp invocation, Up: Changing file attributes": { "content": "", "subsections": [ { "name": "13.3 'chmod': Change access permissions", "content": "'chmod' changes the access permissions of the named files. Synopsis:\n\nchmod [OPTION]... {MODE | --reference=REFFILE} FILE...\n\n'chmod' never changes the permissions of symbolic links, since the\n'chmod' system call cannot change their permissions. This is not a\nproblem since the permissions of symbolic links are never used." } ] }, "However, for each symbolic link listed on the command line, 'chmod'": { "content": "changes the permissions of the pointed-to file. In contrast, 'chmod'\nignores symbolic links encountered during recursive directory\ntraversals.\n\nOnly a process whose effective user ID matches the user ID of the\nfile, or a process with appropriate privileges, is permitted to change\nthe file mode bits of a file.\n\nA successful use of 'chmod' clears the set-group-ID bit of a regular\nfile if the file's group ID does not match the user's effective group ID\nor one of the user's supplementary group IDs, unless the user has\nappropriate privileges. Additional restrictions may cause the\nset-user-ID and set-group-ID bits of MODE or REFFILE to be ignored.", "subsections": [] }, "This behavior depends on the policy and functionality of the underlying": { "content": "'chmod' system call. When in doubt, check the underlying system\nbehavior.\n\nIf used, MODE specifies the new file mode bits. For details, see the\nsection on *note File permissions::. If you really want MODE to have a\nleading '-', you should use '--' first, e.g., 'chmod -- -w file'.", "subsections": [] }, "Typically, though, 'chmod a-w file' is preferable, and 'chmod -w file'": { "content": "(without the '--') complains if it behaves differently from what 'chmod\na-w file' would do.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-c'\n'--changes'\nVerbosely describe the action for each FILE whose permissions\nactually changes.\n\n'-f'\n'--silent'\n'--quiet'\nDo not print error messages about files whose permissions cannot be\nchanged.\n\n'--preserve-root'\nFail upon any attempt to recursively change the root directory,\n'/'. Without '--recursive', this option has no effect. *Note\nTreating / specially::.\n\n'--no-preserve-root'\nCancel the effect of any preceding '--preserve-root' option. *Note\nTreating / specially::.\n\n'-v'\n'--verbose'\nVerbosely describe the action or non-action taken for every FILE.\n\n'--reference=REFFILE'\nChange the mode of each FILE to be the same as that of REFFILE.\n*Note File permissions::. If REFFILE is a symbolic link, do not\nuse the mode of the symbolic link, but rather that of the file it\nrefers to.\n\n'-R'\n'--recursive'\nRecursively change permissions of directories and their contents.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nExamples:\n\n# Change file permissions of FOO to be world readable\n# and user writable, with no other permissions.\nchmod 644 foo\nchmod a=r,u+w foo\n\n# Add user and group execute permissions to FOO.\nchmod +110 file\nchmod ug+x file\n\n# Set file permissions of DIR and subsidiary files to\n# be the umask default, assuming execute permissions for\n# directories and for files already executable.\nchmod -R a=,+rwX dir\n", "subsections": [] }, "File: coreutils.info, Node: touch invocation, Prev: chmod invocation, Up: Changing file attributes": { "content": "", "subsections": [ { "name": "13.4 'touch': Change file timestamps", "content": "'touch' changes the access and/or modification timestamps of the\nspecified files. Synopsis:\n\ntouch [OPTION]... FILE...\n\nAny FILE argument that does not exist is created empty, unless option\n'--no-create' ('-c') or '--no-dereference' ('-h') was in effect.\n\nA FILE argument string of '-' is handled specially and causes 'touch'\nto change the times of the file associated with standard output.\n\nBy default, 'touch' sets file timestamps to the current time." } ] }, "Because 'touch' acts on its operands left to right, the resulting": { "content": "timestamps of earlier and later operands may disagree.\n\nWhen setting file timestamps to the current time, 'touch' can change\nthe timestamps for files that the user does not own but has write\npermission for. Otherwise, the user must own the files. Some older\nsystems have a further restriction: the user must own the files unless\nboth the access and modification timestamps are being set to the current\ntime.\n\nThe 'touch' command cannot set a file's status change timestamp to a\nuser-specified value, and cannot change the file's birth time (if\nsupported) at all. Also, 'touch' has issues similar to those affecting\nall programs that update file timestamps. For example, 'touch' may set\na file's timestamp to a value that differs slightly from the requested\ntime. *Note File timestamps::.\n\nTimestamps assume the time zone rules specified by the 'TZ'\nenvironment variable, or by the system default rules if 'TZ' is not set.\n*Note Specifying the Time Zone with 'TZ': (libc)TZ Variable. You can\navoid ambiguities during daylight saving transitions by using UTC\ntimestamps.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-a'\n'--time=atime'\n'--time=access'\n'--time=use'\nChange the access timestamp only. *Note File timestamps::.\n\n'-c'\n'--no-create'\nDo not warn about or create files that do not exist.\n\n'-d TIME'\n'--date=TIME'\nUse TIME instead of the current time. It can contain month names,\ntime zones, 'am' and 'pm', 'yesterday', etc. For example,\n'--date=\"2004-02-27 14:19:13.489392193 +0530\"' specifies the\ninstant of time that is 489,392,193 nanoseconds after February 27,\n2004 at 2:19:13 PM in a time zone that is 5 hours and 30 minutes\neast of UTC. *Note Date input formats::. File systems that do not\nsupport high-resolution timestamps silently ignore any excess\nprecision here.\n\n'-f'\nIgnored; for compatibility with BSD versions of 'touch'.\n\n'-h'\n'--no-dereference'\nAttempt to change the timestamps of a symbolic link, rather than\nwhat the link refers to. When using this option, empty files are\nnot created, but option '-c' must also be used to avoid warning\nabout files that do not exist. Not all systems support changing\nthe timestamps of symlinks, since underlying system support for\nthis action was not required until POSIX 2008. Also, on some\nsystems, the mere act of examining a symbolic link changes the\naccess timestamp, such that only changes to the modification\ntimestamp will persist long enough to be observable. When coupled\nwith option '-r', a reference timestamp is taken from a symbolic\nlink rather than the file it refers to.\n\n'-m'\n'--time=mtime'\n'--time=modify'\nChange the modification timestamp only.\n\n'-r FILE'\n'--reference=FILE'\nUse the times of the reference FILE instead of the current time.\nIf this option is combined with the '--date=TIME' ('-d TIME')\noption, the reference FILE's time is the origin for any relative\nTIMEs given, but is otherwise ignored. For example, '-r foo -d '-5\nseconds'' specifies a timestamp equal to five seconds before the\ncorresponding timestamp for 'foo'. If FILE is a symbolic link, the\nreference timestamp is taken from the target of the symlink, unless\n'-h' was also in effect.\n\n'-t [[CC]YY]MMDDHHMM[.SS]'\nUse the argument (optional four-digit or two-digit years, months,\ndays, hours, minutes, optional seconds) instead of the current\ntime. If the year is specified with only two digits, then CC is 20\nfor years in the range 0 ... 68, and 19 for years in 69 ... 99. If\nno digits of the year are specified, the argument is interpreted as\na date in the current year. On the atypical systems that support\nleap seconds, SS may be '60'.\n\nOn systems predating POSIX 1003.1-2001, 'touch' supports an obsolete\nsyntax, as follows. If no timestamp is given with any of the '-d',\n'-r', or '-t' options, and if there are two or more FILEs and the first\nFILE is of the form 'MMDDHHMM[YY]' and this would be a valid argument to\nthe '-t' option (if the YY, if any, were moved to the front), and if the\nrepresented year is in the range 1969-1999, that argument is interpreted\nas the time for the other files instead of as a file name. Although\nthis obsolete behavior can be controlled with the 'POSIX2VERSION'\nenvironment variable (*note Standards conformance::), portable scripts\nshould avoid commands whose behavior depends on this variable. For\nexample, use 'touch ./12312359 main.c' or 'touch -t 12312359 main.c'\nrather than the ambiguous 'touch 12312359 main.c'.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: Disk usage, Next: Printing text, Prev: Changing file attributes, Up: Top": { "content": "", "subsections": [] }, "14 Disk usage": { "content": "", "subsections": [] }, "No disk can hold an infinite amount of data. These commands report how": { "content": "much disk storage is in use or available, report other file and file\nstatus information, and write buffers to disk.\n\n* Menu:\n\n* df invocation:: Report file system disk space usage.\n* du invocation:: Estimate file space usage.\n* stat invocation:: Report file or file system status.\n* sync invocation:: Synchronize cached writes to persistent storage.\n* truncate invocation:: Shrink or extend the size of a file.\n", "subsections": [] }, "File: coreutils.info, Node: df invocation, Next: du invocation, Up: Disk usage": { "content": "", "subsections": [ { "name": "14.1 'df': Report file system disk space usage", "content": "'df' reports the amount of disk space used and available on file\nsystems. Synopsis:\n\ndf [OPTION]... [FILE]...\n\nWith no arguments, 'df' reports the space used and available on all\ncurrently mounted file systems (of all types). Otherwise, 'df' reports\non the file system containing each argument FILE.\n\nNormally the disk space is printed in units of 1024 bytes, but this\ncan be overridden (*note Block size::). Non-integer quantities are\nrounded up to the next higher unit.\n\nFor bind mounts and without arguments, 'df' only outputs the\nstatistics for that device with the shortest mount point name in the\nlist of file systems (MTAB), i.e., it hides duplicate entries, unless\nthe '-a' option is specified.\n\nWith the same logic, 'df' elides a mount entry of a dummy pseudo\ndevice if there is another mount entry of a real block device for that\nmount point with the same device number, e.g. the early-boot pseudo\nfile system 'rootfs' is not shown per default when already the real root\ndevice has been mounted.\n\nIf an argument FILE resolves to a special file containing a mounted\nfile system, 'df' shows the space available on that file system rather\nthan on the file system containing the device node. GNU 'df' does not\nattempt to determine the disk usage on unmounted file systems, because\non most kinds of systems doing so requires extremely nonportable\nintimate knowledge of file system structures.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-a'\n'--all'\nInclude in the listing dummy, duplicate, or inaccessible file\nsystems, which are omitted by default. Dummy file systems are\ntypically special purpose pseudo file systems such as '/proc', with\nno associated storage. Duplicate file systems are local or remote\nfile systems that are mounted at separate locations in the local\nfile hierarchy, or bind mounted locations. Inaccessible file\nsystems are those which are mounted but subsequently over-mounted\nby another file system at that point, or otherwise inaccessible due\nto permissions of the mount point etc.\n\n'-B SIZE'\n'--block-size=SIZE'\nScale sizes by SIZE before printing them (*note Block size::). For\nexample, '-BG' prints sizes in units of 1,073,741,824 bytes.\n\n'-h'\n'--human-readable'\nAppend a size letter to each size, such as 'M' for mebibytes.\nPowers of 1024 are used, not 1000; 'M' stands for 1,048,576 bytes.\nThis option is equivalent to '--block-size=human-readable'. Use\nthe '--si' option if you prefer powers of 1000.\n\n'-H'\nEquivalent to '--si'.\n\n'-i'\n'--inodes'\nList inode usage information instead of block usage. An inode\n(short for index node) contains information about a file such as\nits owner, permissions, timestamps, and location on the disk.\n\n'-k'\nPrint sizes in 1024-byte blocks, overriding the default block size\n(*note Block size::). This option is equivalent to\n'--block-size=1K'.\n\n'-l'\n'--local'\nLimit the listing to local file systems. By default, remote file\nsystems are also listed.\n\n'--no-sync'\nDo not invoke the 'sync' system call before getting any usage data.\nThis may make 'df' run significantly faster on systems with many\ndisks, but on some systems (notably SunOS) the results may be\nslightly out of date. This is the default.\n\n'--output'\n'--output[=FIELDLIST]'\nUse the output format defined by FIELDLIST, or print all fields if\nFIELDLIST is omitted. In the latter case, the order of the\ncolumns conforms to the order of the field descriptions below.\n\nThe use of the '--output' together with each of the options '-i',\n'-P', and '-T' is mutually exclusive.\n\nFIELDLIST is a comma-separated list of columns to be included in\n'df''s output and therefore effectively controls the order of\noutput columns. Each field can thus be used at the place of\nchoice, but yet must only be used once.\n\nValid field names in the FIELDLIST are:\n'source'\nThe source of the mount point, usually a device.\n'fstype'\nFile system type.\n\n'itotal'\nTotal number of inodes.\n'iused'\nNumber of used inodes.\n'iavail'\nNumber of available inodes.\n'ipcent'\nPercentage of IUSED divided by ITOTAL.\n\n'size'\nTotal number of blocks.\n'used'\nNumber of used blocks.\n'avail'\nNumber of available blocks.\n'pcent'\nPercentage of USED divided by SIZE.\n\n'file'\nThe file name if specified on the command line.\n'target'\nThe mount point.\n\nThe fields for block and inodes statistics are affected by the\nscaling options like '-h' as usual.\n\nThe definition of the FIELDLIST can even be split among several\n'--output' uses.\n\n#!/bin/sh\n# Print the TARGET (i.e., the mount point) along with their percentage\n# statistic regarding the blocks and the inodes.\ndf --out=target --output=pcent,ipcent\n\n# Print all available fields.\ndf --o\n\n'-P'\n'--portability'\nUse the POSIX output format. This is like the default format\nexcept for the following:\n\n1. The information about each file system is always printed on\nexactly one line; a mount device is never put on a line by\nitself. This means that if the mount device name is more than\n20 characters long (e.g., for some network mounts), the\ncolumns are misaligned.\n\n2. The labels in the header output line are changed to conform to\nPOSIX.\n\n3. The default block size and output format are unaffected by the\n'DFBLOCKSIZE', 'BLOCKSIZE' and 'BLOCKSIZE' environment\nvariables. However, the default block size is still affected\nby 'POSIXLYCORRECT': it is 512 if 'POSIXLYCORRECT' is set,\n1024 otherwise. *Note Block size::.\n\n'--si'\nAppend an SI-style abbreviation to each size, such as 'M' for\nmegabytes. Powers of 1000 are used, not 1024; 'M' stands for\n1,000,000 bytes. This option is equivalent to '--block-size=si'.\nUse the '-h' or '--human-readable' option if you prefer powers of\n1024.\n\n'--sync'\nInvoke the 'sync' system call before getting any usage data. On\nsome systems (notably SunOS), doing this yields more up to date\nresults, but in general this option makes 'df' much slower,\nespecially when there are many or very busy file systems.\n\n'--total'\nPrint a grand total of all arguments after all arguments have been\nprocessed. This can be used to find out the total disk size, usage\nand available space of all listed devices. If no arguments are\nspecified df will try harder to elide file systems insignificant to\nthe total available space, by suppressing duplicate remote file\nsystems.\n\nFor the grand total line, 'df' prints '\"total\"' into the SOURCE\ncolumn, and '\"-\"' into the TARGET column. If there is no SOURCE\ncolumn (see '--output'), then 'df' prints '\"total\"' into the TARGET\ncolumn, if present.\n\n'-t FSTYPE'\n'--type=FSTYPE'\nLimit the listing to file systems of type FSTYPE. Multiple file\nsystem types can be specified by giving multiple '-t' options. By\ndefault, nothing is omitted.\n\n'-T'\n'--print-type'\nPrint each file system's type. The types printed here are the same\nones you can include or exclude with '-t' and '-x'. The particular\ntypes printed are whatever is supported by the system. Here are\nsome of the common names (this list is certainly not exhaustive):\n\n'nfs'\nAn NFS file system, i.e., one mounted over a network from\nanother machine. This is the one type name which seems to be\nused uniformly by all systems.\n\n'ext2, ext3, ext4, xfs, btrfs...'\nA file system on a locally-mounted hard disk. (The system\nmight even support more than one type here; Linux does.)\n\n'iso9660, cdfs'\nA file system on a CD or DVD drive. HP-UX uses 'cdfs', most\nother systems use 'iso9660'.\n\n'ntfs,fat'\nFile systems used by MS-Windows / MS-DOS.\n\n'-x FSTYPE'\n'--exclude-type=FSTYPE'\nLimit the listing to file systems not of type FSTYPE. Multiple\nfile system types can be eliminated by giving multiple '-x'\noptions. By default, no file system types are omitted.\n\n'-v'\nIgnored; for compatibility with System V versions of 'df'.\n\n'df' is installed only on systems that have usable mount tables, so\nportable scripts should not rely on its existence.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure. Failure includes the case where no output is\ngenerated, so you can inspect the exit status of a command like 'df -t\next3 -t reiserfs DIR' to test whether DIR is on a file system of type\n'ext3' or 'reiserfs'.\n\nSince the list of file systems (MTAB) is needed to determine the file\nsystem type, failure includes the cases when that list cannot be read\nand one or more of the options '-a', '-l', '-t' or '-x' is used together\nwith a file name argument.\n" } ] }, "File: coreutils.info, Node: du invocation, Next: stat invocation, Prev: df invocation, Up: Disk usage": { "content": "", "subsections": [ { "name": "14.2 'du': Estimate file space usage", "content": "'du' reports the amount of disk space used by the set of specified files\nand for each subdirectory (of directory arguments). Synopsis:\n\ndu [OPTION]... [FILE]...\n\nWith no arguments, 'du' reports the disk space for the current\ndirectory. Normally the disk space is printed in units of 1024 bytes,\nbut this can be overridden (*note Block size::). Non-integer quantities\nare rounded up to the next higher unit.\n\nIf two or more hard links point to the same file, only one of the\nhard links is counted. The FILE argument order affects which links are\ncounted, and changing the argument order may change the numbers and\nentries that 'du' outputs.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-0'\n'--null'\nOutput a zero byte (ASCII NUL) at the end of each line, rather than\na newline. This option enables other programs to parse the output\neven when that output would contain data with embedded newlines.\n\n'-a'\n'--all'\nShow counts for all files, not just directories.\n\n'--apparent-size'\nPrint apparent sizes, rather than disk usage. The apparent size of\na file is the number of bytes reported by 'wc -c' on regular files,\nor more generally, 'ls -l --block-size=1' or 'stat --format=%s'.\nFor example, a file containing the word 'zoo' with no newline\nwould, of course, have an apparent size of 3. Such a small file\nmay require anywhere from 0 to 16 KiB or more of disk space,\ndepending on the type and configuration of the file system on which\nthe file resides. However, a sparse file created with this\ncommand:\n\ndd bs=1 seek=2GiB if=/dev/null of=big\n\nhas an apparent size of 2 GiB, yet on most modern systems, it\nactually uses almost no disk space.\n\n'-B SIZE'\n'--block-size=SIZE'\nScale sizes by SIZE before printing them (*note Block size::). For\nexample, '-BG' prints sizes in units of 1,073,741,824 bytes.\n\n'-b'\n'--bytes'\nEquivalent to '--apparent-size --block-size=1'.\n\n'-c'\n'--total'\nPrint a grand total of all arguments after all arguments have been\nprocessed. This can be used to find out the total disk usage of a\ngiven set of files or directories.\n\n'-D'\n'--dereference-args'\nDereference symbolic links that are command line arguments. Does\nnot affect other symbolic links. This is helpful for finding out\nthe disk usage of directories, such as '/usr/tmp', which are often\nsymbolic links.\n\n'-d DEPTH'\n'--max-depth=DEPTH'\nShow the total for each directory (and file if -all) that is at\nmost MAXDEPTH levels down from the root of the hierarchy. The\nroot is at level 0, so 'du --max-depth=0' is equivalent to 'du -s'.\n\n'--files0-from=FILE'\nDisallow processing files named on the command line, and instead\nprocess those named in file FILE; each name being terminated by a\nzero byte (ASCII NUL). This is useful when the list of file names\nis so long that it may exceed a command line length limitation. In\nsuch cases, running 'du' via 'xargs' is undesirable because it\nsplits the list into pieces and makes 'du' print with the '--total'\n('-c') option for each sublist rather than for the entire list.\nOne way to produce a list of ASCII NUL terminated file names is\nwith GNU 'find', using its '-print0' predicate. If FILE is '-'\nthen the ASCII NUL terminated file names are read from standard\ninput.\n\n'-H'\nEquivalent to '--dereference-args' ('-D').\n\n'-h'\n'--human-readable'\nAppend a size letter to each size, such as 'M' for mebibytes.\nPowers of 1024 are used, not 1000; 'M' stands for 1,048,576 bytes.\nThis option is equivalent to '--block-size=human-readable'. Use\nthe '--si' option if you prefer powers of 1000.\n\n'--inodes'\nList inode usage information instead of block usage. This option\nis useful for finding directories which contain many files, and\ntherefore eat up most of the inodes space of a file system (see\n'df', option '--inodes'). It can well be combined with the options\n'-a', '-c', '-h', '-l', '-s', '-S', '-t' and '-x'; however, passing\nother options regarding the block size, for example '-b', '-m' and\n'--apparent-size', is ignored.\n\n'-k'\nPrint sizes in 1024-byte blocks, overriding the default block size\n(*note Block size::). This option is equivalent to\n'--block-size=1K'.\n\n'-L'\n'--dereference'\nDereference symbolic links (show the disk space used by the file or\ndirectory that the link points to instead of the space used by the\nlink).\n\n'-l'\n'--count-links'\nCount the size of all files, even if they have appeared already (as\na hard link).\n\n'-m'\nPrint sizes in 1,048,576-byte blocks, overriding the default block\nsize (*note Block size::). This option is equivalent to\n'--block-size=1M'.\n\n'-P'\n'--no-dereference'\nFor each symbolic links encountered by 'du', consider the disk\nspace used by the symbolic link.\n\n'-S'\n'--separate-dirs'\nNormally, in the output of 'du' (when not using '--summarize'), the\nsize listed next to a directory name, D, represents the sum of\nsizes of all entries beneath D as well as the size of D itself.\nWith '--separate-dirs', the size reported for a directory name, D,\nwill exclude the size of any subdirectories.\n\n'--si'\nAppend an SI-style abbreviation to each size, such as 'M' for\nmegabytes. Powers of 1000 are used, not 1024; 'M' stands for\n1,000,000 bytes. This option is equivalent to '--block-size=si'.\nUse the '-h' or '--human-readable' option if you prefer powers of\n1024.\n\n'-s'\n'--summarize'\nDisplay only a total for each argument.\n\n'-t SIZE'\n'--threshold=SIZE'\nExclude entries based on a given SIZE. The SIZE refers to used\nblocks in normal mode (*note Block size::), or inodes count in\nconjunction with the '--inodes' option.\n\nIf SIZE is positive, then 'du' will only print entries with a size\ngreater than or equal to that.\n\nIf SIZE is negative, then 'du' will only print entries with a size\nsmaller than or equal to that.\n\nAlthough GNU 'find' can be used to find files of a certain size,\n'du''s '--threshold' option can be used to also filter directories\nbased on a given size.\n\nPlease note that the '--threshold' option can be combined with the\n'--apparent-size' option, and in this case would elide entries\nbased on its apparent size.\n\nPlease note that the '--threshold' option can be combined with the\n'--inodes' option, and in this case would elide entries based on\nits inodes count.\n\nHere's how you would use '--threshold' to find directories with a\nsize greater than or equal to 200 megabytes:\n\ndu --threshold=200MB\n\nHere's how you would use '--threshold' to find directories and\nfiles - note the '-a' - with an apparent size smaller than or equal\nto 500 bytes:\n\ndu -a -t -500 --apparent-size\n\nHere's how you would use '--threshold' to find directories on the\nroot file system with more than 20000 inodes used in the directory\ntree below:\n\ndu --inodes -x --threshold=20000 /\n\n'--time'\nShow the most recent modification timestamp (mtime) of any file in\nthe directory, or any of its subdirectories. *Note File\ntimestamps::.\n\n'--time=ctime'\n'--time=status'\n'--time=use'\nShow the most recent status change timestamp (ctime) of any file in\nthe directory, or any of its subdirectories. *Note File\ntimestamps::.\n\n'--time=atime'\n'--time=access'\nShow the most recent access timestamp (atime) of any file in the\ndirectory, or any of its subdirectories. *Note File timestamps::.\n\n'--time-style=STYLE'\nList timestamps in style STYLE. This option has an effect only if\nthe '--time' option is also specified. The STYLE should be one of\nthe following:\n\n'+FORMAT'\nList timestamps using FORMAT, where FORMAT is interpreted like\nthe format argument of 'date' (*note date invocation::). For\nexample, '--time-style=\"+%Y-%m-%d %H:%M:%S\"' causes 'du' to\nlist timestamps like '2002-03-30 23:45:56'. As with 'date',\nFORMAT's interpretation is affected by the 'LCTIME' locale\ncategory.\n\n'full-iso'\nList timestamps in full using ISO 8601-like date, time, and\ntime zone components with nanosecond precision, e.g.,\n'2002-03-30 23:45:56.477817180 -0700'. This style is\nequivalent to '+%Y-%m-%d %H:%M:%S.%N %z'.\n\n'long-iso'\nList ISO 8601 date and time components with minute precision,\ne.g., '2002-03-30 23:45'. These timestamps are shorter than\n'full-iso' timestamps, and are usually good enough for\neveryday work. This style is equivalent to '+%Y-%m-%d %H:%M'.\n\n'iso'\nList ISO 8601 dates for timestamps, e.g., '2002-03-30'. This\nstyle is equivalent to '+%Y-%m-%d'.\n\nYou can specify the default value of the '--time-style' option with\nthe environment variable 'TIMESTYLE'; if 'TIMESTYLE' is not set\nthe default style is 'long-iso'. For compatibility with 'ls', if\n'TIMESTYLE' begins with '+' and contains a newline, the newline\nand any later characters are ignored; if 'TIMESTYLE' begins with\n'posix-' the 'posix-' is ignored; and if 'TIMESTYLE' is 'locale'\nit is ignored.\n\n'-X FILE'\n'--exclude-from=FILE'\nLike '--exclude', except take the patterns to exclude from FILE,\none per line. If FILE is '-', take the patterns from standard\ninput.\n\n'--exclude=PATTERN'\nWhen recursing, skip subdirectories or files matching PATTERN. For\nexample, 'du --exclude='*.o'' excludes files whose names end in\n'.o'.\n\n'-x'\n'--one-file-system'\nSkip directories that are on different file systems from the one\nthat the argument being processed is on.\n\nOn BSD systems, 'du' reports sizes that are half the correct values\nfor files that are NFS-mounted from HP-UX systems. On HP-UX systems, it\nreports sizes that are twice the correct values for files that are\nNFS-mounted from BSD systems. This is due to a flaw in HP-UX; it also\naffects the HP-UX 'du' program.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: stat invocation, Next: sync invocation, Prev: du invocation, Up: Disk usage": { "content": "", "subsections": [ { "name": "14.3 'stat': Report file or file system status", "content": "'stat' displays information about the specified file(s). Synopsis:\n\nstat [OPTION]... [FILE]...\n\nWith no option, 'stat' reports all information about the given files." } ] }, "But it also can be used to report the information of the file systems": { "content": "the given files are located on. If the files are links, 'stat' can also\ngive information about the files the links point to.\n\nDue to shell aliases and built-in 'stat' functions, using an\nunadorned 'stat' interactively or in a script may get you different\nfunctionality than that described here. Invoke it via 'env' (i.e., 'env\nstat ...') to avoid interference from the shell.\n\n'-L'\n'--dereference'\nChange how 'stat' treats symbolic links. With this option, 'stat'\nacts on the file referenced by each symbolic link argument.\nWithout it, 'stat' acts on any symbolic link argument directly.\n\n'-f'\n'--file-system'\nReport information about the file systems where the given files are\nlocated instead of information about the files themselves. This\noption implies the '-L' option.\n\n'--cached=MODE'\nControl how attributes are read from the file system; if supported\nby the system. This allows one to control the trade-off between\nfreshness and efficiency of attribute access, especially useful\nwith remote file systems. MODE can be:\n\n'always'\nAlways read the already cached attributes if available.\n\n'never'\nAlways sychronize with the latest file system attributes.\nThis also mounts automounted files.\n\n'default'\nLeave the caching behavior to the underlying file system.\n\n'-c'\n'--format=FORMAT'\nUse FORMAT rather than the default format. FORMAT is automatically\nnewline-terminated, so running a command like the following with\ntwo or more FILE operands produces a line of output for each\noperand:\n$ stat --format=%d:%i / /usr\n2050:2\n2057:2\n\n'--printf=FORMAT'\nUse FORMAT rather than the default format. Like '--format', but\ninterpret backslash escapes, and do not output a mandatory trailing\nnewline. If you want a newline, include '\\n' in the FORMAT.\nHere's how you would use '--printf' to print the device and inode\nnumbers of '/' and '/usr':\n$ stat --printf='%d:%i\\n' / /usr\n2050:2\n2057:2\n\n'-t'\n'--terse'\nPrint the information in terse form, suitable for parsing by other\nprograms.\n\nThe output of the following commands are identical and the\n'--format' also identifies the items printed (in fuller form) in\nthe default format. Note the format string would include another\n'%C' at the end with an active SELinux security context.\n$ stat --format=\"%n %s %b %f %u %g %D %i %h %t %T %X %Y %Z %W %o\" ...\n$ stat --terse ...\n\nThe same illustrating terse output in '--file-system' mode:\n$ stat -f --format=\"%n %i %l %t %s %S %b %f %a %c %d\" ...\n$ stat -f --terse ...\n\nThe valid FORMAT directives for files with '--format' and '--printf'\nare:\n\n* %a - Permission bits in octal (note '#' and '0' printf flags)\n* %A - Permission bits in symbolic form (similar to 'ls -ld')\n* %b - Number of blocks allocated (see '%B')\n* %B - The size in bytes of each block reported by '%b'\n* %C - The SELinux security context of a file, if available\n* %d - Device number in decimal\n* %D - Device number in hex\n* %f - Raw mode in hex\n* %F - File type\n* %g - Group ID of owner\n* %G - Group name of owner\n* %h - Number of hard links\n* %i - Inode number\n* %m - Mount point (See note below)\n* %n - File name\n* %N - Quoted file name with dereference if symbolic link (see below)\n* %o - Optimal I/O transfer size hint\n* %s - Total size, in bytes\n* %t - Major device type in hex (see below)\n* %T - Minor device type in hex (see below)\n* %u - User ID of owner\n* %U - User name of owner\n* %w - Time of file birth, or '-' if unknown\n* %W - Time of file birth as seconds since Epoch, or '0'\n* %x - Time of last access\n* %X - Time of last access as seconds since Epoch\n* %y - Time of last data modification\n* %Y - Time of last data modification as seconds since Epoch\n* %z - Time of last status change\n* %Z - Time of last status change as seconds since Epoch\n\nThe '%a' format prints the octal mode, and so it is useful to control\nthe zero padding of the output with the '#' and '0' printf flags. For\nexample to pad to at least 3 wide while making larger numbers\nunambiguously octal, you can use '%#03a'.\n\nThe '%N' format can be set with the environment variable\n'QUOTINGSTYLE'. If that environment variable is not set, the default\nvalue is 'shell-escape-always'. Valid quoting styles are:\n'literal'\nOutput strings as-is; this is the same as the '-N' or '--literal'\noption.\n'shell'\nQuote strings for the shell if they contain shell metacharacters or\nwould cause ambiguous output. The quoting is suitable for\nPOSIX-compatible shells like 'bash', but it does not always work\nfor incompatible shells like 'csh'.\n'shell-always'\nQuote strings for the shell, even if they would normally not\nrequire quoting.\n'shell-escape'\nLike 'shell', but also quoting non-printable characters using the\nPOSIX proposed '$''' syntax suitable for most shells.\n'shell-escape-always'\nLike 'shell-escape', but quote strings even if they would normally\nnot require quoting.\n'c'\nQuote strings as for C character string literals, including the\nsurrounding double-quote characters; this is the same as the '-Q'\nor '--quote-name' option.\n'escape'\nQuote strings as for C character string literals, except omit the\nsurrounding double-quote characters; this is the same as the '-b'\nor '--escape' option.\n'clocale'\nQuote strings as for C character string literals, except use\nsurrounding quotation marks appropriate for the locale.\n'locale'\nQuote strings as for C character string literals, except use\nsurrounding quotation marks appropriate for the locale, and quote\n'like this' instead of \"like this\" in the default C locale. This\nlooks nicer on many displays.\n\nThe '%t' and '%T' formats operate on the strdev member of the\nstat(2) structure, and are only defined for character and block special\nfiles. On some systems or file types, strdev may be used to represent\nother quantities.\n\nThe '%W', '%X', '%Y', and '%Z' formats accept a precision preceded by\na period to specify the number of digits to print after the decimal\npoint. For example, '%.3X' outputs the access timestamp to millisecond\nprecision. If a period is given but no precision, 'stat' uses 9 digits,\nso '%.X' is equivalent to '%.9X'. When discarding excess precision,\ntimestamps are truncated toward minus infinity.\n\nzero pad:\n$ stat -c '[%015Y]' /usr\n[000001288929712]\nspace align:\n$ stat -c '[%15Y]' /usr\n[ 1288929712]\n$ stat -c '[%-15Y]' /usr\n[1288929712 ]\nprecision:\n$ stat -c '[%.3Y]' /usr\n[1288929712.114]\n$ stat -c '[%.Y]' /usr\n[1288929712.114951834]\n\nThe mount point printed by '%m' is similar to that output by 'df',\nexcept that:\n* stat does not dereference symlinks by default (unless '-L' is\nspecified)\n* stat does not search for specified device nodes in the file system\nlist, instead operating on them directly\n* stat outputs the alias for a bind mounted file, rather than the\ninitial mount point of its backing device. One can recursively\ncall stat until there is no change in output, to get the current\nbase mount point\n\nWhen listing file system information ('--file-system' ('-f')), you\nmust use a different set of FORMAT directives:\n\n* %a - Free blocks available to non-super-user\n* %b - Total data blocks in file system\n* %c - Total file nodes in file system\n* %d - Free file nodes in file system\n* %f - Free blocks in file system\n* %i - File System ID in hex\n* %l - Maximum length of file names\n* %n - File name\n* %s - Block size (for faster transfers)\n* %S - Fundamental block size (for block counts)\n* %t - Type in hex\n* %T - Type in human readable form\n\nTimestamps are listed according to the time zone rules specified by\nthe 'TZ' environment variable, or by the system default rules if 'TZ' is\nnot set. *Note Specifying the Time Zone with 'TZ': (libc)TZ Variable.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: sync invocation, Next: truncate invocation, Prev: stat invocation, Up: Disk usage": { "content": "", "subsections": [ { "name": "14.4 'sync': Synchronize cached writes to persistent storage", "content": "'sync' synchronizes in memory files or file systems to persistent\nstorage. Synopsis:\n\nsync [OPTION] [FILE]...\n\n'sync' writes any data buffered in memory out to disk. This can\ninclude (but is not limited to) modified superblocks, modified inodes,\nand delayed reads and writes. This must be implemented by the kernel;" } ] }, "The 'sync' program does nothing but exercise the 'sync', 'syncfs',": { "content": "'fsync', and 'fdatasync' system calls.\n\nThe kernel keeps data in memory to avoid doing (relatively slow) disk\nreads and writes. This improves performance, but if the computer\ncrashes, data may be lost or the file system corrupted as a result. The\n'sync' command instructs the kernel to write data in memory to\npersistent storage.\n\nIf any argument is specified then only those files will be\nsynchronized using the fsync(2) syscall by default.\n\nIf at least one file is specified, it is possible to change the\nsynchronization method with the following options. Also see *note\nCommon options::.\n\n'-d'\n'--data'\nUse fdatasync(2) to sync only the data for the file, and any\nmetadata required to maintain file system consistency.\n\n'-f'\n'--file-system'\nSynchronize all the I/O waiting for the file systems that contain\nthe file, using the syscall syncfs(2). Note you would usually\nnot specify this option if passing a device node like '/dev/sda'\nfor example, as that would sync the containing file system rather\nthan the referenced one. Note also that depending on the system,\npassing individual device nodes or files may have different sync\ncharacteristics than using no arguments. I.e., arguments passed to\nfsync(2) may provide greater guarantees through write barriers,\nthan a global sync(2) used when no arguments are provided.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: truncate invocation, Prev: sync invocation, Up: Disk usage": { "content": "", "subsections": [ { "name": "14.5 'truncate': Shrink or extend the size of a file", "content": "'truncate' shrinks or extends the size of each FILE to the specified\nsize. Synopsis:\n\ntruncate OPTION... FILE...\n\nAny FILE that does not exist is created.\n\nIf a FILE is larger than the specified size, the extra data is lost." } ] }, "If a FILE is shorter, it is extended and the sparse extended part (or": { "content": "hole) reads as zero bytes.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-c'\n'--no-create'\nDo not create files that do not exist.\n\n'-o'\n'--io-blocks'\nTreat SIZE as number of I/O blocks of the FILE rather than bytes.\n\n'-r RFILE'\n'--reference=RFILE'\nBase the size of each FILE on the size of RFILE.\n\n'-s SIZE'\n'--size=SIZE'\nSet or adjust the size of each FILE according to SIZE. SIZE is in\nbytes unless '--io-blocks' is specified. SIZE may be, or may be an\ninteger optionally followed by, one of the following multiplicative\nsuffixes:\n'KB' => 1000 (KiloBytes)\n'K' => 1024 (KibiBytes)\n'MB' => 1000*1000 (MegaBytes)\n'M' => 1024*1024 (MebiBytes)\n'GB' => 1000*1000*1000 (GigaBytes)\n'G' => 1024*1024*1024 (GibiBytes)\nand so on for 'T', 'P', 'E', 'Z', and 'Y'. Binary prefixes can be\nused, too: 'KiB'='K', 'MiB'='M', and so on.\n\nSIZE may also be prefixed by one of the following to adjust the\nsize of each FILE based on its current size:\n'+' => extend by\n'-' => reduce by\n'<' => at most\n'>' => at least\n'/' => round down to multiple of\n'%' => round up to multiple of\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: Printing text, Next: Conditions, Prev: Disk usage, Up: Top": { "content": "", "subsections": [] }, "15 Printing text": { "content": "This section describes commands that display text strings.\n\n* Menu:\n\n* echo invocation:: Print a line of text.\n* printf invocation:: Format and print data.\n* yes invocation:: Print a string until interrupted.\n", "subsections": [] }, "File: coreutils.info, Node: echo invocation, Next: printf invocation, Up: Printing text": { "content": "", "subsections": [ { "name": "15.1 'echo': Print a line of text", "content": "'echo' writes each given STRING to standard output, with a space between\neach and a newline after the last one. Synopsis:\n\necho [OPTION]... [STRING]...\n\nDue to shell aliases and built-in 'echo' functions, using an\nunadorned 'echo' interactively or in a script may get you different\nfunctionality than that described here. Invoke it via 'env' (i.e., 'env\necho ...') to avoid interference from the shell.\n\nThe program accepts the following options. Also see *note Common\noptions::. Options must precede operands, and the normally-special\nargument '--' has no special meaning and is treated like any other\nSTRING.\n\n'-n'\nDo not output the trailing newline.\n\n'-e'\nEnable interpretation of the following backslash-escaped characters\nin each STRING:\n\n'\\a'\nalert (bell)\n'\\b'\nbackspace\n'\\c'\nproduce no further output\n'\\e'\nescape\n'\\f'\nform feed\n'\\n'\nnewline\n'\\r'\ncarriage return\n'\\t'\nhorizontal tab\n'\\v'\nvertical tab\n'\\\\'\nbackslash\n'\\0NNN'\nthe eight-bit value that is the octal number NNN (zero to\nthree octal digits), if NNN is a nine-bit value, the ninth bit\nis ignored\n'\\NNN'\nthe eight-bit value that is the octal number NNN (one to three\noctal digits), if NNN is a nine-bit value, the ninth bit is\nignored\n'\\xHH'\nthe eight-bit value that is the hexadecimal number HH (one or\ntwo hexadecimal digits)\n\n'-E'\nDisable interpretation of backslash escapes in each STRING. This\nis the default. If '-e' and '-E' are both specified, the last one\ngiven takes effect.\n\nIf the 'POSIXLYCORRECT' environment variable is set, then when\n'echo''s first argument is not '-n' it outputs option-like arguments\ninstead of treating them as options. For example, 'echo -ne hello'\noutputs '-ne hello' instead of plain 'hello'. Also backslash escapes\nare always enabled.\n\nPOSIX does not require support for any options, and says that the\nbehavior of 'echo' is implementation-defined if any STRING contains a\nbackslash or if the first argument is '-n'. Portable programs can use\nthe 'printf' command if they need to omit trailing newlines or output\ncontrol characters or backslashes. *Note printf invocation::.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: printf invocation, Next: yes invocation, Prev: echo invocation, Up: Printing text": { "content": "", "subsections": [ { "name": "15.2 'printf': Format and print data", "content": "'printf' does formatted printing of text. Synopsis:\n\nprintf FORMAT [ARGUMENT]...\n\n'printf' prints the FORMAT string, interpreting '%' directives and\n'\\' escapes to format numeric and string arguments in a way that is\nmostly similar to the C 'printf' function. *Note 'printf' format\ndirectives: (libc)Output Conversion Syntax, for details. The\ndifferences are listed below.\n\nDue to shell aliases and built-in 'printf' functions, using an\nunadorned 'printf' interactively or in a script may get you different\nfunctionality than that described here. Invoke it via 'env' (i.e., 'env\nprintf ...') to avoid interference from the shell.\n\n* The FORMAT argument is reused as necessary to convert all the given\nARGUMENTs. For example, the command 'printf %s a b' outputs 'ab'.\n\n* Missing ARGUMENTs are treated as null strings or as zeros,\ndepending on whether the context expects a string or a number. For\nexample, the command 'printf %sx%d' prints 'x0'.\n\n* An additional escape, '\\c', causes 'printf' to produce no further\noutput. For example, the command 'printf 'A%sC\\cD%sF' B E' prints\n'ABC'.\n\n* The hexadecimal escape sequence '\\xHH' has at most two digits, as\nopposed to C where it can have an unlimited number of digits. For\nexample, the command 'printf '\\x07e'' prints two bytes, whereas the\nC statement 'printf (\"\\x07e\")' prints just one.\n\n* An additional directive '%b', prints its argument string with '\\'\nescapes interpreted in the same way as in the FORMAT string, except\nthat octal escapes are of the form '\\0OOO' where OOO is 0 to 3\noctal digits. If '\\OOO' is nine-bit value, ignore the ninth bit.\nIf a precision is also given, it limits the number of bytes printed\nfrom the converted string.\n\n* An additional directive '%q', prints its argument string in a\nformat that can be reused as input by most shells. Non-printable\ncharacters are escaped with the POSIX proposed '$''' syntax, and\nshell metacharacters are quoted appropriately. This is an\nequivalent format to 'ls --quoting=shell-escape' output.\n\n* Numeric arguments must be single C constants, possibly with leading\n'+' or '-'. For example, 'printf %.4d -3' outputs '-0003'.\n\n* If the leading character of a numeric argument is '\"' or ''' then\nits value is the numeric value of the immediately following\ncharacter. Any remaining characters are silently ignored if the\n'POSIXLYCORRECT' environment variable is set; otherwise, a warning\nis printed. For example, 'printf \"%d\" \"'a\"' outputs '97' on hosts\nthat use the ASCII character set, since 'a' has the numeric value\n97 in ASCII.\n\nA floating point argument is interpreted according to the\n'LCNUMERIC' category of either the current or the C locale, and is\nprinted according to the current locale. For example, in a locale whose\ndecimal point character is a comma, the command 'printf '%g %g' 2,5 2.5'\noutputs '2,5 2,5'. *Note Floating point::.\n\n'printf' interprets '\\OOO' in FORMAT as an octal number (if OOO is 1\nto 3 octal digits) specifying a byte to print, and '\\xHH' as a\nhexadecimal number (if HH is 1 to 2 hex digits) specifying a character\nto print. Note however that when '\\OOO' specifies a number larger than\n255, 'printf' ignores the ninth bit. For example, 'printf '\\400'' is\nequivalent to 'printf '\\0''.\n\n'printf' interprets two character syntaxes introduced in ISO C 99:\n'\\u' for 16-bit Unicode (ISO/IEC 10646) characters, specified as four\nhexadecimal digits HHHH, and '\\U' for 32-bit Unicode characters,\nspecified as eight hexadecimal digits HHHHHHHH. 'printf' outputs the" } ] }, "Unicode characters according to the 'LCCTYPE' locale. Unicode": { "content": "characters in the ranges U+0000...U+009F, U+D800...U+DFFF cannot be\nspecified by this syntax, except for U+0024 ($), U+0040 (@), and U+0060\n()??.\n\nThe processing of '\\u' and '\\U' requires a full-featured 'iconv'\nfacility. It is activated on systems with glibc 2.2 (or newer), or when\n'libiconv' is installed prior to this package. Otherwise '\\u' and '\\U'\nwill print as-is.\n\nThe only options are a lone '--help' or '--version'. *Note Common\noptions::. Options must precede operands.\n\nThe Unicode character syntaxes are useful for writing strings in a\nlocale independent way. For example, a string containing the Euro\ncurrency symbol\n\n$ env printf '\\u20AC 14.95'\n\nwill be output correctly in all locales supporting the Euro symbol\n(ISO-8859-15, UTF-8, and others). Similarly, a Chinese string\n\n$ env printf '\\u4e2d\\u6587'\n\nwill be output correctly in all Chinese locales (GB2312, BIG5, UTF-8,\netc).\n\nNote that in these examples, the 'printf' command has been invoked\nvia 'env' to ensure that we run the program found via your shell's\nsearch path, and not a shell alias or a built-in function.\n\nFor larger strings, you don't need to look up the hexadecimal code\nvalues of each character one by one. ASCII characters mixed with \\u\nescape sequences is also known as the JAVA source file encoding. You\ncan use GNU recode 3.5c (or newer) to convert strings to this encoding.", "subsections": [] }, "Here is how to convert a piece of text into a shell script which will": { "content": "output this text in a locale-independent way:\n\n$ LCCTYPE=zhCN.big5 /usr/local/bin/printf \\\n'\\u4e2d\\u6587\\n' > sample.txt\n$ recode BIG5..JAVA < sample.txt \\\n| sed -e \"s|^|/usr/local/bin/printf '|\" -e \"s|$|\\\\\\\\n'|\" \\\n> sample.sh\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: yes invocation, Prev: printf invocation, Up: Printing text": { "content": "", "subsections": [ { "name": "15.3 'yes': Print a string until interrupted", "content": "'yes' prints the command line arguments, separated by spaces and\nfollowed by a newline, forever until it is killed. If no arguments are\ngiven, it prints 'y' followed by a newline forever until killed.\n\nUpon a write error, 'yes' exits with status '1'.\n\nThe only options are a lone '--help' or '--version'. To output an\nargument that begins with '-', precede it with '--', e.g., 'yes --\n--help'. *Note Common options::.\n" } ] }, "File: coreutils.info, Node: Conditions, Next: Redirection, Prev: Printing text, Up: Top": { "content": "", "subsections": [] }, "16 Conditions": { "content": "", "subsections": [] }, "This section describes commands that are primarily useful for their exit": { "content": "status, rather than their output. Thus, they are often used as the\ncondition of shell 'if' statements, or as the last command in a\npipeline.\n\n* Menu:\n\n* false invocation:: Do nothing, unsuccessfully.\n* true invocation:: Do nothing, successfully.\n* test invocation:: Check file types and compare values.\n* expr invocation:: Evaluate expressions.\n", "subsections": [] }, "File: coreutils.info, Node: false invocation, Next: true invocation, Up: Conditions": { "content": "", "subsections": [ { "name": "16.1 'false': Do nothing, unsuccessfully", "content": "'false' does nothing except return an exit status of 1, meaning\n\"failure\". It can be used as a place holder in shell scripts where an\nunsuccessful command is needed. In most modern shells, 'false' is a\nbuilt-in command, so when you use 'false' in a script, you're probably\nusing the built-in command, not the one documented here.\n\n'false' honors the '--help' and '--version' options.\n\nThis version of 'false' is implemented as a C program, and is thus\nmore secure and faster than a shell script implementation, and may\nsafely be used as a dummy shell for the purpose of disabling accounts.\n\nNote that 'false' (unlike all other programs documented herein) exits\nunsuccessfully, even when invoked with '--help' or '--version'.\n\nPortable programs should not assume that the exit status of 'false'\nis 1, as it is greater than 1 on some non-GNU hosts.\n" } ] }, "File: coreutils.info, Node: true invocation, Next: test invocation, Prev: false invocation, Up: Conditions": { "content": "", "subsections": [ { "name": "16.2 'true': Do nothing, successfully", "content": "'true' does nothing except return an exit status of 0, meaning\n\"success\". It can be used as a place holder in shell scripts where a\nsuccessful command is needed, although the shell built-in command ':'\n(colon) may do the same thing faster. In most modern shells, 'true' is\na built-in command, so when you use 'true' in a script, you're probably\nusing the built-in command, not the one documented here.\n\n'true' honors the '--help' and '--version' options.\n\nNote, however, that it is possible to cause 'true' to exit with\nnonzero status: with the '--help' or '--version' option, and with\nstandard output already closed or redirected to a file that evokes an\nI/O error. For example, using a Bourne-compatible shell:\n\n$ ./true --version >&-\n./true: write error: Bad file number\n$ ./true --version > /dev/full\n./true: write error: No space left on device\n\nThis version of 'true' is implemented as a C program, and is thus\nmore secure and faster than a shell script implementation, and may\nsafely be used as a dummy shell for the purpose of disabling accounts.\n" } ] }, "File: coreutils.info, Node: test invocation, Next: expr invocation, Prev: true invocation, Up: Conditions": { "content": "", "subsections": [ { "name": "16.3 'test': Check file types and compare values", "content": "'test' returns a status of 0 (true) or 1 (false) depending on the\nevaluation of the conditional expression EXPR. Each part of the\nexpression must be a separate argument.\n\n'test' has file status checks, string operators, and numeric\ncomparison operators.\n\n'test' has an alternate form that uses opening and closing square\nbrackets instead a leading 'test'. For example, instead of 'test -d /',\nyou can write '[ -d / ]'. The square brackets must be separate\narguments; for example, '[-d /]' does not have the desired effect.\nSince 'test EXPR' and '[ EXPR ]' have the same meaning, only the former\nform is discussed below.\n\nSynopses:\n\ntest EXPRESSION\ntest\n[ EXPRESSION ]\n[ ]\n[ OPTION\n\nDue to shell aliases and built-in 'test' functions, using an\nunadorned 'test' interactively or in a script may get you different\nfunctionality than that described here. Invoke it via 'env' (i.e., 'env\ntest ...') to avoid interference from the shell.\n\nIf EXPRESSION is omitted, 'test' returns false. If EXPRESSION is a\nsingle argument, 'test' returns false if the argument is null and true\notherwise. The argument can be any string, including strings like '-d',\n'-1', '--', '--help', and '--version' that most other programs would\ntreat as options. To get help and version information, invoke the\ncommands '[ --help' and '[ --version', without the usual closing\nbrackets. *Note Common options::.\n\nExit status:\n\n0 if the expression is true,\n1 if the expression is false,\n2 if an error occurred.\n\n* Menu:\n\n* File type tests:: -[bcdfhLpSt]\n* Access permission tests:: -[gkruwxOG]\n* File characteristic tests:: -e -s -nt -ot -ef\n* String tests:: -z -n = == !=\n* Numeric tests:: -eq -ne -lt -le -gt -ge\n* Connectives for test:: ! -a -o\n" } ] }, "File: coreutils.info, Node: File type tests, Next: Access permission tests, Up: test invocation": { "content": "", "subsections": [] }, "These options test for particular types of files. (Everything's a file,": { "content": "but not all files are the same!)\n\n'-b FILE'\nTrue if FILE exists and is a block special device.\n\n'-c FILE'\nTrue if FILE exists and is a character special device.\n\n'-d FILE'\nTrue if FILE exists and is a directory.\n\n'-f FILE'\nTrue if FILE exists and is a regular file.\n\n'-h FILE'\n'-L FILE'\nTrue if FILE exists and is a symbolic link. Unlike all other\nfile-related tests, this test does not dereference FILE if it is a\nsymbolic link.\n\n'-p FILE'\nTrue if FILE exists and is a named pipe.\n\n'-S FILE'\nTrue if FILE exists and is a socket.\n\n'-t FD'\nTrue if FD is a file descriptor that is associated with a terminal.\n", "subsections": [] }, "File: coreutils.info, Node: Access permission tests, Next: File characteristic tests, Prev: File type tests, Up: test invocation": { "content": "These options test for particular access permissions.\n\n'-g FILE'\nTrue if FILE exists and has its set-group-ID bit set.\n\n'-k FILE'\nTrue if FILE exists and has its \"sticky\" bit set.\n\n'-r FILE'\nTrue if FILE exists and read permission is granted.\n\n'-u FILE'\nTrue if FILE exists and has its set-user-ID bit set.\n\n'-w FILE'\nTrue if FILE exists and write permission is granted.\n\n'-x FILE'\nTrue if FILE exists and execute permission is granted (or search\npermission, if it is a directory).\n\n'-O FILE'\nTrue if FILE exists and is owned by the current effective user ID.\n\n'-G FILE'\nTrue if FILE exists and is owned by the current effective group ID.\n", "subsections": [] }, "File: coreutils.info, Node: File characteristic tests, Next: String tests, Prev: Access permission tests, Up: test invocation": { "content": "These options test other file characteristics.\n\n'-e FILE'\nTrue if FILE exists.\n\n'-s FILE'\nTrue if FILE exists and has a size greater than zero.\n\n'FILE1 -nt FILE2'\nTrue if FILE1 is newer (according to modification date) than FILE2,\nor if FILE1 exists and FILE2 does not.\n\n'FILE1 -ot FILE2'\nTrue if FILE1 is older (according to modification date) than FILE2,\nor if FILE2 exists and FILE1 does not.\n\n'FILE1 -ef FILE2'\nTrue if FILE1 and FILE2 have the same device and inode numbers,\ni.e., if they are hard links to each other.\n\n'-N FILE'\nTrue if FILE exists and has been modified (mtime) since it was last\nread (atime).\n", "subsections": [] }, "File: coreutils.info, Node: String tests, Next: Numeric tests, Prev: File characteristic tests, Up: test invocation": { "content": "", "subsections": [] }, "These options test string characteristics. You may need to quote STRING": { "content": "arguments for the shell. For example:\n\ntest -n \"$V\"\n\nThe quotes here prevent the wrong arguments from being passed to\n'test' if '$V' is empty or contains special characters.\n\n'-z STRING'\nTrue if the length of STRING is zero.\n\n'-n STRING'\n'STRING'\nTrue if the length of STRING is nonzero.\n\n'STRING1 = STRING2'\nTrue if the strings are equal.\n\n'STRING1 == STRING2'\nTrue if the strings are equal (synonym for =).\n\n'STRING1 != STRING2'\nTrue if the strings are not equal.\n", "subsections": [] }, "File: coreutils.info, Node: Numeric tests, Next: Connectives for test, Prev: String tests, Up: test invocation": { "content": "", "subsections": [] }, "Numeric relational operators. The arguments must be entirely numeric": { "content": "(possibly negative), or the special expression '-l STRING', which\nevaluates to the length of STRING.\n\n'ARG1 -eq ARG2'\n'ARG1 -ne ARG2'\n'ARG1 -lt ARG2'\n'ARG1 -le ARG2'\n'ARG1 -gt ARG2'\n'ARG1 -ge ARG2'\nThese arithmetic binary operators return true if ARG1 is equal,\nnot-equal, less-than, less-than-or-equal, greater-than, or\ngreater-than-or-equal than ARG2, respectively.\n\nFor example:\n\ntest -1 -gt -2 && echo yes\n=> yes\ntest -l abc -gt 1 && echo yes\n=> yes\ntest 0x100 -eq 1\nerror-> test: integer expression expected before -eq\n", "subsections": [] }, "File: coreutils.info, Node: Connectives for test, Prev: Numeric tests, Up: test invocation": { "content": "", "subsections": [] }, "Note it's preferred to use shell logical primitives rather than these": { "content": "logical connectives internal to 'test', because an expression may become\nambiguous depending on the expansion of its parameters.\n\nFor example, this becomes ambiguous when '$1' is set to ''!'' and\n'$2' to the empty string '''':\n\ntest \"$1\" -a \"$2\"\n\nand should be written as:\n\ntest \"$1\" && test \"$2\"\n\nNote the shell logical primitives also benefit from short circuit\noperation, which can be significant for file attribute tests.\n\n'! EXPR'\nTrue if EXPR is false. '!' has lower precedence than all parts of\nEXPR. Note '!' needs to be specified to the left of a binary\nexpression, I.e., ''!' 1 -gt 2' rather than '1 '!' -gt 2'. Also\n'!' is often a shell special character and is best used quoted.\n\n'EXPR1 -a EXPR2'\nTrue if both EXPR1 and EXPR2 are true. '-a' is left associative,\nand has a higher precedence than '-o'.\n\n'EXPR1 -o EXPR2'\nTrue if either EXPR1 or EXPR2 is true. '-o' is left associative.\n", "subsections": [] }, "File: coreutils.info, Node: expr invocation, Prev: test invocation, Up: Conditions": { "content": "", "subsections": [ { "name": "16.4 'expr': Evaluate expressions", "content": "'expr' evaluates an expression and writes the result on standard output.\nEach token of the expression must be a separate argument.\n\nOperands are either integers or strings. Integers consist of one or\nmore decimal digits, with an optional leading '-'. 'expr' converts\nanything appearing in an operand position to an integer or a string\ndepending on the operation being applied to it.\n\nStrings are not quoted for 'expr' itself, though you may need to\nquote them to protect characters with special meaning to the shell,\ne.g., spaces. However, regardless of whether it is quoted, a string\noperand should not be a parenthesis or any of 'expr''s operators like\n'+', so you cannot safely pass an arbitrary string '$str' to expr merely\nby quoting it to the shell. One way to work around this is to use the\nGNU extension '+', (e.g., '+ \"$str\" = foo'); a more portable way is to\nuse '\" $str\"' and to adjust the rest of the expression to take the\nleading space into account (e.g., '\" $str\" = \" foo\"').\n\nYou should not pass a negative integer or a string with leading '-'\nas 'expr''s first argument, as it might be misinterpreted as an option;\nthis can be avoided by parenthesization. Also, portable scripts should\nnot use a string operand that happens to take the form of an integer;\nthis can be worked around by inserting leading spaces as mentioned\nabove.\n\nOperators may be given as infix symbols or prefix keywords." } ] }, "Parentheses may be used for grouping in the usual manner. You must": { "content": "quote parentheses and many operators to avoid the shell evaluating them,\nhowever.\n\nWhen built with support for the GNU MP library, 'expr' uses\narbitrary-precision arithmetic; otherwise, it uses native arithmetic\ntypes and may fail due to arithmetic overflow.\n\nThe only options are '--help' and '--version'. *Note Common\noptions::. Options must precede operands.\n\nExit status:\n\n0 if the expression is neither null nor 0,\n1 if the expression is null or 0,\n2 if the expression is invalid,\n3 if an internal error occurred (e.g., arithmetic overflow).\n\n* Menu:\n\n* String expressions:: + : match substr index length\n* Numeric expressions:: + - * / %\n* Relations for expr:: | & < <= = == != >= >\n* Examples of expr:: Examples.\n", "subsections": [] }, "File: coreutils.info, Node: String expressions, Next: Numeric expressions, Up: expr invocation": { "content": "'expr' supports pattern matching and other string operators. These have\nhigher precedence than both the numeric and relational operators (in the\nnext sections).\n\n'STRING : REGEX'\nPerform pattern matching. The arguments are converted to strings\nand the second is considered to be a (basic, a la GNU 'grep')\nregular expression, with a '^' implicitly prepended. The first\nargument is then matched against this regular expression.\n\nIf the match succeeds and REGEX uses '\\(' and '\\)', the ':'\nexpression returns the part of STRING that matched the\nsubexpression; otherwise, it returns the number of characters\nmatched.\n\nIf the match fails, the ':' operator returns the null string if\n'\\(' and '\\)' are used in REGEX, otherwise 0.\n\nOnly the first '\\( ... \\)' pair is relevant to the return value;\nadditional pairs are meaningful only for grouping the regular\nexpression operators.\n\nIn the regular expression, '\\+', '\\?', and '\\|' are operators which\nrespectively match one or more, zero or one, or separate\nalternatives. SunOS and other 'expr''s treat these as regular\ncharacters. (POSIX allows either behavior.) *Note Regular\nExpression Library: (regex)Top, for details of regular expression\nsyntax. Some examples are in *note Examples of expr::.\n\n'match STRING REGEX'\nAn alternative way to do pattern matching. This is the same as\n'STRING : REGEX'.\n\n'substr STRING POSITION LENGTH'\nReturns the substring of STRING beginning at POSITION with length\nat most LENGTH. If either POSITION or LENGTH is negative, zero, or\nnon-numeric, returns the null string.\n\n'index STRING CHARSET'\nReturns the first position in STRING where the first character in\nCHARSET was found. If no character in CHARSET is found in STRING,\nreturn 0.\n\n'length STRING'\nReturns the length of STRING.\n\n'+ TOKEN'\nInterpret TOKEN as a string, even if it is a keyword like MATCH or\nan operator like '/'. This makes it possible to test 'expr length\n+ \"$x\"' or 'expr + \"$x\" : '.*/\\(.\\)'' and have it do the right\nthing even if the value of $X happens to be (for example) '/' or\n'index'. This operator is a GNU extension. Portable shell scripts\nshould use '\" $token\" : ' \\(.*\\)'' instead of '+ \"$token\"'.\n\nTo make 'expr' interpret keywords as strings, you must use the\n'quote' operator.\n", "subsections": [] }, "File: coreutils.info, Node: Numeric expressions, Next: Relations for expr, Prev: String expressions, Up: expr invocation": { "content": "'expr' supports the usual numeric operators, in order of increasing\nprecedence. These numeric operators have lower precedence than the\nstring operators described in the previous section, and higher\nprecedence than the connectives (next section).\n\n'+ -'\nAddition and subtraction. Both arguments are converted to\nintegers; an error occurs if this cannot be done.\n\n'* / %'\nMultiplication, division, remainder. Both arguments are converted\nto integers; an error occurs if this cannot be done.\n", "subsections": [] }, "File: coreutils.info, Node: Relations for expr, Next: Examples of expr, Prev: Numeric expressions, Up: expr invocation": { "content": "'expr' supports the usual logical connectives and relations. These have\nlower precedence than the string and numeric operators (previous\nsections). Here is the list, lowest-precedence operator first.\n\n'|'\nReturns its first argument if that is neither null nor zero,\notherwise its second argument if it is neither null nor zero,\notherwise 0. It does not evaluate its second argument if its first\nargument is neither null nor zero.\n\n'&'\nReturn its first argument if neither argument is null or zero,\notherwise 0. It does not evaluate its second argument if its first\nargument is null or zero.\n\n'< <= = == != >= >'\nCompare the arguments and return 1 if the relation is true, 0\notherwise. '==' is a synonym for '='. 'expr' first tries to\nconvert both arguments to integers and do a numeric comparison; if\neither conversion fails, it does a lexicographic comparison using\nthe character collating sequence specified by the 'LCCOLLATE'\nlocale.\n", "subsections": [] }, "File: coreutils.info, Node: Examples of expr, Prev: Relations for expr, Up: expr invocation": { "content": "Here are a few examples, including quoting for shell metacharacters.\n\nTo add 1 to the shell variable 'foo', in Bourne-compatible shells:\n\nfoo=$(expr $foo + 1)\n\nTo print the non-directory part of the file name stored in '$fname',\nwhich need not contain a '/':\n\nexpr $fname : '.*/\\(.*\\)' '|' $fname\n\nAn example showing that '\\+' is an operator:\n\nexpr aaa : 'a\\+'\n=> 3\n\nexpr abc : 'a\\(.\\)c'\n=> b\nexpr index abcdef cz\n=> 3\nexpr index index a\nerror-> expr: syntax error\nexpr index + index a\n=> 0\n", "subsections": [] }, "File: coreutils.info, Node: Redirection, Next: File name manipulation, Prev: Conditions, Up: Top": { "content": "", "subsections": [] }, "17 Redirection": { "content": "Unix shells commonly provide several forms of \"redirection\"--ways to\nchange the input source or output destination of a command. But one\nuseful redirection is performed by a separate command, not by the shell;\nit's described here.\n\n* Menu:\n\n* tee invocation:: Redirect output to multiple files or processes.\n", "subsections": [] }, "File: coreutils.info, Node: tee invocation, Up: Redirection": { "content": "", "subsections": [ { "name": "17.1 'tee': Redirect output to multiple files or processes", "content": "" } ] }, "The 'tee' command copies standard input to standard output and also to": { "content": "any files given as arguments. This is useful when you want not only to\nsend some data down a pipe, but also to save a copy. Synopsis:\n\ntee [OPTION]... [FILE]...\n\nIf a file being written to does not already exist, it is created. If\na file being written to already exists, the data it previously contained\nis overwritten unless the '-a' option is used.\n\nIn previous versions of GNU coreutils (v5.3.0 - v8.23), a FILE of '-'\ncaused 'tee' to send another copy of input to standard output. However,\nas the interleaved output was not very useful, 'tee' now conforms to\nPOSIX which explicitly mandates it to treat '-' as a file with such\nname.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-a'\n'--append'\nAppend standard input to the given files rather than overwriting\nthem.\n\n'-i'\n'--ignore-interrupts'\nIgnore interrupt signals.\n\n'-p'\n'--output-error[=MODE]'\nAdjust the behavior with errors on the outputs, with the long form\noption supporting selection between the following MODEs:\n\n'warn'\nWarn on error opening or writing any output, including pipes.\nWriting is continued to still open files/pipes. Exit status\nindicates failure if any output has an error.\n\n'warn-nopipe'\nThis is the default MODE when not specified, or when the short\nform '-p' is used. Warn on error opening or writing any\noutput, except pipes. Writing is continued to still open\nfiles/pipes. Exit status indicates failure if any non pipe\noutput had an error.\n\n'exit'\nExit on error opening or writing any output, including pipes.\n\n'exit-nopipe'\nExit on error opening or writing any output, except pipes.\n\nThe 'tee' command is useful when you happen to be transferring a\nlarge amount of data and also want to summarize that data without\nreading it a second time. For example, when you are downloading a DVD\nimage, you often want to verify its signature or checksum right away.\nThe inefficient way to do it is simply:\n\nwget https://example.com/some.iso && sha1sum some.iso\n\nOne problem with the above is that it makes you wait for the download\nto complete before starting the time-consuming SHA1 computation.", "subsections": [] }, "Perhaps even more importantly, the above requires reading the DVD image": { "content": "a second time (the first was from the network).\n\nThe efficient way to do it is to interleave the download and SHA1\ncomputation. Then, you'll get the checksum for free, because the entire\nprocess parallelizes so well:\n\n# slightly contrived, to demonstrate process substitution\nwget -O - https://example.com/dvd.iso \\\n| tee >(sha1sum > dvd.sha1) > dvd.iso\n\nThat makes 'tee' write not just to the expected output file, but also\nto a pipe running 'sha1sum' and saving the final checksum in a file\nnamed 'dvd.sha1'.\n\nNote, however, that this example relies on a feature of modern shells\ncalled \"process substitution\" (the '>(command)' syntax, above; *Note", "subsections": [] }, "Process Substitution: (bash)Process Substitution.), so it works with": { "content": "'zsh', 'bash', and 'ksh', but not with '/bin/sh'. So if you write code\nlike this in a shell script, be sure to start the script with\n'#!/bin/bash'.\n\nNote also that if any of the process substitutions (or piped stdout)\nmight exit early without consuming all the data, the '-p' option is\nneeded to allow 'tee' to continue to process the input to any remaining\noutputs.\n\nSince the above example writes to one file and one process, a more\nconventional and portable use of 'tee' is even better:\n\nwget -O - https://example.com/dvd.iso \\\n| tee dvd.iso | sha1sum > dvd.sha1\n\nYou can extend this example to make 'tee' write to two processes,\ncomputing MD5 and SHA1 checksums in parallel. In this case, process\nsubstitution is required:\n\nwget -O - https://example.com/dvd.iso \\\n| tee >(sha1sum > dvd.sha1) \\\n>(md5sum > dvd.md5) \\\n> dvd.iso\n\nThis technique is also useful when you want to make a compressed\ncopy of the contents of a pipe. Consider a tool to graphically\nsummarize disk usage data from 'du -ak'. For a large hierarchy, 'du\n-ak' can run for a long time, and can easily produce terabytes of data,\nso you won't want to rerun the command unnecessarily. Nor will you want\nto save the uncompressed output.\n\nDoing it the inefficient way, you can't even start the GUI until\nafter you've compressed all of the 'du' output:\n\ndu -ak | gzip -9 > /tmp/du.gz\ngzip -d /tmp/du.gz | xdiskusage -a\n\nWith 'tee' and process substitution, you start the GUI right away and\neliminate the decompression completely:\n\ndu -ak | tee >(gzip -9 > /tmp/du.gz) | xdiskusage -a\n\nFinally, if you regularly create more than one type of compressed\ntarball at once, for example when 'make dist' creates both\n'gzip'-compressed and 'bzip2'-compressed tarballs, there may be a better\nway. Typical 'automake'-generated 'Makefile' rules create the two\ncompressed tar archives with commands in sequence, like this (slightly\nsimplified):\n\ntardir=your-pkg-M.N\ntar chof - \"$tardir\" | gzip -9 -c > your-pkg-M.N.tar.gz\ntar chof - \"$tardir\" | bzip2 -9 -c > your-pkg-M.N.tar.bz2\n\nHowever, if the hierarchy you are archiving and compressing is larger\nthan a couple megabytes, and especially if you are using a\nmulti-processor system with plenty of memory, then you can do much\nbetter by reading the directory contents only once and running the\ncompression programs in parallel:\n\ntardir=your-pkg-M.N\ntar chof - \"$tardir\" \\\n| tee >(gzip -9 -c > your-pkg-M.N.tar.gz) \\\n| bzip2 -9 -c > your-pkg-M.N.tar.bz2\n\nIf you want to further process the output from process substitutions,\nand those processes write atomically (i.e., write less than the system's\nPIPEBUF size at a time), that's possible with a construct like:\n\ntardir=your-pkg-M.N\ntar chof - \"$tardir\" \\\n| tee >(md5sum --tag) > >(sha256sum --tag) \\\n| sort | gpg --clearsign > your-pkg-M.N.tar.sig\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: File name manipulation, Next: Working context, Prev: Redirection, Up: Top": { "content": "", "subsections": [] }, "18 File name manipulation": { "content": "This section describes commands that manipulate file names.\n\n* Menu:\n\n* basename invocation:: Strip directory and suffix from a file name.\n* dirname invocation:: Strip last file name component.\n* pathchk invocation:: Check file name validity and portability.\n* mktemp invocation:: Create temporary file or directory.\n* realpath invocation:: Print resolved file names.\n", "subsections": [] }, "File: coreutils.info, Node: basename invocation, Next: dirname invocation, Up: File name manipulation": { "content": "", "subsections": [ { "name": "18.1 'basename': Strip directory and suffix from a file name", "content": "'basename' removes any leading directory components from NAME.\nSynopsis:\n\nbasename NAME [SUFFIX]\nbasename OPTION... NAME...\n\nIf SUFFIX is specified and is identical to the end of NAME, it is\nremoved from NAME as well. Note that since trailing slashes are removed\nprior to suffix matching, SUFFIX will do nothing if it contains slashes.\n'basename' prints the result on standard output.\n\nTogether, 'basename' and 'dirname' are designed such that if 'ls\n\"$name\"' succeeds, then the command sequence 'cd \"$(dirname \"$name\")\";\nls \"$(basename \"$name\")\"' will, too. This works for everything except\nfile names containing a trailing newline.\n\nPOSIX allows the implementation to define the results if NAME is\nempty or '//'. In the former case, GNU 'basename' returns the empty\nstring. In the latter case, the result is '//' on platforms where // is\ndistinct from /, and '/' on platforms where there is no difference.\n\nThe program accepts the following options. Also see *note Common\noptions::. Options must precede operands.\n\n'-a'\n'--multiple'\nSupport more than one argument. Treat every argument as a NAME.\nWith this, an optional SUFFIX must be specified using the '-s'\noption.\n\n'-s SUFFIX'\n'--suffix=SUFFIX'\nRemove a trailing SUFFIX. This option implies the '-a' option.\n\n'-z'\n'--zero'\nOutput a zero byte (ASCII NUL) at the end of each line, rather than\na newline. This option enables other programs to parse the output\neven when that output would contain data with embedded newlines.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nExamples:\n\n# Output \"sort\".\nbasename /usr/bin/sort\n\n# Output \"stdio\".\nbasename include/stdio.h .h\n\n# Output \"stdio\".\nbasename -s .h include/stdio.h\n\n# Output \"stdio\" followed by \"stdlib\"\nbasename -a -s .h include/stdio.h include/stdlib.h\n" } ] }, "File: coreutils.info, Node: dirname invocation, Next: pathchk invocation, Prev: basename invocation, Up: File name manipulation": { "content": "", "subsections": [ { "name": "18.2 'dirname': Strip last file name component", "content": "'dirname' prints all but the final slash-delimited component of each\nNAME. Slashes on either side of the final component are also removed." } ] }, "If the string contains no slash, 'dirname' prints '.' (meaning the": { "content": "current directory). Synopsis:\n\ndirname [OPTION] NAME...\n\nNAME need not be a file name, but if it is, this operation\neffectively lists the directory that contains the final component,\nincluding the case when the final component is itself a directory.\n\nTogether, 'basename' and 'dirname' are designed such that if 'ls\n\"$name\"' succeeds, then the command sequence 'cd \"$(dirname \"$name\")\";\nls \"$(basename \"$name\")\"' will, too. This works for everything except\nfile names containing a trailing newline.\n\nPOSIX allows the implementation to define the results if NAME is\n'//'. With GNU 'dirname', the result is '//' on platforms where // is\ndistinct from /, and '/' on platforms where there is no difference.\n\nThe program accepts the following option. Also see *note Common\noptions::.\n\n'-z'\n'--zero'\nOutput a zero byte (ASCII NUL) at the end of each line, rather than\na newline. This option enables other programs to parse the output\neven when that output would contain data with embedded newlines.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nExamples:\n\n# Output \"/usr/bin\".\ndirname /usr/bin/sort\ndirname /usr/bin//.//\n\n# Output \"dir1\" followed by \"dir2\"\ndirname dir1/str dir2/str\n\n# Output \".\".\ndirname stdio.h\n", "subsections": [] }, "File: coreutils.info, Node: pathchk invocation, Next: mktemp invocation, Prev: dirname invocation, Up: File name manipulation": { "content": "", "subsections": [ { "name": "18.3 'pathchk': Check file name validity and portability", "content": "'pathchk' checks validity and portability of file names. Synopsis:\n\npathchk [OPTION]... NAME...\n\nFor each NAME, 'pathchk' prints an error message if any of these\nconditions is true:\n\n1. One of the existing directories in NAME does not have search\n(execute) permission,\n2. The length of NAME is larger than the maximum supported by the\noperating system.\n3. The length of one component of NAME is longer than its file\nsystem's maximum.\n\nA nonexistent NAME is not an error, so long a file with that name\ncould be created under the above conditions.\n\nThe program accepts the following options. Also see *note Common\noptions::. Options must precede operands.\n\n'-p'\nInstead of performing checks based on the underlying file system,\nprint an error message if any of these conditions is true:\n\n1. A file name is empty.\n\n2. A file name contains a character outside the POSIX portable\nfile name character set, namely, the ASCII letters and digits,\n'.', '', '-', and '/'.\n\n3. The length of a file name or one of its components exceeds the\nPOSIX minimum limits for portability.\n\n'-P'\nPrint an error message if a file name is empty, or if it contains a\ncomponent that begins with '-'.\n\n'--portability'\nPrint an error message if a file name is not portable to all POSIX\nhosts. This option is equivalent to '-p -P'.\n\nExit status:\n\n0 if all specified file names passed all checks,\n1 otherwise.\n" } ] }, "File: coreutils.info, Node: mktemp invocation, Next: realpath invocation, Prev: pathchk invocation, Up: File name manipulation": { "content": "", "subsections": [ { "name": "18.4 'mktemp': Create temporary file or directory", "content": "'mktemp' manages the creation of temporary files and directories.\nSynopsis:\n\nmktemp [OPTION]... [TEMPLATE]\n\nSafely create a temporary file or directory based on TEMPLATE, and\nprint its name. If given, TEMPLATE must include at least three\nconsecutive 'X's in the last component. If omitted, the template\n'tmp.XXXXXXXXXX' is used, and option '--tmpdir' is implied. The final\nrun of 'X's in the TEMPLATE will be replaced by alpha-numeric\ncharacters; thus, on a case-sensitive file system, and with a TEMPLATE\nincluding a run of N instances of 'X', there are '62N' potential file\nnames.\n\nOlder scripts used to create temporary files by simply joining the\nname of the program with the process id ('$$') as a suffix. However,\nthat naming scheme is easily predictable, and suffers from a race\ncondition where the attacker can create an appropriately named symbolic\nlink, such that when the script then opens a handle to what it thought\nwas an unused file, it is instead modifying an existing file. Using the\nsame scheme to create a directory is slightly safer, since the 'mkdir'\nwill fail if the target already exists, but it is still inferior because\nit allows for denial of service attacks. Therefore, modern scripts\nshould use the 'mktemp' command to guarantee that the generated name\nwill be unpredictable, and that knowledge of the temporary file name\nimplies that the file was created by the current script and cannot be\nmodified by other users.\n\nWhen creating a file, the resulting file has read and write\npermissions for the current user, but no permissions for the group or\nothers; these permissions are reduced if the current umask is more\nrestrictive.\n\nHere are some examples (although note that if you repeat them, you\nwill most likely get different file names):\n\n* Create a temporary file in the current directory.\n$ mktemp file.XXXX\nfile.H47c\n\n* Create a temporary file with a known suffix.\n$ mktemp --suffix=.txt file-XXXX\nfile-H08W.txt\n$ mktemp file-XXXX-XXXX.txt\nfile-XXXX-eI9L.txt\n\n* Create a secure fifo relative to the user's choice of 'TMPDIR', but\nfalling back to the current directory rather than '/tmp'. Note\nthat 'mktemp' does not create fifos, but can create a secure\ndirectory in which the fifo can live. Exit the shell if the\ndirectory or fifo could not be created.\n$ dir=$(mktemp -p \"${TMPDIR:-.}\" -d dir-XXXX) || exit 1\n$ fifo=$dir/fifo\n$ mkfifo \"$fifo\" || { rmdir \"$dir\"; exit 1; }\n\n* Create and use a temporary file if possible, but ignore failure.\nThe file will reside in the directory named by 'TMPDIR', if\nspecified, or else in '/tmp'.\n$ file=$(mktemp -q) && {\n> # Safe to use $file only within this block. Use quotes,\n> # since $TMPDIR, and thus $file, may contain whitespace.\n> echo ... > \"$file\"\n> rm \"$file\"\n> }\n\n* Act as a semi-random character generator (it is not fully random,\nsince it is impacted by the contents of the current directory). To\navoid security holes, do not use the resulting names to create a\nfile.\n$ mktemp -u XXX\nGb9\n$ mktemp -u XXX\nnzC\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-d'\n'--directory'\nCreate a directory rather than a file. The directory will have\nread, write, and search permissions for the current user, but no\npermissions for the group or others; these permissions are reduced\nif the current umask is more restrictive.\n\n'-q'\n'--quiet'\nSuppress diagnostics about failure to create a file or directory.\nThe exit status will still reflect whether a file was created.\n\n'-u'\n'--dry-run'\nGenerate a temporary name that does not name an existing file,\nwithout changing the file system contents. Using the output of\nthis command to create a new file is inherently unsafe, as there is\na window of time between generating the name and using it where\nanother process can create an object by the same name.\n\n'-p DIR'\n'--tmpdir[=DIR]'\nTreat TEMPLATE relative to the directory DIR. If DIR is not\nspecified (only possible with the long option '--tmpdir') or is the\nempty string, use the value of 'TMPDIR' if available, otherwise use\n'/tmp'. If this is specified, TEMPLATE must not be absolute.\nHowever, TEMPLATE can still contain slashes, although intermediate\ndirectories must already exist.\n\n'--suffix=SUFFIX'\nAppend SUFFIX to the TEMPLATE. SUFFIX must not contain slash. If\n'--suffix' is specified, TEMPLATE must end in 'X'; if it is not\nspecified, then an appropriate '--suffix' is inferred by finding\nthe last 'X' in TEMPLATE. This option exists for use with the\ndefault TEMPLATE and for the creation of a SUFFIX that starts with\n'X'.\n\n'-t'\nTreat TEMPLATE as a single file relative to the value of 'TMPDIR'\nif available, or to the directory specified by '-p', otherwise to\n'/tmp'. TEMPLATE must not contain slashes. This option is\ndeprecated; the use of '-p' without '-t' offers better defaults (by\nfavoring the command line over 'TMPDIR') and more flexibility (by\nallowing intermediate directories).\n\nExit status:\n\n0 if the file was created,\n1 otherwise.\n" } ] }, "File: coreutils.info, Node: realpath invocation, Prev: mktemp invocation, Up: File name manipulation": { "content": "", "subsections": [ { "name": "18.5 'realpath': Print the resolved file name.", "content": "'realpath' expands all symbolic links and resolves references to '/./',\n'/../' and extra '/' characters. By default, all but the last component\nof the specified files must exist. Synopsis:\n\nrealpath [OPTION]... FILE...\n\nThe file name canonicalization functionality overlaps with that of\nthe 'readlink' command. This is the preferred command for\ncanonicalization as it's a more suitable and standard name. In addition\nthis command supports relative file name processing functionality.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-e'\n'--canonicalize-existing'\nEnsure that all components of the specified file names exist. If\nany component is missing or unavailable, 'realpath' will output a\ndiagnostic unless the '-q' option is specified, and exit with a\nnonzero exit code. A trailing slash requires that the name resolve\nto a directory.\n\n'-m'\n'--canonicalize-missing'\nIf any component of a specified file name is missing or\nunavailable, treat it as a directory.\n\n'-L'\n'--logical'\nSymbolic links are resolved in the specified file names, but they\nare resolved after any subsequent '..' components are processed.\n\n'-P'\n'--physical'\nSymbolic links are resolved in the specified file names, and they\nare resolved before any subsequent '..' components are processed.\nThis is the default mode of operation.\n\n'-q'\n'--quiet'\nSuppress diagnostic messages for specified file names.\n\n'--relative-to=DIR'\nPrint the resolved file names relative to the specified directory.\nNote this option honors the '-m' and '-e' options pertaining to\nfile existence.\n\n'--relative-base=DIR'\nPrint the resolved file names as relative if the files are\ndescendants of DIR. Otherwise, print the resolved file names as\nabsolute. Note this option honors the '-m' and '-e' options\npertaining to file existence. For details about combining\n'--relative-to' and '--relative-base', *note Realpath usage\nexamples::.\n\n'-s'\n'--strip'\n'--no-symlinks'\nDo not resolve symbolic links. Only resolve references to '/./',\n'/../' and remove extra '/' characters. When combined with the\n'-m' option, realpath operates only on the file name, and does not\ntouch any actual file.\n\n'-z'\n'--zero'\nOutput a zero byte (ASCII NUL) at the end of each line, rather than\na newline. This option enables other programs to parse the output\neven when that output would contain data with embedded newlines.\n\nExit status:\n\n0 if all file names were printed without issue.\n1 otherwise.\n\n* Menu:\n\n* Realpath usage examples:: Realpath usage examples.\n" } ] }, "File: coreutils.info, Node: Realpath usage examples, Up: realpath invocation": { "content": "", "subsections": [] }, "By default, 'realpath' prints the absolute file name of given files": { "content": "(symlinks are resolved, 'words' is resolved to 'american-english'):\n\ncd /home/user\nrealpath /usr/bin/sort /tmp/foo /usr/share/dict/words 1.txt\n=> /usr/bin/sort\n=> /tmp/foo\n=> /usr/share/dict/american-english\n=> /home/user/1.txt\n\nWith '--relative-to', file names are printed relative to the given\ndirectory:\n\nrealpath --relative-to=/usr/bin \\\n/usr/bin/sort /tmp/foo /usr/share/dict/words 1.txt\n=> sort\n=> ../../tmp/foo\n=> ../share/dict/american-english\n=> ../../home/user/1.txt\n\nWith '--relative-base', relative file names are printed if the\nresolved file name is below the given base directory. For files outside\nthe base directory absolute file names are printed:\n\nrealpath --relative-base=/usr \\\n/usr/bin/sort /tmp/foo /usr/share/dict/words 1.txt\n=> bin/sort\n=> /tmp/foo\n=> share/dict/american-english\n=> /home/user/1.txt\n\nWhen both '--relative-to=DIR1' and '--relative-base=DIR2' are used,\nfile names are printed relative to DIR1 if they are located below\nDIR2. If the files are not below DIR2, they are printed as absolute\nfile names:\n\nrealpath --relative-to=/usr/bin --relative-base=/usr \\\n/usr/bin/sort /tmp/foo /usr/share/dict/words 1.txt\n=> sort\n=> /tmp/foo\n=> ../share/dict/american-english\n=> /home/user/1.txt\n\nWhen both '--relative-to=DIR1' and '--relative-base=DIR2' are used,\nDIR1 must be a subdirectory of DIR2. Otherwise, 'realpath' prints\nabsolutes file names.\n", "subsections": [] }, "File: coreutils.info, Node: Working context, Next: User information, Prev: File name manipulation, Up: Top": { "content": "", "subsections": [] }, "19 Working context": { "content": "", "subsections": [] }, "This section describes commands that display or alter the context in": { "content": "which you are working: the current directory, the terminal settings, and\nso forth. See also the user-related commands in the next section.\n\n* Menu:\n\n* pwd invocation:: Print working directory.\n* stty invocation:: Print or change terminal characteristics.\n* printenv invocation:: Print environment variables.\n* tty invocation:: Print file name of terminal on standard input.\n", "subsections": [] }, "File: coreutils.info, Node: pwd invocation, Next: stty invocation, Up: Working context": { "content": "", "subsections": [ { "name": "19.1 'pwd': Print working directory", "content": "'pwd' prints the name of the current directory. Synopsis:\n\npwd [OPTION]...\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-L'\n'--logical'\nIf the contents of the environment variable 'PWD' provide an\nabsolute name of the current directory with no '.' or '..'\ncomponents, but possibly with symbolic links, then output those\ncontents. Otherwise, fall back to default '-P' handling.\n\n'-P'\n'--physical'\nPrint a fully resolved name for the current directory. That is,\nall components of the printed name will be actual directory\nnames--none will be symbolic links.\n\nIf '-L' and '-P' are both given, the last one takes precedence. If\nneither option is given, then this implementation uses '-P' as the\ndefault unless the 'POSIXLYCORRECT' environment variable is set.\n\nDue to shell aliases and built-in 'pwd' functions, using an unadorned\n'pwd' interactively or in a script may get you different functionality\nthan that described here. Invoke it via 'env' (i.e., 'env pwd ...') to\navoid interference from the shell.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: stty invocation, Next: printenv invocation, Prev: pwd invocation, Up: Working context": { "content": "", "subsections": [ { "name": "19.2 'stty': Print or change terminal characteristics", "content": "'stty' prints or changes terminal characteristics, such as baud rate.\nSynopses:\n\nstty [OPTION] [SETTING]...\nstty [OPTION]\n\nIf given no line settings, 'stty' prints the baud rate, line\ndiscipline number (on systems that support it), and line settings that\nhave been changed from the values set by 'stty sane'. By default, mode\nreading and setting are performed on the tty line connected to standard\ninput, although this can be modified by the '--file' option.\n\n'stty' accepts many non-option arguments that change aspects of the\nterminal line operation, as described below.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-a'\n'--all'\nPrint all current settings in human-readable form. This option may\nnot be used in combination with any line settings.\n\n'-F DEVICE'\n'--file=DEVICE'\nSet the line opened by the file name specified in DEVICE instead of\nthe tty line connected to standard input. This option is necessary\nbecause opening a POSIX tty requires use of the 'ONONDELAY' flag\nto prevent a POSIX tty from blocking until the carrier detect line\nis high if the 'clocal' flag is not set. Hence, it is not always\npossible to allow the shell to open the device in the traditional\nmanner.\n\n'-g'\n'--save'\nPrint all current settings in a form that can be used as an\nargument to another 'stty' command to restore the current settings.\nThis option may not be used in combination with any line settings.\n\nMany settings can be turned off by preceding them with a '-'. Such\narguments are marked below with \"May be negated\" in their description." } ] }, "The descriptions themselves refer to the positive case, that is, when": { "content": "not negated (unless stated otherwise, of course).\n\nSome settings are not available on all POSIX systems, since they use\nextensions. Such arguments are marked below with \"Non-POSIX\" in their\ndescription. On non-POSIX systems, those or other settings also may not\nbe available, but it's not feasible to document all the variations: just\ntry it and see.\n\n'stty' is installed only on platforms with the POSIX terminal\ninterface, so portable scripts should not rely on its existence on\nnon-POSIX platforms.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\n* Menu:\n\n* Control:: Control settings\n* Input:: Input settings\n* Output:: Output settings\n* Local:: Local settings\n* Combination:: Combination settings\n* Characters:: Special characters\n* Special:: Special settings\n", "subsections": [] }, "File: coreutils.info, Node: Control, Next: Input, Up: stty invocation": { "content": "Control settings:\n\n'parenb'\nGenerate parity bit in output and expect parity bit in input. May\nbe negated.\n\n'parodd'\nSet odd parity (even if negated). May be negated.\n\n'cmspar'\nUse \"stick\" (mark/space) parity. If parodd is set, the parity bit\nis always 1; if parodd is not set, the parity bit is always zero.\nNon-POSIX. May be negated.\n\n'cs5'\n'cs6'\n'cs7'\n'cs8'\nSet character size to 5, 6, 7, or 8 bits.\n\n'hup'\n'hupcl'\nSend a hangup signal when the last process closes the tty. May be\nnegated.\n\n'cstopb'\nUse two stop bits per character (one if negated). May be negated.\n\n'cread'\nAllow input to be received. May be negated.\n\n'clocal'\nDisable modem control signals. May be negated.\n\n'crtscts'\nEnable RTS/CTS flow control. Non-POSIX. May be negated.\n\n'cdtrdsr'\nEnable DTR/DSR flow control. Non-POSIX. May be negated.\n", "subsections": [] }, "File: coreutils.info, Node: Input, Next: Output, Prev: Control, Up: stty invocation": { "content": "These settings control operations on data received from the terminal.\n\n'ignbrk'\nIgnore break characters. May be negated.\n\n'brkint'\nMake breaks cause an interrupt signal. May be negated.\n\n'ignpar'\nIgnore characters with parity errors. May be negated.\n\n'parmrk'\nMark parity errors (with a 255-0-character sequence). May be\nnegated.\n\n'inpck'\nEnable input parity checking. May be negated.\n\n'istrip'\nClear high (8th) bit of input characters. May be negated.\n\n'inlcr'\nTranslate newline to carriage return. May be negated.\n\n'igncr'\nIgnore carriage return. May be negated.\n\n'icrnl'\nTranslate carriage return to newline. May be negated.\n\n'iutf8'\nAssume input characters are UTF-8 encoded. May be negated.\n\n'ixon'\nEnable XON/XOFF flow control (that is, 'Ctrl-S'/'Ctrl-Q'). May be\nnegated.\n\n'ixoff'\n'tandem'\nEnable sending of 'stop' character when the system input buffer is\nalmost full, and 'start' character when it becomes almost empty\nagain. May be negated.\n\n'iuclc'\nTranslate uppercase characters to lowercase. Non-POSIX. May be\nnegated. Note ilcuc is not implemented, as one would not be able\nto issue almost any (lowercase) Unix command, after invoking it.\n\n'ixany'\nAllow any character to restart output (only the start character if\nnegated). Non-POSIX. May be negated.\n\n'imaxbel'\nEnable beeping and not flushing input buffer if a character arrives\nwhen the input buffer is full. Non-POSIX. May be negated.\n", "subsections": [] }, "File: coreutils.info, Node: Output, Next: Local, Prev: Input, Up: stty invocation": { "content": "These settings control operations on data sent to the terminal.\n\n'opost'\nPostprocess output. May be negated.\n\n'olcuc'\nTranslate lowercase characters to uppercase. Non-POSIX. May be\nnegated. (Note ouclc is not currently implemented.)\n\n'ocrnl'\nTranslate carriage return to newline. Non-POSIX. May be negated.\n\n'onlcr'\nTranslate newline to carriage return-newline. Non-POSIX. May be\nnegated.\n\n'onocr'\nDo not print carriage returns in the first column. Non-POSIX. May\nbe negated.\n\n'onlret'\nNewline performs a carriage return. Non-POSIX. May be negated.\n\n'ofill'\nUse fill (padding) characters instead of timing for delays.\nNon-POSIX. May be negated.\n\n'ofdel'\nUse ASCII DEL characters for fill instead of ASCII NUL characters.\nNon-POSIX. May be negated.\n\n'nl1'\n'nl0'\nNewline delay style. Non-POSIX.\n\n'cr3'\n'cr2'\n'cr1'\n'cr0'\nCarriage return delay style. Non-POSIX.\n\n'tab3'\n'tab2'\n'tab1'\n'tab0'\nHorizontal tab delay style. Non-POSIX.\n\n'bs1'\n'bs0'\nBackspace delay style. Non-POSIX.\n\n'vt1'\n'vt0'\nVertical tab delay style. Non-POSIX.\n\n'ff1'\n'ff0'\nForm feed delay style. Non-POSIX.\n", "subsections": [] }, "File: coreutils.info, Node: Local, Next: Combination, Prev: Output, Up: stty invocation": { "content": "'isig'\nEnable 'interrupt', 'quit', and 'suspend' special characters. May\nbe negated.\n\n'icanon'\nEnable 'erase', 'kill', 'werase', and 'rprnt' special characters.\nMay be negated.\n\n'iexten'\nEnable non-POSIX special characters. May be negated.\n\n'echo'\nEcho input characters. May be negated.\n\n'echoe'\n'crterase'\nEcho 'erase' characters as backspace-space-backspace. May be\nnegated.\n\n'echok'\nEcho a newline after a 'kill' character. May be negated.\n\n'echonl'\nEcho newline even if not echoing other characters. May be negated.\n\n'noflsh'\nDisable flushing after 'interrupt' and 'quit' special characters.\nMay be negated.\n\n'xcase'\nEnable input and output of uppercase characters by preceding their\nlowercase equivalents with '\\', when 'icanon' is set. Non-POSIX.\nMay be negated.\n\n'tostop'\nStop background jobs that try to write to the terminal. Non-POSIX.\nMay be negated.\n\n'echoprt'\n'prterase'\nEcho erased characters backward, between '\\' and '/'. Non-POSIX.\nMay be negated.\n\n'echoctl'\n'ctlecho'\nEcho control characters in hat notation ('^C') instead of\nliterally. Non-POSIX. May be negated.\n\n'echoke'\n'crtkill'\nEcho the 'kill' special character by erasing each character on the\nline as indicated by the 'echoprt' and 'echoe' settings, instead of\nby the 'echoctl' and 'echok' settings. Non-POSIX. May be negated.\n\n'extproc'\nEnable 'LINEMODE', which is used to avoid echoing each character\nover high latency links. See also Internet RFC 1116\n(https://tools.ietf.org/search/rfc1116). Non-POSIX. May be\nnegated.\n\n'flusho'\nDiscard output. Note this setting is currently ignored on\nGNU/Linux systems. Non-POSIX. May be negated.\n", "subsections": [] }, "File: coreutils.info, Node: Combination, Next: Characters, Prev: Local, Up: stty invocation": { "content": "Combination settings:\n\n'evenp'\n'parity'\nSame as 'parenb -parodd cs7'. May be negated. If negated, same as\n'-parenb cs8'.\n\n'oddp'\nSame as 'parenb parodd cs7'. May be negated. If negated, same as\n'-parenb cs8'.\n\n'nl'\nSame as '-icrnl -onlcr'. May be negated. If negated, same as\n'icrnl -inlcr -igncr onlcr -ocrnl -onlret'.\n\n'ek'\nReset the 'erase' and 'kill' special characters to their default\nvalues.\n\n'sane'\nSame as:\n\ncread -ignbrk brkint -inlcr -igncr icrnl\nicanon iexten echo echoe echok -echonl -noflsh\n-ixoff -iutf8 -iuclc -ixany imaxbel -xcase -olcuc -ocrnl\nopost -ofill onlcr -onocr -onlret nl0 cr0 tab0 bs0 vt0 ff0\nisig -tostop -ofdel -echoprt echoctl echoke -extproc\n\nand also sets all special characters to their default values.\n\n'cooked'\nSame as 'brkint ignpar istrip icrnl ixon opost isig icanon', plus\nsets the 'eof' and 'eol' characters to their default values if they\nare the same as the 'min' and 'time' characters. May be negated.\nIf negated, same as 'raw'.\n\n'raw'\nSame as:\n\n-ignbrk -brkint -ignpar -parmrk -inpck -istrip\n-inlcr -igncr -icrnl -ixon -ixoff -icanon -opost\n-isig -iuclc -ixany -imaxbel -xcase min 1 time 0\n\nMay be negated. If negated, same as 'cooked'.\n\n'cbreak'\nSame as '-icanon'. May be negated. If negated, same as 'icanon'.\n\n'pass8'\nSame as '-parenb -istrip cs8'. May be negated. If negated, same\nas 'parenb istrip cs7'.\n\n'litout'\nSame as '-parenb -istrip -opost cs8'. May be negated. If negated,\nsame as 'parenb istrip opost cs7'.\n\n'decctlq'\nSame as '-ixany'. Non-POSIX. May be negated.\n\n'tabs'\nSame as 'tab0'. Non-POSIX. May be negated. If negated, same as\n'tab3'.\n\n'lcase'\n'LCASE'\nSame as 'xcase iuclc olcuc'. Non-POSIX. May be negated. (Used\nfor terminals with uppercase characters only.)\n\n'crt'\nSame as 'echoe echoctl echoke'.\n\n'dec'\nSame as 'echoe echoctl echoke -ixany intr ^C erase ^? kill C-u'.\n", "subsections": [] }, "File: coreutils.info, Node: Characters, Next: Special, Prev: Combination, Up: stty invocation": { "content": "", "subsections": [] }, "The special characters' default values vary from system to system. They": { "content": "are set with the syntax 'name value', where the names are listed below\nand the value can be given either literally, in hat notation ('^C'), or\nas an integer which may start with '0x' to indicate hexadecimal, '0' to\nindicate octal, or any other digit to indicate decimal.\n\nFor GNU stty, giving a value of '^-' or 'undef' disables that special\ncharacter. (This is incompatible with Ultrix 'stty', which uses a value\nof 'u' to disable a special character. GNU 'stty' treats a value 'u'\nlike any other, namely to set that special character to .)\n\n'intr'\nSend an interrupt signal.\n\n'quit'\nSend a quit signal.\n\n'erase'\nErase the last character typed.\n\n'kill'\nErase the current line.\n\n'eof'\nSend an end of file (terminate the input).\n\n'eol'\nEnd the line.\n\n'eol2'\nAlternate character to end the line. Non-POSIX.\n\n'discard'\nAlternate character to toggle discarding of output. Non-POSIX.\n\n'swtch'\nSwitch to a different shell layer. Non-POSIX.\n\n'status'\nSend an info signal. Not currently supported on Linux. Non-POSIX.\n\n'start'\nRestart the output after stopping it.\n\n'stop'\nStop the output.\n\n'susp'\nSend a terminal stop signal.\n\n'dsusp'\nSend a terminal stop signal after flushing the input. Non-POSIX.\n\n'rprnt'\nRedraw the current line. Non-POSIX.\n\n'werase'\nErase the last word typed. Non-POSIX.\n\n'lnext'\nEnter the next character typed literally, even if it is a special\ncharacter. Non-POSIX.\n", "subsections": [] }, "File: coreutils.info, Node: Special, Prev: Characters, Up: stty invocation": { "content": "'min N'\nSet the minimum number of characters that will satisfy a read until\nthe time value has expired, when '-icanon' is set.\n\n'time N'\nSet the number of tenths of a second before reads time out if the\nminimum number of characters have not been read, when '-icanon' is\nset.\n\n'ispeed N'\nSet the input speed to N.\n\n'ospeed N'\nSet the output speed to N.\n\n'rows N'\nTell the tty kernel driver that the terminal has N rows.\nNon-POSIX.\n\n'cols N'\n'columns N'\nTell the kernel that the terminal has N columns. Non-POSIX.\n\n'drain'\nApply settings after first waiting for pending output to be\ntransmitted. This is enabled by default for GNU 'stty'. It is\nuseful to disable this option in cases where the system may be in a\nstate where serial transmission is not possible. For example, if\nthe system has received the 'DC3' character with 'ixon' (software\nflow control) enabled, then 'stty' would block without '-drain'\nbeing specified. May be negated. Non-POSIX.\n\n'size'\nPrint the number of rows and columns that the kernel thinks the\nterminal has. (Systems that don't support rows and columns in the\nkernel typically use the environment variables 'LINES' and\n'COLUMNS' instead; however, GNU 'stty' does not know anything about\nthem.) Non-POSIX.\n\n'line N'\nUse line discipline N. Non-POSIX.\n\n'speed'\nPrint the terminal speed.\n\n'N'\nSet the input and output speeds to N. N can be one of: 0 50 75 110\n134 134.5 150 200 300 600 1200 1800 2400 4800 9600 19200 38400\n'exta' 'extb'. 'exta' is the same as 19200; 'extb' is the same as\n38400. Many systems, including GNU/Linux, support higher speeds.\nThe 'stty' command includes support for speeds of 57600, 115200,\n230400, 460800, 500000, 576000, 921600, 1000000, 1152000, 1500000,\n2000000, 2500000, 3000000, 3500000, or 4000000 where the system\nsupports these. 0 hangs up the line if '-clocal' is set.\n", "subsections": [] }, "File: coreutils.info, Node: printenv invocation, Next: tty invocation, Prev: stty invocation, Up: Working context": { "content": "", "subsections": [ { "name": "19.3 'printenv': Print all or some environment variables", "content": "'printenv' prints environment variable values. Synopsis:\n\nprintenv [OPTION] [VARIABLE]...\n\nIf no VARIABLEs are specified, 'printenv' prints the value of every\nenvironment variable. Otherwise, it prints the value of each VARIABLE\nthat is set, and nothing for those that are not set.\n\nThe program accepts the following option. Also see *note Common\noptions::.\n\n'-0'\n'--null'\nOutput a zero byte (ASCII NUL) at the end of each line, rather than\na newline. This option enables other programs to parse the output\neven when that output would contain data with embedded newlines.\n\nExit status:\n\n0 if all variables specified were found\n1 if at least one specified variable was not found\n2 if a write error occurred\n" } ] }, "File: coreutils.info, Node: tty invocation, Prev: printenv invocation, Up: Working context": { "content": "", "subsections": [ { "name": "19.4 'tty': Print file name of terminal on standard input", "content": "'tty' prints the file name of the terminal connected to its standard\ninput. It prints 'not a tty' if standard input is not a terminal.\nSynopsis:\n\ntty [OPTION]...\n\nThe program accepts the following option. Also see *note Common\noptions::.\n\n'-s'\n'--silent'\n'--quiet'\nPrint nothing; only return an exit status.\n\nExit status:\n\n0 if standard input is a terminal\n1 if standard input is a non-terminal file\n2 if given incorrect arguments\n3 if a write error occurs\n" } ] }, "File: coreutils.info, Node: User information, Next: System context, Prev: Working context, Up: Top": { "content": "", "subsections": [] }, "20 User information": { "content": "This section describes commands that print user-related information:\nlogins, groups, and so forth.\n\n* Menu:\n\n* id invocation:: Print user identity.\n* logname invocation:: Print current login name.\n* whoami invocation:: Print effective user ID.\n* groups invocation:: Print group names a user is in.\n* users invocation:: Print login names of users currently logged in.\n* who invocation:: Print who is currently logged in.\n", "subsections": [] }, "File: coreutils.info, Node: id invocation, Next: logname invocation, Up: User information": { "content": "", "subsections": [ { "name": "20.1 'id': Print user identity", "content": "'id' prints information about the given user, or the process running it\nif no user is specified. Synopsis:\n\nid [OPTION]... [USER]...\n\nUSER can be either a user ID or a name, with name look-up taking\nprecedence unless the ID is specified with a leading '+'. *Note\nDisambiguating names and IDs::.\n\nBy default, it prints the real user ID, real group ID, effective user\nID if different from the real user ID, effective group ID if different\nfrom the real group ID, and supplemental group IDs. In addition, if\nSELinux is enabled and the 'POSIXLYCORRECT' environment variable is not\nset, then print 'context=C', where C is the security context.\n\nEach of these numeric values is preceded by an identifying string and\nfollowed by the corresponding user or group name in parentheses.\n\nThe options cause 'id' to print only part of the above information.\nAlso see *note Common options::.\n\n'-g'\n'--group'\nPrint only the group ID.\n\n'-G'\n'--groups'\nPrint only the group ID and the supplementary groups.\n\n'-n'\n'--name'\nPrint the user or group name instead of the ID number. Requires\n'-u', '-g', or '-G'.\n\n'-r'\n'--real'\nPrint the real, instead of effective, user or group ID. Requires\n'-u', '-g', or '-G'.\n\n'-u'\n'--user'\nPrint only the user ID.\n\n'-Z'\n'--context'\nPrint only the security context of the process, which is generally\nthe user's security context inherited from the parent process. If\nneither SELinux or SMACK is enabled then print a warning and set\nthe exit status to 1.\n\n'-z'\n'--zero'\nDelimit output items with ASCII NUL characters. This option is not\npermitted when using the default format. When multiple users are\nspecified, and the '--groups' option is also in effect, groups are\ndelimited with a single NUL character, while users are delimited\nwith two NUL characters.\n\nExample:\n$ id -Gn --zero\nusers devs \n\nPrimary and supplementary groups for a process are normally inherited\nfrom its parent and are usually unchanged since login. This means that\nif you change the group database after logging in, 'id' will not reflect\nyour changes within your existing login session. Running 'id' with a\nuser argument causes the user and group database to be consulted afresh,\nand so will give a different result.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: logname invocation, Next: whoami invocation, Prev: id invocation, Up: User information": { "content": "", "subsections": [ { "name": "20.2 'logname': Print current login name", "content": "'logname' prints the calling user's name, as found in a\nsystem-maintained file (often '/var/run/utmp' or '/etc/utmp'), and exits\nwith a status of 0. If there is no entry for the calling process,\n'logname' prints an error message and exits with a status of 1.\n\nThe only options are '--help' and '--version'. *Note Common\noptions::.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: whoami invocation, Next: groups invocation, Prev: logname invocation, Up: User information": { "content": "", "subsections": [ { "name": "20.3 'whoami': Print effective user ID", "content": "'whoami' prints the user name associated with the current effective user\nID. It is equivalent to the command 'id -un'.\n\nThe only options are '--help' and '--version'. *Note Common\noptions::.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: groups invocation, Next: users invocation, Prev: whoami invocation, Up: User information": { "content": "", "subsections": [ { "name": "20.4 'groups': Print group names a user is in", "content": "'groups' prints the names of the primary and any supplementary groups\nfor each given USERNAME, or the current process if no names are given." } ] }, "If more than one name is given, the name of each user is printed before": { "content": "the list of that user's groups and the user name is separated from the\ngroup list by a colon. Synopsis:\n\ngroups [USERNAME]...\n\nThe group lists are equivalent to the output of the command 'id -Gn'.\n\nThe only options are '--help' and '--version'. *Note Common\noptions::.\n\nPrimary and supplementary groups for a process are normally inherited\nfrom its parent and are usually unchanged since login. This means that\nif you change the group database after logging in, 'groups' will not\nreflect your changes within your existing login session. Running\n'groups' with a list of users causes the user and group database to be\nconsulted afresh, and so will give a different result.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: users invocation, Next: who invocation, Prev: groups invocation, Up: User information": { "content": "", "subsections": [ { "name": "20.5 'users': Print login names of users currently logged in", "content": "'users' prints on a single line a blank-separated list of user names of\nusers currently logged in to the current host. Each user name\ncorresponds to a login session, so if a user has more than one login\nsession, that user's name will appear the same number of times in the\noutput. Synopsis:\n\nusers [FILE]\n\nWith no FILE argument, 'users' extracts its information from a\nsystem-maintained file (often '/var/run/utmp' or '/etc/utmp'). If a\nfile argument is given, 'users' uses that file instead. A common choice\nis '/var/log/wtmp'.\n\nThe only options are '--help' and '--version'. *Note Common\noptions::.\n\nThe 'users' command is installed only on platforms with the POSIX\n'' include file or equivalent, so portable scripts should not\nrely on its existence on non-POSIX platforms.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: who invocation, Prev: users invocation, Up: User information": { "content": "", "subsections": [ { "name": "20.6 'who': Print who is currently logged in", "content": "'who' prints information about users who are currently logged on.\nSynopsis:\n\nwho [OPTION] [FILE] [am i]\n\nIf given no non-option arguments, 'who' prints the following\ninformation for each user currently logged on: login name, terminal\nline, login time, and remote hostname or X display.\n\nIf given one non-option argument, 'who' uses that instead of a\ndefault system-maintained file (often '/var/run/utmp' or '/etc/utmp') as\nthe name of the file containing the record of users logged on.\n'/var/log/wtmp' is commonly given as an argument to 'who' to look at who\nhas previously logged on.\n\nIf given two non-option arguments, 'who' prints only the entry for\nthe user running it (determined from its standard input), preceded by\nthe hostname. Traditionally, the two arguments given are 'am i', as in\n'who am i'.\n\nTimestamps are listed according to the time zone rules specified by\nthe 'TZ' environment variable, or by the system default rules if 'TZ' is\nnot set. *Note Specifying the Time Zone with 'TZ': (libc)TZ Variable.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-a'\n'--all'\nSame as '-b -d --login -p -r -t -T -u'.\n\n'-b'\n'--boot'\nPrint the date and time of last system boot.\n\n'-d'\n'--dead'\nPrint information corresponding to dead processes.\n\n'-H'\n'--heading'\nPrint a line of column headings.\n\n'-l'\n'--login'\nList only the entries that correspond to processes via which the\nsystem is waiting for a user to login. The user name is always\n'LOGIN'.\n\n'--lookup'\nAttempt to canonicalize hostnames found in utmp through a DNS\nlookup. This is not the default because it can cause significant\ndelays on systems with automatic dial-up internet access.\n\n'-m'\nSame as 'who am i'.\n\n'-p'\n'--process'\nList active processes spawned by init.\n\n'-q'\n'--count'\nPrint only the login names and the number of users logged on.\nOverrides all other options.\n\n'-r'\n'--runlevel'\nPrint the current (and maybe previous) run-level of the init\nprocess.\n\n'-s'\nIgnored; for compatibility with other versions of 'who'.\n\n'-t'\n'--time'\nPrint last system clock change.\n\n'-u'\nAfter the login time, print the number of hours and minutes that\nthe user has been idle. '.' means the user was active in the last\nminute. 'old' means the user has been idle for more than 24 hours.\n\n'-w'\n'-T'\n'--mesg'\n'--message'\n'--writable'\nAfter each login name print a character indicating the user's\nmessage status:\n\n'+' allowing 'write' messages\n'-' disallowing 'write' messages\n'?' cannot find terminal device\n\nThe 'who' command is installed only on platforms with the POSIX\n'' include file or equivalent, so portable scripts should not\nrely on its existence on non-POSIX platforms.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: System context, Next: SELinux context, Prev: User information, Up: Top": { "content": "", "subsections": [] }, "21 System context": { "content": "", "subsections": [] }, "This section describes commands that print or change system-wide": { "content": "information.\n\n* Menu:\n\n* date invocation:: Print or set system date and time.\n* arch invocation:: Print machine hardware name.\n* nproc invocation:: Print the number of processors.\n* uname invocation:: Print system information.\n* hostname invocation:: Print or set system name.\n* hostid invocation:: Print numeric host identifier.\n* uptime invocation:: Print system uptime and load.\n", "subsections": [] }, "File: coreutils.info, Node: date invocation, Next: arch invocation, Up: System context": { "content": "", "subsections": [ { "name": "21.1 'date': Print or set system date and time", "content": "Synopses:\n\ndate [OPTION]... [+FORMAT]\ndate [-u|--utc|--universal] [ MMDDhhmm[[CC]YY][.ss] ]\n\nInvoking 'date' with no FORMAT argument is equivalent to invoking it\nwith a default format that depends on the 'LCTIME' locale category. In\nthe default C locale, this format is ''+%a %b %e %H:%M:%S %Z %Y'', so\nthe output looks like 'Thu Mar 3 13:47:51 PST 2005'.\n\nNormally, 'date' uses the time zone rules indicated by the 'TZ'\nenvironment variable, or the system default rules if 'TZ' is not set.\n*Note Specifying the Time Zone with 'TZ': (libc)TZ Variable.\n\nIf given an argument that starts with a '+', 'date' prints the\ncurrent date and time (or the date and time specified by the '--date'\noption, see below) in the format defined by that argument, which is\nsimilar to that of the 'strftime' function. Except for conversion\nspecifiers, which start with '%', characters in the format string are\nprinted unchanged. The conversion specifiers are described below.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\n* Menu:\n\n* Time conversion specifiers:: %[HIklMNpPrRsSTXzZ]\n* Date conversion specifiers:: %[aAbBcCdDeFgGhjmuUVwWxyY]\n* Literal conversion specifiers:: %[%nt]\n* Padding and other flags:: Pad with zeros, spaces, etc.\n* Setting the time:: Changing the system clock.\n* Options for date:: Instead of the current time.\n* Date input formats:: Specifying date strings.\n* Examples of date:: Examples.\n" } ] }, "File: coreutils.info, Node: Time conversion specifiers, Next: Date conversion specifiers, Up: date invocation": { "content": "'date' conversion specifiers related to times.\n\n'%H'\nhour ('00'...'23')\n'%I'\nhour ('01'...'12')\n'%k'\nhour, space padded (' 0'...'23'); equivalent to '%H'. This is a\nGNU extension.\n'%l'\nhour, space padded (' 1'...'12'); equivalent to '%I'. This is a\nGNU extension.\n'%M'\nminute ('00'...'59')\n'%N'\nnanoseconds ('000000000'...'999999999'). This is a GNU extension.\n'%p'\nlocale's equivalent of either 'AM' or 'PM'; blank in many locales.\nNoon is treated as 'PM' and midnight as 'AM'.\n'%P'\nlike '%p', except lower case. This is a GNU extension.\n'%r'\nlocale's 12-hour clock time (e.g., '11:11:04 PM')\n'%R'\n24-hour hour and minute. Same as '%H:%M'.\n'%s'\nseconds since the epoch, i.e., since 1970-01-01 00:00:00 UTC. Leap\nseconds are not counted unless leap second support is available.\n*Note %s-examples::, for examples. This is a GNU extension.\n'%S'\nsecond ('00'...'60'). This may be '60' if leap seconds are\nsupported.\n'%T'\n24-hour hour, minute, and second. Same as '%H:%M:%S'.\n'%X'\nlocale's time representation (e.g., '23:13:48')\n'%z'\nFour-digit numeric time zone, e.g., '-0600' or '+0530', or '-0000'\nif no time zone is determinable. This value reflects the numeric\ntime zone appropriate for the current time, using the time zone\nrules specified by the 'TZ' environment variable. A time zone is\nnot determinable if its numeric offset is zero and its abbreviation\nbegins with '-'. The time (and optionally, the time zone rules)\ncan be overridden by the '--date' option.\n'%:z'\nNumeric time zone with ':', e.g., '-06:00' or '+05:30'), or\n'-00:00' if no time zone is determinable. This is a GNU extension.\n'%::z'\nNumeric time zone to the nearest second with ':' (e.g., '-06:00:00'\nor '+05:30:00'), or '-00:00:00' if no time zone is determinable.\nThis is a GNU extension.\n'%:::z'\nNumeric time zone with ':' using the minimum necessary precision\n(e.g., '-06', '+05:30', or '-04:56:02'), or '-00' if no time zone\nis determinable. This is a GNU extension.\n'%Z'\nalphabetic time zone abbreviation (e.g., 'EDT'), or nothing if no\ntime zone is determinable. See '%z' for how it is determined.\n", "subsections": [] }, "File: coreutils.info, Node: Date conversion specifiers, Next: Literal conversion specifiers, Prev: Time conversion specifiers, Up: date invocation": { "content": "'date' conversion specifiers related to dates.\n\n'%a'\nlocale's abbreviated weekday name (e.g., 'Sun')\n'%A'\nlocale's full weekday name, variable length (e.g., 'Sunday')\n'%b'\nlocale's abbreviated month name (e.g., 'Jan')\n'%B'\nlocale's full month name, variable length (e.g., 'January')\n'%c'\nlocale's date and time (e.g., 'Thu Mar 3 23:05:25 2005')\n'%C'\ncentury. This is like '%Y', except the last two digits are\nomitted. For example, it is '20' if '%Y' is '2000', and is '-0' if\n'%Y' is '-001'. It is normally at least two characters, but it may\nbe more.\n'%d'\nday of month (e.g., '01')\n'%D'\ndate; same as '%m/%d/%y'\n'%e'\nday of month, space padded; same as '%d'\n'%F'\nfull date in ISO 8601 format; like '%+4Y-%m-%d' except that any\nflags or field width override the '+' and (after subtracting 6) the\n'4'. This is a good choice for a date format, as it is standard\nand is easy to sort in the usual case where years are in the range\n0000...9999.\n'%g'\nyear corresponding to the ISO week number, but without the century\n(range '00' through '99'). This has the same format and value as\n'%y', except that if the ISO week number (see '%V') belongs to the\nprevious or next year, that year is used instead.\n'%G'\nyear corresponding to the ISO week number. This has the same\nformat and value as '%Y', except that if the ISO week number (see\n'%V') belongs to the previous or next year, that year is used\ninstead. It is normally useful only if '%V' is also used; for\nexample, the format '%G-%m-%d' is probably a mistake, since it\ncombines the ISO week number year with the conventional month and\nday.\n'%h'\nsame as '%b'\n'%j'\nday of year ('001'...'366')\n'%m'\nmonth ('01'...'12')\n'%q'\nquarter of year ('1'...'4')\n'%u'\nday of week ('1'...'7') with '1' corresponding to Monday\n'%U'\nweek number of year, with Sunday as the first day of the week\n('00'...'53'). Days in a new year preceding the first Sunday are\nin week zero.\n'%V'\nISO week number, that is, the week number of year, with Monday as\nthe first day of the week ('01'...'53'). If the week containing\nJanuary 1 has four or more days in the new year, then it is\nconsidered week 1; otherwise, it is week 53 of the previous year,\nand the next week is week 1. (See the ISO 8601 standard.)\n'%w'\nday of week ('0'...'6') with 0 corresponding to Sunday\n'%W'\nweek number of year, with Monday as first day of week\n('00'...'53'). Days in a new year preceding the first Monday are\nin week zero.\n'%x'\nlocale's date representation (e.g., '12/31/99')\n'%y'\nlast two digits of year ('00'...'99')\n'%Y'\nyear. This is normally at least four characters, but it may be\nmore. Year '0000' precedes year '0001', and year '-001' precedes\nyear '0000'.\n", "subsections": [] }, "File: coreutils.info, Node: Literal conversion specifiers, Next: Padding and other flags, Prev: Date conversion specifiers, Up: date invocation": { "content": "'date' conversion specifiers that produce literal strings.\n\n'%%'\na literal %\n'%n'\na newline\n'%t'\na horizontal tab\n", "subsections": [] }, "File: coreutils.info, Node: Padding and other flags, Next: Setting the time, Prev: Literal conversion specifiers, Up: date invocation": { "content": "", "subsections": [] }, "Unless otherwise specified, 'date' normally pads numeric fields with": { "content": "zeros, so that, for example, numeric months are always output as two\ndigits. Seconds since the epoch are not padded, though, since there is\nno natural width for them.\n\nThe following optional flags can appear after the '%':\n\n'-'\n(hyphen) Do not pad the field; useful if the output is intended for\nhuman consumption. This is a GNU extension.\n''\n(underscore) Pad with spaces; useful if you need a fixed number of\ncharacters in the output, but zeros are too distracting. This is a\nGNU extension.\n'0'\n(zero) Pad with zeros even if the conversion specifier would\nnormally pad with spaces.\n'+'\nPad with zeros, like '0'. In addition, precede any year number\nwith '+' if it exceeds 9999 or if its field width exceeds 4;\nsimilarly, precede any century number with '+' if it exceeds 99 or\nif its field width exceeds 2. This supports ISO 8601 formats for\ndates far in the future; for example, the command 'date\n--date=12019-02-25 +%+13F' outputs the string '+012019-02-25'.\n'^'\nUse upper case characters if possible. This is a GNU extension.\n'#'\nUse opposite case characters if possible. A field that is normally\nupper case becomes lower case, and vice versa. This is a GNU\nextension.\n\nHere are some examples of padding:\n\ndate +%d/%m -d \"Feb 1\"\n=> 01/02\ndate +%-d/%-m -d \"Feb 1\"\n=> 1/2\ndate +%d/%m -d \"Feb 1\"\n=> 1/ 2\n\nYou can optionally specify the field width (after any flag, if\npresent) as a decimal number. If the natural size of the output of the\nfield has less than the specified number of characters, the result is\nwritten right adjusted and padded to the given size. For example, '%9B'\nprints the right adjusted month name in a field of width 9.\n\nAn optional modifier can follow the optional flag and width\nspecification. The modifiers are:\n\n'E'\nUse the locale's alternate representation for date and time. This\nmodifier applies to the '%c', '%C', '%x', '%X', '%y' and '%Y'\nconversion specifiers. In a Japanese locale, for example, '%Ex'\nmight yield a date format based on the Japanese Emperors' reigns.\n\n'O'\nUse the locale's alternate numeric symbols for numbers. This\nmodifier applies only to numeric conversion specifiers.\n\nIf the format supports the modifier but no alternate representation\nis available, it is ignored.\n\nPOSIX specifies the behavior of flags and field widths only for '%C',\n'%F', '%G', and '%Y' (all without modifiers), and requires a flag to be\npresent if and only if a field width is also present. Other\ncombinations of flags, field widths and modifiers are GNU extensions.\n", "subsections": [] }, "File: coreutils.info, Node: Setting the time, Next: Options for date, Prev: Padding and other flags, Up: date invocation": { "content": "If given an argument that does not start with '+', 'date' sets the\nsystem clock to the date and time specified by that argument (as\ndescribed below). You must have appropriate privileges to set the\nsystem clock. Note for changes to persist across a reboot, the hardware\nclock may need to be updated from the system clock, which might not\nhappen automatically on your system.\n\nThe argument must consist entirely of digits, which have the\nfollowing meaning:\n\n'MM'\nmonth\n'DD'\nday within month\n'hh'\nhour\n'mm'\nminute\n'CC'\nfirst two digits of year (optional)\n'YY'\nlast two digits of year (optional)\n'ss'\nsecond (optional)\n\nNote, the '--date' and '--set' options may not be used with an\nargument in the above format. The '--universal' option may be used with\nsuch an argument to indicate that the specified date and time are\nrelative to Universal Time rather than to the local time zone.\n", "subsections": [] }, "File: coreutils.info, Node: Options for date, Next: Examples of date, Prev: Setting the time, Up: date invocation": { "content": "The program accepts the following options. Also see *note Common\noptions::.\n\n'-d DATESTR'\n'--date=DATESTR'\nDisplay the date and time specified in DATESTR instead of the\ncurrent date and time. DATESTR can be in almost any common format.\nIt can contain month names, time zones, 'am' and 'pm', 'yesterday',\netc. For example, '--date=\"2004-02-27 14:19:13.489392193 +0530\"'\nspecifies the instant of time that is 489,392,193 nanoseconds after\nFebruary 27, 2004 at 2:19:13 PM in a time zone that is 5 hours and\n30 minutes east of UTC.\nNote: input currently must be in locale independent format. E.g.,\nthe LCTIME=C below is needed to print back the correct date in\nmany locales:\ndate -d \"$(LCTIME=C date)\"\n*Note Date input formats::.\n\n'--debug'\nAnnotate the parsed date, display the effective time zone, and warn\nabout potential misuse.\n\n'-f DATEFILE'\n'--file=DATEFILE'\nParse each line in DATEFILE as with '-d' and display the resulting\ndate and time. If DATEFILE is '-', use standard input. This is\nuseful when you have many dates to process, because the system\noverhead of starting up the 'date' executable many times can be\nconsiderable.\n\n'-I[TIMESPEC]'\n'--iso-8601[=TIMESPEC]'\nDisplay the date using an ISO 8601 format, '%Y-%m-%d'.\n\nThe argument TIMESPEC specifies the number of additional terms of\nthe time to include. It can be one of the following:\n'auto'\nPrint just the date. This is the default if TIMESPEC is\nomitted.\n\n'hours'\nAppend the hour of the day to the date.\n\n'minutes'\nAppend the hours and minutes.\n\n'seconds'\nAppend the hours, minutes and seconds.\n\n'ns'\nAppend the hours, minutes, seconds and nanoseconds.\n\nIf showing any time terms, then include the time zone using the\nformat '%:z'. This format is always suitable as input for the\n'--date' ('-d') and '--file' ('-f') options, regardless of the\ncurrent locale.\n\n'-r FILE'\n'--reference=FILE'\nDisplay the date and time of the last modification of FILE, instead\nof the current date and time.\n\n'-R'\n'--rfc-email'\nDisplay the date and time using the format '%a, %d %b %Y %H:%M:%S\n%z', evaluated in the C locale so abbreviations are always in\nEnglish. For example:\n\nFri, 09 Sep 2005 13:51:39 -0700\n\nThis format conforms to Internet RFCs 5322\n(https://tools.ietf.org/search/rfc5322), 2822\n(https://tools.ietf.org/search/rfc2822) and 822\n(https://tools.ietf.org/search/rfc822), the current and previous\nstandards for Internet email. For compatibility with older\nversions of 'date', '--rfc-2822' and '--rfc-822' are aliases for\n'--rfc-email'.\n\n'--rfc-3339=TIMESPEC'\nDisplay the date using a format specified by Internet RFC 3339\n(https://tools.ietf.org/search/rfc3339). This is like\n'--iso-8601', except that a space rather than a 'T' separates dates\nfrom times. This format is always suitable as input for the\n'--date' ('-d') and '--file' ('-f') options, regardless of the\ncurrent locale.\n\nThe argument TIMESPEC specifies how much of the time to include.\nIt can be one of the following:\n\n'date'\nPrint just the full-date, e.g., '2005-09-14'. This is\nequivalent to the format '%Y-%m-%d'.\n\n'seconds'\nPrint the full-date and full-time separated by a space, e.g.,\n'2005-09-14 00:56:06+05:30'. The output ends with a numeric\ntime-offset; here the '+05:30' means that local time is five\nhours and thirty minutes east of UTC. This is equivalent to\nthe format '%Y-%m-%d %H:%M:%S%:z'.\n\n'ns'\nLike 'seconds', but also print nanoseconds, e.g., '2005-09-14\n00:56:06.998458565+05:30'. This is equivalent to the format\n'%Y-%m-%d %H:%M:%S.%N%:z'.\n\n'-s DATESTR'\n'--set=DATESTR'\nSet the date and time to DATESTR. See '-d' above. See also *note\nSetting the time::.\n\n'-u'\n'--utc'\n'--universal'\nUse Universal Time by operating as if the 'TZ' environment variable\nwere set to the string 'UTC0'. UTC stands for Coordinated\nUniversal Time, established in 1960. Universal Time is often\ncalled \"Greenwich Mean Time\" (GMT) for historical reasons.\nTypically, systems ignore leap seconds and thus implement an\napproximation to UTC rather than true UTC.\n", "subsections": [] }, "File: coreutils.info, Node: Date input formats, Next: Version sort ordering, Prev: File timestamps, Up: Top": { "content": "", "subsections": [] }, "29 Date input formats": { "content": "First, a quote:\n\nOur units of temporal measurement, from seconds on up to months,\nare so complicated, asymmetrical and disjunctive so as to make\ncoherent mental reckoning in time all but impossible. Indeed, had\nsome tyrannical god contrived to enslave our minds to time, to make\nit all but impossible for us to escape subjection to sodden\nroutines and unpleasant surprises, he could hardly have done better\nthan handing down our present system. It is like a set of\ntrapezoidal building blocks, with no vertical or horizontal\nsurfaces, like a language in which the simplest thought demands\nornate constructions, useless particles and lengthy\ncircumlocutions. Unlike the more successful patterns of language\nand science, which enable us to face experience boldly or at least\nlevel-headedly, our system of temporal calculation silently and\npersistently encourages our terror of time.\n\n... It is as though architects had to measure length in feet, width\nin meters and height in ells; as though basic instruction manuals\ndemanded a knowledge of five different languages. It is no wonder\nthen that we often look into our own immediate past or future, last\nTuesday or a week from Sunday, with feelings of helpless confusion.\n...\n\n--Robert Grudin, 'Time and the Art of Living'.\n\nThis section describes the textual date representations that GNU\nprograms accept. These are the strings you, as a user, can supply as\narguments to the various programs. The C interface (via the\n'parsedatetime' function) is not described here.\n\n* Menu:\n\n* General date syntax:: Common rules.\n* Calendar date items:: 19 Dec 1994.\n* Time of day items:: 9:20pm.\n* Time zone items:: EST, PDT, UTC, ...\n* Combined date and time of day items:: 1972-09-24T20:02:00,000000-0500.\n* Day of week items:: Monday and others.\n* Relative items in date strings:: next tuesday, 2 years ago.\n* Pure numbers in date strings:: 19931219, 1440.\n* Seconds since the Epoch:: @1078100502.\n* Specifying time zone rules:: TZ=\"America/NewYork\", TZ=\"UTC0\".\n* Authors of parsedatetime:: Bellovin, Eggert, Salz, Berets, et al.\n", "subsections": [] }, "File: coreutils.info, Node: General date syntax, Next: Calendar date items, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.1 General date syntax", "content": "A \"date\" is a string, possibly empty, containing many items separated by\nwhitespace. The whitespace may be omitted when no ambiguity arises." } ] }, "The empty string means the beginning of today (i.e., midnight). Order": { "content": "of the items is immaterial. A date string may contain many flavors of\nitems:\n\n* calendar date items\n* time of day items\n* time zone items\n* combined date and time of day items\n* day of the week items\n* relative items\n* pure numbers.\n\nWe describe each of these item types in turn, below.\n\nA few ordinal numbers may be written out in words in some contexts.", "subsections": [] }, "This is most useful for specifying day of the week items or relative": { "content": "items (see below). Among the most commonly used ordinal numbers, the\nword 'last' stands for -1, 'this' stands for 0, and 'first' and 'next'\nboth stand for 1. Because the word 'second' stands for the unit of time\nthere is no way to write the ordinal number 2, but for convenience\n'third' stands for 3, 'fourth' for 4, 'fifth' for 5, 'sixth' for 6,\n'seventh' for 7, 'eighth' for 8, 'ninth' for 9, 'tenth' for 10,\n'eleventh' for 11 and 'twelfth' for 12.\n\nWhen a month is written this way, it is still considered to be\nwritten numerically, instead of being \"spelled in full\"; this changes\nthe allowed strings.\n\nIn the current implementation, only English is supported for words\nand abbreviations like 'AM', 'DST', 'EST', 'first', 'January', 'Sunday',\n'tomorrow', and 'year'.\n\nThe output of the 'date' command is not always acceptable as a date\nstring, not only because of the language problem, but also because there\nis no standard meaning for time zone items like 'IST'. When using\n'date' to generate a date string intended to be parsed later, specify a\ndate format that is independent of language and that does not use time\nzone items other than 'UTC' and 'Z'. Here are some ways to do this:\n\n$ LCALL=C TZ=UTC0 date\nMon Mar 1 00:21:42 UTC 2004\n$ TZ=UTC0 date +'%Y-%m-%d %H:%M:%SZ'\n2004-03-01 00:21:42Z\n$ date --rfc-3339=ns # --rfc-3339 is a GNU extension.\n2004-02-29 16:21:42.692722128-08:00\n$ date --rfc-2822 # a GNU extension\nSun, 29 Feb 2004 16:21:42 -0800\n$ date +'%Y-%m-%d %H:%M:%S %z' # %z is a GNU extension.\n2004-02-29 16:21:42 -0800\n$ date +'@%s.%N' # %s and %N are GNU extensions.\n@1078100502.692722128\n\nAlphabetic case is completely ignored in dates. Comments may be\nintroduced between round parentheses, as long as included parentheses\nare properly nested. Hyphens not followed by a digit are currently\nignored. Leading zeros on numbers are ignored.\n\nInvalid dates like '2005-02-29' or times like '24:00' are rejected.", "subsections": [] }, "In the typical case of a host that does not support leap seconds, a time": { "content": "like '23:59:60' is rejected even if it corresponds to a valid leap\nsecond.\n", "subsections": [] }, "File: coreutils.info, Node: Calendar date items, Next: Time of day items, Prev: General date syntax, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.2 Calendar date items", "content": "A \"calendar date item\" specifies a day of the year. It is specified\ndifferently, depending on whether the month is specified numerically or\nliterally. All these strings specify the same calendar date:\n\n1972-09-24 # ISO 8601.\n72-9-24 # Assume 19xx for 69 through 99,\n# 20xx for 00 through 68.\n72-09-24 # Leading zeros are ignored.\n9/24/72 # Common U.S. writing.\n24 September 1972\n24 Sept 72 # September has a special abbreviation.\n24 Sep 72 # Three-letter abbreviations always allowed.\nSep 24, 1972\n24-sep-72\n24sep72\n\nThe year can also be omitted. In this case, the last specified year\nis used, or the current year if none. For example:\n\n9/24\nsep 24\n\nHere are the rules.\n\nFor numeric months, the ISO 8601 format 'YEAR-MONTH-DAY' is allowed,\nwhere YEAR is any positive number, MONTH is a number between 01 and 12,\nand DAY is a number between 01 and 31. A leading zero must be present\nif a number is less than ten. If YEAR is 68 or smaller, then 2000 is\nadded to it; otherwise, if YEAR is less than 100, then 1900 is added to\nit. The construct 'MONTH/DAY/YEAR', popular in the United States, is\naccepted. Also 'MONTH/DAY', omitting the year.\n\nLiteral months may be spelled out in full: 'January', 'February',\n'March', 'April', 'May', 'June', 'July', 'August', 'September',\n'October', 'November' or 'December'. Literal months may be abbreviated\nto their first three letters, possibly followed by an abbreviating dot.\nIt is also permitted to write 'Sept' instead of 'September'.\n\nWhen months are written literally, the calendar date may be given as\nany of the following:\n\nDAY MONTH YEAR\nDAY MONTH\nMONTH DAY YEAR\nDAY-MONTH-YEAR\n\nOr, omitting the year:\n\nMONTH DAY\n" } ] }, "File: coreutils.info, Node: Time of day items, Next: Time zone items, Prev: Calendar date items, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.3 Time of day items", "content": "A \"time of day item\" in date strings specifies the time on a given day.\nHere are some examples, all of which represent the same time:\n\n20:02:00.000000\n20:02\n8:02pm\n20:02-0500 # In EST (U.S. Eastern Standard Time).\n\nMore generally, the time of day may be given as 'HOUR:MINUTE:SECOND',\nwhere HOUR is a number between 0 and 23, MINUTE is a number between 0\nand 59, and SECOND is a number between 0 and 59 possibly followed by '.'\nor ',' and a fraction containing one or more digits. Alternatively,\n':SECOND' can be omitted, in which case it is taken to be zero. On the\nrare hosts that support leap seconds, SECOND may be 60.\n\nIf the time is followed by 'am' or 'pm' (or 'a.m.' or 'p.m.'), HOUR\nis restricted to run from 1 to 12, and ':MINUTE' may be omitted (taken\nto be zero). 'am' indicates the first half of the day, 'pm' indicates\nthe second half of the day. In this notation, 12 is the predecessor of\n1: midnight is '12am' while noon is '12pm'. (This is the zero-oriented\ninterpretation of '12am' and '12pm', as opposed to the old tradition\nderived from Latin which uses '12m' for noon and '12pm' for midnight.)\n\nThe time may alternatively be followed by a time zone correction,\nexpressed as 'SHHMM', where S is '+' or '-', HH is a number of zone\nhours and MM is a number of zone minutes. The zone minutes term, MM,\nmay be omitted, in which case the one- or two-digit correction is\ninterpreted as a number of hours. You can also separate HH from MM with\na colon. When a time zone correction is given this way, it forces\ninterpretation of the time relative to Coordinated Universal Time (UTC),\noverriding any previous specification for the time zone or the local\ntime zone. For example, '+0530' and '+05:30' both stand for the time\nzone 5.5 hours ahead of UTC (e.g., India). This is the best way to\nspecify a time zone correction by fractional parts of an hour. The\nmaximum zone correction is 24 hours.\n\nEither 'am'/'pm' or a time zone correction may be specified, but not\nboth.\n" } ] }, "File: coreutils.info, Node: Time zone items, Next: Combined date and time of day items, Prev: Time of day items, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.4 Time zone items", "content": "A \"time zone item\" specifies an international time zone, indicated by a\nsmall set of letters, e.g., 'UTC' or 'Z' for Coordinated Universal Time." } ] }, "Any included periods are ignored. By following a non-daylight-saving": { "content": "time zone by the string 'DST' in a separate word (that is, separated by\nsome white space), the corresponding daylight saving time zone may be\nspecified. Alternatively, a non-daylight-saving time zone can be\nfollowed by a time zone correction, to add the two values. This is\nnormally done only for 'UTC'; for example, 'UTC+05:30' is equivalent to\n'+05:30'.\n\nTime zone items other than 'UTC' and 'Z' are obsolescent and are not\nrecommended, because they are ambiguous; for example, 'EST' has a\ndifferent meaning in Australia than in the United States, and 'A' has\ndifferent meaning as a military time zone than as an obsolescent RFC 822\ntime zone. Instead, it's better to use unambiguous numeric time zone\ncorrections like '-0500', as described in the previous section.\n\nIf neither a time zone item nor a time zone correction is supplied,\ntimestamps are interpreted using the rules of the default time zone\n(*note Specifying time zone rules::).\n", "subsections": [] }, "File: coreutils.info, Node: Combined date and time of day items, Next: Day of week items, Prev: Time zone items, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.5 Combined date and time of day items", "content": "" } ] }, "The ISO 8601 date and time of day extended format consists of an ISO": { "content": "8601 date, a 'T' character separator, and an ISO 8601 time of day. This\nformat is also recognized if the 'T' is replaced by a space.\n\nIn this format, the time of day should use 24-hour notation.", "subsections": [] }, "Fractional seconds are allowed, with either comma or period preceding": { "content": "the fraction. ISO 8601 fractional minutes and hours are not supported.", "subsections": [] }, "Typically, hosts support nanosecond timestamp resolution; excess": { "content": "precision is silently discarded.\n\nHere are some examples:\n\n2012-09-24T20:02:00.052-05:00\n2012-12-31T23:59:59,999999999+11:00\n1970-01-01 00:00Z\n", "subsections": [] }, "File: coreutils.info, Node: Day of week items, Next: Relative items in date strings, Prev: Combined date and time of day items, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.6 Day of week items", "content": "" } ] }, "The explicit mention of a day of the week will forward the date (only if": { "content": "necessary) to reach that day of the week in the future.\n\nDays of the week may be spelled out in full: 'Sunday', 'Monday',\n'Tuesday', 'Wednesday', 'Thursday', 'Friday' or 'Saturday'. Days may be\nabbreviated to their first three letters, optionally followed by a\nperiod. The special abbreviations 'Tues' for 'Tuesday', 'Wednes' for\n'Wednesday' and 'Thur' or 'Thurs' for 'Thursday' are also allowed.\n\nA number may precede a day of the week item to move forward\nsupplementary weeks. It is best used in expression like 'third monday'.", "subsections": [] }, "In this context, 'last DAY' or 'next DAY' is also acceptable; they move": { "content": "one week before or after the day that DAY by itself would represent.\n\nA comma following a day of the week item is ignored.\n", "subsections": [] }, "File: coreutils.info, Node: Relative items in date strings, Next: Pure numbers in date strings, Prev: Day of week items, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.7 Relative items in date strings", "content": "\"Relative items\" adjust a date (or the current date if none) forward or\nbackward. The effects of relative items accumulate. Here are some\nexamples:\n\n1 year\n1 year ago\n3 years\n2 days\n\nThe unit of time displacement may be selected by the string 'year' or\n'month' for moving by whole years or months. These are fuzzy units, as\nyears and months are not all of equal duration. More precise units are\n'fortnight' which is worth 14 days, 'week' worth 7 days, 'day' worth 24\nhours, 'hour' worth 60 minutes, 'minute' or 'min' worth 60 seconds, and\n'second' or 'sec' worth one second. An 's' suffix on these units is\naccepted and ignored.\n\nThe unit of time may be preceded by a multiplier, given as an\noptionally signed number. Unsigned numbers are taken as positively\nsigned. No number at all implies 1 for a multiplier. Following a\nrelative item by the string 'ago' is equivalent to preceding the unit by\na multiplier with value -1.\n\nThe string 'tomorrow' is worth one day in the future (equivalent to\n'day'), the string 'yesterday' is worth one day in the past (equivalent\nto 'day ago').\n\nThe strings 'now' or 'today' are relative items corresponding to\nzero-valued time displacement, these strings come from the fact a\nzero-valued time displacement represents the current time when not\notherwise changed by previous items. They may be used to stress other\nitems, like in '12:00 today'. The string 'this' also has the meaning of\na zero-valued time displacement, but is preferred in date strings like\n'this thursday'.\n\nWhen a relative item causes the resulting date to cross a boundary\nwhere the clocks were adjusted, typically for daylight saving time, the\nresulting date and time are adjusted accordingly.\n\nThe fuzz in units can cause problems with relative items. For\nexample, '2003-07-31 -1 month' might evaluate to 2003-07-01, because\n2003-06-31 is an invalid date. To determine the previous month more\nreliably, you can ask for the month before the 15th of the current\nmonth. For example:\n\n$ date -R\nThu, 31 Jul 2003 13:02:39 -0700\n$ date --date='-1 month' +'Last month was %B?'\nLast month was July?\n$ date --date=\"$(date +%Y-%m-15) -1 month\" +'Last month was %B!'\nLast month was June!\n\nAlso, take care when manipulating dates around clock changes such as\ndaylight saving leaps. In a few cases these have added or subtracted as\nmuch as 24 hours from the clock, so it is often wise to adopt universal\ntime by setting the 'TZ' environment variable to 'UTC0' before embarking\non calendrical calculations.\n" } ] }, "File: coreutils.info, Node: Pure numbers in date strings, Next: Seconds since the Epoch, Prev: Relative items in date strings, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.8 Pure numbers in date strings", "content": "" } ] }, "The precise interpretation of a pure decimal number depends on the": { "content": "context in the date string.\n\nIf the decimal number is of the form YYYYMMDD and no other calendar\ndate item (*note Calendar date items::) appears before it in the date\nstring, then YYYY is read as the year, MM as the month number and DD as\nthe day of the month, for the specified calendar date.\n\nIf the decimal number is of the form HHMM and no other time of day\nitem appears before it in the date string, then HH is read as the hour\nof the day and MM as the minute of the hour, for the specified time of\nday. MM can also be omitted.\n\nIf both a calendar date and a time of day appear to the left of a\nnumber in the date string, but no relative item, then the number\noverrides the year.\n", "subsections": [] }, "File: coreutils.info, Node: Seconds since the Epoch, Next: Specifying time zone rules, Prev: Pure numbers in date strings, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.9 Seconds since the Epoch", "content": "If you precede a number with '@', it represents an internal timestamp as\na count of seconds. The number can contain an internal decimal point\n(either '.' or ','); any excess precision not supported by the internal\nrepresentation is truncated toward minus infinity. Such a number cannot\nbe combined with any other date item, as it specifies a complete\ntimestamp.\n\nInternally, computer times are represented as a count of seconds\nsince an epoch--a well-defined point of time. On GNU and POSIX systems,\nthe epoch is 1970-01-01 00:00:00 UTC, so '@0' represents this time, '@1'\nrepresents 1970-01-01 00:00:01 UTC, and so forth. GNU and most other\nPOSIX-compliant systems support such times as an extension to POSIX,\nusing negative counts, so that '@-1' represents 1969-12-31 23:59:59 UTC.\n\nTraditional Unix systems count seconds with 32-bit two's-complement\nintegers and can represent times from 1901-12-13 20:45:52 through\n2038-01-19 03:14:07 UTC. More modern systems use 64-bit counts of\nseconds with nanosecond subcounts, and can represent all the times in\nthe known lifetime of the universe to a resolution of 1 nanosecond.\n\nOn most hosts, these counts ignore the presence of leap seconds. For\nexample, on most hosts '@915148799' represents 1998-12-31 23:59:59 UTC,\n'@915148800' represents 1999-01-01 00:00:00 UTC, and there is no way to\nrepresent the intervening leap second 1998-12-31 23:59:60 UTC.\n" } ] }, "File: coreutils.info, Node: Specifying time zone rules, Next: Authors of parsedatetime, Prev: Seconds since the Epoch, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.10 Specifying time zone rules", "content": "" } ] }, "Normally, dates are interpreted using the rules of the current time": { "content": "zone, which in turn are specified by the 'TZ' environment variable, or\nby a system default if 'TZ' is not set. To specify a different set of\ndefault time zone rules that apply just to one date, start the date with\na string of the form 'TZ=\"RULE\"'. The two quote characters ('\"') must\nbe present in the date, and any quotes or backslashes within RULE must\nbe escaped by a backslash.\n\nFor example, with the GNU 'date' command you can answer the question\n\"What time is it in New York when a Paris clock shows 6:30am on October\n31, 2004?\" by using a date beginning with 'TZ=\"Europe/Paris\"' as shown\nin the following shell transcript:\n\n$ export TZ=\"America/NewYork\"\n$ date --date='TZ=\"Europe/Paris\" 2004-10-31 06:30'\nSun Oct 31 01:30:00 EDT 2004\n\nIn this example, the '--date' operand begins with its own 'TZ'\nsetting, so the rest of that operand is processed according to\n'Europe/Paris' rules, treating the string '2004-10-31 06:30' as if it\nwere in Paris. However, since the output of the 'date' command is\nprocessed according to the overall time zone rules, it uses New York\ntime. (Paris was normally six hours ahead of New York in 2004, but this\nexample refers to a brief Halloween period when the gap was five hours.)\n\nA 'TZ' value is a rule that typically names a location in the 'tz'\ndatabase (https://www.iana.org/time-zones). A recent catalog of\nlocation names appears in the TWiki Date and Time Gateway\n(https://twiki.org/cgi-bin/xtra/tzdatepick.html). A few non-GNU hosts\nrequire a colon before a location name in a 'TZ' setting, e.g.,\n'TZ=\":America/NewYork\"'.\n\nThe 'tz' database includes a wide variety of locations ranging from\n'Arctic/Longyearbyen' to 'Antarctica/SouthPole', but if you are at sea\nand have your own private time zone, or if you are using a non-GNU host\nthat does not support the 'tz' database, you may need to use a POSIX\nrule instead. Simple POSIX rules like 'UTC0' specify a time zone\nwithout daylight saving time; other rules can specify simple daylight\nsaving regimes. *Note Specifying the Time Zone with 'TZ': (libc)TZ\nVariable.\n", "subsections": [] }, "File: coreutils.info, Node: Authors of parsedatetime, Prev: Specifying time zone rules, Up: Date input formats": { "content": "", "subsections": [ { "name": "29.11 Authors of 'parsedatetime'", "content": "'parsedatetime' started life as 'getdate', as originally implemented by\nSteven M. Bellovin () while at the University of" } ] }, "North Carolina at Chapel Hill. The code was later tweaked by a couple": { "content": "of people on Usenet, then completely overhauled by Rich $alz\n() and Jim Berets () in August, 1990.", "subsections": [] }, "Various revisions for the GNU system were made by David MacKenzie, Jim": { "content": "", "subsections": [] }, "Meyering, Paul Eggert and others, including renaming it to 'getdate' to": { "content": "avoid a conflict with the alternative Posix function 'getdate', and a\nlater rename to 'parsedatetime'. The Posix function 'getdate' can\nparse more locale-specific dates using 'strptime', but relies on an\nenvironment variable and external file, and lacks the thread-safety of\n'parsedatetime'.\n\nThis chapter was originally produced by Franc,ois Pinard\n() from the 'parsedatetime.y' source code, and\nthen edited by K. Berry ().\n", "subsections": [] }, "File: coreutils.info, Node: Examples of date, Prev: Options for date, Up: date invocation": { "content": "", "subsections": [] }, "Here are a few examples. Also see the documentation for the '-d' option": { "content": "in the previous section.\n\n* To print the date of the day before yesterday:\n\ndate --date='2 days ago'\n\n* To print the date of the day three months and one day hence:\n\ndate --date='3 months 1 day'\n\n* To print the day of year of Christmas in the current year:\n\ndate --date='25 Dec' +%j\n\n* To print the current full month name and the day of the month:\n\ndate '+%B %d'\n\nBut this may not be what you want because for the first nine days\nof the month, the '%d' expands to a zero-padded two-digit field,\nfor example 'date -d 1may '+%B %d'' will print 'May 01'.\n\n* To print a date without the leading zero for one-digit days of the\nmonth, you can use the (GNU extension) '-' flag to suppress the\npadding altogether:\n\ndate -d 1may '+%B %-d'\n\n* To print the current date and time in the format required by many\nnon-GNU versions of 'date' when setting the system clock:\n\ndate +%m%d%H%M%Y.%S\n\n* To set the system clock forward by two minutes:\n\ndate --set='+2 minutes'\n\n* To print the date in Internet RFC 5322 format, use 'date\n--rfc-email'. Here is some example output:\n\nFri, 09 Sep 2005 13:51:39 -0700\n\n* To convert a date string to the number of seconds since the epoch\n(which is 1970-01-01 00:00:00 UTC), use the '--date' option with\nthe '%s' format. That can be useful in sorting and/or graphing\nand/or comparing data by date. The following command outputs the\nnumber of the seconds since the epoch for the time two minutes\nafter the epoch:\n\ndate --date='1970-01-01 00:02:00 +0000' +%s\n120\n\nIf you do not specify time zone information in the date string,\n'date' uses your computer's idea of the time zone when interpreting\nthe string. For example, if your computer's time zone is that of\nCambridge, Massachusetts, which was then 5 hours (i.e., 18,000\nseconds) behind UTC:\n\n# local time zone used\ndate --date='1970-01-01 00:02:00' +%s\n18120\n\n* If you're sorting or graphing dated data, your raw date values may\nbe represented as seconds since the epoch. But few people can look\nat the date '946684800' and casually note \"Oh, that's the first\nsecond of the year 2000 in Greenwich, England.\"\n\ndate --date='2000-01-01 UTC' +%s\n946684800\n\nAn alternative is to use the '--utc' ('-u') option. Then you may\nomit 'UTC' from the date string. Although this produces the same\nresult for '%s' and many other format sequences, with a time zone\noffset different from zero, it would give a different result for\nzone-dependent formats like '%z'.\n\ndate -u --date=2000-01-01 +%s\n946684800\n\nTo convert such an unwieldy number of seconds back to a more\nreadable form, use a command like this:\n\n# local time zone used\ndate -d '1970-01-01 UTC 946684800 seconds' +\"%Y-%m-%d %T %z\"\n1999-12-31 19:00:00 -0500\n\nOr if you do not mind depending on the '@' feature present since\ncoreutils 5.3.0, you could shorten this to:\n\ndate -d @946684800 +\"%F %T %z\"\n1999-12-31 19:00:00 -0500\n\nOften it is better to output UTC-relative date and time:\n\ndate -u -d '1970-01-01 946684800 seconds' +\"%Y-%m-%d %T %z\"\n2000-01-01 00:00:00 +0000\n\n* Typically the seconds count omits leap seconds, but some systems\nare exceptions. Because leap seconds are not predictable, the\nmapping between the seconds count and a future timestamp is not\nreliable on the atypical systems that include leap seconds in their\ncounts.\n\nHere is how the two kinds of systems handle the leap second at\n2012-06-30 23:59:60 UTC:\n\n# Typical systems ignore leap seconds:\ndate --date='2012-06-30 23:59:59 +0000' +%s\n1341100799\ndate --date='2012-06-30 23:59:60 +0000' +%s\ndate: invalid date '2012-06-30 23:59:60 +0000'\ndate --date='2012-07-01 00:00:00 +0000' +%s\n1341100800\n\n# Atypical systems count leap seconds:\ndate --date='2012-06-30 23:59:59 +0000' +%s\n1341100823\ndate --date='2012-06-30 23:59:60 +0000' +%s\n1341100824\ndate --date='2012-07-01 00:00:00 +0000' +%s\n1341100825\n", "subsections": [] }, "File: coreutils.info, Node: arch invocation, Next: nproc invocation, Prev: date invocation, Up: System context": { "content": "", "subsections": [ { "name": "21.2 'arch': Print machine hardware name", "content": "'arch' prints the machine hardware name, and is equivalent to 'uname\n-m'. Synopsis:\n\narch [OPTION]\n\nThe program accepts the *note Common options:: only.\n\n'arch' is not installed by default, so portable scripts should not\nrely on its existence.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: nproc invocation, Next: uname invocation, Prev: arch invocation, Up: System context": { "content": "", "subsections": [ { "name": "21.3 'nproc': Print the number of available processors", "content": "" } ] }, "Print the number of processing units available to the current process,": { "content": "which may be less than the number of online processors. If this\ninformation is not accessible, then print the number of processors\ninstalled. If the 'OMPNUMTHREADS' or 'OMPTHREADLIMIT' environment\nvariables are set, then they will determine the minimum and maximum\nreturned value respectively. The result is guaranteed to be greater\nthan zero. Synopsis:\n\nnproc [OPTION]\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'--all'\nPrint the number of installed processors on the system, which may\nbe greater than the number online or available to the current\nprocess. The 'OMPNUMTHREADS' or 'OMPTHREADLIMIT' environment\nvariables are not honored in this case.\n\n'--ignore=NUMBER'\nIf possible, exclude this NUMBER of processing units.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: uname invocation, Next: hostname invocation, Prev: nproc invocation, Up: System context": { "content": "", "subsections": [ { "name": "21.4 'uname': Print system information", "content": "'uname' prints information about the machine and operating system it is\nrun on. If no options are given, 'uname' acts as if the '-s' option\nwere given. Synopsis:\n\nuname [OPTION]...\n\nIf multiple options or '-a' are given, the selected information is\nprinted in this order:\n\nKERNEL-NAME NODENAME KERNEL-RELEASE KERNEL-VERSION\nMACHINE PROCESSOR HARDWARE-PLATFORM OPERATING-SYSTEM\n\nThe information may contain internal spaces, so such output cannot be\nparsed reliably. In the following example, RELEASE is\n'2.2.18ss.e820-bda652a #4 SMP Tue Jun 5 11:24:08 PDT 2001':\n\nuname -a\n=> Linux dumdum 2.2.18 #4 SMP Tue Jun 5 11:24:08 PDT 2001 i686 unknown unknown GNU/Linux\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-a'\n'--all'\nPrint all of the below information, except omit the processor type\nand the hardware platform name if they are unknown.\n\n'-i'\n'--hardware-platform'\nPrint the hardware platform name (sometimes called the hardware\nimplementation). Print 'unknown' if this information is not\navailable. Note this is non-portable (even across GNU/Linux\ndistributions).\n\n'-m'\n'--machine'\nPrint the machine hardware name (sometimes called the hardware\nclass or hardware type).\n\n'-n'\n'--nodename'\nPrint the network node hostname.\n\n'-p'\n'--processor'\nPrint the processor type (sometimes called the instruction set\narchitecture or ISA). Print 'unknown' if this information is not\navailable. Note this is non-portable (even across GNU/Linux\ndistributions).\n\n'-o'\n'--operating-system'\nPrint the name of the operating system.\n\n'-r'\n'--kernel-release'\nPrint the kernel release.\n\n'-s'\n'--kernel-name'\nPrint the kernel name. POSIX 1003.1-2001 (*note Standards\nconformance::) calls this \"the implementation of the operating\nsystem\", because the POSIX specification itself has no notion of\n\"kernel\". The kernel name might be the same as the operating\nsystem name printed by the '-o' or '--operating-system' option, but\nit might differ. Some operating systems (e.g., FreeBSD, HP-UX)\nhave the same name as their underlying kernels; others (e.g.,\nGNU/Linux, Solaris) do not.\n\n'-v'\n'--kernel-version'\nPrint the kernel version.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: hostname invocation, Next: hostid invocation, Prev: uname invocation, Up: System context": { "content": "", "subsections": [ { "name": "21.5 'hostname': Print or set system name", "content": "" } ] }, "With no arguments, 'hostname' prints the name of the current host": { "content": "system. With one argument, it sets the current host name to the\nspecified string. You must have appropriate privileges to set the host\nname. Synopsis:\n\nhostname [NAME]\n\nThe only options are '--help' and '--version'. *Note Common\noptions::.\n\n'hostname' is not installed by default, and other packages also\nsupply a 'hostname' command, so portable scripts should not rely on its\nexistence or on the exact behavior documented above.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n", "subsections": [] }, "File: coreutils.info, Node: hostid invocation, Next: uptime invocation, Prev: hostname invocation, Up: System context": { "content": "", "subsections": [ { "name": "21.6 'hostid': Print numeric host identifier", "content": "'hostid' prints the numeric identifier of the current host in\nhexadecimal. This command accepts no arguments. The only options are\n'--help' and '--version'. *Note Common options::.\n\nFor example, here's what it prints on one system I use:\n\n$ hostid\n1bac013d\n\nOn that system, the 32-bit quantity happens to be closely related to\nthe system's Internet address, but that isn't always the case.\n\n'hostid' is installed only on systems that have the 'gethostid'\nfunction, so portable scripts should not rely on its existence.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: uptime invocation, Prev: hostid invocation, Up: System context": { "content": "", "subsections": [ { "name": "21.7 'uptime': Print system uptime and load", "content": "'uptime' prints the current time, the system's uptime, the number of\nlogged-in users and the current load average.\n\nIf an argument is specified, it is used as the file to be read to\ndiscover how many users are logged in. If no argument is specified, a\nsystem default is used ('uptime --help' indicates the default setting).\n\nThe only options are '--help' and '--version'. *Note Common\noptions::.\n\nFor example, here's what it prints right now on one system I use:\n\n$ uptime\n14:07 up 3:35, 3 users, load average: 1.39, 1.15, 1.04\n\nThe precise method of calculation of load average varies somewhat\nbetween systems. Some systems calculate it as the average number of\nrunnable processes over the last 1, 5 and 15 minutes, but some systems\nalso include processes in the uninterruptible sleep state (that is,\nthose processes which are waiting for disk I/O). The Linux kernel\nincludes uninterruptible processes.\n\n'uptime' is installed only on platforms with infrastructure for\nobtaining the boot time, and other packages also supply an 'uptime'\ncommand, so portable scripts should not rely on its existence or on the\nexact behavior documented above.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: SELinux context, Next: Modified command invocation, Prev: System context, Up: Top": { "content": "", "subsections": [] }, "22 SELinux context": { "content": "This section describes commands for operations with SELinux contexts.\n\n* Menu:\n\n* chcon invocation:: Change SELinux context of file\n* runcon invocation:: Run a command in specified SELinux context\n", "subsections": [] }, "File: coreutils.info, Node: chcon invocation, Next: runcon invocation, Up: SELinux context": { "content": "", "subsections": [ { "name": "22.1 'chcon': Change SELinux context of file", "content": "'chcon' changes the SELinux security context of the selected files.\nSynopses:\n\nchcon [OPTION]... CONTEXT FILE...\nchcon [OPTION]... [-u USER] [-r ROLE] [-l RANGE] [-t TYPE] FILE...\nchcon [OPTION]... --reference=RFILE FILE...\n\nChange the SELinux security context of each FILE to CONTEXT. With\n'--reference', change the security context of each FILE to that of\nRFILE.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'--dereference'\nDo not affect symbolic links but what they refer to; this is the\ndefault.\n\n'-h'\n'--no-dereference'\nAffect the symbolic links themselves instead of any referenced\nfile.\n\n'--reference=RFILE'\nUse RFILE's security context rather than specifying a CONTEXT\nvalue.\n\n'-R'\n'--recursive'\nOperate on files and directories recursively.\n\n'--preserve-root'\nRefuse to operate recursively on the root directory, '/', when used\ntogether with the '--recursive' option. *Note Treating /\nspecially::.\n\n'--no-preserve-root'\nDo not treat the root directory, '/', specially when operating\nrecursively; this is the default. *Note Treating / specially::.\n\n'-H'\nIf '--recursive' ('-R') is specified and a command line argument is\na symbolic link to a directory, traverse it. *Note Traversing\nsymlinks::.\n\n'-L'\nIn a recursive traversal, traverse every symbolic link to a\ndirectory that is encountered. *Note Traversing symlinks::.\n\n'-P'\nDo not traverse any symbolic links. This is the default if none of\n'-H', '-L', or '-P' is specified. *Note Traversing symlinks::.\n\n'-v'\n'--verbose'\nOutput a diagnostic for every file processed.\n\n'-u USER'\n'--user=USER'\nSet user USER in the target security context.\n\n'-r ROLE'\n'--role=ROLE'\nSet role ROLE in the target security context.\n\n'-t TYPE'\n'--type=TYPE'\nSet type TYPE in the target security context.\n\n'-l RANGE'\n'--range=RANGE'\nSet range RANGE in the target security context.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: runcon invocation, Prev: chcon invocation, Up: SELinux context": { "content": "", "subsections": [ { "name": "22.2 'runcon': Run a command in specified SELinux context", "content": "'runcon' runs file in specified SELinux security context.\n\nSynopses:\nruncon CONTEXT COMMAND [ARGS]\nruncon [ -c ] [-u USER] [-r ROLE] [-t TYPE] [-l RANGE] COMMAND [ARGS]\n\nRun COMMAND with completely-specified CONTEXT, or with current or\ntransitioned security context modified by one or more of LEVEL, ROLE,\nTYPE and USER.\n\nIf none of '-c', '-t', '-u', '-r', or '-l' is specified, the first\nargument is used as the complete context. Any additional arguments\nafter COMMAND are interpreted as arguments to the command.\n\nWith neither CONTEXT nor COMMAND, print the current security context.\n\nNote also the 'setpriv' command which can be used to set the\nNONEWPRIVS bit using 'setpriv --no-new-privs runcon ...', thus\ndisallowing usage of a security context with more privileges than the\nprocess would normally have.\n\n'runcon' accepts the following options. Also see *note Common\noptions::.\n\n'-c'\n'--compute'\nCompute process transition context before modifying.\n\n'-u USER'\n'--user=USER'\nSet user USER in the target security context.\n\n'-r ROLE'\n'--role=ROLE'\nSet role ROLE in the target security context.\n\n'-t TYPE'\n'--type=TYPE'\nSet type TYPE in the target security context.\n\n'-l RANGE'\n'--range=RANGE'\nSet range RANGE in the target security context.\n\nExit status:\n\n126 if COMMAND is found but cannot be invoked\n127 if 'runcon' itself fails or if COMMAND cannot be found\nthe exit status of COMMAND otherwise\n" } ] }, "File: coreutils.info, Node: Modified command invocation, Next: Process control, Prev: SELinux context, Up: Top": { "content": "", "subsections": [] }, "23 Modified command invocation": { "content": "", "subsections": [] }, "This section describes commands that run other commands in some context": { "content": "different than the current one: a modified environment, as a different\nuser, etc.\n\n* Menu:\n\n* chroot invocation:: Modify the root directory.\n* env invocation:: Modify environment variables.\n* nice invocation:: Modify niceness.\n* nohup invocation:: Immunize to hangups.\n* stdbuf invocation:: Modify buffering of standard streams.\n* timeout invocation:: Run with time limit.\n", "subsections": [] }, "File: coreutils.info, Node: chroot invocation, Next: env invocation, Up: Modified command invocation": { "content": "", "subsections": [ { "name": "23.1 'chroot': Run a command with a different root directory", "content": "'chroot' runs a command with a specified root directory. On many\nsystems, only the super-user can do this.(1). Synopses:\n\nchroot OPTION NEWROOT [COMMAND [ARGS]...]\nchroot OPTION\n\nOrdinarily, file names are looked up starting at the root of the\ndirectory structure, i.e., '/'. 'chroot' changes the root to the\ndirectory NEWROOT (which must exist), then changes the working directory\nto '/', and finally runs COMMAND with optional ARGS. If COMMAND is not\nspecified, the default is the value of the 'SHELL' environment variable\nor '/bin/sh' if not set, invoked with the '-i' option. COMMAND must not\nbe a special built-in utility (*note Special built-in utilities::).\n\nThe program accepts the following options. Also see *note Common\noptions::. Options must precede operands.\n\n'--groups=GROUPS'\nUse this option to override the supplementary GROUPS to be used by\nthe new process. The items in the list (names or numeric IDs) must\nbe separated by commas. Use '--groups=''' to disable the\nsupplementary group look-up implicit in the '--userspec' option.\n\n'--userspec=USER[:GROUP]'\nBy default, COMMAND is run with the same credentials as the\ninvoking process. Use this option to run it as a different USER\nand/or with a different primary GROUP. If a USER is specified then\nthe supplementary groups are set according to the system defined\nlist for that user, unless overridden with the '--groups' option.\n\n'--skip-chdir'\nUse this option to not change the working directory to '/' after\nchanging the root directory to NEWROOT, i.e., inside the chroot.\nThis option is only permitted when NEWROOT is the old '/'\ndirectory, and therefore is mostly useful together with the\n'--groups' and '--userspec' options to retain the previous working\ndirectory.\n\nThe user and group name look-up performed by the '--userspec' and\n'--groups' options, is done both outside and inside the chroot, with\nsuccessful look-ups inside the chroot taking precedence. If the\nspecified user or group items are intended to represent a numeric ID,\nthen a name to ID resolving step is avoided by specifying a leading '+'.\n*Note Disambiguating names and IDs::.\n\nHere are a few tips to help avoid common problems in using chroot." } ] }, "To start with a simple example, make COMMAND refer to a statically": { "content": "linked binary. If you were to use a dynamically linked executable, then\nyou'd have to arrange to have the shared libraries in the right place\nunder your new root directory.\n\nFor example, if you create a statically linked 'ls' executable, and\nput it in '/tmp/empty', you can run this command as root:\n\n$ chroot /tmp/empty /ls -Rl /\n\nThen you'll see output like this:\n\n/:\ntotal 1023\n-rwxr-xr-x 1 0 0 1041745 Aug 16 11:17 ls\n\nIf you want to use a dynamically linked executable, say 'bash', then\nfirst run 'ldd bash' to see what shared objects it needs. Then, in\naddition to copying the actual binary, also copy the listed files to the\nrequired positions under your intended new root directory. Finally, if\nthe executable requires any other files (e.g., data, state, device\nfiles), copy them into place, too.\n\n'chroot' is installed only on systems that have the 'chroot'\nfunction, so portable scripts should not rely on its existence.\n\nExit status:\n\n125 if 'chroot' itself fails\n126 if COMMAND is found but cannot be invoked\n127 if COMMAND cannot be found\nthe exit status of COMMAND otherwise\n\n---------- Footnotes ----------\n\n(1) However, some systems (e.g., FreeBSD) can be configured to allow\ncertain regular users to use the 'chroot' system call, and hence to run\nthis program. Also, on Cygwin, anyone can run the 'chroot' command,\nbecause the underlying function is non-privileged due to lack of support\nin MS-Windows. Furthermore, the 'chroot' command avoids the 'chroot'\nsystem call when NEWROOT is identical to the old '/' directory for\nconsistency with systems where this is allowed for non-privileged users.\n", "subsections": [] }, "File: coreutils.info, Node: env invocation, Next: nice invocation, Prev: chroot invocation, Up: Modified command invocation": { "content": "", "subsections": [ { "name": "23.2 'env': Run a command in a modified environment", "content": "'env' runs a command with a modified environment. Synopses:\n\nenv [OPTION]... [NAME=VALUE]... [COMMAND [ARGS]...]\nenv -[v]S'[OPTION]... [NAME=VALUE]... [COMMAND [ARGS]...]'\nenv\n\n'env' is commonly used on first line of scripts (shebang line):\n#!/usr/bin/env COMMAND\n#!/usr/bin/env -[v]S[OPTION]... [NAME=VALUE]... COMMAND [ARGS]...\n\nOperands of the form 'VARIABLE=VALUE' set the environment variable\nVARIABLE to value VALUE. VALUE may be empty ('VARIABLE='). Setting a\nvariable to an empty value is different from unsetting it. These\noperands are evaluated left-to-right, so if two operands mention the\nsame variable the earlier is ignored.\n\nEnvironment variable names can be empty, and can contain any\ncharacters other than '=' and ASCII NUL. However, it is wise to limit\nyourself to names that consist solely of underscores, digits, and ASCII\nletters, and that begin with a non-digit, as applications like the shell\ndo not work well with other names.\n\nThe first operand that does not contain the character '=' specifies\nthe program to invoke; it is searched for according to the 'PATH'\nenvironment variable. Any remaining arguments are passed as arguments\nto that program. The program should not be a special built-in utility\n(*note Special built-in utilities::).\n\nModifications to 'PATH' take effect prior to searching for COMMAND." } ] }, "Use caution when reducing 'PATH'; behavior is not portable when 'PATH'": { "content": "is undefined or omits key directories such as '/bin'.\n\nIn the rare case that a utility contains a '=' in the name, the only\nway to disambiguate it from a variable assignment is to use an\nintermediate command for COMMAND, and pass the problematic program name\nvia ARGS. For example, if './prog=' is an executable in the current\n'PATH':\n\nenv prog= true # runs 'true', with prog= in environment\nenv ./prog= true # runs 'true', with ./prog= in environment\nenv -- prog= true # runs 'true', with prog= in environment\nenv sh -c '\\prog= true' # runs 'prog=' with argument 'true'\nenv sh -c 'exec \"$@\"' sh prog= true # also runs 'prog='\n\nIf no command name is specified following the environment\nspecifications, the resulting environment is printed. This is like\nspecifying the 'printenv' program.\n\nFor some examples, suppose the environment passed to 'env' contains\n'LOGNAME=rms', 'EDITOR=emacs', and 'PATH=.:/gnubin:/hacks':\n\n* Output the current environment.\n$ env | LCALL=C sort\nEDITOR=emacs\nLOGNAME=rms\nPATH=.:/gnubin:/hacks\n\n* Run 'foo' with a reduced environment, preserving only the original\n'PATH' to avoid problems in locating 'foo'.\nenv - PATH=\"$PATH\" foo\n\n* Run 'foo' with the environment containing 'LOGNAME=rms',\n'EDITOR=emacs', and 'PATH=.:/gnubin:/hacks', and guarantees that\n'foo' was found in the file system rather than as a shell built-in.\nenv foo\n\n* Run 'nemacs' with the environment containing 'LOGNAME=foo',\n'EDITOR=emacs', 'PATH=.:/gnubin:/hacks', and 'DISPLAY=gnu:0'.\nenv DISPLAY=gnu:0 LOGNAME=foo nemacs\n\n* Attempt to run the program '/energy/--' (as that is the only\npossible path search result); if the command exists, the\nenvironment will contain 'LOGNAME=rms' and 'PATH=/energy', and the\narguments will be 'e=mc2', 'bar', and 'baz'.\nenv -u EDITOR PATH=/energy -- e=mc2 bar baz\n\n\nThe program accepts the following options. Also see *note Common\noptions::. Options must precede operands.\n\n'-0'\n'--null'\nOutput a zero byte (ASCII NUL) at the end of each line, rather than\na newline. This option enables other programs to parse the output\neven when that output would contain data with embedded newlines.\n\n'-u NAME'\n'--unset=NAME'\nRemove variable NAME from the environment, if it was in the\nenvironment.\n\n'-'\n'-i'\n'--ignore-environment'\nStart with an empty environment, ignoring the inherited\nenvironment.\n\n'-C DIR'\n'--chdir=DIR'\nChange the working directory to DIR before invoking COMMAND. This\ndiffers from the shell built-in 'cd' in that it starts COMMAND as a\nsubprocess rather than altering the shell's own working directory;\nthis allows it to be chained with other commands that run commands\nin a different context. For example:\n\n# Run 'true' with /chroot as its root directory and /srv as its working\n# directory.\nchroot /chroot env --chdir=/srv true\n# Run 'true' with /build as its working directory, FOO=bar in its\n# environment, and a time limit of five seconds.\nenv --chdir=/build FOO=bar timeout 5 true\n\n'--default-signal[=SIG]'\nUnblock and reset signal SIG to its default signal handler.\nWithout SIG all known signals are unblocked and reset to their\ndefaults. Multiple signals can be comma-separated. The following\ncommand runs 'seq' with SIGINT and SIGPIPE set to their default\n(which is to terminate the program):\n\nenv --default-signal=PIPE,INT seq 1000 | head -n1\n\nIn the following example, we see how this is not possible to do\nwith traditional shells. Here the first trap command sets SIGPIPE\nto ignore. The second trap command ostensibly sets it back to its\ndefault, but POSIX mandates that the shell must not change\ninherited state of the signal - so it is a no-op.\n\ntrap '' PIPE && sh -c 'trap - PIPE ; seq inf | head -n1'\n\nUsing '--default-signal=PIPE' we can ensure the signal handling is\nset to its default behavior:\n\ntrap '' PIPE && sh -c 'env --default-signal=PIPE seq inf | head -n1'\n\n'--ignore-signal[=SIG]'\nIgnore signal SIG when running a program. Without SIG all known\nsignals are set to ignore. Multiple signals can be\ncomma-separated. The following command runs 'seq' with SIGINT set\nto be ignored - pressing 'Ctrl-C' will not terminate it:\n\nenv --ignore-signal=INT seq inf > /dev/null\n\n'SIGCHLD' is special, in that '--ignore-signal=CHLD' might have no\neffect (POSIX says it's unspecified).\n\nMost operating systems do not allow ignoring 'SIGKILL', 'SIGSTOP'\n(and possibly other signals). Attempting to ignore these signals\nwill fail.\n\nMultiple (and contradictory) '--default-signal=SIG' and\n'--ignore-signal=SIG' options are processed left-to-right, with the\nlatter taking precedence. In the following example, 'SIGPIPE' is\nset to default while 'SIGINT' is ignored:\n\nenv --default-signal=INT,PIPE --ignore-signal=INT\n\n'--block-signal[=SIG]'\nBlock signal(s) SIG from being delivered.\n\n'--list-signal-handling'\nList blocked or ignored signals to stderr, before executing a\ncommand.\n\n'-v'\n'--debug'\nShow verbose information for each processing step.\n\n$ env -v -uTERM A=B uname -s\nunset: TERM\nsetenv: A=B\nexecuting: uname\narg[0]= 'uname'\narg[1]= '-s'\nLinux\n\nWhen combined with '-S' it is recommended to list '-v' first, e.g.\n'env -vS'string''.\n\n'-S STRING'\n'--split-string=STRING'\nprocess and split STRING into separate arguments used to pass\nmultiple arguments on shebang lines. 'env' supports FreeBSD's\nsyntax of several escape sequences and environment variable\nexpansions. See below for details and examples.\n\nExit status:\n\n0 if no COMMAND is specified and the environment is output\n125 if 'env' itself fails\n126 if COMMAND is found but cannot be invoked\n127 if COMMAND cannot be found\nthe exit status of COMMAND otherwise\n\n", "subsections": [] }, "The '-S'/'--split-string' options enable using multiple arguments on the": { "content": "first one of scripts (shebang line, '#!').\n\nWhen a script's interpreter is in a known location, scripts typically\ncontain the absolute file name in their first line:\n\nShell script: #!/bin/sh\necho hello\n\nPerl script: #!/usr/bin/perl\nprint \"hello\\n\";\n\nPython script: #!/usr/bin/python3\nprint(\"hello\")\n\n\nWhen a script's interpreter is in a non-standard location in the\n'PATH' environment variable, it is recommended to use 'env' on the first\nline of the script to find the executable and run it:\n\nShell script: #!/usr/bin/env bash\necho hello\n\nPerl script: #!/usr/bin/env perl\nprint \"hello\\n\";\n\nPython script: #!/usr/bin/env python3\nprint(\"hello\")\n\n\nMost operating systems (e.g. GNU/Linux, BSDs) treat all text after\nthe first space as a single argument. When using 'env' in a script it\nis thus not possible to specify multiple arguments.\n\nIn the following example:\n#!/usr/bin/env perl -T -w\nprint \"hello\\n\";\n\nThe operating system treats 'perl -T -w' as one argument (the\nprogram's name), and executing the script fails with:\n\n/usr/bin/env: 'perl -T -w': No such file or directory\n\nThe '-S' option instructs 'env' to split the single string into\nmultiple arguments. The following example works as expected:\n\n$ cat hello.pl\n#!/usr/bin/env -S perl -T -w\nprint \"hello\\n\";\n\n$ chmod a+x hello.pl\n$ ./hello.pl\nhello\n\nAnd is equivalent to running 'perl -T -w hello.pl' on the command\nline prompt.\n", "subsections": [] }, "Testing and troubleshooting": { "content": "...........................\n", "subsections": [] }, "To test 'env -S' on the command line, use single quotes for the '-S'": { "content": "string to emulate a single paramter. Single quotes are not needed when\nusing 'env -S' in a shebang line on the first line of a script (the\noperating system already treats it as one argument).\n\nThe following command is equivalent to the 'hello.pl' script above:\n\n$ env -S'perl -T -w' hello.pl\n\nTo troubleshoot '-S' usage add the '-v' as the first argument (before\n'-S').\n\nUsing '-vS' on a shebang line in a script:\n\n$ cat hello-debug.pl\n#!/usr/bin/env -vS perl -T -w\nprint \"hello\\n\";\n\n$ chmod a+x hello-debug.pl\n$ ./hello-debug.pl\nsplit -S: 'perl -T -w'\ninto: 'perl'\n& '-T'\n& '-w'\nexecuting: perl\narg[0]= 'perl'\narg[1]= '-T'\narg[2]= '-w'\narg[3]= './hello-debug.pl'\nhello\n\nUsing '-vS' on the command line prompt (adding single quotes):\n\n$ env -vS'perl -T -w' hello-debug.pl\nsplit -S: 'perl -T -w'\ninto: 'perl'\n& '-T'\n& '-w'\nexecuting: perl\narg[0]= 'perl'\narg[1]= '-T'\narg[2]= '-w'\narg[3]= 'hello-debug.pl'\nhello\n\n", "subsections": [] }, "Splitting arguments by whitespace": { "content": ".................................\n", "subsections": [] }, "Running 'env -Sstring' splits the STRING into arguments based on": { "content": "unquoted spaces or tab characters.\n\nIn the following contrived example the 'awk' variable 'OFS' will be\n'xyz' as these spaces are inside double quotes. The other\nspace characters are used as argument separators:\n\n$ cat one.awk\n#!/usr/bin/env -S awk -v OFS=\" xyz \" -f\nBEGIN {print 1,2,3}\n\n$ chmod a+x one.awk\n$ ./one.awk\n1 xyz 2 xyz 3\n\nWhen using '-S' on the command line prompt, remember to add single\nquotes around the entire string:\n\n$ env -S'awk -v OFS=\" xyz \" -f' one.awk\n1 xyz 2 xyz 3\n", "subsections": [] }, "Escape sequences": { "content": "................\n\n'env' supports several escape sequences. These sequences are processed\nwhen unquoted or inside double quotes (unless otherwise noted). Single\nquotes disable escape sequences except '\\'' and '\\\\'.\n\n'\\c' Ignore the remaining characters in the string. Cannot be used\ninside double quotes.\n\n'\\f' form-feed character (ASCII 0x0C)\n\n'\\n' new-line character (ASCII 0x0A)\n\n'\\r' carriage-return character (ASCII 0x0D)\n\n'\\t' tab character (ASCII 0x09)\n\n'\\v' vertical tab character (ASCII 0x0B)\n\n'\\#' A hash '#' character. Used when a '#' character is needed as\nthe first character of an argument (see 'comments' section\nbelow).\n\n'\\$' A dollar-sign character '$'. Unescaped '$' characters are used\nto expand environment variables (see 'variables' section\nbelow).\n\n'\\' Inside double-quotes, replaced with a single space character.\nOutside quotes, treated as an argument separator. '\\' can be\nused to avoid space characters in a shebang line (see examples\nbelow).\n\n'\\\"' A double-quote character.\n\n'\\'' A single-quote character. This escape sequence works inside\nsingle-quoted strings.\n\n'\\\\' A backslash character. This escape sequence works inside\nsingle-quoted strings.\n\n\nThe following 'awk' script will use tab character as input and output\nfield separator (instead of spaces and tabs):\n\n$ cat tabs.awk\n#!/usr/bin/env -S awk -v FS=\"\\t\" -v OFS=\"\\t\" -f\n...\n", "subsections": [] }, "Comments": { "content": "........\n\nThe escape sequence '\\c' (used outside single/double quotes) causes\n'env' to ignore the rest of the string.\n\nThe '#' character causes 'env' to ignore the rest of the string when\nit appears as the first character of an argument. Use '\\#' to reverse\nthis behavior.\n\n$ env -S'printf %s\\n A B C'\nA\nB\nC\n\n$ env -S'printf %s\\n A# B C'\nA#\nB\nC\n\n$ env -S'printf %s\\n A #B C'\nA\n\n$ env -S'printf %s\\n A \\#B C'\nA\n#B\nC\n\n$ env -S'printf %s\\n A\\cB C'\nA\n\nNOTE: The above examples use single quotes as they are executed on\nthe command-line.\n", "subsections": [] }, "Environment variable expansion": { "content": "..............................\n\nThe pattern '${VARNAME}' is used to substitute a value from the\nenvironment variable. The pattern must include the curly braces\n('{','}'). Without them 'env' will reject the string. Special shell\nvariables (such as '$@', '$*', '$$') are not supported.\n\nIf the environment variable is empty or not set, the pattern will be\nreplaced by an empty string. The value of '${VARNAME}' will be that of\nthe executed 'env', before any modifications using\n'-i'/'--ignore-environment'/'-u'/'--unset' or setting new values using\n'VAR=VALUE'.\n\nThe following python script prepends '/opt/custom/modules' to the\npython module search path environment variable ('PYTHONPATH'):\n\n$ cat custom.py\n#!/usr/bin/env -S PYTHONPATH=/opt/custom/modules/:${PYTHONPATH} python\nprint \"hello\"\n...\n\nThe expansion of '${PYTHONPATH}' is performed by 'env', not by a\nshell. If the curly braces are omitted, 'env' will fail:\n\n$ cat custom.py\n#!/usr/bin/env -S PYTHONPATH=/opt/custom/modules/:$PYTHONPATH python\nprint \"hello\"\n...\n\n$ chmod a+x custom.py\n$ custom.py\n/usr/bin/env: only ${VARNAME} expansion is supported, error at: $PYTHONPATH python\n\nEnvironment variable expansion happens before clearing the\nenvironment (with '-i') or unsetting specific variables (with '-u'):\n\n$ env -S'-i OLDUSER=${USER} env'\nOLDUSER=gordon\n\nUse '-v' to diagnose the operations step-by-step:\n\n$ env -vS'-i OLDUSER=${USER} env'\nexpanding ${USER} into 'gordon'\nsplit -S: '-i OLDUSER=${USER} env'\ninto: '-i'\n& 'OLDUSER=gordon'\n& 'env'\ncleaning environ\nsetenv: OLDUSER=gordon\nexecuting: env\narg[0]= 'env'\nOLDUSER=gordon\n", "subsections": [] }, "File: coreutils.info, Node: nice invocation, Next: nohup invocation, Prev: env invocation, Up: Modified command invocation": { "content": "", "subsections": [ { "name": "23.3 'nice': Run a command with modified niceness", "content": "'nice' prints a process's \"niceness\", or runs a command with modified\nniceness. \"niceness\" affects how favorably the process is scheduled in\nthe system. Synopsis:\n\nnice [OPTION]... [COMMAND [ARG]...]\n\nIf no arguments are given, 'nice' prints the current niceness." } ] }, "Otherwise, 'nice' runs the given COMMAND with its niceness adjusted. By": { "content": "default, its niceness is incremented by 10.\n\nNiceness values range at least from -20 (process has high priority\nand gets more resources, thus slowing down other processes) through 19\n(process has lower priority and runs slowly itself, but has less impact\non the speed of other running processes). Some systems may have a wider\nrange of niceness values; conversely, other systems may enforce more\nrestrictive limits. An attempt to set the niceness outside the\nsupported range is treated as an attempt to use the minimum or maximum\nsupported value.\n\nA niceness should not be confused with a scheduling priority, which\nlets applications determine the order in which threads are scheduled to\nrun. Unlike a priority, a niceness is merely advice to the scheduler,\nwhich the scheduler is free to ignore. Also, as a point of terminology,\nPOSIX defines the behavior of 'nice' in terms of a \"nice value\", which\nis the non-negative difference between a niceness and the minimum\nniceness. Though 'nice' conforms to POSIX, its documentation and\ndiagnostics use the term \"niceness\" for compatibility with historical\npractice.\n\nCOMMAND must not be a special built-in utility (*note Special\nbuilt-in utilities::).\n\nDue to shell aliases and built-in 'nice' functions, using an\nunadorned 'nice' interactively or in a script may get you different\nfunctionality than that described here. Invoke it via 'env' (i.e., 'env\nnice ...') to avoid interference from the shell.\n\nNote to change the \"niceness\" of an existing process, one needs to\nuse the 'renice' command.\n\nThe program accepts the following option. Also see *note Common\noptions::. Options must precede operands.\n\n'-n ADJUSTMENT'\n'--adjustment=ADJUSTMENT'\nAdd ADJUSTMENT instead of 10 to the command's niceness. If\nADJUSTMENT is negative and you lack appropriate privileges, 'nice'\nissues a warning but otherwise acts as if you specified a zero\nadjustment.\n\nFor compatibility 'nice' also supports an obsolete option syntax\n'-ADJUSTMENT'. New scripts should use '-n ADJUSTMENT' instead.\n\n'nice' is installed only on systems that have the POSIX 'setpriority'\nfunction, so portable scripts should not rely on its existence on\nnon-POSIX platforms.\n\nExit status:\n\n0 if no COMMAND is specified and the niceness is output\n125 if 'nice' itself fails\n126 if COMMAND is found but cannot be invoked\n127 if COMMAND cannot be found\nthe exit status of COMMAND otherwise\n\nIt is sometimes useful to run a non-interactive program with reduced\nniceness.\n\n$ nice factor 4611686018427387903\n\nSince 'nice' prints the current niceness, you can invoke it through\nitself to demonstrate how it works.\n\nThe default behavior is to increase the niceness by '10':\n\n$ nice\n0\n$ nice nice\n10\n$ nice -n 10 nice\n10\n\nThe ADJUSTMENT is relative to the current niceness. In the next\nexample, the first 'nice' invocation runs the second one with niceness\n10, and it in turn runs the final one with a niceness that is 3 more:\n\n$ nice nice -n 3 nice\n13\n\nSpecifying a niceness larger than the supported range is the same as\nspecifying the maximum supported value:\n\n$ nice -n 10000000000 nice\n19\n\nOnly a privileged user may run a process with lower niceness:\n\n$ nice -n -1 nice\nnice: cannot set niceness: Permission denied\n0\n$ sudo nice -n -1 nice\n-1\n", "subsections": [] }, "File: coreutils.info, Node: nohup invocation, Next: stdbuf invocation, Prev: nice invocation, Up: Modified command invocation": { "content": "", "subsections": [ { "name": "23.4 'nohup': Run a command immune to hangups", "content": "'nohup' runs the given COMMAND with hangup signals ignored, so that the\ncommand can continue running in the background after you log out.\nSynopsis:\n\nnohup COMMAND [ARG]...\n\nIf standard input is a terminal, redirect it so that terminal\nsessions do not mistakenly consider the terminal to be used by the\ncommand. Make the substitute file descriptor unreadable, so that\ncommands that mistakenly attempt to read from standard input can report\nan error. This redirection is a GNU extension; programs intended to be\nportable to non-GNU hosts can use 'nohup COMMAND [ARG]... 0>/dev/null'\ninstead.\n\nIf standard output is a terminal, the command's standard output is\nappended to the file 'nohup.out'; if that cannot be written to, it is\nappended to the file '$HOME/nohup.out'; and if that cannot be written\nto, the command is not run. Any 'nohup.out' or '$HOME/nohup.out' file\ncreated by 'nohup' is made readable and writable only to the user,\nregardless of the current umask settings.\n\nIf standard error is a terminal, it is normally redirected to the\nsame file descriptor as the (possibly-redirected) standard output." } ] }, "However, if standard output is closed, standard error terminal output is": { "content": "instead appended to the file 'nohup.out' or '$HOME/nohup.out' as above.\n\nTo capture the command's output to a file other than 'nohup.out' you\ncan redirect it. For example, to capture the output of 'make':\n\nnohup make > make.log\n\n'nohup' does not automatically put the command it runs in the\nbackground; you must do that explicitly, by ending the command line with\nan '&'. Also, 'nohup' does not alter the niceness of COMMAND; use\n'nice' for that, e.g., 'nohup nice COMMAND'.\n\nCOMMAND must not be a special built-in utility (*note Special\nbuilt-in utilities::).\n\nThe only options are '--help' and '--version'. *Note Common\noptions::. Options must precede operands.\n\nExit status:\n\n125 if 'nohup' itself fails, and 'POSIXLYCORRECT' is not set\n126 if COMMAND is found but cannot be invoked\n127 if COMMAND cannot be found\nthe exit status of COMMAND otherwise\n\nIf 'POSIXLYCORRECT' is set, internal failures give status 127\ninstead of 125.\n", "subsections": [] }, "File: coreutils.info, Node: stdbuf invocation, Next: timeout invocation, Prev: nohup invocation, Up: Modified command invocation": { "content": "", "subsections": [ { "name": "23.5 'stdbuf': Run a command with modified I/O stream buffering", "content": "'stdbuf' allows one to modify the buffering operations of the three\nstandard I/O streams associated with a program. Synopsis:\n\nstdbuf OPTION... COMMAND\n\nCOMMAND must start with the name of a program that\n1. uses the ISO C 'FILE' streams for input/output (note the programs\n'dd' and 'cat' don't do that),\n\n2. does not adjust the buffering of its standard streams (note the\nprogram 'tee' is not in this category).\n\nAny additional ARGs are passed as additional arguments to the\nCOMMAND.\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'-i MODE'\n'--input=MODE'\nAdjust the standard input stream buffering.\n\n'-o MODE'\n'--output=MODE'\nAdjust the standard output stream buffering.\n\n'-e MODE'\n'--error=MODE'\nAdjust the standard error stream buffering.\n\nThe MODE can be specified as follows:\n\n'L'\nSet the stream to line buffered mode. In this mode data is\ncoalesced until a newline is output or input is read from any\nstream attached to a terminal device. This option is invalid with\nstandard input.\n\n'0'\nDisable buffering of the selected stream. In this mode, data is\noutput immediately and only the amount of data requested is read\nfrom input. Note the difference in function for input and output.\nDisabling buffering for input will not influence the responsiveness\nor blocking behavior of the stream input functions. For example\n'fread' will still block until 'EOF' or error, even if the\nunderlying 'read' returns less data than requested.\n\n'SIZE'\nSpecify the size of the buffer to use in fully buffered mode. SIZE\nmay be, or may be an integer optionally followed by, one of the\nfollowing multiplicative suffixes:\n'KB' => 1000 (KiloBytes)\n'K' => 1024 (KibiBytes)\n'MB' => 1000*1000 (MegaBytes)\n'M' => 1024*1024 (MebiBytes)\n'GB' => 1000*1000*1000 (GigaBytes)\n'G' => 1024*1024*1024 (GibiBytes)\nand so on for 'T', 'P', 'E', 'Z', and 'Y'. Binary prefixes can be\nused, too: 'KiB'='K', 'MiB'='M', and so on.\n\n'stdbuf' is installed only on platforms that use the Executable and" } ] }, "Linkable Format (ELF) and support the 'constructor' attribute, so": { "content": "portable scripts should not rely on its existence.\n\nExit status:\n\n125 if 'stdbuf' itself fails\n126 if COMMAND is found but cannot be invoked\n127 if COMMAND cannot be found\nthe exit status of COMMAND otherwise\n", "subsections": [] }, "File: coreutils.info, Node: timeout invocation, Prev: stdbuf invocation, Up: Modified command invocation": { "content": "", "subsections": [ { "name": "23.6 'timeout': Run a command with a time limit", "content": "'timeout' runs the given COMMAND and kills it if it is still running\nafter the specified time interval. Synopsis:\n\ntimeout [OPTION] DURATION COMMAND [ARG]...\n\nCOMMAND must not be a special built-in utility (*note Special\nbuilt-in utilities::).\n\nThe program accepts the following options. Also see *note Common\noptions::. Options must precede operands.\n\n'--preserve-status'\nReturn the exit status of the managed COMMAND on timeout, rather\nthan a specific exit status indicating a timeout. This is useful\nif the managed COMMAND supports running for an indeterminate amount\nof time.\n\n'--foreground'\nDon't create a separate background program group, so that the\nmanaged COMMAND can use the foreground TTY normally. This is\nneeded to support timing out commands not started directly from an\ninteractive shell, in two situations.\n1. COMMAND is interactive and needs to read from the terminal for\nexample\n2. the user wants to support sending signals directly to COMMAND\nfrom the terminal (like Ctrl-C for example)\n\nNote in this mode of operation, any children of COMMAND will not be\ntimed out. Also SIGCONT will not be sent to COMMAND, as it's\ngenerally not needed with foreground processes, and can cause\nintermittent signal delivery issues with programs that are monitors\nthemselves (like GDB for example).\n\n'-k DURATION'\n'--kill-after=DURATION'\nEnsure the monitored COMMAND is killed by also sending a 'KILL'\nsignal, after the specified DURATION. Without this option, if the\nselected signal proves not to be fatal, 'timeout' does not kill the\nCOMMAND.\n\n'-s SIGNAL'\n'--signal=SIGNAL'\nSend this SIGNAL to COMMAND on timeout, rather than the default\n'TERM' signal. SIGNAL may be a name like 'HUP' or a number. *Note\nSignal specifications::.\n\n'-v'\n'--verbose'\nDiagnose to stderr, any signal sent upon timeout.\n\nDURATION is a floating point number in either the current or the C\nlocale (*note Floating point::) followed by an optional unit:\n's' for seconds (the default)\n'm' for minutes\n'h' for hours\n'd' for days\nA duration of 0 disables the associated timeout. Note that the\nactual timeout duration is dependent on system conditions, which should\nbe especially considered when specifying sub-second timeouts.\n\nExit status:\n\n124 if COMMAND times out\n125 if 'timeout' itself fails\n126 if COMMAND is found but cannot be invoked\n127 if COMMAND cannot be found\n137 if COMMAND is sent the KILL(9) signal (128+9)\nthe exit status of COMMAND otherwise\n" } ] }, "File: coreutils.info, Node: Process control, Next: Delaying, Prev: Modified command invocation, Up: Top": { "content": "", "subsections": [] }, "24 Process control": { "content": "* Menu:\n\n* kill invocation:: Sending a signal to processes.\n", "subsections": [] }, "File: coreutils.info, Node: kill invocation, Up: Process control": { "content": "", "subsections": [ { "name": "24.1 'kill': Send a signal to processes", "content": "" } ] }, "The 'kill' command sends a signal to processes, causing them to": { "content": "terminate or otherwise act upon receiving the signal in some way.\nAlternatively, it lists information about signals. Synopses:\n\nkill [-s SIGNAL | --signal SIGNAL | -SIGNAL] PID...\nkill [-l | --list | -t | --table] [SIGNAL]...\n\nDue to shell aliases and built-in 'kill' functions, using an\nunadorned 'kill' interactively or in a script may get you different\nfunctionality than that described here. Invoke it via 'env' (i.e., 'env\nkill ...') to avoid interference from the shell.\n\nThe first form of the 'kill' command sends a signal to all PID\narguments. The default signal to send if none is specified is 'TERM'.", "subsections": [] }, "The special signal number '0' does not denote a valid signal, but can be": { "content": "used to test whether the PID arguments specify processes to which a\nsignal could be sent.\n\nIf PID is positive, the signal is sent to the process with the\nprocess ID PID. If PID is zero, the signal is sent to all processes in\nthe process group of the current process. If PID is -1, the signal is\nsent to all processes for which the user has permission to send a\nsignal. If PID is less than -1, the signal is sent to all processes in\nthe process group that equals the absolute value of PID.\n\nIf PID is not positive, a system-dependent set of system processes is\nexcluded from the list of processes to which the signal is sent.\n\nIf a negative PID argument is desired as the first one, it should be\npreceded by '--'. However, as a common extension to POSIX, '--' is not\nrequired with 'kill -SIGNAL -PID'. The following commands are\nequivalent:\n\nkill -15 -1\nkill -TERM -1\nkill -s TERM -- -1\nkill -- -1\n\nThe first form of the 'kill' command succeeds if every PID argument\nspecifies at least one process that the signal was sent to.\n\nThe second form of the 'kill' command lists signal information.", "subsections": [] }, "Either the '-l' or '--list' option, or the '-t' or '--table' option must": { "content": "be specified. Without any SIGNAL argument, all supported signals are\nlisted. The output of '-l' or '--list' is a list of the signal names,\none per line; if SIGNAL is already a name, the signal number is printed\ninstead. The output of '-t' or '--table' is a table of signal numbers,\nnames, and descriptions. This form of the 'kill' command succeeds if\nall SIGNAL arguments are valid and if there is no output error.\n\nThe 'kill' command also supports the '--help' and '--version'\noptions. *Note Common options::.\n\nA SIGNAL may be a signal name like 'HUP', or a signal number like\n'1', or an exit status of a process terminated by the signal. A signal\nname can be given in canonical form or prefixed by 'SIG'. The case of\nthe letters is ignored, except for the '-SIGNAL' option which must use\nupper case to avoid ambiguity with lower case option letters. *Note", "subsections": [] }, "Signal specifications::, for a list of supported signal names and": { "content": "numbers.\n", "subsections": [] }, "File: coreutils.info, Node: Delaying, Next: Numeric operations, Prev: Process control, Up: Top": { "content": "", "subsections": [] }, "25 Delaying": { "content": "* Menu:\n\n* sleep invocation:: Delay for a specified time.\n", "subsections": [] }, "File: coreutils.info, Node: sleep invocation, Up: Delaying": { "content": "", "subsections": [ { "name": "25.1 'sleep': Delay for a specified time", "content": "'sleep' pauses for an amount of time specified by the sum of the values\nof the command line arguments. Synopsis:\n\nsleep NUMBER[smhd]...\n\nEach argument is a non-negative number followed by an optional unit;\nthe default is seconds. The units are:\n\n's'\nseconds\n'm'\nminutes\n'h'\nhours\n'd'\ndays\n\nAlthough portable POSIX scripts must give 'sleep' a single\nnon-negative integer argument without a suffix, GNU 'sleep' also accepts\ntwo or more arguments, unit suffixes, and floating-point numbers in\neither the current or the C locale. *Note Floating point::.\n\nFor instance, the following could be used to 'sleep' for 1 second,\n234 milli-, 567 micro- and 890 nanoseconds:\n\nsleep 1234e-3 567.89e-6\n\nThe only options are '--help' and '--version'. *Note Common\noptions::.\n\nDue to shell aliases and built-in 'sleep' functions, using an\nunadorned 'sleep' interactively or in a script may get you different\nfunctionality than that described here. Invoke it via 'env' (i.e., 'env\nsleep ...') to avoid interference from the shell.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: Numeric operations, Next: File permissions, Prev: Delaying, Up: Top": { "content": "", "subsections": [] }, "26 Numeric operations": { "content": "These programs do numerically-related operations.\n\n* Menu:\n\n* factor invocation:: Show factors of numbers.\n* numfmt invocation:: Reformat numbers.\n* seq invocation:: Print sequences of numbers.\n", "subsections": [] }, "File: coreutils.info, Node: factor invocation, Next: numfmt invocation, Up: Numeric operations": { "content": "", "subsections": [ { "name": "26.1 'factor': Print prime factors", "content": "'factor' prints prime factors. Synopses:\n\nfactor [NUMBER]...\nfactor OPTION\n\nIf no NUMBER is specified on the command line, 'factor' reads numbers\nfrom standard input, delimited by newlines, tabs, or spaces.\n\nThe 'factor' command supports only a small number of options:\n\n'--help'\nPrint a short help on standard output, then exit without further\nprocessing.\n\n'--version'\nPrint the program version on standard output, then exit without\nfurther processing.\n\nFactoring the product of the eighth and ninth Mersenne primes takes\nabout 30 milliseconds of CPU time on a 2.2 GHz Athlon.\n\nM8=$(echo 2^31-1|bc)\nM9=$(echo 2^61-1|bc)\nn=$(echo \"$M8 * $M9\" | bc)\n/usr/bin/time -f %U factor $n\n4951760154835678088235319297: 2147483647 2305843009213693951\n0.03\n\nSimilarly, factoring the eighth Fermat number 2^{256}+1 takes about\n20 seconds on the same machine.\n\nFactoring large numbers is, in general, hard. The Pollard-Brent rho\nalgorithm used by 'factor' is particularly effective for numbers with\nrelatively small factors. If you wish to factor large numbers which do\nnot have small factors (for example, numbers which are the product of\ntwo large primes), other methods are far better.\n\nIf 'factor' is built without using GNU MP, only single-precision\narithmetic is available, and so large numbers (typically 2^{128} and\nabove) will not be supported. The single-precision code uses an\nalgorithm which is designed for factoring smaller numbers.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: numfmt invocation, Next: seq invocation, Prev: factor invocation, Up: Numeric operations": { "content": "", "subsections": [ { "name": "26.2 'numfmt': Reformat numbers", "content": "'numfmt' reads numbers in various representations and reformats them as\nrequested. The most common usage is converting numbers to/from human\nrepresentation (e.g. '4G' ==> '4,000,000,000').\n\nnumfmt [OPTION]... [NUMBER]\n\n'numfmt' converts each NUMBER on the command-line according to the\nspecified options (see below). If no NUMBERs are given, it reads\nnumbers from standard input. 'numfmt' can optionally extract numbers\nfrom specific columns, maintaining proper line padding and alignment.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n\nSee '--invalid' for additional information regarding exit status.\n\n\nThe program accepts the following options. Also see *note Common\noptions::.\n\n'--debug'\nPrint (to standard error) warning messages about possible erroneous\nusage.\n\n'-d D'\n'--delimiter=D'\nUse the character D as input field separator (default: whitespace).\nNote: Using non-default delimiter turns off automatic padding.\n\n'--field=FIELDS'\nConvert the number in input field FIELDS (default: 1). FIELDS\nsupports 'cut' style field ranges:\n\nN N'th field, counted from 1\nN- from N'th field, to end of line\nN-M from N'th to M'th field (inclusive)\n-M from first to M'th field (inclusive)\n- all fields\n\n'--format=FORMAT'\nUse printf-style floating FORMAT string. The FORMAT string must\ncontain one '%f' directive, optionally with ''', '-', '0', width or\nprecision modifiers. The ''' modifier will enable '--grouping',\nthe '-' modifier will enable left-aligned '--padding' and the width\nmodifier will enable right-aligned '--padding'. The '0' width\nmodifier (without the '-' modifier) will generate leading zeros on\nthe number, up to the specified width. A precision specification\nlike '%.1f' will override the precision determined from the input\ndata or set due to '--to' option auto scaling.\n\n'--from=UNIT'\nAuto-scales input numbers according to UNIT. See UNITS below. The\ndefault is no scaling, meaning suffixes (e.g. 'M', 'G') will\ntrigger an error.\n\n'--from-unit=N'\nSpecify the input unit size (instead of the default 1). Use this\noption when the input numbers represent other units (e.g. if the\ninput number '10' represents 10 units of 512 bytes, use\n'--from-unit=512'). Suffixes are handled as with '--from=auto'.\n\n'--grouping'\nGroup digits in output numbers according to the current locale's\ngrouping rules (e.g Thousands Separator character, commonly '.'\n(dot) or ',' comma). This option has no effect in 'POSIX/C'\nlocale.\n\n'--header[=N]'\nPrint the first N (default: 1) lines without any conversion.\n\n'--invalid=MODE'\nThe default action on input errors is to exit immediately with\nstatus code 2. '--invalid='abort'' explicitly specifies this\ndefault mode. With a MODE of 'fail', print a warning for each\nconversion error, and exit with status 2. With a MODE of 'warn',\nexit with status 0, even in the presence of conversion errors, and\nwith a MODE of 'ignore' do not even print diagnostics.\n\n'--padding=N'\nPad the output numbers to N characters, by adding spaces. If N is\na positive number, numbers will be right-aligned. If N is a\nnegative number, numbers will be left-aligned. By default, numbers\nare automatically aligned based on the input line's width (only\nwith the default delimiter).\n\n'--round=METHOD'\nWhen converting number representations, round the number according\nto METHOD, which can be 'up', 'down', 'from-zero' (the default),\n'towards-zero', 'nearest'.\n\n'--suffix=SUFFIX'\nAdd 'SUFFIX' to the output numbers, and accept optional 'SUFFIX' in\ninput numbers.\n\n'--to=UNIT'\nAuto-scales output numbers according to UNIT. See Units below.\nThe default is no scaling, meaning all the digits of the number are\nprinted.\n\n'--to-unit=N'\nSpecify the output unit size (instead of the default 1). Use this\noption when the output numbers represent other units (e.g. to\nrepresent '4,000,000' bytes in blocks of 1KB, use '--to=si\n--to-unit=1000'). Suffixes are handled as with '--from=auto'.\n\n'-z'\n'--zero-terminated'\nDelimit items with a zero byte rather than a newline (ASCII LF).\nI.e., treat input as items separated by ASCII NUL and terminate\noutput items with ASCII NUL. This option can be useful in\nconjunction with 'perl -0' or 'find -print0' and 'xargs -0' which\ndo the same in order to reliably handle arbitrary file names (even\nthose containing blanks or other special characters). Note with\n'-z' the newline character is treated as a field separator.\n\n\nThe following are the possible UNIT options with '--from=UNITS' and\n'--to=UNITS':\n" } ] }, "NONE": { "content": "No scaling is performed. For input numbers, no suffixes are\naccepted, and any trailing characters following the number will\ntrigger an error. For output numbers, all digits of the numbers\nwill be printed.\n\nSI\nAuto-scale numbers according to the International System of Units\n(SI) standard. For input numbers, accept one of the following\nsuffixes. For output numbers, values larger than 1000 will be\nrounded, and printed with one of the following suffixes:\n\n'K' => 1000^1 = 10^3 (Kilo)\n'M' => 1000^2 = 10^6 (Mega)\n'G' => 1000^3 = 10^9 (Giga)\n'T' => 1000^4 = 10^{12} (Tera)\n'P' => 1000^5 = 10^{15} (Peta)\n'E' => 1000^6 = 10^{18} (Exa)\n'Z' => 1000^7 = 10^{21} (Zetta)\n'Y' => 1000^8 = 10^{24} (Yotta)\n", "subsections": [] }, "IEC": { "content": "Auto-scale numbers according to the International Electrotechnical\nCommission (IEC) standard. For input numbers, accept one of the\nfollowing suffixes. For output numbers, values larger than 1024\nwill be rounded, and printed with one of the following suffixes:\n\n'K' => 1024^1 = 2^{10} (Kibi)\n'M' => 1024^2 = 2^{20} (Mebi)\n'G' => 1024^3 = 2^{30} (Gibi)\n'T' => 1024^4 = 2^{40} (Tebi)\n'P' => 1024^5 = 2^{50} (Pebi)\n'E' => 1024^6 = 2^{60} (Exbi)\n'Z' => 1024^7 = 2^{70} (Zebi)\n'Y' => 1024^8 = 2^{80} (Yobi)\n\nThe 'iec' option uses a single letter suffix (e.g. 'G'), which is\nnot fully standard, as the iec standard recommends a two-letter\nsymbol (e.g 'Gi') - but in practice, this method common. Compare\nwith the 'iec-i' option.\n", "subsections": [] }, "IEC-I": { "content": "Auto-scale numbers according to the International Electrotechnical\nCommission (IEC) standard. For input numbers, accept one of the\nfollowing suffixes. For output numbers, values larger than 1024\nwill be rounded, and printed with one of the following suffixes:\n\n'Ki' => 1024^1 = 2^{10} (Kibi)\n'Mi' => 1024^2 = 2^{20} (Mebi)\n'Gi' => 1024^3 = 2^{30} (Gibi)\n'Ti' => 1024^4 = 2^{40} (Tebi)\n'Pi' => 1024^5 = 2^{50} (Pebi)\n'Ei' => 1024^6 = 2^{60} (Exbi)\n'Zi' => 1024^7 = 2^{70} (Zebi)\n'Yi' => 1024^8 = 2^{80} (Yobi)\n\nThe 'iec-i' option uses a two-letter suffix symbol (e.g. 'Gi'), as\nthe iec standard recommends, but this is not always common in\npractice. Compare with the 'iec' option.\n", "subsections": [] }, "AUTO": { "content": "'auto' can only be used with '--from'. With this method, numbers\nwith 'K','M','G','T','P','E','Z','Y' suffixes are interpreted as\nSI values, and numbers with 'Ki',\n'Mi','Gi','Ti','Pi','Ei','Zi','Yi' suffixes are interpreted as\nIEC values.\n\n\nConverting a single number from/to human representation:\n$ numfmt --to=si 500000\n500K\n\n$ numfmt --to=iec 500000\n489K\n\n$ numfmt --to=iec-i 500000\n489Ki\n\n$ numfmt --from=si 1M\n1000000\n\n$ numfmt --from=iec 1M\n1048576\n\n# with '--from=auto', M=Mega, Mi=Mebi\n$ numfmt --from=auto 1M\n1000000\n$ numfmt --from=auto 1Mi\n1048576\n\nConverting from 'SI' to 'IEC' scales (e.g. when a harddisk capacity\nis advertised as '1TB', while checking the drive's capacity gives lower\nvalues):\n\n$ numfmt --from=si --to=iec 1T\n932G\n\nConverting a single field from an input file / piped input (these\ncontrived examples are for demonstration purposes only, as both 'ls' and\n'df' support the '--human-readable' option to output sizes in\nhuman-readable format):\n\n# Third field (file size) will be shown in SI representation\n$ ls -log | numfmt --field 3 --header --to=si | head -n4\n-rw-r--r-- 1 94K Aug 23 2011 ABOUT-NLS\n-rw-r--r-- 1 3.7K Jan 7 16:15 AUTHORS\n-rw-r--r-- 1 36K Jun 1 2011 COPYING\n-rw-r--r-- 1 0 Jan 7 15:15 ChangeLog\n\n# Second field (size) will be shown in IEC representation\n$ df --block-size=1 | numfmt --field 2 --header --to=iec | head -n4\nFile system 1B-blocks Used Available Use% Mounted on\nrootfs 132G 104741408 26554036 80% /\ntmpfs 794M 7580 804960 1% /run/shm\n/dev/sdb1 694G 651424756 46074696 94% /home\n\nOutput can be tweaked using '--padding' or '--format':\n\n# Pad to 10 characters, right-aligned\n$ du -s * | numfmt --to=si --padding=10\n2.5K config.log\n108 config.status\n1.7K configure\n20 configure.ac\n\n# Pad to 10 characters, left-aligned\n$ du -s * | numfmt --to=si --padding=-10\n2.5K config.log\n108 config.status\n1.7K configure\n20 configure.ac\n\n# Pad to 10 characters, left-aligned, using 'format'\n$ du -s * | numfmt --to=si --format=\"%10f\"\n2.5K config.log\n108 config.status\n1.7K configure\n20 configure.ac\n\n# Pad to 10 characters, left-aligned, using 'format'\n$ du -s * | numfmt --to=si --padding=\"%-10f\"\n2.5K config.log\n108 config.status\n1.7K configure\n20 configure.ac\n\nWith locales that support grouping digits, using '--grouping' or\n'--format' enables grouping. In 'POSIX' locale, grouping is silently\nignored:\n\n$ LCALL=C numfmt --from=iec --grouping 2G\n2147483648\n\n$ LCALL=enUS.utf8 numfmt --from=iec --grouping 2G\n2,147,483,648\n\n$ LCALL=taIN numfmt --from=iec --grouping 2G\n2,14,74,83,648\n\n$ LCALL=C ./src/numfmt --from=iec --format=\"==%'15f==\" 2G\n== 2147483648==\n\n$ LCALL=enUS.utf8 ./src/numfmt --from=iec --format=\"==%'15f==\" 2G\n== 2,147,483,648==\n\n$ LCALL=enUS.utf8 ./src/numfmt --from=iec --format=\"==%'-15f==\" 2G\n==2,147,483,648 ==\n\n$ LCALL=taIN ./src/numfmt --from=iec --format=\"==%'15f==\" 2G\n== 2,14,74,83,648==\n", "subsections": [] }, "File: coreutils.info, Node: seq invocation, Prev: numfmt invocation, Up: Numeric operations": { "content": "", "subsections": [ { "name": "26.3 'seq': Print numeric sequences", "content": "'seq' prints a sequence of numbers to standard output. Synopses:\n\nseq [OPTION]... LAST\nseq [OPTION]... FIRST LAST\nseq [OPTION]... FIRST INCREMENT LAST\n\n'seq' prints the numbers from FIRST to LAST by INCREMENT. By\ndefault, each number is printed on a separate line. When INCREMENT is\nnot specified, it defaults to '1', even when FIRST is larger than LAST.\nFIRST also defaults to '1'. So 'seq 1' prints '1', but 'seq 0' and 'seq\n10 5' produce no output. The sequence of numbers ends when the sum of\nthe current number and INCREMENT would become greater than LAST, so 'seq\n1 10 10' only produces '1'. INCREMENT must not be '0'; use the tool\n'yes' to get repeated output of a constant number. FIRST, INCREMENT and\nLAST must not be 'NaN'. Floating-point numbers may be specified in\neither the current or the C locale. *Note Floating point::.\n\nThe program accepts the following options. Also see *note Common\noptions::. Options must precede operands.\n\n'-f FORMAT'\n'--format=FORMAT'\nPrint all numbers using FORMAT. FORMAT must contain exactly one of\nthe 'printf'-style floating point conversion specifications '%a',\n'%e', '%f', '%g', '%A', '%E', '%F', '%G'. The '%' may be followed\nby zero or more flags taken from the set '-+#0 '', then an optional\nwidth containing one or more digits, then an optional precision\nconsisting of a '.' followed by zero or more digits. FORMAT may\nalso contain any number of '%%' conversion specifications. All\nconversion specifications have the same meaning as with 'printf'.\n\nThe default format is derived from FIRST, STEP, and LAST. If these\nall use a fixed point decimal representation, the default format is\n'%.Pf', where P is the minimum precision that can represent the\noutput numbers exactly. Otherwise, the default format is '%g'.\n\n'-s STRING'\n'--separator=STRING'\nSeparate numbers with STRING; default is a newline. The output\nalways terminates with a newline.\n\n'-w'\n'--equal-width'\nPrint all numbers with the same width, by padding with leading\nzeros. FIRST, STEP, and LAST should all use a fixed point decimal\nrepresentation. (To have other kinds of padding, use '--format').\n\nYou can get finer-grained control over output with '-f':\n\n$ seq -f '(%9.2E)' -9e5 1.1e6 1.3e6\n(-9.00E+05)\n( 2.00E+05)\n( 1.30E+06)\n\nIf you want hexadecimal integer output, you can use 'printf' to\nperform the conversion:\n\n$ printf '%x\\n' $(seq 1048575 1024 1050623)\nfffff\n1003ff\n1007ff\n\nFor very long lists of numbers, use xargs to avoid system limitations\non the length of an argument list:\n\n$ seq 1000000 | xargs printf '%x\\n' | tail -n 3\nf423e\nf423f\nf4240\n\nTo generate octal output, use the printf '%o' format instead of '%x'.\n\nOn most systems, seq can produce whole-number output for values up to\nat least 2^{53}. Larger integers are approximated. The details differ\ndepending on your floating-point implementation. *Note Floating\npoint::. A common case is that 'seq' works with integers through\n2^{64}, and larger integers may not be numerically correct:\n\n$ seq 50000000000000000000 2 50000000000000000004\n50000000000000000000\n50000000000000000000\n50000000000000000004\n\nHowever, note that when limited to non-negative whole numbers, an\nincrement of 1 and no format-specifying option, seq can print\narbitrarily large numbers.\n\nBe careful when using 'seq' with outlandish values: otherwise you may\nsee surprising results, as 'seq' uses floating point internally. For\nexample, on the x86 platform, where the internal representation uses a\n64-bit fraction, the command:\n\nseq 1 0.0000000000000000001 1.0000000000000000009\n\noutputs 1.0000000000000000007 twice and skips 1.0000000000000000008.\n\nAn exit status of zero indicates success, and a nonzero value\nindicates failure.\n" } ] }, "File: coreutils.info, Node: File permissions, Next: File timestamps, Prev: Numeric operations, Up: Top": { "content": "", "subsections": [] }, "27 File permissions": { "content": "Each file has a set of \"file mode bits\" that control the kinds of access\nthat users have to that file. They can be represented either in\nsymbolic form or as an octal number.\n\n* Menu:\n\n* Mode Structure:: Structure of file mode bits.\n* Symbolic Modes:: Mnemonic representation of file mode bits.\n* Numeric Modes:: File mode bits as octal numbers.\n* Operator Numeric Modes:: ANDing, ORing, and setting modes octally.\n* Directory Setuid and Setgid:: Set-user-ID and set-group-ID on directories.\n", "subsections": [] }, "File: coreutils.info, Node: Mode Structure, Next: Symbolic Modes, Up: File permissions": { "content": "", "subsections": [ { "name": "27.1 Structure of File Mode Bits", "content": "The file mode bits have two parts: the \"file permission bits\", which\ncontrol ordinary access to the file, and \"special mode bits\", which\naffect only some files.\n\nThere are three kinds of permissions that a user can have for a file:\n\n1. permission to read the file. For directories, this means\npermission to list the contents of the directory.\n2. permission to write to (change) the file. For directories, this\nmeans permission to create and remove files in the directory.\n3. permission to execute the file (run it as a program). For\ndirectories, this means permission to access files in the\ndirectory.\n\nThere are three categories of users who may have different\npermissions to perform any of the above operations on a file:\n\n1. the file's owner;\n2. other users who are in the file's group;\n3. everyone else.\n\nFiles are given an owner and group when they are created. Usually\nthe owner is the current user and the group is the group of the\ndirectory the file is in, but this varies with the operating system, the\nfile system the file is created on, and the way the file is created." } ] }, "You can change the owner and group of a file by using the 'chown' and": { "content": "'chgrp' commands.\n\nIn addition to the three sets of three permissions listed above, the\nfile mode bits have three special components, which affect only\nexecutable files (programs) and, on most systems, directories:\n\nThe \"set-user-ID bit\" (\"setuid bit\").\nOn execution, set the process's effective user ID to that of the\nfile. For directories on a few systems, give files created in the\ndirectory the same owner as the directory, no matter who creates\nthem, and set the set-user-ID bit of newly-created subdirectories.\n\nThe \"set-group-ID bit\" (\"setgid bit\").\nOn execution, set the process's effective group ID to that of the\nfile. For directories on most systems, give files created in the\ndirectory the same group as the directory, no matter what group the\nuser who creates them is in, and set the set-group-ID bit of\nnewly-created subdirectories.\n\nThe \"restricted deletion flag\" or \"sticky bit\".\nPrevent unprivileged users from removing or renaming a file in a\ndirectory unless they own the file or the directory; this is\ncommonly found on world-writable directories like '/tmp'. For\nregular files on some older systems, save the program's text image\non the swap device so it will load more quickly when run, so that\nthe image is \"sticky\".\n\nIn addition to the file mode bits listed above, there may be file\nattributes specific to the file system, e.g., access control lists\n(ACLs), whether a file is compressed, whether a file can be modified\n(immutability), and whether a file can be dumped. These are usually set\nusing programs specific to the file system. For example:\n\next2\nOn GNU and GNU/Linux the file attributes specific to the ext2 file\nsystem are set using 'chattr'.\n", "subsections": [] }, "FFS": { "content": "On FreeBSD the file flags specific to the FFS file system are set\nusing 'chflags'.\n\nEven if a file's mode bits allow an operation on that file, that\noperation may still fail, because:\n\n* the file-system-specific attributes or flags do not permit it; or\n\n* the file system is mounted as read-only.\n\nFor example, if the immutable attribute is set on a file, it cannot\nbe modified, regardless of the fact that you may have just run 'chmod\na+w FILE'.\n", "subsections": [] }, "File: coreutils.info, Node: Symbolic Modes, Next: Numeric Modes, Prev: Mode Structure, Up: File permissions": { "content": "", "subsections": [ { "name": "27.2 Symbolic Modes", "content": "\"Symbolic modes\" represent changes to files' mode bits as operations on\nsingle-character symbols. They allow you to modify either all or\nselected parts of files' mode bits, optionally based on their previous\nvalues, and perhaps on the current 'umask' as well (*note Umask and\nProtection::).\n\nThe format of symbolic modes is:\n\n[ugoa...][-+=]PERMS...[,...]\n\nwhere PERMS is either zero or more letters from the set 'rwxXst', or a\nsingle letter from the set 'ugo'.\n\nThe following sections describe the operators and other details of\nsymbolic modes.\n\n* Menu:\n\n* Setting Permissions:: Basic operations on permissions.\n* Copying Permissions:: Copying existing permissions.\n* Changing Special Mode Bits:: Special mode bits.\n* Conditional Executability:: Conditionally affecting executability.\n* Multiple Changes:: Making multiple changes.\n* Umask and Protection:: The effect of the umask.\n" } ] }, "File: coreutils.info, Node: Setting Permissions, Next: Copying Permissions, Up: Symbolic Modes": { "content": "", "subsections": [] }, "The basic symbolic operations on a file's permissions are adding,": { "content": "removing, and setting the permission that certain users have to read,\nwrite, and execute or search the file. These operations have the\nfollowing format:\n\nUSERS OPERATION PERMISSIONS\n", "subsections": [] }, "The spaces between the three parts above are shown for readability only;": { "content": "symbolic modes cannot contain spaces.\n\nThe USERS part tells which users' access to the file is changed. It\nconsists of one or more of the following letters (or it can be empty;\n*note Umask and Protection::, for a description of what happens then).", "subsections": [] }, "When more than one of these letters is given, the order that they are in": { "content": "does not matter.\n\n'u'\nthe user who owns the file;\n'g'\nother users who are in the file's group;\n'o'\nall other users;\n'a'\nall users; the same as 'ugo'.\n\nThe OPERATION part tells how to change the affected users' access to\nthe file, and is one of the following symbols:\n\n'+'\nto add the PERMISSIONS to whatever permissions the USERS already\nhave for the file;\n'-'\nto remove the PERMISSIONS from whatever permissions the USERS\nalready have for the file;\n'='\nto make the PERMISSIONS the only permissions that the USERS have\nfor the file.\n\nThe PERMISSIONS part tells what kind of access to the file should be\nchanged; it is normally zero or more of the following letters. As with\nthe USERS part, the order does not matter when more than one letter is\ngiven. Omitting the PERMISSIONS part is useful only with the '='\noperation, where it gives the specified USERS no access at all to the\nfile.\n\n'r'\nthe permission the USERS have to read the file;\n'w'\nthe permission the USERS have to write to the file;\n'x'\nthe permission the USERS have to execute the file, or search it if\nit is a directory.\n\nFor example, to give everyone permission to read and write a regular\nfile, but not to execute it, use:\n\na=rw\n\nTo remove write permission for all users other than the file's owner,\nuse:\n\ngo-w\n", "subsections": [] }, "The above command does not affect the access that the owner of the file": { "content": "has to it, nor does it affect whether other users can read or execute\nthe file.\n\nTo give everyone except a file's owner no permission to do anything\nwith that file, use the mode below. Other users could still remove the\nfile, if they have write permission on the directory it is in.\n\ngo=\n\nAnother way to specify the same thing is:\n\nog-rwx\n", "subsections": [] }, "File: coreutils.info, Node: Copying Permissions, Next: Changing Special Mode Bits, Prev: Setting Permissions, Up: Symbolic Modes": { "content": "", "subsections": [] }, "You can base a file's permissions on its existing permissions. To do": { "content": "this, instead of using a series of 'r', 'w', or 'x' letters after the\noperator, you use the letter 'u', 'g', or 'o'. For example, the mode\n\no+g\n\nadds the permissions for users who are in a file's group to the\npermissions that other users have for the file. Thus, if the file\nstarted out as mode 664 ('rw-rw-r--'), the above mode would change it to\nmode 666 ('rw-rw-rw-'). If the file had started out as mode 741\n('rwxr----x'), the above mode would change it to mode 745 ('rwxr--r-x').\nThe '-' and '=' operations work analogously.\n", "subsections": [] }, "File: coreutils.info, Node: Changing Special Mode Bits, Next: Conditional Executability, Prev: Copying Permissions, Up: Symbolic Modes": { "content": "", "subsections": [] }, "In addition to changing a file's read, write, and execute/search": { "content": "permissions, you can change its special mode bits. *Note Mode\nStructure::, for a summary of these special mode bits.\n\nTo change the file mode bits to set the user ID on execution, use 'u'\nin the USERS part of the symbolic mode and 's' in the PERMISSIONS part.\n\nTo change the file mode bits to set the group ID on execution, use\n'g' in the USERS part of the symbolic mode and 's' in the PERMISSIONS\npart.\n\nTo set both user and group ID on execution, omit the USERS part of\nthe symbolic mode (or use 'a') and use 's' in the PERMISSIONS part.\n\nTo change the file mode bits to set the restricted deletion flag or\nsticky bit, omit the USERS part of the symbolic mode (or use 'a') and\nuse 't' in the PERMISSIONS part.\n\nFor example, to set the set-user-ID mode bit of a program, you can\nuse the mode:\n\nu+s\n\nTo remove both set-user-ID and set-group-ID mode bits from it, you\ncan use the mode:\n\na-s\n\nTo set the restricted deletion flag or sticky bit, you can use the\nmode:\n\n+t\n\nThe combination 'o+s' has no effect. On GNU systems the combinations\n'u+t' and 'g+t' have no effect, and 'o+t' acts like plain '+t'.\n\nThe '=' operator is not very useful with special mode bits. For\nexample, the mode:\n\no=t\n\ndoes set the restricted deletion flag or sticky bit, but it also removes\nall read, write, and execute/search permissions that users not in the\nfile's group might have had for it.\n\n*Note Directory Setuid and Setgid::, for additional rules concerning\nset-user-ID and set-group-ID bits and directories.\n", "subsections": [] }, "File: coreutils.info, Node: Conditional Executability, Next: Multiple Changes, Prev: Changing Special Mode Bits, Up: Symbolic Modes": { "content": "", "subsections": [] }, "There is one more special type of symbolic permission: if you use 'X'": { "content": "instead of 'x', execute/search permission is affected only if the file\nis a directory or already had execute permission.\n\nFor example, this mode:\n\na+X\n\ngives all users permission to search directories, or to execute files if\nanyone could execute them before.\n", "subsections": [] }, "File: coreutils.info, Node: Multiple Changes, Next: Umask and Protection, Prev: Conditional Executability, Up: Symbolic Modes": { "content": "", "subsections": [] }, "The format of symbolic modes is actually more complex than described": { "content": "above (*note Setting Permissions::). It provides two ways to make\nmultiple changes to files' mode bits.\n\nThe first way is to specify multiple OPERATION and PERMISSIONS parts\nafter a USERS part in the symbolic mode.\n\nFor example, the mode:\n\nog+rX-w\n\ngives users other than the owner of the file read permission and, if it\nis a directory or if someone already had execute permission to it, gives\nthem execute/search permission; and it also denies them write permission\nto the file. It does not affect the permission that the owner of the\nfile has for it. The above mode is equivalent to the two modes:\n\nog+rX\nog-w\n\nThe second way to make multiple changes is to specify more than one\nsimple symbolic mode, separated by commas. For example, the mode:\n\na+r,go-w\n\ngives everyone permission to read the file and removes write permission\non it for all users except its owner. Another example:\n\nu=rwx,g=rx,o=\n\nsets all of the permission bits for the file explicitly. (It gives\nusers who are not in the file's group no permission at all for it.)\n\nThe two methods can be combined. The mode:\n\na+r,g+x-w\n\ngives all users permission to read the file, and gives users who are in\nthe file's group permission to execute/search it as well, but not\npermission to write to it. The above mode could be written in several\ndifferent ways; another is:\n\nu+r,g+rx,o+r,g-w\n", "subsections": [] }, "File: coreutils.info, Node: Umask and Protection, Prev: Multiple Changes, Up: Symbolic Modes": { "content": "", "subsections": [] }, "If the USERS part of a symbolic mode is omitted, it defaults to 'a'": { "content": "(affect all users), except that any permissions that are set in the\nsystem variable 'umask' are not affected. The value of 'umask' can be\nset using the 'umask' command. Its default value varies from system to\nsystem.\n\nOmitting the USERS part of a symbolic mode is generally not useful\nwith operations other than '+'. It is useful with '+' because it allows\nyou to use 'umask' as an easily customizable protection against giving\naway more permission to files than you intended to.\n\nAs an example, if 'umask' has the value 2, which removes write\npermission for users who are not in the file's group, then the mode:\n\n+w\n\nadds permission to write to the file to its owner and to other users who\nare in the file's group, but not to other users. In contrast, the\nmode:\n\na+w\n\nignores 'umask', and does give write permission for the file to all\nusers.\n", "subsections": [] }, "File: coreutils.info, Node: Numeric Modes, Next: Operator Numeric Modes, Prev: Symbolic Modes, Up: File permissions": { "content": "", "subsections": [ { "name": "27.3 Numeric Modes", "content": "" } ] }, "As an alternative to giving a symbolic mode, you can give an octal (base": { "content": "8) number that represents the mode.\n\nThe permissions granted to the user, to other users in the file's\ngroup, and to other users not in the file's group each require three\nbits: one bit for read, one for write, and one for execute/search\npermission. These three bits are represented as one octal digit; for\nexample, if all three are present, the resulting 111 (in binary) is\nrepresented as the digit 7 (in octal). The three special mode bits also\nrequire one bit each, and they are as a group represented as another\noctal digit. Here is how the bits are arranged, starting with the\nhighest valued bit:\n\nValue in Corresponding\nMode Mode Bit\n\nSpecial mode bits:\n4000 Set user ID\n2000 Set group ID\n1000 Restricted deletion flag or sticky bit\n\nThe file's owner:\n400 Read\n200 Write\n100 Execute/search\n\nOther users in the file's group:\n40 Read\n20 Write\n10 Execute/search\n\nOther users not in the file's group:\n4 Read\n2 Write\n1 Execute/search\n\nFor example, numeric mode '4751' corresponds to symbolic mode\n'u=srwx,g=rx,o=x', and numeric mode '664' corresponds to symbolic mode\n'ug=rw,o=r'. Numeric mode '0' corresponds to symbolic mode 'a='.\n\nA numeric mode is usually shorter than the corresponding symbolic\nmode, but it is limited in that normally it cannot take into account the\nprevious file mode bits; it can only set them absolutely. The\nset-user-ID and set-group-ID bits of directories are an exception to\nthis general limitation. *Note Directory Setuid and Setgid::. Also,\noperator numeric modes can take previous file mode bits into account.\n*Note Operator Numeric Modes::.\n\nNumeric modes are always interpreted in octal; you do not have to add\na leading '0', as you do in C. Mode '0055' is the same as mode '55'.", "subsections": [] }, "However, modes of five digits or more, such as '00055', are sometimes": { "content": "special (*note Directory Setuid and Setgid::).\n", "subsections": [] }, "File: coreutils.info, Node: Operator Numeric Modes, Next: Directory Setuid and Setgid, Prev: Numeric Modes, Up: File permissions": { "content": "", "subsections": [ { "name": "27.4 Operator Numeric Modes", "content": "" } ] }, "An operator numeric mode is a numeric mode that is prefixed by a '-',": { "content": "'+', or '=' operator, which has the same interpretation as in symbolic\nmodes. For example, '+440' enables read permission for the file's owner\nand group, '-1' disables execute permission for other users, and '=600'\nclears all permissions except for enabling read-write permissions for\nthe file's owner. Operator numeric modes can be combined with symbolic\nmodes by separating them with a comma; for example, '=0,u+r' clears all\npermissions except for enabling read permission for the file's owner.\n\nThe commands 'chmod =755 DIR' and 'chmod 755 DIR' differ in that the\nformer clears the directory DIR's setuid and setgid bits, whereas the\nlatter preserves them. *Note Directory Setuid and Setgid::.\n\nOperator numeric modes are a GNU extension.\n", "subsections": [] }, "File: coreutils.info, Node: Directory Setuid and Setgid, Prev: Operator Numeric Modes, Up: File permissions": { "content": "", "subsections": [ { "name": "27.5 Directories and the Set-User-ID and Set-Group-ID Bits", "content": "" } ] }, "On most systems, if a directory's set-group-ID bit is set, newly created": { "content": "subfiles inherit the same group as the directory, and newly created\nsubdirectories inherit the set-group-ID bit of the parent directory. On\na few systems, a directory's set-user-ID bit has a similar effect on the\nownership of new subfiles and the set-user-ID bits of new\nsubdirectories. These mechanisms let users share files more easily, by\nlessening the need to use 'chmod' or 'chown' to share new files.\n\nThese convenience mechanisms rely on the set-user-ID and set-group-ID\nbits of directories. If commands like 'chmod' and 'mkdir' routinely\ncleared these bits on directories, the mechanisms would be less\nconvenient and it would be harder to share files. Therefore, a command\nlike 'chmod' does not affect the set-user-ID or set-group-ID bits of a\ndirectory unless the user specifically mentions them in a symbolic mode,\nor uses an operator numeric mode such as '=755', or sets them in a\nnumeric mode, or clears them in a numeric mode that has five or more\noctal digits. For example, on systems that support set-group-ID\ninheritance:\n\n# These commands leave the set-user-ID and\n# set-group-ID bits of the subdirectories alone,\n# so that they retain their default values.\nmkdir A B C\nchmod 755 A\nchmod 0755 B\nchmod u=rwx,go=rx C\nmkdir -m 755 D\nmkdir -m 0755 E\nmkdir -m u=rwx,go=rx F\n\nIf you want to try to set these bits, you must mention them\nexplicitly in the symbolic or numeric modes, e.g.:\n\n# These commands try to set the set-user-ID\n# and set-group-ID bits of the subdirectories.\nmkdir G\nchmod 6755 G\nchmod +6000 G\nchmod u=rwx,go=rx,a+s G\nmkdir -m 6755 H\nmkdir -m +6000 I\nmkdir -m u=rwx,go=rx,a+s J\n\nIf you want to try to clear these bits, you must mention them\nexplicitly in a symbolic mode, or use an operator numeric mode, or\nspecify a numeric mode with five or more octal digits, e.g.:\n\n# These commands try to clear the set-user-ID\n# and set-group-ID bits of the directory D.\nchmod a-s D\nchmod -6000 D\nchmod =755 D\nchmod 00755 D\n\nThis behavior is a GNU extension. Portable scripts should not rely\non requests to set or clear these bits on directories, as POSIX allows\nimplementations to ignore these requests. The GNU behavior with numeric\nmodes of four or fewer digits is intended for scripts portable to\nsystems that preserve these bits; the behavior with numeric modes of\nfive or more digits is for scripts portable to systems that do not\npreserve the bits.\n", "subsections": [] }, "File: coreutils.info, Node: File timestamps, Next: Date input formats, Prev: File permissions, Up: Top": { "content": "", "subsections": [] }, "28 File timestamps": { "content": "", "subsections": [] }, "Standard POSIX files have three timestamps: the access timestamp (atime)": { "content": "of the last read, the modification timestamp (mtime) of the last write,\nand the status change timestamp (ctime) of the last change to the file's\nmeta-information. Some file systems support a fourth time: the birth\ntimestamp (birthtime) of when the file was created; by definition,\nbirthtime never changes.\n\nOne common example of a ctime change is when the permissions of a\nfile change. Changing the permissions doesn't access the file, so atime\ndoesn't change, nor does it modify the file, so the mtime doesn't\nchange. Yet, something about the file itself has changed, and this must\nbe noted somewhere. This is the job of the ctime field. This is\nnecessary, so that, for example, a backup program can make a fresh copy\nof the file, including the new permissions value. Another operation\nthat modifies a file's ctime without affecting the others is renaming.\n\nNaively, a file's atime, mtime, and ctime are set to the current time\nwhenever you read, write, or change the attributes of the file\nrespectively, and searching a directory counts as reading it. A file's\natime and mtime can also be set directly, via the 'touch' command (*note\ntouch invocation::). In practice, though, timestamps are not updated\nquite that way.\n\nFor efficiency reasons, many systems are lazy about updating atimes:\nwhen a program accesses a file, they may delay updating the file's\natime, or may not update the file's atime if the file has been accessed\nrecently, or may not update the atime at all. Similar laziness, though\ntypically not quite so extreme, applies to mtimes and ctimes.\n\nSome systems emulate timestamps instead of supporting them directly,\nand these emulations may disagree with the naive interpretation. For\nexample, a system may fake an atime or ctime by using the mtime.\n\nThe determination of what time is \"current\" depends on the platform.", "subsections": [] }, "Platforms with network file systems often use different clocks for the": { "content": "operating system and for file systems; because updates typically uses\nfile systems' clocks by default, clock skew can cause the resulting file\ntimestamps to appear to be in a program's \"future\" or \"past\".\n\nWhen the system updates a file timestamp to a desired time T (which\nis either the current time, or a time specified via the 'touch'\ncommand), there are several reasons the file's timestamp may be set to a\nvalue that differs from T. First, T may have a higher resolution than\nsupported. Second, a file system may use different resolutions for\ndifferent types of times. Third, file timestamps may use a different\nresolution than operating system timestamps. Fourth, the operating\nsystem primitives used to update timestamps may employ yet a different\nresolution. For example, in theory a file system might use\n10-microsecond resolution for access timestamp and 100-nanosecond\nresolution for modification timestamp, and the operating system might\nuse nanosecond resolution for the current time and microsecond\nresolution for the primitive that 'touch' uses to set a file's timestamp\nto an arbitrary value.\n", "subsections": [] }, "File: coreutils.info, Node: Version sort ordering, Next: Opening the software toolbox, Prev: Date input formats, Up: Top": { "content": "", "subsections": [] }, "30 Version sort ordering": { "content": "* Menu:\n\n* Version sort overview::\n* Implementation Details::\n* Differences from the official Debian Algorithm::\n* Advanced Topics::\n", "subsections": [] }, "File: coreutils.info, Node: Version sort overview, Next: Implementation Details, Up: Version sort ordering": { "content": "", "subsections": [ { "name": "30.1 Version sort overview", "content": "\"version sort\" ordering (and similarly, \"natural sort\" ordering) is a\nmethod to sort items such as file names and lines of text in an order\nthat feels more natural to people, when the text contains a mixture of\nletters and digits.\n\nStandard sorting usually does not produce the order that one expects\nbecause comparisons are made on a character-by-character basis.\n\nCompare the sorting of the following items:\n\nAlphabetical sort: Version Sort:\n\na1 a1\na120 a2\na13 a13\na2 a120\n\nversion sort functionality in GNU coreutils is available in the 'ls\n-v', 'ls --sort=version', 'sort -V', 'sort --version-sort' commands.\n\n* Menu:\n\n* Using version sort in GNU coreutils::\n* Origin of version sort and differences from natural sort::\n* Correct/Incorrect ordering and Expected/Unexpected results::\n" } ] }, "File: coreutils.info, Node: Using version sort in GNU coreutils, Next: Origin of version sort and differences from natural sort, Up: Version sort overview": { "content": "Two GNU coreutils programs use version sort: 'ls' and 'sort'.\n\nTo list files in version sort order, use 'ls' with '-v' or\n'--sort=version' options:\n\ndefault sort: version sort:\n\n$ ls -1 $ ls -1 -v\na1 a1\na100 a1.4\na1.13 a1.13\na1.4 a1.40\na1.40 a2\na2 a100\n\nTo sort text files in version sort order, use 'sort' with the '-V'\noption:\n\n$ cat input\nb3\nb11\nb1\nb20\n\n\nalphabetical order: version sort order:\n\n$ sort input $ sort -V input\nb1 b1\nb11 b3\nb20 b11\nb3 b20\n\nTo sort a specific column in a file use '-k/--key' with 'V' ordering\noption:\n\n$ cat input2\n1000 b3 apples\n2000 b11 oranges\n3000 b1 potatoes\n4000 b20 bananas\n\n$ sort -k2V,2 input2\n3000 b1 potatoes\n1000 b3 apples\n2000 b11 oranges\n4000 b20 bananas\n", "subsections": [] }, "File: coreutils.info, Node: Origin of version sort and differences from natural sort, Next: Correct/Incorrect ordering and Expected/Unexpected results, Prev: Using version sort in GNU coreutils, Up: Version sort overview": { "content": "In GNU coreutils, the name \"version sort\" was chosen because it is based\non Debian GNU/Linux's algorithm of sorting packages' versions.\n\nIts goal is to answer the question \"which package is newer,\n'firefox-60.7.2' or 'firefox-60.12.3' ?\"\n\nIn coreutils this algorithm was slightly modified to work on more\ngeneral input such as textual strings and file names (see *note\nDifferences from the official Debian Algorithm::).\n\nIn other contexts, such as other programs and other programming\nlanguages, a similar sorting functionality is called natural sort\n(https://en.wikipedia.org/wiki/Naturalsortorder).\n", "subsections": [] }, "File: coreutils.info, Node: Correct/Incorrect ordering and Expected/Unexpected results, Prev: Origin of version sort and differences from natural sort, Up: Version sort overview": { "content": "Currently there is no standard for version/natural sort ordering.\n\nThat is: there is no one correct way or universally agreed-upon way\nto order items. Each program and each programming language can decide\nits own ordering algorithm and call it 'natural sort' (or other various\nnames).\n\nSee *note Other version/natural sort implementations:: for many\nexamples of differing sorting possibilities, each with its own rules and\nvariations.\n\nIf you do suspect a bug in coreutils' implementation of version-sort,\nsee *note Reporting bugs or incorrect results:: on how to report them.\n", "subsections": [] }, "File: coreutils.info, Node: Implementation Details, Next: Differences from the official Debian Algorithm, Prev: Version sort overview, Up: Version sort ordering": { "content": "", "subsections": [ { "name": "30.2 Implementation Details", "content": "GNU coreutils' version sort algorithm is based on Debian's versioning\nscheme\n(https://www.debian.org/doc/debian-policy/ch-controlfields.html#version),\nspecifically on the \"upstream version\" part.\n\nThis section describes the ordering rules.\n\nThe next section (*note Differences from the official Debian" } ] }, "Algorithm::) describes some differences between GNU coreutils": { "content": "implementation and Debian's official algorithm.\n\n* Menu:\n\n* Version-sort ordering rules::\n* Version sort is not the same as numeric sort::\n* Punctuation Characters::\n* Punctuation Characters vs letters::\n* Tilde ~ character::\n* Version sort ignores locale::\n", "subsections": [] }, "File: coreutils.info, Node: Version-sort ordering rules, Next: Version sort is not the same as numeric sort, Up: Implementation Details": { "content": "The version sort ordering rules are:\n\n1. The strings are compared from left to right.\n\n2. First the initial part of each string consisting entirely of\nnon-digit characters is determined.\n\n1. These two parts (one of which may be empty) are compared\nlexically. If a difference is found it is returned.\n\n2. The lexical comparison is a comparison of ASCII values\nmodified so that:\n\n1. all the letters sort earlier than all the non-letters and\n2. so that a tilde sorts before anything, even the end of a\npart.\n\n3. Then the initial part of the remainder of each string which\nconsists entirely of digit characters is determined. The numerical\nvalues of these two parts are compared, and any difference found is\nreturned as the result of the comparison.\n1. For these purposes an empty string (which can only occur at\nthe end of one or both version strings being compared) counts\nas zero.\n\n4. These two steps (comparing and removing initial non-digit strings\nand initial digit strings) are repeated until a difference is found\nor both strings are exhausted.\n\nConsider the version-sort comparison of two file names: 'foo07.7z'\nand 'foo7a.7z'. The two strings will be broken down to the following\nparts, and the parts compared respectively from each string:\n\nfoo vs foo (rule 2, non-digits characters)\n07 vs 7 (rule 3, digits characters)\n. vs a. (rule 2)\n7 vs 7 (rule 3)\nz vs z (rule 2)\n\nComparison flow based on above algorithm:\n\n1. The first parts ('foo') are identical in both strings.\n\n2. The second parts ('07' and '7') are compared numerically, and are\nidentical.\n\n3. The third parts (''.'' vs ''a.'') are compared lexically by ASCII\nvalue (rule 2.2).\n\n4. The first character of the first string (''.'') is compared to the\nfirst character of the second string (''a'').\n\n5. Rule 2.2.1 dictates that \"all letters sorts earlier than all\nnon-letters\". Hence, ''a'' comes before ''.''.\n\n6. The returned result is that 'foo7a.7z' comes before 'foo07.7z'.\n\nResult when using sort:\n\n$ cat input3\nfoo07.7z\nfoo7a.7z\n\n$ sort -V input3\nfoo7a.7z\nfoo07.7z\n\nSee *note Differences from the official Debian Algorithm:: for\nadditional rules that extend the Debian algorithm in coreutils.\n", "subsections": [] }, "File: coreutils.info, Node: Version sort is not the same as numeric sort, Next: Punctuation Characters, Prev: Version-sort ordering rules, Up: Implementation Details": { "content": "Consider the following text file:\n\n$ cat input4\n8.10\n8.5\n8.1\n8.01\n8.010\n8.100\n8.49\n\n\n\nNumerical Sort: Version Sort:\n\n$ sort -n input4 $ sort -V input4\n8.01 8.01\n8.010 8.1\n8.1 8.5\n8.10 8.010\n8.100 8.10\n8.49 8.49\n8.5 8.100\n\nNumeric sort ('sort -n') treats the entire string as a single numeric\nvalue, and compares it to other values. For example, '8.1', '8.10' and\n'8.100' are numerically equivalent, and are ordered together.", "subsections": [] }, "Similarly, '8.49' is numerically smaller than '8.5', and appears before": { "content": "first.\n\nVersion sort ('sort -V') first breaks down the string into digits and\nnon-digits parts, and only then compares each part (see annotated\nexample in Version-sort ordering rules).\n\nComparing the string '8.1' to '8.01', first the ''8'' characters are\ncompared (and are identical), then the dots (''.'') are compared and are\nidentical, and lastly the remaining digits are compared numerically ('1'\nand '01') - which are numerically equivalent. Hence, '8.01' and '8.1'\nare grouped together.\n\nSimilarly, comparing '8.5' to '8.49' - the ''8'' and ''.'' parts are\nidentical, then the numeric values '5' and '49' are compared. The\nresulting '5' appears before '49'.\n\nThis sorting order (where '8.5' comes before '8.49') is common when\nassigning versions to computer programs (while perhaps not intuitive or\n'natural' for people).\n", "subsections": [] }, "File: coreutils.info, Node: Punctuation Characters, Next: Punctuation Characters vs letters, Prev: Version sort is not the same as numeric sort, Up: Implementation Details": { "content": "Punctuation characters are sorted by ASCII order (rule 2.2).\n\n$ touch 1.0.5src.tar.gz 1.0src.tar.gz\n\n$ ls -v -1\n1.0.5src.tar.gz\n1.0src.tar.gz\n\nWhy is '1.0.5src.tar.gz' listed before '1.0src.tar.gz' ?\n\nBased on the *note algorithm: Version-sort ordering rules. above, the\nstrings are broken down into the following parts:\n\n1 vs 1 (rule 3, all digit characters)\n. vs . (rule 2, all non-digit characters)\n0 vs 0 (rule 3)\n. vs src.tar.gz (rule 2)\n5 vs empty string (no more character in the file name)\nsrc.tar.gz vs empty string\n\nThe fourth parts (''.'' and 'src.tar.gz') are compared lexically by\nASCII order. The character ''.'' (ASCII value 46) is smaller than ''''\n(ASCII value 95) - and should be listed before it.\n\nHence, '1.0.5src.tar.gz' is listed first.\n\nIf a different character appears instead of the underscore (for\nexample, percent sign ''%'' ASCII value 37, which is smaller than dot's\nASCII value of 46), that file will be listed first:\n\n$ touch 1.0.5src.tar.gz 1.0%zzzzz.gz\n1.0%zzzzz.gz\n1.0.5src.tar.gz\n\nThe same reasoning applies to the following example: The character\n''.'' has ASCII value 46, and is smaller than slash character ''/''\nASCII value 47:\n\n$ cat input5\n3.0/\n3.0.5\n\n$ sort -V input5\n3.0.5\n3.0/\n\nFile: coreutils.info, Node: Punctuation Characters vs letters, Next: Tilde ~ character, Prev: Punctuation Characters, Up: Implementation Details\n\n", "subsections": [] }, "Rule 2.2.1 dictates that letters sorts earlier than all non-letters": { "content": "(after breaking down a string to digits and non-digits parts).\n\n$ cat input6\na%\naz\n\n$ sort -V input6\naz\na%\n\nThe input strings consist entirely of non-digits, and based on the\nabove algorithm have only one part, all non-digit characters (''a%'' vs\n''az'').\n\nEach part is then compared lexically, character-by-character. ''a''\ncompares identically in both strings.\n\nRule 2.2.1 dictates that letters (''z'') sorts earlier than all\nnon-letters (''%'') - hence ''az'' appears first (despite ''z'' having\nASCII value of 122, much bigger than ''%'' with ASCII value 37).\n\nFile: coreutils.info, Node: Tilde ~ character, Next: Version sort ignores locale, Prev: Punctuation Characters vs letters, Up: Implementation Details\n\n\nRule 2.2.2 dictates that tilde character ''~'' (ASCII 126) sorts before\nall other non-digit characters, including an empty part.\n\n$ cat input7\n1\n1%\n1.2\n1~\n~\n\n$ sort -V input7\n~\n1~\n1\n1%\n1.2\n\nThe sorting algorithm starts by breaking down the string into\nnon-digits (rule 2) and digits parts (rule 3).\n\nIn the above input file, only the last line in the input file starts\nwith a non-digit (''~''). This is the first part. All other lines in\nthe input file start with a digit - their first non-digit part is empty.\n\nBased on rule 2.2.2, tilde ''~'' sorts before all other non-digits\nincluding the empty part - hence it comes before all other strings, and\nis listed first in the sorted output.\n\nThe remaining lines ('1', '1%', '1.2', '1~') follow similar logic:\nThe digit part is extracted (1 for all strings) and compares identical.", "subsections": [] }, "The following extracted parts for the remaining input lines are: empty": { "content": "part, '%', '.', '~'.\n\nTilde sorts before all others, hence the line '1~' appears next.\n\nThe remaining lines ('1', '1%', '1.2') are sorted based on previously\nexplained rules.\n\nFile: coreutils.info, Node: Version sort ignores locale, Prev: Tilde ~ character, Up: Implementation Details\n\n", "subsections": [] }, "In version sort, unicode characters are compared byte-by-byte according": { "content": "to their binary representation, ignoring their unicode value or the\ncurrent locale.\n\nMost commonly, unicode characters (e.g. Greek Small Letter Alpha\nU+03B1 '??') are encoded as UTF-8 bytes (e.g. '??' is encoded as UTF-8\nsequence '0xCE 0xB1'). The encoding will be compared byte-by-byte, e.g.\nfirst '0xCE' (decimal value 206) then '0xB1' (decimal value 177).\n\n$ touch aa az \"a%\" \"a??\"\n\n$ ls -1 -v\naa\naz\na%\na??\n\nIgnoring the first letter ('a') which is identical in all strings,\nthe compared values are:\n\n''a'' and ''z'' are letters, and sort earlier than all other\nnon-digit characters.\n\nThen, percent sign ''%'' (ASCII value 37) is compared to the first\nbyte of the UTF-8 sequence of ''??'', which is 0xCE or 206). The value\n37 is smaller, hence ''a%'' is listed before ''a??''.\n", "subsections": [] }, "File: coreutils.info, Node: Differences from the official Debian Algorithm, Next: Advanced Topics, Prev: Implementation Details, Up: Version sort ordering": { "content": "", "subsections": [ { "name": "30.3 Differences from the official Debian Algorithm", "content": "" } ] }, "The GNU coreutils' version sort algorithm differs slightly from the": { "content": "official Debian algorithm, in order to accommodate more general usage\nand file name listing.\n\n* Menu:\n\n* Minus/Hyphen and Colon characters::\n* Additional hard-coded priorities in GNU coreutils' version sort::\n* Special handling of file extensions::\n", "subsections": [] }, "File: coreutils.info, Node: Minus/Hyphen and Colon characters, Next: Additional hard-coded priorities in GNU coreutils' version sort, Up: Differences from the official Debian Algorithm": { "content": "In Debian's version string syntax the version consists of three parts:\n[epoch:]upstreamversion[-debianrevision]\nThe 'epoch' and 'debianrevision' parts are optional.\n\nExample of such version strings:\n\n60.7.2esr-1~deb9u1\n52.9.0esr-1~deb9u1\n1:2.3.4-1+b2\n327-2\n1:1.0.13-3\n2:1.19.2-1+deb9u5\n\nIf the 'debianrevision part' is not present, hyphen characters '-'\nare not allowed. If epoch is not present, colons ':' are not allowed.\n\nIf these parts are present, hyphen and/or colons can appear only once\nin valid Debian version strings.\n\nIn GNU coreutils, such restrictions are not reasonable (a file name\ncan have many hyphens, a line of text can have many colons).\n\nAs a result, in GNU coreutils hyphens and colons are treated exactly\nlike all other punctuation characters (i.e., they are sorted after\nletters. See Punctuation Characters above).\n\nIn Debian, these characters are treated differently than in\ncoreutils: a version string with hyphen will sort before similar strings\nwithout hyphens.\n\nCompare:\n\n$ touch abb ab-cd\n\n$ ls -v -1\nabb\nab-cd\n\nWith Debian's 'dpkg' they will be listed as 'ab-cd' first and 'abb'\nsecond.\n\nFor further technical details see bug35939\n(https://bugs.gnu.org/35939).\n", "subsections": [] }, "File: coreutils.info, Node: Additional hard-coded priorities in GNU coreutils' version sort, Next: Special handling of file extensions, Prev: Minus/Hyphen and Colon characters, Up: Differences from the official Debian Algorithm": { "content": "", "subsections": [] }, "In GNU coreutils' version sort algorithm, the following items have": { "content": "special priority and sort earlier than all other characters (listed in\norder);\n\n1. The empty string\n\n2. The string ''.'' (a single dot character, ASCII 46)\n\n3. The string ''..'' (two dot characters)\n\n4. Strings start with a dot (''.'') sort earlier than strings starting\nwith any other characters.\n\nExample:\n\n$ printf \"%s\\n\" a \"\" b \".\" c \"..\" \".d20\" \".d3\" | sort -V\n\n.\n..\n.d3\n.d20\na\nb\nc\n\nThese priorities make perfect sense for 'ls -v': The special files\ndot ''.'' and dot-dot ''..'' will be listed first, followed by any\nhidden files (files starting with a dot), followed by non-hidden files.\n\nFor 'sort -V' these priorities might seem arbitrary. However,\nbecause the sorting code is shared between the 'ls' and 'sort' program,\nthe ordering rules are the same.\n", "subsections": [] }, "File: coreutils.info, Node: Special handling of file extensions, Prev: Additional hard-coded priorities in GNU coreutils' version sort, Up: Differences from the official Debian Algorithm": { "content": "GNU coreutils' version sort algorithm implements specialized handling of\nfile extensions (or strings that look like file names with extensions).\n\nThis nuanced implementation enables slightly more natural ordering of\nfiles.\n\nThe additional rules are:\n\n1. A suffix (i.e., a file extension) is defined as: a dot, followed by\na letter or tilde, followed by one or more letters, digits, or\ntildes (possibly repeated more than once), until the end of the\nstring (technically, matching the regular expression\n'(\\.[A-Za-z~][A-Za-z0-9~]*)*').\n\n2. If the strings contains suffixes, the suffixes are temporarily\nremoved, and the strings are compared without them (using the *note\nalgorithm: Version-sort ordering rules. above).\n\n3. If the suffix-less strings are identical, the suffix is restored\nand the entire strings are compared.\n\n4. If the non-suffixed strings differ, the result is returned and the\nsuffix is effectively ignored.\n\nExamples for rule 1:\n\n* 'hello-8.txt': the suffix is '.txt'\n\n* 'hello-8.2.txt': the suffix is '.txt' (''.2'' is not included\nbecause the dot is not followed by a letter)\n\n* 'hello-8.0.12.tar.gz': the suffix is '.tar.gz' (''.0.12'' is not\nincluded)\n\n* 'hello-8.2': no suffix (suffix is an empty string)\n\n* 'hello.foobar65': the suffix is '.foobar65'\n\n* 'gcc-c++-10.8.12-0.7rc2.fc9.tar.bz2': the suffix is '.fc9.tar.bz2'\n('.7rc2' is not included as it begins with a digit)\n\nExamples for rule 2:\n\n* Comparing 'hello-8.txt' to 'hello-8.2.12.txt', the '.txt' suffix is\ntemporarily removed from both strings.\n\n* Comparing 'foo-10.3.tar.gz' to 'foo-10.tar.xz', the suffixes\n'.tar.gz' and '.tar.xz' are temporarily removed from the strings.\n\nExample for rule 3:\n\n* Comparing 'hello.foobar65' to 'hello.foobar4', the suffixes\n('.foobar65' and '.foobar4') are temporarily removed. The\nremaining strings are identical ('hello'). The suffixes are then\nrestored, and the entire strings are compared ('hello.foobar4'\ncomes first).\n\nExamples for rule 4:\n\n* When comparing the strings 'hello-8.2.txt' and 'hello-8.10.txt',\nthe suffixes ('.txt') are temporarily removed. The remaining\nstrings ('hello-8.2' and 'hello-8.10') are compared as previously\ndescribed ('hello-8.2' comes first). (In this case the suffix\nremoval algorithm does not have a noticeable effect on the\nresulting order.)\n\nHow does the suffix-removal algorithm effect ordering results?\n\nConsider the comparison of hello-8.txt and hello-8.2.txt.\n\nWithout the suffix-removal algorithm, the strings will be broken down\nto the following parts:\n\nhello- vs hello- (rule 2, all non-digit characters)\n8 vs 8 (rule 3, all digit characters)\n.txt vs . (rule 2)\nempty vs 2\nempty vs .txt\n\nThe comparison of the third parts (''.'' vs ''.txt'') will determine\nthat the shorter string comes first - resulting in 'hello-8.2.txt'\nappearing first.\n\nIndeed this is the order in which Debian's 'dpkg' compares the\nstrings.\n\nA more natural result is that 'hello-8.txt' should come before\n'hello-8.2.txt', and this is where the suffix-removal comes into play:\n\nThe suffixes ('.txt') are removed, and the remaining strings are\nbroken down into the following parts:\n\nhello- vs hello- (rule 2, all non-digit characters)\n8 vs 8 (rule 3, all digit characters)\nempty vs . (rule 2)\nempty vs 2\n\nAs empty strings sort before non-empty strings, the result is\n'hello-8' being first.\n\nA real-world example would be listing files such as:\n'gcc10.fc9.tar.gz' and 'gcc10.8.12.7rc2.fc9.tar.bz2': Debian's\nalgorithm would list 'gcc10.8.12.7rc2.fc9.tar.bz2' first, while 'ls -v'\nwill list 'gcc10.fc9.tar.gz' first.\n\nThese priorities make sense for 'ls -v': Versioned files will be\nlisted in a more natural order.\n\nFor 'sort -V' these priorities might seem arbitrary. However,\nbecause the sorting code is shared between the 'ls' and 'sort' program,\nthe ordering rules are the same.\n", "subsections": [] }, "File: coreutils.info, Node: Advanced Topics, Prev: Differences from the official Debian Algorithm, Up: Version sort ordering": { "content": "", "subsections": [ { "name": "30.4 Advanced Topics", "content": "* Menu:\n\n* Comparing two strings using Debian's algorithm::\n* Reporting bugs or incorrect results::\n* Other version/natural sort implementations::\n* Related Source code::\n" } ] }, "File: coreutils.info, Node: Comparing two strings using Debian's algorithm, Next: Reporting bugs or incorrect results, Up: Advanced Topics": { "content": "", "subsections": [] }, "The Debian program 'dpkg' (available on all Debian and Ubuntu": { "content": "installations) can compare two strings using the '--compare-versions'\noption.\n\nTo use it, create a helper shell function (simply copy & paste the\nfollowing snippet to your shell command-prompt):\n\ncompver() {\ndpkg --compare-versions \"$1\" lt \"$2\" \\\n&& printf \"%s\\n\" \"$1\" \"$2\" \\\n|| printf \"%s\\n\" \"$2\" \"$1\" ; \\\n}\n\nThen compare two strings by calling compver:\n\n$ compver 8.49 8.5\n8.5\n8.49\n\nNote that 'dpkg' will warn if the strings have invalid syntax:\n\n$ compver \"foo07.7z\" \"foo7a.7z\"\ndpkg: warning: version 'foo07.7z' has bad syntax:\nversion number does not start with digit\ndpkg: warning: version 'foo7a.7z' has bad syntax:\nversion number does not start with digit\nfoo7a.7z\nfoo07.7z\n\n$ compver \"3.0/\" \"3.0.5\"\ndpkg: warning: version '3.0/' has bad syntax:\ninvalid character in version number\n3.0.5\n3.0/\n\nTo illustrate the different handling of hyphens between Debian and\ncoreutils' algorithms (see *note Minus/Hyphen and Colon characters::):\n\n$ compver abb ab-cd 2>/dev/null $ printf \"abb\\nab-cd\\n\" | sort -V\nab-cd abb\nabb ab-cd\n\nTo illustrate the different handling of file extension: (see *note\nSpecial handling of file extensions::):\n\n$ compver hello-8.txt hello-8.2.txt 2>/dev/null\nhello-8.2.txt\nhello-8.txt\n\n$ printf \"%s\\n\" hello-8.txt hello-8.2.txt | sort -V\nhello-8.txt\nhello-8.2.txt\n", "subsections": [] }, "File: coreutils.info, Node: Reporting bugs or incorrect results, Next: Other version/natural sort implementations, Prev: Comparing two strings using Debian's algorithm, Up: Advanced Topics": { "content": "", "subsections": [] }, "If you suspect a bug in GNU coreutils' version sort (i.e., in the output": { "content": "of 'ls -v' or 'sort -V'), please first check the following:\n\n1. Is the result consistent with Debian's own ordering (using 'dpkg',\nsee *note Comparing two strings using Debian's algorithm::) ? If\nit is, then this is not a bug - please do not report it.\n\n2. If the result differs from Debian's, is it explained by one of the\nsections in *note Differences from the official Debian Algorithm::?\nIf it is, then this is not a bug - please do not report it.\n\n3. If you have a question about specific ordering which is not\nexplained here, please write to , and provide a\nconcise example that will help us diagnose the issue.\n\n4. If you still suspect a bug which is not explained by the above,\nplease write to with a concrete example of\nthe suspected incorrect output, with details on why you think it is\nincorrect.\n", "subsections": [] }, "File: coreutils.info, Node: Other version/natural sort implementations, Next: Related Source code, Prev: Reporting bugs or incorrect results, Up: Advanced Topics": { "content": "", "subsections": [] }, "As previously mentioned, there are multiple variations on": { "content": "version/natural sort, each with its own rules. Some examples are:\n\n* Natural Sorting variants in Rosetta Code\n(https://rosettacode.org/wiki/Naturalsorting).\n\n* Python's natsort package (https://pypi.org/project/natsort/)\n(includes detailed description of their sorting rules: natsort -\nhow it works\n(https://natsort.readthedocs.io/en/master/howitworks.html)).\n\n* Ruby's versionsorter (https://github.com/github/versionsorter).\n\n* Perl has multiple packages for natual and version sorts (each\nlikely with its own rules and nuances): Sort::Naturally\n(https://metacpan.org/pod/Sort::Naturally), Sort::Versions\n(https://metacpan.org/pod/Sort::Versions), CPAN::Version\n(https://metacpan.org/pod/CPAN::Version).\n\n* PHP has a built-in function natsort\n(https://www.php.net/manual/en/function.natsort.php).\n\n* NodeJS's natural-sort package\n(https://www.npmjs.com/package/natural-sort).\n\n* In zsh, the glob modifier\n(http://zsh.sourceforge.net/Doc/Release/Expansion.html#Glob-Qualifiers)\n'*(n)' will expand to files in natural sort order.\n\n* When writing 'C' programs, the GNU libc library ('glibc') provides\nthe strvercmp(3)\n(http://man7.org/linux/man-pages/man3/strverscmp.3.html) function\nto compare two strings, and versionsort(3)\n(http://man7.org/linux/man-pages/man3/versionsort.3.html) function\nto compare two directory entries (despite the names, they are not\nidentical to GNU coreutils' version sort ordering).\n\n* Using Debian's sorting algorithm in:\n\n* python: Stack Overflow Example #4957741\n(https://stackoverflow.com/a/4957741).\n\n* NodeJS: deb-version-compare\n(https://www.npmjs.com/package/deb-version-compare).\n", "subsections": [] }, "File: coreutils.info, Node: Related Source code, Prev: Other version/natural sort implementations, Up: Advanced Topics": { "content": "* Debian's code which splits a version string into\n'epoch/upstreamversion/debianrevision' parts:\nparsehelp.c:parseversion()\n(https://git.dpkg.org/cgit/dpkg/dpkg.git/tree/lib/dpkg/parsehelp.c#n191).\n\n* Debian's code which performs the 'upstreamversion' comparison:\nversion.c\n(https://git.dpkg.org/cgit/dpkg/dpkg.git/tree/lib/dpkg/version.c#n140).\n\n* GNULIB code (used by GNU coreutils) which performs the version\ncomparison: filevercmp.c\n(https://git.savannah.gnu.org/cgit/gnulib.git/tree/lib/filevercmp.c).\n", "subsections": [] }, "File: coreutils.info, Node: Opening the software toolbox, Next: GNU Free Documentation License, Prev: Version sort ordering, Up: Top": { "content": "", "subsections": [] }, "31 Opening the Software Toolbox": { "content": "An earlier version of this chapter appeared in the 'What's GNU?' column\nof the June 1994 'Linux Journal'\n(https://www.linuxjournal.com/article.php?sid=2762). It was written by\nArnold Robbins.\n\n* Menu:\n\n* Toolbox introduction:: Toolbox introduction\n* I/O redirection:: I/O redirection\n* The who command:: The 'who' command\n* The cut command:: The 'cut' command\n* The sort command:: The 'sort' command\n* The uniq command:: The 'uniq' command\n* Putting the tools together:: Putting the tools together\n", "subsections": [] }, "File: coreutils.info, Node: Toolbox introduction, Next: I/O redirection, Up: Opening the software toolbox": { "content": "", "subsections": [ { "name": "Toolbox Introduction", "content": "" } ] }, "This month's column is only peripherally related to the GNU Project, in": { "content": "that it describes a number of the GNU tools on your GNU/Linux system and\nhow they might be used. What it's really about is the \"Software Tools\"\nphilosophy of program development and usage.\n\nThe software tools philosophy was an important and integral concept\nin the initial design and development of Unix (of which Linux and GNU\nare essentially clones). Unfortunately, in the modern day press of\nInternetworking and flashy GUIs, it seems to have fallen by the wayside.", "subsections": [] }, "This is a shame, since it provides a powerful mental model for solving": { "content": "many kinds of problems.\n\nMany people carry a Swiss Army knife around in their pants pockets\n(or purse). A Swiss Army knife is a handy tool to have: it has several\nknife blades, a screwdriver, tweezers, toothpick, nail file, corkscrew,\nand perhaps a number of other things on it. For the everyday, small\nmiscellaneous jobs where you need a simple, general purpose tool, it's\njust the thing.\n\nOn the other hand, an experienced carpenter doesn't build a house\nusing a Swiss Army knife. Instead, he has a toolbox chock full of\nspecialized tools--a saw, a hammer, a screwdriver, a plane, and so on.", "subsections": [] }, "And he knows exactly when and where to use each tool; you won't catch": { "content": "him hammering nails with the handle of his screwdriver.\n\nThe Unix developers at Bell Labs were all professional programmers\nand trained computer scientists. They had found that while a\none-size-fits-all program might appeal to a user because there's only\none program to use, in practice such programs are\n\na. difficult to write,\n\nb. difficult to maintain and debug, and\n\nc. difficult to extend to meet new situations.\n\nInstead, they felt that programs should be specialized tools. In\nshort, each program \"should do one thing well.\" No more and no less.", "subsections": [] }, "Such programs are simpler to design, write, and get right--they only do": { "content": "one thing.\n\nFurthermore, they found that with the right machinery for hooking\nprograms together, that the whole was greater than the sum of the parts.", "subsections": [] }, "By combining several special purpose programs, you could accomplish a": { "content": "specific task that none of the programs was designed for, and accomplish\nit much more quickly and easily than if you had to write a special\npurpose program. We will see some (classic) examples of this further on\nin the column. (An important additional point was that, if necessary,\ntake a detour and build any software tools you may need first, if you\ndon't already have something appropriate in the toolbox.)\n", "subsections": [] }, "File: coreutils.info, Node: I/O redirection, Next: The who command, Prev: Toolbox introduction, Up: Opening the software toolbox": { "content": "", "subsections": [ { "name": "I/O Redirection", "content": "" } ] }, "Hopefully, you are familiar with the basics of I/O redirection in the": { "content": "shell, in particular the concepts of \"standard input,\" \"standard\noutput,\" and \"standard error\". Briefly, \"standard input\" is a data\nsource, where data comes from. A program should not need to either know\nor care if the data source is a disk file, a keyboard, a magnetic tape,\nor even a punched card reader. Similarly, \"standard output\" is a data\nsink, where data goes to. The program should neither know nor care\nwhere this might be. Programs that only read their standard input, do\nsomething to the data, and then send it on, are called \"filters\", by\nanalogy to filters in a water pipeline.\n\nWith the Unix shell, it's very easy to set up data pipelines:\n\nprogramtocreatedata | filter1 | ... | filterN > final.pretty.data\n\nWe start out by creating the raw data; each filter applies some\nsuccessive transformation to the data, until by the time it comes out of\nthe pipeline, it is in the desired form.\n\nThis is fine and good for standard input and standard output. Where\ndoes the standard error come in to play? Well, think about 'filter1' in\nthe pipeline above. What happens if it encounters an error in the data\nit sees? If it writes an error message to standard output, it will just\ndisappear down the pipeline into 'filter2''s input, and the user will\nprobably never see it. So programs need a place where they can send\nerror messages so that the user will notice them. This is standard\nerror, and it is usually connected to your console or window, even if\nyou have redirected standard output of your program away from your\nscreen.\n\nFor filter programs to work together, the format of the data has to\nbe agreed upon. The most straightforward and easiest format to use is\nsimply lines of text. Unix data files are generally just streams of\nbytes, with lines delimited by the ASCII LF (Line Feed) character,\nconventionally called a \"newline\" in the Unix literature. (This is\n''\\n'' if you're a C programmer.) This is the format used by all the\ntraditional filtering programs. (Many earlier operating systems had\nelaborate facilities and special purpose programs for managing binary\ndata. Unix has always shied away from such things, under the philosophy\nthat it's easiest to simply be able to view and edit your data with a\ntext editor.)\n\nOK, enough introduction. Let's take a look at some of the tools, and\nthen we'll see how to hook them together in interesting ways. In the\nfollowing discussion, we will only present those command line options\nthat interest us. As you should always do, double check your system\ndocumentation for the full story.\n", "subsections": [] }, "File: coreutils.info, Node: The who command, Next: The cut command, Prev: I/O redirection, Up: Opening the software toolbox": { "content": "", "subsections": [ { "name": "The 'who' Command", "content": "" } ] }, "The first program is the 'who' command. By itself, it generates a list": { "content": "of the users who are currently logged in. Although I'm writing this on\na single-user system, we'll pretend that several people are logged in:\n\n$ who\n-| arnold console Jan 22 19:57\n-| miriam ttyp0 Jan 23 14:19(:0.0)\n-| bill ttyp1 Jan 21 09:32(:0.0)\n-| arnold ttyp2 Jan 23 20:48(:0.0)\n\nHere, the '$' is the usual shell prompt, at which I typed 'who'.", "subsections": [] }, "There are three people logged in, and I am logged in twice. On": { "content": "traditional Unix systems, user names are never more than eight\ncharacters long. This little bit of trivia will be useful later. The\noutput of 'who' is nice, but the data is not all that exciting.\n", "subsections": [] }, "File: coreutils.info, Node: The cut command, Next: The sort command, Prev: The who command, Up: Opening the software toolbox": { "content": "", "subsections": [ { "name": "The 'cut' Command", "content": "" } ] }, "The next program we'll look at is the 'cut' command. This program cuts": { "content": "out columns or fields of input data. For example, we can tell it to\nprint just the login name and full name from the '/etc/passwd' file.\nThe '/etc/passwd' file has seven fields, separated by colons:\n\narnold:xyzzy:2076:10:Arnold D. Robbins:/home/arnold:/bin/bash\n\nTo get the first and fifth fields, we would use 'cut' like this:\n\n$ cut -d: -f1,5 /etc/passwd\n-| root:Operator\n...\n-| arnold:Arnold D. Robbins\n-| miriam:Miriam A. Robbins\n...\n\nWith the '-c' option, 'cut' will cut out specific characters (i.e.,\ncolumns) in the input lines. This is useful for input data that has\nfixed width fields, and does not have a field separator. For example,\nlist the Monday dates for the current month:\n\n$ cal | cut -c 3-5\n-|Mo\n-|\n-| 6\n-| 13\n-| 20\n-| 27\n", "subsections": [] }, "File: coreutils.info, Node: The sort command, Next: The uniq command, Prev: The cut command, Up: Opening the software toolbox": { "content": "", "subsections": [ { "name": "The 'sort' Command", "content": "" } ] }, "Next we'll look at the 'sort' command. This is one of the most powerful": { "content": "commands on a Unix-style system; one that you will often find yourself\nusing when setting up fancy data plumbing.\n\nThe 'sort' command reads and sorts each file named on the command\nline. It then merges the sorted data and writes it to standard output.", "subsections": [] }, "It will read standard input if no files are given on the command line": { "content": "(thus making it into a filter). The sort is based on the character\ncollating sequence or based on user-supplied ordering criteria.\n", "subsections": [] }, "File: coreutils.info, Node: The uniq command, Next: Putting the tools together, Prev: The sort command, Up: Opening the software toolbox": { "content": "", "subsections": [ { "name": "The 'uniq' Command", "content": "" } ] }, "Finally (at least for now), we'll look at the 'uniq' program. When": { "content": "sorting data, you will often end up with duplicate lines, lines that are\nidentical. Usually, all you need is one instance of each line. This is\nwhere 'uniq' comes in. The 'uniq' program reads its standard input. It\nprints only one copy of each repeated line. It does have several\noptions. Later on, we'll use the '-c' option, which prints each unique\nline, preceded by a count of the number of times that line occurred in\nthe input.\n", "subsections": [] }, "File: coreutils.info, Node: Putting the tools together, Prev: The uniq command, Up: Opening the software toolbox": { "content": "", "subsections": [ { "name": "Putting the Tools Together", "content": "" } ] }, "Now, let's suppose this is a large ISP server system with dozens of": { "content": "users logged in. The management wants the system administrator to write\na program that will generate a sorted list of logged in users.", "subsections": [] }, "Furthermore, even if a user is logged in multiple times, his or her name": { "content": "should only show up in the output once.\n\nThe administrator could sit down with the system documentation and\nwrite a C program that did this. It would take perhaps a couple of\nhundred lines of code and about two hours to write it, test it, and\ndebug it. However, knowing the software toolbox, the administrator can\ninstead start out by generating just a list of logged on users:\n\n$ who | cut -c1-8\n-| arnold\n-| miriam\n-| bill\n-| arnold\n\nNext, sort the list:\n\n$ who | cut -c1-8 | sort\n-| arnold\n-| arnold\n-| bill\n-| miriam\n\nFinally, run the sorted list through 'uniq', to weed out duplicates:\n\n$ who | cut -c1-8 | sort | uniq\n-| arnold\n-| bill\n-| miriam\n\nThe 'sort' command actually has a '-u' option that does what 'uniq'\ndoes. However, 'uniq' has other uses for which one cannot substitute\n'sort -u'.\n\nThe administrator puts this pipeline into a shell script, and makes\nit available for all the users on the system ('#' is the system\nadministrator, or 'root', prompt):\n\n# cat > /usr/local/bin/listusers\nwho | cut -c1-8 | sort | uniq\n^D\n# chmod +x /usr/local/bin/listusers\n\nThere are four major points to note here. First, with just four\nprograms, on one command line, the administrator was able to save about\ntwo hours worth of work. Furthermore, the shell pipeline is just about\nas efficient as the C program would be, and it is much more efficient in\nterms of programmer time. People time is much more expensive than\ncomputer time, and in our modern \"there's never enough time to do\neverything\" society, saving two hours of programmer time is no mean\nfeat.\n\nSecond, it is also important to emphasize that with the combination\nof the tools, it is possible to do a special purpose job never imagined\nby the authors of the individual programs.\n\nThird, it is also valuable to build up your pipeline in stages, as we\ndid here. This allows you to view the data at each stage in the\npipeline, which helps you acquire the confidence that you are indeed\nusing these tools correctly.\n\nFinally, by bundling the pipeline in a shell script, other users can\nuse your command, without having to remember the fancy plumbing you set\nup for them. In terms of how you run them, shell scripts and compiled\nprograms are indistinguishable.\n\nAfter the previous warm-up exercise, we'll look at two additional,\nmore complicated pipelines. For them, we need to introduce two more\ntools.\n\nThe first is the 'tr' command, which stands for \"transliterate.\" The\n'tr' command works on a character-by-character basis, changing\ncharacters. Normally it is used for things like mapping upper case to\nlower case:\n\n$ echo ThIs ExAmPlE HaS MIXED case! | tr '[:upper:]' '[:lower:]'\n-| this example has mixed case!\n\nThere are several options of interest:\n\n'-c'\nwork on the complement of the listed characters, i.e., operations\napply to characters not in the given set\n\n'-d'\ndelete characters in the first set from the output\n\n'-s'\nsqueeze repeated characters in the output into just one character.\n\nWe will be using all three options in a moment.\n\nThe other command we'll look at is 'comm'. The 'comm' command takes\ntwo sorted input files as input data, and prints out the files' lines in\nthree columns. The output columns are the data lines unique to the\nfirst file, the data lines unique to the second file, and the data lines\nthat are common to both. The '-1', '-2', and '-3' command line options\nomit the respective columns. (This is non-intuitive and takes a\nlittle getting used to.) For example:\n\n$ cat f1\n-| 11111\n-| 22222\n-| 33333\n-| 44444\n$ cat f2\n-| 00000\n-| 22222\n-| 33333\n-| 55555\n$ comm f1 f2\n-| 00000\n-| 11111\n-| 22222\n-| 33333\n-| 44444\n-| 55555\n\nThe file name '-' tells 'comm' to read standard input instead of a\nregular file.\n\nNow we're ready to build a fancy pipeline. The first application is\na word frequency counter. This helps an author determine if he or she\nis over-using certain words.\n\nThe first step is to change the case of all the letters in our input\nfile to one case. \"The\" and \"the\" are the same word when doing\ncounting.\n\n$ tr '[:upper:]' '[:lower:]' < whats.gnu | ...\n\nThe next step is to get rid of punctuation. Quoted words and\nunquoted words should be treated identically; it's easiest to just get\nthe punctuation out of the way.\n\n$ tr '[:upper:]' '[:lower:]' < whats.gnu | tr -cd '[:alnum:] \\n' | ...\n\nThe second 'tr' command operates on the complement of the listed\ncharacters, which are all the letters, the digits, the underscore, and\nthe blank. The '\\n' represents the newline character; it has to be left\nalone. (The ASCII tab character should also be included for good\nmeasure in a production script.)\n\nAt this point, we have data consisting of words separated by blank\nspace. The words only contain alphanumeric characters (and the\nunderscore). The next step is break the data apart so that we have one\nword per line. This makes the counting operation much easier, as we\nwill see shortly.\n\n$ tr '[:upper:]' '[:lower:]' < whats.gnu | tr -cd '[:alnum:] \\n' |\n> tr -s ' ' '\\n' | ...\n\nThis command turns blanks into newlines. The '-s' option squeezes\nmultiple newline characters in the output into just one, removing blank\nlines. (The '>' is the shell's \"secondary prompt.\" This is what the\nshell prints when it notices you haven't finished typing in all of a\ncommand.)\n\nWe now have data consisting of one word per line, no punctuation, all\none case. We're ready to count each word:\n\n$ tr '[:upper:]' '[:lower:]' < whats.gnu | tr -cd '[:alnum:] \\n' |\n> tr -s ' ' '\\n' | sort | uniq -c | ...\n\nAt this point, the data might look something like this:\n\n60 a\n2 able\n6 about\n1 above\n2 accomplish\n1 acquire\n1 actually\n2 additional\n\nThe output is sorted by word, not by count! What we want is the most\nfrequently used words first. Fortunately, this is easy to accomplish,\nwith the help of two more 'sort' options:\n\n'-n'\ndo a numeric sort, not a textual one\n\n'-r'\nreverse the order of the sort\n\nThe final pipeline looks like this:\n\n$ tr '[:upper:]' '[:lower:]' < whats.gnu | tr -cd '[:alnum:] \\n' |\n> tr -s ' ' '\\n' | sort | uniq -c | sort -n -r\n-| 156 the\n-| 60 a\n-| 58 to\n-| 51 of\n-| 51 and\n...\n\nWhew! That's a lot to digest. Yet, the same principles apply. With\nsix commands, on two lines (really one long one split for convenience),\nwe've created a program that does something interesting and useful, in\nmuch less time than we could have written a C program to do the same\nthing.\n\nA minor modification to the above pipeline can give us a simple\nspelling checker! To determine if you've spelled a word correctly, all\nyou have to do is look it up in a dictionary. If it is not there, then\nchances are that your spelling is incorrect. So, we need a dictionary.", "subsections": [] }, "The conventional location for a dictionary is '/usr/dict/words'. On my": { "content": "GNU/Linux system,(1) this is a sorted, 45,402 word dictionary.\n\nNow, how to compare our file with the dictionary? As before, we\ngenerate a sorted list of words, one per line:\n\n$ tr '[:upper:]' '[:lower:]' < whats.gnu | tr -cd '[:alnum:] \\n' |\n> tr -s ' ' '\\n' | sort -u | ...\n\nNow, all we need is a list of words that are not in the dictionary.\nHere is where the 'comm' command comes in.\n\n$ tr '[:upper:]' '[:lower:]' < whats.gnu | tr -cd '[:alnum:] \\n' |\n> tr -s ' ' '\\n' | sort -u |\n> comm -23 - /usr/dict/words\n\nThe '-2' and '-3' options eliminate lines that are only in the\ndictionary (the second file), and lines that are in both files. Lines\nonly in the first file (standard input, our stream of words), are words\nthat are not in the dictionary. These are likely candidates for\nspelling errors. This pipeline was the first cut at a production\nspelling checker on Unix.\n\nThere are some other tools that deserve brief mention.\n\n'grep'\nsearch files for text that matches a regular expression\n\n'wc'\ncount lines, words, characters\n\n'tee'\na T-fitting for data pipes, copies data to files and to standard\noutput\n\n'sed'\nthe stream editor, an advanced tool\n\n'awk'\na data manipulation language, another advanced tool\n\nThe software tools philosophy also espoused the following bit of\nadvice: \"Let someone else do the hard part.\" This means, take something\nthat gives you most of what you need, and then massage it the rest of\nthe way until it's in the form that you want.\n\nTo summarize:\n\n1. Each program should do one thing well. No more, no less.\n\n2. Combining programs with appropriate plumbing leads to results where\nthe whole is greater than the sum of the parts. It also leads to\nnovel uses of programs that the authors might never have imagined.\n\n3. Programs should never print extraneous header or trailer data,\nsince these could get sent on down a pipeline. (A point we didn't\nmention earlier.)\n\n4. Let someone else do the hard part.\n\n5. Know your toolbox! Use each program appropriately. If you don't\nhave an appropriate tool, build one.\n\nAll the programs discussed are available as described in GNU core\nutilities (https://www.gnu.org/software/coreutils/coreutils.html).\n\nNone of what I have presented in this column is new. The Software", "subsections": [] }, "Tools philosophy was first introduced in the book 'Software Tools', by": { "content": "Brian Kernighan and P.J. Plauger (Addison-Wesley, ISBN 0-201-03669-X).", "subsections": [] }, "This book showed how to write and use software tools. It was written in": { "content": "1976, using a preprocessor for FORTRAN named 'ratfor' (RATional\nFORtran). At the time, C was not as ubiquitous as it is now; FORTRAN\nwas. The last chapter presented a 'ratfor' to FORTRAN processor,\nwritten in 'ratfor'. 'ratfor' looks an awful lot like C; if you know C,\nyou won't have any problem following the code.\n\nIn 1981, the book was updated and made available as 'Software Tools\nin Pascal' (Addison-Wesley, ISBN 0-201-10342-7). Both books are still\nin print and are well worth reading if you're a programmer. They\ncertainly made a major change in how I view programming.\n\nThe programs in both books are available from Brian Kernighan's home\npage (https://www.cs.princeton.edu/~bwk/). For a number of years, there\nwas an active Software Tools Users Group, whose members had ported the\noriginal 'ratfor' programs to essentially every computer system with a\nFORTRAN compiler. The popularity of the group waned in the middle 1980s\nas Unix began to spread beyond universities.\n\nWith the current proliferation of GNU code and other clones of Unix\nprograms, these programs now receive little attention; modern C versions\nare much more efficient and do more than these programs do.", "subsections": [] }, "Nevertheless, as exposition of good programming style, and evangelism": { "content": "for a still-valuable philosophy, these books are unparalleled, and I\nrecommend them highly.\n\nAcknowledgment: I would like to express my gratitude to Brian", "subsections": [] }, "Kernighan of Bell Labs, the original Software Toolsmith, for reviewing": { "content": "this column.\n\n---------- Footnotes ----------\n\n(1) Redhat Linux 6.1, for the November 2000 revision of this article.\n", "subsections": [] }, "File: coreutils.info, Node: GNU Free Documentation License, Next: Concept index, Prev: Opening the software toolbox, Up: Top": { "content": "", "subsections": [] }, "Appendix A GNU Free Documentation License": { "content": "Version 1.3, 3 November 2008\n\nCopyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.\n\n\nEveryone is permitted to copy and distribute verbatim copies\nof this license document, but changing it is not allowed.\n\n0. PREAMBLE\n\nThe purpose of this License is to make a manual, textbook, or other\nfunctional and useful document \"free\" in the sense of freedom: to\nassure everyone the effective freedom to copy and redistribute it,\nwith or without modifying it, either commercially or\nnoncommercially. Secondarily, this License preserves for the\nauthor and publisher a way to get credit for their work, while not\nbeing considered responsible for modifications made by others.\n\nThis License is a kind of \"copyleft\", which means that derivative\nworks of the document must themselves be free in the same sense.\nIt complements the GNU General Public License, which is a copyleft\nlicense designed for free software.\n\nWe have designed this License in order to use it for manuals for\nfree software, because free software needs free documentation: a\nfree program should come with manuals providing the same freedoms\nthat the software does. But this License is not limited to\nsoftware manuals; it can be used for any textual work, regardless\nof subject matter or whether it is published as a printed book. We\nrecommend this License principally for works whose purpose is\ninstruction or reference.\n\n1. APPLICABILITY AND DEFINITIONS\n\nThis License applies to any manual or other work, in any medium,\nthat contains a notice placed by the copyright holder saying it can\nbe distributed under the terms of this License. Such a notice\ngrants a world-wide, royalty-free license, unlimited in duration,\nto use that work under the conditions stated herein. The\n\"Document\", below, refers to any such manual or work. Any member\nof the public is a licensee, and is addressed as \"you\". 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The relationship could be a matter of\nhistorical connection with the subject or with related matters, or\nof legal, commercial, philosophical, ethical or political position\nregarding them.\n\nThe \"Invariant Sections\" are certain Secondary Sections whose\ntitles are designated, as being those of Invariant Sections, in the\nnotice that says that the Document is released under this License.\nIf a section does not fit the above definition of Secondary then it\nis not allowed to be designated as Invariant. The Document may\ncontain zero Invariant Sections. If the Document does not identify\nany Invariant Sections then there are none.\n\nThe \"Cover Texts\" are certain short passages of text that are\nlisted, as Front-Cover Texts or Back-Cover Texts, in the notice\nthat says that the Document is released under this License. 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Copying with changes limited to the covers, as\nlong as they preserve the title of the Document and satisfy these\nconditions, can be treated as verbatim copying in other respects.\n\nIf the required texts for either cover are too voluminous to fit\nlegibly, you should put the first ones listed (as many as fit\nreasonably) on the actual cover, and continue the rest onto\nadjacent pages.\n\nIf you publish or distribute Opaque copies of the Document\nnumbering more than 100, you must either include a machine-readable\nTransparent copy along with each Opaque copy, or state in or with\neach Opaque copy a computer-network location from which the general\nnetwork-using public has access to download using public-standard\nnetwork protocols a complete Transparent copy of the Document, free\nof added material. If you use the latter option, you must take\nreasonably prudent steps, when you begin distribution of Opaque\ncopies in quantity, to ensure that this Transparent copy will\nremain thus accessible at the stated location until at least one\nyear after the last time you distribute an Opaque copy (directly or\nthrough your agents or retailers) of that edition to the public.\n\nIt is requested, but not required, that you contact the authors of\nthe Document well before redistributing any large number of copies,\nto give them a chance to provide you with an updated version of the\nDocument.\n\n4. MODIFICATIONS\n\nYou may copy and distribute a Modified Version of the Document\nunder the conditions of sections 2 and 3 above, provided that you\nrelease the Modified Version under precisely this License, with the\nModified Version filling the role of the Document, thus licensing\ndistribution and modification of the Modified Version to whoever\npossesses a copy of it. In addition, you must do these things in\nthe Modified Version:\n\nA. Use in the Title Page (and on the covers, if any) a title\ndistinct from that of the Document, and from those of previous\nversions (which should, if there were any, be listed in the\nHistory section of the Document). You may use the same title\nas a previous version if the original publisher of that\nversion gives permission.\n\nB. List on the Title Page, as authors, one or more persons or\nentities responsible for authorship of the modifications in\nthe Modified Version, together with at least five of the\nprincipal authors of the Document (all of its principal\nauthors, if it has fewer than five), unless they release you\nfrom this requirement.\n\nC. State on the Title page the name of the publisher of the\nModified Version, as the publisher.\n\nD. Preserve all the copyright notices of the Document.\n\nE. Add an appropriate copyright notice for your modifications\nadjacent to the other copyright notices.\n\nF. Include, immediately after the copyright notices, a license\nnotice giving the public permission to use the Modified\nVersion under the terms of this License, in the form shown in\nthe Addendum below.\n\nG. Preserve in that license notice the full lists of Invariant\nSections and required Cover Texts given in the Document's\nlicense notice.\n\nH. Include an unaltered copy of this License.\n\nI. Preserve the section Entitled \"History\", Preserve its Title,\nand add to it an item stating at least the title, year, new\nauthors, and publisher of the Modified Version as given on the\nTitle Page. If there is no section Entitled \"History\" in the\nDocument, create one stating the title, year, authors, and\npublisher of the Document as given on its Title Page, then add\nan item describing the Modified Version as stated in the\nprevious sentence.\n\nJ. 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COMBINING DOCUMENTS\n\nYou may combine the Document with other documents released under\nthis License, under the terms defined in section 4 above for\nmodified versions, provided that you include in the combination all\nof the Invariant Sections of all of the original documents,\nunmodified, and list them all as Invariant Sections of your\ncombined work in its license notice, and that you preserve all\ntheir Warranty Disclaimers.\n\nThe combined work need only contain one copy of this License, and\nmultiple identical Invariant Sections may be replaced with a single\ncopy. If there are multiple Invariant Sections with the same name\nbut different contents, make the title of each such section unique\nby adding at the end of it, in parentheses, the name of the\noriginal author or publisher of that section if known, or else a\nunique number. Make the same adjustment to the section titles in\nthe list of Invariant Sections in the license notice of the\ncombined work.\n\nIn the combination, you must combine any sections Entitled\n\"History\" in the various original documents, forming one section\nEntitled \"History\"; likewise combine any sections Entitled\n\"Acknowledgements\", and any sections Entitled \"Dedications\". You\nmust delete all sections Entitled \"Endorsements.\"\n\n6. COLLECTIONS OF DOCUMENTS\n\nYou may make a collection consisting of the Document and other\ndocuments released under this License, and replace the individual\ncopies of this License in the various documents with a single copy\nthat is included in the collection, provided that you follow the\nrules of this License for verbatim copying of each of the documents\nin all other respects.\n\nYou may extract a single document from such a collection, and\ndistribute it individually under this License, provided you insert\na copy of this License into the extracted document, and follow this\nLicense in all other respects regarding verbatim copying of that\ndocument.\n\n7. AGGREGATION WITH INDEPENDENT WORKS\n\nA compilation of the Document or its derivatives with other\nseparate and independent documents or works, in or on a volume of a\nstorage or distribution medium, is called an \"aggregate\" if the\ncopyright resulting from the compilation is not used to limit the\nlegal rights of the compilation's users beyond what the individual\nworks permit. When the Document is included in an aggregate, this\nLicense does not apply to the other works in the aggregate which\nare not themselves derivative works of the Document.\n\nIf the Cover Text requirement of section 3 is applicable to these\ncopies of the Document, then if the Document is less than one half\nof the entire aggregate, the Document's Cover Texts may be placed\non covers that bracket the Document within the aggregate, or the\nelectronic equivalent of covers if the Document is in electronic\nform. Otherwise they must appear on printed covers that bracket\nthe whole aggregate.\n\n8. TRANSLATION\n\nTranslation is considered a kind of modification, so you may\ndistribute translations of the Document under the terms of section\n4. Replacing Invariant Sections with translations requires special\npermission from their copyright holders, but you may include\ntranslations of some or all Invariant Sections in addition to the\noriginal versions of these Invariant Sections. You may include a\ntranslation of this License, and all the license notices in the\nDocument, and any Warranty Disclaimers, provided that you also\ninclude the original English version of this License and the\noriginal versions of those notices and disclaimers. In case of a\ndisagreement between the translation and the original version of\nthis License or a notice or disclaimer, the original version will\nprevail.\n\nIf a section in the Document is Entitled \"Acknowledgements\",\n\"Dedications\", or \"History\", the requirement (section 4) to\nPreserve its Title (section 1) will typically require changing the\nactual title.\n\n9. TERMINATION\n\nYou may not copy, modify, sublicense, or distribute the Document\nexcept as expressly provided under this License. Any attempt\notherwise to copy, modify, sublicense, or distribute it is void,\nand will automatically terminate your rights under this License.\n\nHowever, if you cease all violation of this License, then your\nlicense from a particular copyright holder is reinstated (a)\nprovisionally, unless and until the copyright holder explicitly and\nfinally terminates your license, and (b) permanently, if the\ncopyright holder fails to notify you of the violation by some\nreasonable means prior to 60 days after the cessation.\n\nMoreover, your license from a particular copyright holder is\nreinstated permanently if the copyright holder notifies you of the\nviolation by some reasonable means, this is the first time you have\nreceived notice of violation of this License (for any work) from\nthat copyright holder, and you cure the violation prior to 30 days\nafter your receipt of the notice.\n\nTermination of your rights under this section does not terminate\nthe licenses of parties who have received copies or rights from you\nunder this License. If your rights have been terminated and not\npermanently reinstated, receipt of a copy of some or all of the\nsame material does not give you any rights to use it.\n\n10. FUTURE REVISIONS OF THIS LICENSE\n\nThe Free Software Foundation may publish new, revised versions of\nthe GNU Free Documentation License from time to time. Such new\nversions will be similar in spirit to the present version, but may\ndiffer in detail to address new problems or concerns. See\n.\n\nEach version of the License is given a distinguishing version\nnumber. If the Document specifies that a particular numbered\nversion of this License \"or any later version\" applies to it, you\nhave the option of following the terms and conditions either of\nthat specified version or of any later version that has been\npublished (not as a draft) by the Free Software Foundation. If the\nDocument does not specify a version number of this License, you may\nchoose any version ever published (not as a draft) by the Free\nSoftware Foundation. If the Document specifies that a proxy can\ndecide which future versions of this License can be used, that\nproxy's public statement of acceptance of a version permanently\nauthorizes you to choose that version for the Document.\n\n11. RELICENSING\n\n\"Massive Multiauthor Collaboration Site\" (or \"MMC Site\") means any\nWorld Wide Web server that publishes copyrightable works and also\nprovides prominent facilities for anybody to edit those works. A\npublic wiki that anybody can edit is an example of such a server.\nA \"Massive Multiauthor Collaboration\" (or \"MMC\") contained in the\nsite means any set of copyrightable works thus published on the MMC\nsite.\n\n\"CC-BY-SA\" means the Creative Commons Attribution-Share Alike 3.0\nlicense published by Creative Commons Corporation, a not-for-profit\ncorporation with a principal place of business in San Francisco,\nCalifornia, as well as future copyleft versions of that license\npublished by that same organization.\n\n\"Incorporate\" means to publish or republish a Document, in whole or\nin part, as part of another Document.\n\nAn MMC is \"eligible for relicensing\" if it is licensed under this\nLicense, and if all works that were first published under this\nLicense somewhere other than this MMC, and subsequently\nincorporated in whole or in part into the MMC, (1) had no cover\ntexts or invariant sections, and (2) were thus incorporated prior\nto November 1, 2008.\n\nThe operator of an MMC Site may republish an MMC contained in the\nsite under CC-BY-SA on the same site at any time before August 1,\n2009, provided the MMC is eligible for relicensing.\n", "subsections": [ { "name": "ADDENDUM: How to use this License for your documents", "content": "" } ] }, "To use this License in a document you have written, include a copy of": { "content": "the License in the document and put the following copyright and license\nnotices just after the title page:\n\nCopyright (C) YEAR YOUR NAME.\nPermission is granted to copy, distribute and/or modify this document\nunder the terms of the GNU Free Documentation License, Version 1.3\nor any later version published by the Free Software Foundation;\nwith no Invariant Sections, no Front-Cover Texts, and no Back-Cover\nTexts. A copy of the license is included in the section entitled ``GNU\nFree Documentation License''.\n\nIf you have Invariant Sections, Front-Cover Texts and Back-Cover\nTexts, replace the \"with...Texts.\" line with this:\n\nwith the Invariant Sections being LIST THEIR TITLES, with\nthe Front-Cover Texts being LIST, and with the Back-Cover Texts\nbeing LIST.\n\nIf you have Invariant Sections without Cover Texts, or some other\ncombination of the three, merge those two alternatives to suit the\nsituation.\n\nIf your document contains nontrivial examples of program code, we\nrecommend releasing these examples in parallel under your choice of free\nsoftware license, such as the GNU General Public License, to permit\ntheir use in free software.\n", "subsections": [] }, "File: coreutils.info, Node: Concept index, Prev: GNU Free Documentation License, Up: Top": { "content": "", "subsections": [] }, "Index": { "content": "* Menu:\n\n* !: Connectives for test.\n(line 23)\n* !=: String tests. (line 28)\n* %: Numeric expressions. (line 16)\n* %b: printf invocation. (line 37)\n* %q: printf invocation. (line 44)\n* &: Relations for expr. (line 17)\n* *: Numeric expressions. (line 16)\n* +: String expressions. (line 53)\n* + <1>: Numeric expressions. (line 12)\n* +PAGERANGE: pr invocation. (line 39)\n* -: Numeric expressions. (line 12)\n* - <1>: env invocation. (line 102)\n* - and Unix rm: rm invocation. (line 113)\n* -, removing files beginning with: rm invocation. (line 101)\n* --: Common options. (line 43)\n* --across: pr invocation. (line 62)\n* --additional-suffix: split invocation. (line 135)\n* --address-radix: od invocation. (line 36)\n* --adjustment: nice invocation. (line 51)\n* --all: unexpand invocation. (line 51)\n* --all <1>: Which files are listed.\n(line 13)\n* --all <2>: df invocation. (line 42)\n* --all <3>: du invocation. (line 32)\n* --all <4>: stty invocation. (line 26)\n* --all <5>: who invocation. (line 35)\n* --all <6>: nproc invocation. (line 20)\n* --all <7>: uname invocation. (line 30)\n* --all-repeated: uniq invocation. (line 69)\n* --almost-all: Which files are listed.\n(line 17)\n* --apparent-size: du invocation. (line 35)\n* --append: tee invocation. (line 27)\n* --archive: cp invocation. (line 63)\n* --attributes-only: cp invocation. (line 72)\n* --author: What information is listed.\n(line 10)\n* --auto-reference: Output formatting in ptx.\n(line 45)\n* --backup: Backup options. (line 13)\n* --backup <1>: cp invocation. (line 79)\n* --backup <2>: install invocation. (line 41)\n* --backup <3>: mv invocation. (line 59)\n* --backup <4>: ln invocation. (line 82)\n* --base16: basenc invocation. (line 49)\n* --base2lsbf: basenc invocation. (line 55)\n* --base2msbf: basenc invocation. (line 59)\n* --base32: basenc invocation. (line 35)\n* --base32hex: basenc invocation. (line 42)\n* --base64: basenc invocation. (line 23)\n* --base64url: basenc invocation. (line 29)\n* --batch-size: sort invocation. (line 262)\n* --before: tac invocation. (line 21)\n* --binary: md5sum invocation. (line 41)\n* --block-size: Block size. (line 121)\n* --block-size <1>: df invocation. (line 54)\n* --block-size <2>: du invocation. (line 52)\n* --block-size=SIZE: Block size. (line 12)\n* --body-numbering: nl invocation. (line 45)\n* --boot: who invocation. (line 39)\n* --bourne-shell: dircolors invocation.\n(line 34)\n* --break-file: Input processing in ptx.\n(line 8)\n* --buffer-size: sort invocation. (line 316)\n* --bytes: fold invocation. (line 23)\n* --bytes <1>: head invocation. (line 24)\n* --bytes <2>: tail invocation. (line 39)\n* --bytes <3>: split invocation. (line 41)\n* --bytes <4>: wc invocation. (line 43)\n* --bytes <5>: cut invocation. (line 26)\n* --bytes <6>: du invocation. (line 57)\n* --c-shell: dircolors invocation.\n(line 40)\n* --cached=MODE: stat invocation. (line 33)\n* --canonicalize: readlink invocation. (line 31)\n* --canonicalize-existing: readlink invocation. (line 38)\n* --canonicalize-existing <1>: realpath invocation. (line 22)\n* --canonicalize-missing: readlink invocation. (line 45)\n* --canonicalize-missing <1>: realpath invocation. (line 30)\n* --changes: chown invocation. (line 73)\n* --changes <1>: chgrp invocation. (line 24)\n* --changes <2>: chmod invocation. (line 43)\n* --characters: cut invocation. (line 34)\n* --chars: wc invocation. (line 47)\n* --chdir: env invocation. (line 107)\n* --check: sort invocation. (line 39)\n* --check <1>: sort invocation. (line 47)\n* --check-chars: uniq invocation. (line 133)\n* --classify: General output formatting.\n(line 46)\n* --color: General output formatting.\n(line 22)\n* --columns: pr invocation. (line 49)\n* --compare: install invocation. (line 46)\n* --complement: cut invocation. (line 86)\n* --compute: runcon invocation. (line 32)\n* --context: What information is listed.\n(line 259)\n* --context <1>: cp invocation. (line 384)\n* --context <2>: install invocation. (line 139)\n* --context <3>: mv invocation. (line 117)\n* --context <4>: mkdir invocation. (line 56)\n* --context <5>: mkfifo invocation. (line 28)\n* --context <6>: mknod invocation. (line 53)\n* --context <7>: id invocation. (line 51)\n* --count: uniq invocation. (line 55)\n* --count <1>: who invocation. (line 69)\n* --count-links: du invocation. (line 123)\n* --crown-margin: fmt invocation. (line 34)\n* --csh: dircolors invocation.\n(line 40)\n* --data: sync invocation. (line 32)\n* --date: touch invocation. (line 56)\n* --date <1>: Options for date. (line 11)\n* --dead: who invocation. (line 43)\n* --debug: Options for date. (line 25)\n* --debug <1>: env invocation. (line 173)\n* --debug <2>: numfmt invocation. (line 29)\n* --decode: base64 invocation. (line 30)\n* --delimiter: cut invocation. (line 66)\n* --delimiter <1>: numfmt invocation. (line 34)\n* --delimiters: paste invocation. (line 61)\n* --dereference: Which files are listed.\n(line 83)\n* --dereference <1>: cp invocation. (line 149)\n* --dereference <2>: chown invocation. (line 106)\n* --dereference <3>: chgrp invocation. (line 34)\n* --dereference <4>: du invocation. (line 117)\n* --dereference <5>: stat invocation. (line 22)\n* --dereference <6>: chcon invocation. (line 21)\n* --dereference-args: du invocation. (line 67)\n* --dereference-command-line: Which files are listed.\n(line 36)\n* --dereference-command-line-symlink-to-dir: Which files are listed.\n(line 41)\n* --dictionary-order: sort invocation. (line 87)\n* --digits: csplit invocation. (line 81)\n* --dir: rm invocation. (line 35)\n* --directory: Which files are listed.\n(line 28)\n* --directory <1>: install invocation. (line 67)\n* --directory <2>: ln invocation. (line 88)\n* --directory <3>: mktemp invocation. (line 85)\n* --dired: What information is listed.\n(line 16)\n* --double-space: pr invocation. (line 74)\n* --dry-run: mktemp invocation. (line 97)\n* --echo: shuf invocation. (line 19)\n* --elide-empty-files: split invocation. (line 140)\n* --elide-empty-files <1>: csplit invocation. (line 95)\n* --endian: od invocation. (line 51)\n* --equal-width: seq invocation. (line 49)\n* --error: stdbuf invocation. (line 34)\n* --escape: Formatting the file names.\n(line 11)\n* --exact: shred invocation. (line 164)\n* --exclude-from=FILE: du invocation. (line 252)\n* --exclude-type: df invocation. (line 223)\n* --exclude=PATTERN: du invocation. (line 257)\n* --expand-tabs: pr invocation. (line 98)\n* --field: numfmt invocation. (line 38)\n* --field-separator: sort invocation. (line 332)\n* --fields: cut invocation. (line 43)\n* --file: stty invocation. (line 31)\n* --file <1>: Options for date. (line 30)\n* --file-system: stat invocation. (line 28)\n* --file-system <1>: sync invocation. (line 37)\n* --file-type: General output formatting.\n(line 57)\n* --files0-from=FILE: wc invocation. (line 64)\n* --files0-from=FILE <1>: sort invocation. (line 218)\n* --files0-from=FILE <2>: du invocation. (line 79)\n* --filter: split invocation. (line 63)\n* --first-line-number: pr invocation. (line 174)\n* --flag-truncation: Output formatting in ptx.\n(line 71)\n* --follow: tail invocation. (line 56)\n* --footer-numbering: nl invocation. (line 70)\n* --force: cp invocation. (line 115)\n* --force <1>: mv invocation. (line 64)\n* --force <2>: rm invocation. (line 39)\n* --force <3>: shred invocation. (line 123)\n* --force <4>: ln invocation. (line 94)\n* --foreground: timeout invocation. (line 24)\n* --form-feed: pr invocation. (line 106)\n* --format: od invocation. (line 90)\n* --format <1>: What information is listed.\n(line 131)\n* --format <2>: General output formatting.\n(line 10)\n* --format <3>: General output formatting.\n(line 16)\n* --format <4>: General output formatting.\n(line 103)\n* --format <5>: General output formatting.\n(line 113)\n* --format <6>: numfmt invocation. (line 48)\n* --format <7>: seq invocation. (line 28)\n* --format=FORMAT: stat invocation. (line 50)\n* --format=roff: Output formatting in ptx.\n(line 100)\n* --format=tex: Output formatting in ptx.\n(line 118)\n* --from: chown invocation. (line 83)\n* --from <1>: numfmt invocation. (line 59)\n* --from-unit: numfmt invocation. (line 64)\n* --full-time: What information is listed.\n(line 100)\n* --gap-size: Output formatting in ptx.\n(line 26)\n* --general-numeric-sort: sort invocation. (line 105)\n* --goal: fmt invocation. (line 64)\n* --group: uniq invocation. (line 100)\n* --group <1>: install invocation. (line 73)\n* --group <2>: id invocation. (line 29)\n* --group-directories-first: Which files are listed.\n(line 50)\n* --grouping: numfmt invocation. (line 70)\n* --groups: id invocation. (line 33)\n* --groups <1>: chroot invocation. (line 24)\n* --hardware-platform: uname invocation. (line 35)\n* --head-count: shuf invocation. (line 31)\n* --header: pr invocation. (line 111)\n* --header <1>: General options in join.\n(line 25)\n* --header <2>: numfmt invocation. (line 76)\n* --header-numbering: nl invocation. (line 74)\n* --header=N: numfmt invocation. (line 76)\n* --heading: who invocation. (line 47)\n* --help: Common options. (line 36)\n* --hex-suffixes: split invocation. (line 131)\n* --hide-control-chars: Formatting the file names.\n(line 23)\n* --hide=PATTERN: Which files are listed.\n(line 57)\n* --human-numeric-sort: sort invocation. (line 126)\n* --human-readable: Block size. (line 121)\n* --human-readable <1>: What information is listed.\n(line 116)\n* --human-readable <2>: df invocation. (line 59)\n* --human-readable <3>: du invocation. (line 96)\n* --hyperlink: General output formatting.\n(line 61)\n* --ignore: nproc invocation. (line 26)\n* --ignore-backups: Which files are listed.\n(line 23)\n* --ignore-case: sort invocation. (line 94)\n* --ignore-case <1>: uniq invocation. (line 59)\n* --ignore-case <2>: Charset selection in ptx.\n(line 18)\n* --ignore-case <3>: General options in join.\n(line 35)\n* --ignore-environment: env invocation. (line 102)\n* --ignore-fail-on-non-empty: rmdir invocation. (line 17)\n* --ignore-file: Input processing in ptx.\n(line 26)\n* --ignore-garbage: base64 invocation. (line 36)\n* --ignore-interrupts: tee invocation. (line 32)\n* --ignore-leading-blanks: sort invocation. (line 79)\n* --ignore-missing: md5sum invocation. (line 76)\n* --ignore-nonprinting: sort invocation. (line 143)\n* --ignore=PATTERN: Which files are listed.\n(line 69)\n* --indent: pr invocation. (line 180)\n* --indicator-style: General output formatting.\n(line 46)\n* --indicator-style <1>: General output formatting.\n(line 57)\n* --indicator-style <2>: General output formatting.\n(line 70)\n* --indicator-style <3>: General output formatting.\n(line 108)\n* --initial: expand invocation. (line 46)\n* --inode: What information is listed.\n(line 123)\n* --inodes: df invocation. (line 69)\n* --inodes <1>: du invocation. (line 102)\n* --input: stdbuf invocation. (line 26)\n* --input-range: shuf invocation. (line 23)\n* --interactive: cp invocation. (line 139)\n* --interactive <1>: mv invocation. (line 70)\n* --interactive <2>: rm invocation. (line 54)\n* --interactive <3>: ln invocation. (line 98)\n* --invalid: numfmt invocation. (line 79)\n* --io-blocks: truncate invocation. (line 26)\n* --iso-8601[=TIMESPEC]: Options for date. (line 38)\n* --iterations=NUMBER: shred invocation. (line 127)\n* --join-blank-lines: nl invocation. (line 82)\n* --join-lines: pr invocation. (line 124)\n* --keep-files: csplit invocation. (line 86)\n* --kernel-name: uname invocation. (line 66)\n* --kernel-release: uname invocation. (line 62)\n* --kernel-version: uname invocation. (line 77)\n* --key: sort invocation. (line 231)\n* --kibibytes: General output formatting.\n(line 89)\n* --kill-after: timeout invocation. (line 41)\n* --length: pr invocation. (line 133)\n* --length <1>: b2sum invocation. (line 12)\n* --line-bytes: split invocation. (line 56)\n* --line-increment: nl invocation. (line 78)\n* --lines: head invocation. (line 40)\n* --lines <1>: tail invocation. (line 125)\n* --lines <2>: split invocation. (line 33)\n* --lines <3>: wc invocation. (line 55)\n* --link: cp invocation. (line 145)\n* --literal: Formatting the file names.\n(line 17)\n* --local: df invocation. (line 80)\n* --logical: ln invocation. (line 102)\n* --logical <1>: realpath invocation. (line 35)\n* --logical <2>: pwd invocation. (line 15)\n* --login: who invocation. (line 51)\n* --lookup: who invocation. (line 56)\n* --machine: uname invocation. (line 42)\n* --macro-name: Output formatting in ptx.\n(line 94)\n* --max-depth=DEPTH: du invocation. (line 74)\n* --max-line-length: wc invocation. (line 59)\n* --max-unchanged-stats: tail invocation. (line 113)\n* --merge: pr invocation. (line 140)\n* --merge <1>: sort invocation. (line 53)\n* --mesg: who invocation. (line 94)\n* --message: who invocation. (line 94)\n* --mode: install invocation. (line 79)\n* --mode <1>: mkdir invocation. (line 19)\n* --mode <2>: mkfifo invocation. (line 21)\n* --mode <3>: mknod invocation. (line 47)\n* --month-sort: sort invocation. (line 150)\n* --multiple: basename invocation. (line 32)\n* --name: id invocation. (line 37)\n* --no-clobber: cp invocation. (line 156)\n* --no-clobber <1>: mv invocation. (line 77)\n* --no-create: touch invocation. (line 52)\n* --no-create <1>: truncate invocation. (line 22)\n* --no-dereference: cp invocation. (line 162)\n* --no-dereference <1>: ln invocation. (line 108)\n* --no-dereference <2>: chown invocation. (line 118)\n* --no-dereference <3>: chgrp invocation. (line 46)\n* --no-dereference <4>: touch invocation. (line 70)\n* --no-dereference <5>: du invocation. (line 133)\n* --no-dereference <6>: chcon invocation. (line 26)\n* --no-file-warnings: pr invocation. (line 187)\n* --no-group: What information is listed.\n(line 110)\n* --no-newline: readlink invocation. (line 50)\n* --no-preserve-root: rm invocation. (line 88)\n* --no-preserve-root <1>: chown invocation. (line 131)\n* --no-preserve-root <2>: chgrp invocation. (line 59)\n* --no-preserve-root <3>: chmod invocation. (line 58)\n* --no-preserve-root <4>: chcon invocation. (line 43)\n* --no-renumber: nl invocation. (line 101)\n* --no-symlinks: realpath invocation. (line 64)\n* --no-sync: df invocation. (line 84)\n* --no-target-directory: Target directory. (line 15)\n* --no-target-directory <1>: cp invocation. (line 354)\n* --no-target-directory <2>: install invocation. (line 130)\n* --no-target-directory <3>: mv invocation. (line 112)\n* --no-target-directory <4>: ln invocation. (line 175)\n* --nodename: uname invocation. (line 47)\n* --null: du invocation. (line 26)\n* --null <1>: printenv invocation. (line 19)\n* --null <2>: env invocation. (line 90)\n* --number: cat invocation. (line 31)\n* --number <1>: split invocation. (line 79)\n* --number-format: nl invocation. (line 90)\n* --number-lines: pr invocation. (line 153)\n* --number-nonblank: cat invocation. (line 20)\n* --number-separator: nl invocation. (line 105)\n* --number-width: nl invocation. (line 115)\n* --numeric-sort: sort invocation. (line 160)\n* --numeric-suffixes: split invocation. (line 117)\n* --numeric-uid-gid: What information is listed.\n(line 225)\n* --omit-header: pr invocation. (line 210)\n* --omit-pagination: pr invocation. (line 220)\n* --one-file-system: cp invocation. (line 378)\n* --one-file-system <1>: rm invocation. (line 65)\n* --one-file-system <2>: du invocation. (line 263)\n* --only-delimited: cut invocation. (line 74)\n* --only-file: Input processing in ptx.\n(line 35)\n* --operating-system: uname invocation. (line 58)\n* --output: sort invocation. (line 288)\n* --output <1>: shuf invocation. (line 36)\n* --output <2>: df invocation. (line 91)\n* --output <3>: stdbuf invocation. (line 30)\n* --output-delimiter: cut invocation. (line 79)\n* --output-duplicates: od invocation. (line 150)\n* --output-error: tee invocation. (line 36)\n* --output-tabs: pr invocation. (line 117)\n* --owner: install invocation. (line 91)\n* --padding: numfmt invocation. (line 87)\n* --pages=PAGERANGE: pr invocation. (line 39)\n* --pagewidth: pr invocation. (line 239)\n* --parallel: sort invocation. (line 360)\n* --parents: cp invocation. (line 239)\n* --parents <1>: mkdir invocation. (line 34)\n* --parents <2>: rmdir invocation. (line 22)\n* --physical: ln invocation. (line 127)\n* --physical <1>: realpath invocation. (line 40)\n* --physical <2>: pwd invocation. (line 22)\n* --pid: tail invocation. (line 131)\n* --portability: df invocation. (line 148)\n* --portability <1>: pathchk invocation. (line 44)\n* --prefix: csplit invocation. (line 63)\n* --preserve: cp invocation. (line 169)\n* --preserve-context: install invocation. (line 96)\n* --preserve-root: rm invocation. (line 81)\n* --preserve-root <1>: chown invocation. (line 126)\n* --preserve-root <2>: chgrp invocation. (line 54)\n* --preserve-root <3>: chmod invocation. (line 53)\n* --preserve-root <4>: chcon invocation. (line 38)\n* --preserve-status: timeout invocation. (line 18)\n* --preserve-timestamps: install invocation. (line 103)\n* --print-database: dircolors invocation.\n(line 45)\n* --print-type: df invocation. (line 200)\n* --printf=FORMAT: stat invocation. (line 59)\n* --process: who invocation. (line 65)\n* --processor: uname invocation. (line 51)\n* --quiet: head invocation. (line 47)\n* --quiet <1>: tail invocation. (line 153)\n* --quiet <2>: csplit invocation. (line 106)\n* --quiet <3>: md5sum invocation. (line 82)\n* --quiet <4>: readlink invocation. (line 57)\n* --quiet <5>: chown invocation. (line 79)\n* --quiet <6>: chgrp invocation. (line 30)\n* --quiet <7>: chmod invocation. (line 49)\n* --quiet <8>: mktemp invocation. (line 92)\n* --quiet <9>: realpath invocation. (line 46)\n* --quiet <10>: tty invocation. (line 18)\n* --quote-name: Formatting the file names.\n(line 30)\n* --quoting-style: Formatting the file names.\n(line 11)\n* --quoting-style <1>: Formatting the file names.\n(line 17)\n* --quoting-style <2>: Formatting the file names.\n(line 30)\n* --quoting-style <3>: Formatting the file names.\n(line 34)\n* --random-sort: sort invocation. (line 189)\n* --random-source: sort invocation. (line 304)\n* --random-source <1>: shuf invocation. (line 42)\n* --random-source <2>: shred invocation. (line 133)\n* --range: chcon invocation. (line 77)\n* --range <1>: runcon invocation. (line 48)\n* --read-bytes: od invocation. (line 76)\n* --real: id invocation. (line 42)\n* --recursive: Which files are listed.\n(line 90)\n* --recursive <1>: cp invocation. (line 252)\n* --recursive <2>: rm invocation. (line 95)\n* --recursive <3>: chown invocation. (line 150)\n* --recursive <4>: chgrp invocation. (line 77)\n* --recursive <5>: chmod invocation. (line 73)\n* --recursive <6>: chcon invocation. (line 35)\n* --reference: chown invocation. (line 135)\n* --reference <1>: chgrp invocation. (line 63)\n* --reference <2>: chmod invocation. (line 66)\n* --reference <3>: touch invocation. (line 89)\n* --reference <4>: truncate invocation. (line 30)\n* --reference <5>: Options for date. (line 65)\n* --reference <6>: chcon invocation. (line 30)\n* --references: Input processing in ptx.\n(line 48)\n* --reflink[=WHEN]: cp invocation. (line 265)\n* --regex: tac invocation. (line 26)\n* --relative: ln invocation. (line 136)\n* --relative-base: realpath invocation. (line 54)\n* --relative-base <1>: Realpath usage examples.\n(line 6)\n* --relative-to: realpath invocation. (line 49)\n* --relative-to <1>: Realpath usage examples.\n(line 6)\n* --remove: shred invocation. (line 144)\n* --remove-destination: cp invocation. (line 295)\n* --remove=unlink: shred invocation. (line 144)\n* --remove=wipe: shred invocation. (line 144)\n* --remove=wipesync: shred invocation. (line 144)\n* --repeat: shuf invocation. (line 47)\n* --repeated: uniq invocation. (line 63)\n* --retry: tail invocation. (line 156)\n* --reverse: sort invocation. (line 183)\n* --reverse <1>: Sorting the output. (line 27)\n* --rfc-2822: Options for date. (line 76)\n* --rfc-3339=TIMESPEC: Options for date. (line 85)\n* --rfc-822: Options for date. (line 76)\n* --rfc-email: Options for date. (line 70)\n* --right-side-refs: Output formatting in ptx.\n(line 56)\n* --role: chcon invocation. (line 69)\n* --role <1>: runcon invocation. (line 40)\n* --round: numfmt invocation. (line 94)\n* --round=down: numfmt invocation. (line 94)\n* --round=from-zero: numfmt invocation. (line 94)\n* --round=nearest: numfmt invocation. (line 94)\n* --round=towards-zero: numfmt invocation. (line 94)\n* --round=up: numfmt invocation. (line 94)\n* --runlevel: who invocation. (line 74)\n* --save: stty invocation. (line 41)\n* --section-delimiter: nl invocation. (line 63)\n* --sentence-regexp: Input processing in ptx.\n(line 65)\n* --sep-string: pr invocation. (line 201)\n* --separate-dirs: du invocation. (line 138)\n* --separator: tac invocation. (line 30)\n* --separator <1>: pr invocation. (line 192)\n* --separator <2>: split invocation. (line 148)\n* --separator <3>: seq invocation. (line 44)\n* --serial: paste invocation. (line 52)\n* --set: Options for date. (line 113)\n* --sh: dircolors invocation.\n(line 34)\n* --show-all: cat invocation. (line 16)\n* --show-control-chars: pr invocation. (line 68)\n* --show-control-chars <1>: Formatting the file names.\n(line 78)\n* --show-ends: cat invocation. (line 27)\n* --show-nonprinting: cat invocation. (line 51)\n* --show-nonprinting <1>: pr invocation. (line 225)\n* --show-tabs: cat invocation. (line 44)\n* --si: Block size. (line 121)\n* --si <1>: What information is listed.\n(line 251)\n* --si <2>: df invocation. (line 167)\n* --si <3>: du invocation. (line 145)\n* --signal: timeout invocation. (line 48)\n* --silent: head invocation. (line 47)\n* --silent <1>: tail invocation. (line 153)\n* --silent <2>: csplit invocation. (line 106)\n* --silent <3>: readlink invocation. (line 57)\n* --silent <4>: chown invocation. (line 79)\n* --silent <5>: chgrp invocation. (line 30)\n* --silent <6>: chmod invocation. (line 49)\n* --silent <7>: tty invocation. (line 18)\n* --size: What information is listed.\n(line 236)\n* --size <1>: truncate invocation. (line 34)\n* --size=BYTES: shred invocation. (line 138)\n* --skip-bytes: od invocation. (line 59)\n* --skip-chars: uniq invocation. (line 41)\n* --skip-chdir: chroot invocation. (line 37)\n* --skip-fields: uniq invocation. (line 31)\n* --sleep-interval: tail invocation. (line 173)\n* --sort: sort invocation. (line 105)\n* --sort <1>: sort invocation. (line 126)\n* --sort <2>: sort invocation. (line 150)\n* --sort <3>: sort invocation. (line 160)\n* --sort <4>: sort invocation. (line 189)\n* --sort <5>: Sorting the output. (line 32)\n* --sort <6>: Sorting the output. (line 36)\n* --sort <7>: Sorting the output. (line 60)\n* --sort <8>: Sorting the output. (line 67)\n* --sort <9>: Sorting the output. (line 74)\n* --spaces: fold invocation. (line 29)\n* --sparse=WHEN: cp invocation. (line 299)\n* --split-only: fmt invocation. (line 47)\n* --split-string: env invocation. (line 188)\n* --squeeze-blank: cat invocation. (line 36)\n* --stable: sort invocation. (line 309)\n* --starting-line-number: nl invocation. (line 110)\n* --status: md5sum invocation. (line 90)\n* --strict: md5sum invocation. (line 123)\n* --strings: od invocation. (line 81)\n* --strip: install invocation. (line 113)\n* --strip <1>: realpath invocation. (line 64)\n* --strip-program: install invocation. (line 116)\n* --strip-trailing-slashes: cp invocation. (line 332)\n* --strip-trailing-slashes <1>: mv invocation. (line 98)\n* --suffix: Backup options. (line 49)\n* --suffix <1>: cp invocation. (line 345)\n* --suffix <2>: install invocation. (line 120)\n* --suffix <3>: mv invocation. (line 103)\n* --suffix <4>: ln invocation. (line 166)\n* --suffix <5>: basename invocation. (line 38)\n* --suffix <6>: mktemp invocation. (line 113)\n* --suffix <7>: numfmt invocation. (line 99)\n* --suffix-format: csplit invocation. (line 67)\n* --suffix-length: split invocation. (line 109)\n* --summarize: du invocation. (line 153)\n* --suppress-matched: csplit invocation. (line 89)\n* --symbolic: ln invocation. (line 160)\n* --symbolic-link: cp invocation. (line 337)\n* --sync: df invocation. (line 174)\n* --sysv: sum invocation. (line 31)\n* --tabs: expand invocation. (line 22)\n* --tabs <1>: unexpand invocation. (line 24)\n* --tabsize: General output formatting.\n(line 117)\n* --tag: md5sum invocation. (line 99)\n* --tagged-paragraph: fmt invocation. (line 40)\n* --target-directory: Target directory. (line 31)\n* --target-directory <1>: cp invocation. (line 350)\n* --target-directory <2>: install invocation. (line 125)\n* --target-directory <3>: mv invocation. (line 108)\n* --target-directory <4>: ln invocation. (line 171)\n* --temporary-directory: sort invocation. (line 352)\n* --terse: stat invocation. (line 70)\n* --text: md5sum invocation. (line 109)\n* --threshold: du invocation. (line 157)\n* --time: Sorting the output. (line 13)\n* --time <1>: Sorting the output. (line 44)\n* --time <2>: Sorting the output. (line 52)\n* --time <3>: touch invocation. (line 48)\n* --time <4>: touch invocation. (line 85)\n* --time <5>: du invocation. (line 197)\n* --time <6>: du invocation. (line 204)\n* --time <7>: du invocation. (line 210)\n* --time <8>: who invocation. (line 82)\n* --time-style: Formatting file timestamps.\n(line 24)\n* --time-style <1>: du invocation. (line 214)\n* --tmpdir: mktemp invocation. (line 105)\n* --to: numfmt invocation. (line 103)\n* --to-unit: numfmt invocation. (line 108)\n* --total: df invocation. (line 180)\n* --total <1>: du invocation. (line 61)\n* --traditional: od invocation. (line 200)\n* --type: df invocation. (line 194)\n* --type <1>: chcon invocation. (line 73)\n* --type <2>: runcon invocation. (line 44)\n* --unbuffered: split invocation. (line 155)\n* --uniform-spacing: fmt invocation. (line 53)\n* --unique: sort invocation. (line 368)\n* --unique <1>: uniq invocation. (line 127)\n* --universal: Options for date. (line 119)\n* --unset: env invocation. (line 96)\n* --update: cp invocation. (line 359)\n* --update <1>: mv invocation. (line 84)\n* --user: id invocation. (line 47)\n* --user <1>: chcon invocation. (line 65)\n* --user <2>: runcon invocation. (line 36)\n* --userspec: chroot invocation. (line 30)\n* --utc: Options for date. (line 119)\n* --verbose: head invocation. (line 51)\n* --verbose <1>: tail invocation. (line 184)\n* --verbose <2>: split invocation. (line 159)\n* --verbose <3>: cp invocation. (line 374)\n* --verbose <4>: install invocation. (line 135)\n* --verbose <5>: mv invocation. (line 95)\n* --verbose <6>: rm invocation. (line 99)\n* --verbose <7>: shred invocation. (line 159)\n* --verbose <8>: ln invocation. (line 180)\n* --verbose <9>: mkdir invocation. (line 51)\n* --verbose <10>: readlink invocation. (line 61)\n* --verbose <11>: rmdir invocation. (line 31)\n* --verbose <12>: chown invocation. (line 142)\n* --verbose <13>: chgrp invocation. (line 69)\n* --verbose <14>: chmod invocation. (line 63)\n* --verbose <15>: chcon invocation. (line 61)\n* --verbose <16>: timeout invocation. (line 54)\n* --version: Common options. (line 40)\n* --version-sort: sort invocation. (line 177)\n* --warn: md5sum invocation. (line 118)\n* --width: od invocation. (line 157)\n* --width <1>: fmt invocation. (line 59)\n* --width <2>: pr invocation. (line 229)\n* --width <3>: fold invocation. (line 35)\n* --width <4>: Output formatting in ptx.\n(line 32)\n* --width <5>: General output formatting.\n(line 128)\n* --word-regexp: Input processing in ptx.\n(line 105)\n* --words: wc invocation. (line 51)\n* --wrap: base64 invocation. (line 22)\n* --writable: who invocation. (line 94)\n* --z85: basenc invocation. (line 63)\n* --zero: md5sum invocation. (line 128)\n* --zero <1>: shred invocation. (line 175)\n* --zero <2>: readlink invocation. (line 65)\n* --zero <3>: basename invocation. (line 42)\n* --zero <4>: dirname invocation. (line 31)\n* --zero <5>: realpath invocation. (line 71)\n* --zero <6>: id invocation. (line 58)\n* --zero-terminated: head invocation. (line 55)\n* --zero-terminated <1>: tail invocation. (line 188)\n* --zero-terminated <2>: sort invocation. (line 383)\n* --zero-terminated <3>: shuf invocation. (line 55)\n* --zero-terminated <4>: uniq invocation. (line 139)\n* --zero-terminated <5>: comm invocation. (line 88)\n* --zero-terminated <6>: cut invocation. (line 94)\n* --zero-terminated <7>: paste invocation. (line 72)\n* --zero-terminated <8>: General options in join.\n(line 93)\n* --zero-terminated <9>: numfmt invocation. (line 115)\n* -0: du invocation. (line 26)\n* -0 <1>: printenv invocation. (line 19)\n* -0 <2>: env invocation. (line 90)\n* -1: comm invocation. (line 23)\n* -1 <1>: General options in join.\n(line 40)\n* -1 <2>: General output formatting.\n(line 10)\n* -2: comm invocation. (line 23)\n* -2 <1>: General options in join.\n(line 43)\n* -3: comm invocation. (line 23)\n* -A: cat invocation. (line 16)\n* -A <1>: od invocation. (line 36)\n* -a: od invocation. (line 169)\n* -a <1>: pr invocation. (line 62)\n* -a <2>: split invocation. (line 109)\n* -A <2>: Output formatting in ptx.\n(line 45)\n* -a <3>: General options in join.\n(line 10)\n* -a <4>: unexpand invocation. (line 51)\n* -a <5>: Which files are listed.\n(line 13)\n* -A <3>: Which files are listed.\n(line 17)\n* -a <6>: cp invocation. (line 63)\n* -a <7>: touch invocation. (line 48)\n* -a <8>: df invocation. (line 42)\n* -a <9>: du invocation. (line 32)\n* -a <10>: Connectives for test.\n(line 29)\n* -a <11>: tee invocation. (line 27)\n* -a <12>: basename invocation. (line 32)\n* -a <13>: stty invocation. (line 26)\n* -a <14>: who invocation. (line 35)\n* -a <15>: uname invocation. (line 30)\n* -b: Backup options. (line 13)\n* -b <1>: cat invocation. (line 20)\n* -b <2>: tac invocation. (line 21)\n* -b <3>: nl invocation. (line 45)\n* -b <4>: od invocation. (line 172)\n* -b <5>: fold invocation. (line 23)\n* -b <6>: split invocation. (line 41)\n* -b <7>: csplit invocation. (line 67)\n* -b <8>: md5sum invocation. (line 41)\n* -b <9>: sort invocation. (line 79)\n* -b <10>: Input processing in ptx.\n(line 8)\n* -b <11>: cut invocation. (line 26)\n* -B: Which files are listed.\n(line 23)\n* -b <12>: Formatting the file names.\n(line 11)\n* -b <13>: dircolors invocation.\n(line 34)\n* -b <14>: cp invocation. (line 79)\n* -b <15>: install invocation. (line 41)\n* -b <16>: mv invocation. (line 59)\n* -b <17>: ln invocation. (line 82)\n* -B <1>: df invocation. (line 54)\n* -B <2>: du invocation. (line 52)\n* -b <18>: du invocation. (line 57)\n* -b <19>: File type tests. (line 10)\n* -b <20>: who invocation. (line 39)\n* -c: od invocation. (line 175)\n* -c <1>: fmt invocation. (line 34)\n* -c <2>: pr invocation. (line 68)\n* -c <3>: head invocation. (line 24)\n* -c <4>: tail invocation. (line 39)\n* -C: split invocation. (line 56)\n* -c <5>: wc invocation. (line 43)\n* -c <6>: sort invocation. (line 39)\n* -c <7>: sort invocation. (line 47)\n* -c <8>: shuf invocation. (line 19)\n* -c <9>: uniq invocation. (line 55)\n* -c <10>: cut invocation. (line 34)\n* -c <11>: Sorting the output. (line 13)\n* -C <1>: General output formatting.\n(line 16)\n* -c <12>: dircolors invocation.\n(line 40)\n* -C <2>: install invocation. (line 46)\n* -c <13>: install invocation. (line 57)\n* -c <14>: chown invocation. (line 73)\n* -c <15>: chgrp invocation. (line 24)\n* -c <16>: chmod invocation. (line 43)\n* -c <17>: touch invocation. (line 52)\n* -c <18>: du invocation. (line 61)\n* -c <19>: stat invocation. (line 50)\n* -c <20>: truncate invocation. (line 22)\n* -c <21>: File type tests. (line 13)\n* -c <22>: runcon invocation. (line 32)\n* -C <3>: env invocation. (line 107)\n* -COLUMN: pr invocation. (line 49)\n* -d: nl invocation. (line 63)\n* -d <1>: od invocation. (line 179)\n* -d <2>: base64 invocation. (line 30)\n* -d <3>: pr invocation. (line 74)\n* -d <4>: split invocation. (line 117)\n* -d <5>: sort invocation. (line 87)\n* -d <6>: uniq invocation. (line 63)\n* -D: uniq invocation. (line 69)\n* -d <7>: cut invocation. (line 66)\n* -d <8>: paste invocation. (line 61)\n* -d <9>: Which files are listed.\n(line 28)\n* -D <1>: What information is listed.\n(line 16)\n* -d <10>: cp invocation. (line 109)\n* -D <2>: install invocation. (line 60)\n* -d <11>: install invocation. (line 67)\n* -d <12>: rm invocation. (line 35)\n* -d <13>: ln invocation. (line 88)\n* -d <14>: touch invocation. (line 56)\n* -D <3>: du invocation. (line 67)\n* -d <15>: File type tests. (line 16)\n* -d <16>: mktemp invocation. (line 85)\n* -d <17>: who invocation. (line 43)\n* -d <18>: Options for date. (line 11)\n* -d <19>: numfmt invocation. (line 34)\n* -d DEPTH: du invocation. (line 74)\n* -e: cat invocation. (line 23)\n* -E: cat invocation. (line 27)\n* -e <1>: pr invocation. (line 98)\n* -e <2>: split invocation. (line 140)\n* -e <3>: General options in join.\n(line 21)\n* -e <4>: readlink invocation. (line 38)\n* -e <5>: echo invocation. (line 25)\n* -E <1>: echo invocation. (line 61)\n* -e <6>: File characteristic tests.\n(line 9)\n* -e <7>: realpath invocation. (line 22)\n* -e <8>: stdbuf invocation. (line 34)\n* -ef: File characteristic tests.\n(line 23)\n* -eq: Numeric tests. (line 16)\n* -f: nl invocation. (line 70)\n* -f <1>: od invocation. (line 182)\n* -F: pr invocation. (line 106)\n* -f <2>: pr invocation. (line 106)\n* -f <3>: tail invocation. (line 56)\n* -F <1>: tail invocation. (line 108)\n* -f <4>: csplit invocation. (line 63)\n* -f <5>: sort invocation. (line 94)\n* -f <6>: uniq invocation. (line 31)\n* -f <7>: Charset selection in ptx.\n(line 18)\n* -F <2>: Output formatting in ptx.\n(line 71)\n* -f <8>: cut invocation. (line 43)\n* -f <9>: Sorting the output. (line 20)\n* -F <3>: General output formatting.\n(line 46)\n* -f <10>: cp invocation. (line 115)\n* -f <11>: mv invocation. (line 64)\n* -f <12>: rm invocation. (line 39)\n* -f <13>: shred invocation. (line 123)\n* -F <4>: ln invocation. (line 88)\n* -f <14>: ln invocation. (line 94)\n* -f <15>: readlink invocation. (line 31)\n* -f <16>: chown invocation. (line 79)\n* -f <17>: chgrp invocation. (line 30)\n* -f <18>: chmod invocation. (line 49)\n* -f <19>: touch invocation. (line 66)\n* -f <20>: stat invocation. (line 28)\n* -f <21>: File type tests. (line 19)\n* -F <5>: stty invocation. (line 31)\n* -f <22>: Options for date. (line 30)\n* -f <23>: seq invocation. (line 28)\n* -g: fmt invocation. (line 64)\n* -g <1>: sort invocation. (line 105)\n* -g <2>: Output formatting in ptx.\n(line 26)\n* -g <3>: What information is listed.\n(line 105)\n* -G: What information is listed.\n(line 110)\n* -g <4>: install invocation. (line 73)\n* -g <5>: Access permission tests.\n(line 9)\n* -G <1>: Access permission tests.\n(line 31)\n* -g <6>: stty invocation. (line 41)\n* -g <7>: id invocation. (line 29)\n* -G <2>: id invocation. (line 33)\n* -ge: Numeric tests. (line 16)\n* -gt: Numeric tests. (line 16)\n* -h: Block size. (line 121)\n* -H: Traversing symlinks. (line 18)\n* -h <1>: nl invocation. (line 74)\n* -h <2>: pr invocation. (line 111)\n* -h <3>: sort invocation. (line 126)\n* -H <1>: Which files are listed.\n(line 36)\n* -h <4>: What information is listed.\n(line 116)\n* -H <2>: cp invocation. (line 132)\n* -h <5>: chown invocation. (line 118)\n* -H <3>: chown invocation. (line 153)\n* -h <6>: chgrp invocation. (line 46)\n* -H <4>: chgrp invocation. (line 81)\n* -h <7>: touch invocation. (line 70)\n* -h <8>: df invocation. (line 59)\n* -H <5>: df invocation. (line 65)\n* -H <6>: du invocation. (line 92)\n* -h <9>: du invocation. (line 96)\n* -h <10>: File type tests. (line 23)\n* -H <7>: who invocation. (line 47)\n* -h <11>: chcon invocation. (line 26)\n* -H <8>: chcon invocation. (line 47)\n* -i: nl invocation. (line 78)\n* -i <1>: od invocation. (line 185)\n* -i <2>: base64 invocation. (line 36)\n* -i <3>: pr invocation. (line 117)\n* -i <4>: sort invocation. (line 143)\n* -i <5>: shuf invocation. (line 23)\n* -i <6>: uniq invocation. (line 59)\n* -i <7>: Input processing in ptx.\n(line 26)\n* -i <8>: General options in join.\n(line 35)\n* -i <9>: expand invocation. (line 46)\n* -I: Which files are listed.\n(line 69)\n* -i <10>: What information is listed.\n(line 123)\n* -i <11>: cp invocation. (line 139)\n* -i <12>: mv invocation. (line 70)\n* -i <13>: rm invocation. (line 43)\n* -I <1>: rm invocation. (line 48)\n* -i <14>: ln invocation. (line 98)\n* -i <15>: df invocation. (line 69)\n* -i <16>: tee invocation. (line 32)\n* -i <17>: uname invocation. (line 35)\n* -i <18>: env invocation. (line 102)\n* -i <19>: stdbuf invocation. (line 26)\n* -I[TIMESPEC]: Options for date. (line 38)\n* -j: od invocation. (line 59)\n* -J: pr invocation. (line 124)\n* -k: Block size. (line 121)\n* -k <1>: csplit invocation. (line 86)\n* -k <2>: sort invocation. (line 231)\n* -k <3>: General output formatting.\n(line 89)\n* -k <4>: df invocation. (line 74)\n* -k <5>: du invocation. (line 111)\n* -k <6>: Access permission tests.\n(line 12)\n* -k <7>: timeout invocation. (line 41)\n* -L: Traversing symlinks. (line 22)\n* -l: nl invocation. (line 82)\n* -l <1>: od invocation. (line 188)\n* -l <2>: pr invocation. (line 133)\n* -l <3>: split invocation. (line 33)\n* -l <4>: wc invocation. (line 55)\n* -L <1>: wc invocation. (line 59)\n* -l <5>: b2sum invocation. (line 12)\n* -L <2>: Which files are listed.\n(line 83)\n* -l <6>: What information is listed.\n(line 131)\n* -l <7>: cp invocation. (line 145)\n* -L <3>: cp invocation. (line 149)\n* -L <4>: ln invocation. (line 102)\n* -L <5>: chown invocation. (line 158)\n* -L <6>: chgrp invocation. (line 86)\n* -l <8>: df invocation. (line 80)\n* -L <7>: du invocation. (line 117)\n* -l <9>: du invocation. (line 123)\n* -L <8>: stat invocation. (line 22)\n* -L <9>: File type tests. (line 23)\n* -L <10>: realpath invocation. (line 35)\n* -L <11>: pwd invocation. (line 15)\n* -l <10>: who invocation. (line 51)\n* -L <12>: chcon invocation. (line 52)\n* -l <11>: chcon invocation. (line 77)\n* -l <12>: runcon invocation. (line 48)\n* -le: Numeric tests. (line 16)\n* -lt: Numeric tests. (line 16)\n* -m: pr invocation. (line 140)\n* -m <1>: wc invocation. (line 47)\n* -m <2>: sort invocation. (line 53)\n* -M: sort invocation. (line 150)\n* -M <1>: Output formatting in ptx.\n(line 94)\n* -m <3>: General output formatting.\n(line 103)\n* -m <4>: install invocation. (line 79)\n* -m <5>: mkdir invocation. (line 19)\n* -m <6>: mkfifo invocation. (line 21)\n* -m <7>: mknod invocation. (line 47)\n* -m <8>: readlink invocation. (line 45)\n* -m <9>: touch invocation. (line 85)\n* -m <10>: du invocation. (line 127)\n* -m <11>: realpath invocation. (line 30)\n* -m <12>: who invocation. (line 61)\n* -m <13>: uname invocation. (line 42)\n* -n: cat invocation. (line 31)\n* -n <1>: nl invocation. (line 90)\n* -N: od invocation. (line 76)\n* -n <2>: pr invocation. (line 153)\n* -N <1>: pr invocation. (line 174)\n* -n <3>: head invocation. (line 40)\n* -n <4>: tail invocation. (line 125)\n* -n <5>: split invocation. (line 79)\n* -n <6>: csplit invocation. (line 81)\n* -n <7>: sort invocation. (line 160)\n* -n <8>: shuf invocation. (line 31)\n* -n <9>: cut invocation. (line 70)\n* -n <10>: What information is listed.\n(line 225)\n* -N <2>: Formatting the file names.\n(line 17)\n* -n <11>: cp invocation. (line 156)\n* -n <12>: mv invocation. (line 77)\n* -n <13>: ln invocation. (line 108)\n* -n <14>: readlink invocation. (line 50)\n* -n <15>: echo invocation. (line 22)\n* -N <3>: File characteristic tests.\n(line 27)\n* -n <16>: String tests. (line 19)\n* -n <17>: id invocation. (line 37)\n* -n <18>: uname invocation. (line 47)\n* -n <19>: nice invocation. (line 51)\n* -n NUMBER: shred invocation. (line 127)\n* -ne: Numeric tests. (line 16)\n* -nt: File characteristic tests.\n(line 15)\n* -o: od invocation. (line 191)\n* -o <1>: pr invocation. (line 180)\n* -o <2>: sort invocation. (line 288)\n* -o <3>: shuf invocation. (line 36)\n* -o <4>: Input processing in ptx.\n(line 35)\n* -O: Output formatting in ptx.\n(line 100)\n* -o <5>: What information is listed.\n(line 230)\n* -o <6>: install invocation. (line 91)\n* -o <7>: truncate invocation. (line 26)\n* -O <1>: Access permission tests.\n(line 28)\n* -o <8>: Connectives for test.\n(line 33)\n* -o <9>: uname invocation. (line 58)\n* -o <10>: stdbuf invocation. (line 30)\n* -ot: File characteristic tests.\n(line 19)\n* -P: Traversing symlinks. (line 26)\n* -p: nl invocation. (line 101)\n* -p <1>: General output formatting.\n(line 108)\n* -p <2>: dircolors invocation.\n(line 45)\n* -P <1>: cp invocation. (line 162)\n* -p <3>: cp invocation. (line 169)\n* -p <4>: install invocation. (line 103)\n* -P <2>: ln invocation. (line 127)\n* -p <5>: mkdir invocation. (line 34)\n* -p <6>: rmdir invocation. (line 22)\n* -P <3>: chown invocation. (line 171)\n* -P <4>: chgrp invocation. (line 99)\n* -P <5>: df invocation. (line 148)\n* -P <6>: du invocation. (line 133)\n* -p <7>: File type tests. (line 28)\n* -p <8>: tee invocation. (line 36)\n* -p <9>: pathchk invocation. (line 27)\n* -P <7>: pathchk invocation. (line 40)\n* -p <10>: mktemp invocation. (line 105)\n* -P <8>: realpath invocation. (line 40)\n* -P <9>: pwd invocation. (line 22)\n* -p <11>: who invocation. (line 65)\n* -p <12>: uname invocation. (line 51)\n* -P <10>: chcon invocation. (line 56)\n* -q: head invocation. (line 47)\n* -q <1>: tail invocation. (line 153)\n* -q <2>: csplit invocation. (line 106)\n* -q <3>: Formatting the file names.\n(line 23)\n* -Q: Formatting the file names.\n(line 30)\n* -q <4>: readlink invocation. (line 57)\n* -q <5>: mktemp invocation. (line 92)\n* -q <6>: realpath invocation. (line 46)\n* -q <7>: who invocation. (line 69)\n* -r: tac invocation. (line 26)\n* -r <1>: pr invocation. (line 187)\n* -r <2>: sum invocation. (line 25)\n* -r <3>: sort invocation. (line 183)\n* -R: sort invocation. (line 189)\n* -r <4>: shuf invocation. (line 47)\n* -r <5>: Input processing in ptx.\n(line 48)\n* -R <1>: Output formatting in ptx.\n(line 56)\n* -R <2>: Which files are listed.\n(line 90)\n* -r <6>: Sorting the output. (line 27)\n* -R <3>: cp invocation. (line 252)\n* -r <7>: cp invocation. (line 252)\n* -r <8>: rm invocation. (line 95)\n* -R <4>: rm invocation. (line 95)\n* -r <9>: ln invocation. (line 136)\n* -R <5>: chown invocation. (line 150)\n* -R <6>: chgrp invocation. (line 77)\n* -R <7>: chmod invocation. (line 73)\n* -r <10>: touch invocation. (line 89)\n* -r <11>: truncate invocation. (line 30)\n* -r <12>: Access permission tests.\n(line 15)\n* -r <13>: id invocation. (line 42)\n* -r <14>: who invocation. (line 74)\n* -r <15>: Options for date. (line 65)\n* -R <8>: Options for date. (line 70)\n* -r <16>: uname invocation. (line 62)\n* -R <9>: chcon invocation. (line 35)\n* -r <17>: chcon invocation. (line 69)\n* -r <18>: runcon invocation. (line 40)\n* -S: Backup options. (line 49)\n* -s: cat invocation. (line 36)\n* -s <1>: tac invocation. (line 30)\n* -s <2>: nl invocation. (line 105)\n* -S <1>: od invocation. (line 81)\n* -s <3>: od invocation. (line 194)\n* -s <4>: fmt invocation. (line 47)\n* -s <5>: pr invocation. (line 192)\n* -S <2>: pr invocation. (line 201)\n* -s <6>: fold invocation. (line 29)\n* -s <7>: tail invocation. (line 173)\n* -s <8>: csplit invocation. (line 106)\n* -s <9>: sum invocation. (line 31)\n* -s <10>: sort invocation. (line 309)\n* -S <3>: sort invocation. (line 316)\n* -s <11>: uniq invocation. (line 41)\n* -S <4>: Input processing in ptx.\n(line 65)\n* -s <12>: cut invocation. (line 74)\n* -s <13>: paste invocation. (line 52)\n* -s <14>: What information is listed.\n(line 236)\n* -S <5>: Sorting the output. (line 32)\n* -s <15>: cp invocation. (line 337)\n* -S <6>: cp invocation. (line 345)\n* -s <16>: install invocation. (line 113)\n* -S <7>: install invocation. (line 120)\n* -S <8>: mv invocation. (line 103)\n* -s <17>: ln invocation. (line 160)\n* -S <9>: ln invocation. (line 166)\n* -s <18>: readlink invocation. (line 57)\n* -S <10>: du invocation. (line 138)\n* -s <19>: du invocation. (line 153)\n* -s <20>: truncate invocation. (line 34)\n* -S <11>: File type tests. (line 31)\n* -s <21>: File characteristic tests.\n(line 12)\n* -s <22>: basename invocation. (line 38)\n* -s <23>: realpath invocation. (line 64)\n* -s <24>: tty invocation. (line 18)\n* -s <25>: who invocation. (line 78)\n* -s <26>: Options for date. (line 113)\n* -s <27>: uname invocation. (line 66)\n* -S <12>: env invocation. (line 188)\n* -s <28>: timeout invocation. (line 48)\n* -s <29>: seq invocation. (line 44)\n* -s BYTES: shred invocation. (line 138)\n* -S, env and single quotes: env invocation. (line 264)\n* -t: cat invocation. (line 40)\n* -T: cat invocation. (line 44)\n* -t <1>: od invocation. (line 90)\n* -t <2>: fmt invocation. (line 40)\n* -t <3>: pr invocation. (line 210)\n* -T <1>: pr invocation. (line 220)\n* -t <4>: split invocation. (line 148)\n* -t <5>: md5sum invocation. (line 109)\n* -t <6>: sort invocation. (line 332)\n* -T <2>: sort invocation. (line 352)\n* -T <3>: Output formatting in ptx.\n(line 118)\n* -t <7>: expand invocation. (line 22)\n* -t <8>: unexpand invocation. (line 24)\n* -t <9>: Sorting the output. (line 36)\n* -T <4>: General output formatting.\n(line 117)\n* -t <10>: cp invocation. (line 350)\n* -T <5>: cp invocation. (line 354)\n* -t <11>: install invocation. (line 125)\n* -T <6>: install invocation. (line 130)\n* -t <12>: mv invocation. (line 108)\n* -T <7>: mv invocation. (line 112)\n* -t <13>: ln invocation. (line 171)\n* -T <8>: ln invocation. (line 175)\n* -t <14>: df invocation. (line 194)\n* -T <9>: df invocation. (line 200)\n* -t <15>: du invocation. (line 157)\n* -t <16>: stat invocation. (line 70)\n* -t <17>: File type tests. (line 34)\n* -t <18>: mktemp invocation. (line 121)\n* -t <19>: who invocation. (line 82)\n* -T <10>: who invocation. (line 94)\n* -t <20>: chcon invocation. (line 73)\n* -t <21>: runcon invocation. (line 44)\n* -u: cat invocation. (line 47)\n* -u <1>: fmt invocation. (line 53)\n* -u <2>: split invocation. (line 155)\n* -u <3>: sort invocation. (line 368)\n* -u <4>: uniq invocation. (line 127)\n* -u <5>: Sorting the output. (line 44)\n* -U: Sorting the output. (line 60)\n* -u <6>: cp invocation. (line 359)\n* -u <7>: mv invocation. (line 84)\n* -u <8>: shred invocation. (line 144)\n* -u <9>: Access permission tests.\n(line 18)\n* -u <10>: mktemp invocation. (line 97)\n* -u <11>: id invocation. (line 47)\n* -u <12>: who invocation. (line 85)\n* -u <13>: Options for date. (line 119)\n* -u <14>: chcon invocation. (line 65)\n* -u <15>: runcon invocation. (line 36)\n* -u <16>: env invocation. (line 96)\n* -v: cat invocation. (line 51)\n* -v <1>: nl invocation. (line 110)\n* -v <2>: od invocation. (line 150)\n* -v <3>: pr invocation. (line 225)\n* -v <4>: head invocation. (line 51)\n* -v <5>: tail invocation. (line 184)\n* -V: sort invocation. (line 177)\n* -v <6>: Sorting the output. (line 67)\n* -v <7>: cp invocation. (line 374)\n* -v <8>: install invocation. (line 135)\n* -v <9>: mv invocation. (line 95)\n* -v <10>: rm invocation. (line 99)\n* -v <11>: shred invocation. (line 159)\n* -v <12>: ln invocation. (line 180)\n* -v <13>: mkdir invocation. (line 51)\n* -v <14>: readlink invocation. (line 61)\n* -v <15>: rmdir invocation. (line 31)\n* -v <16>: chown invocation. (line 142)\n* -v <17>: chgrp invocation. (line 69)\n* -v <18>: chmod invocation. (line 63)\n* -v <19>: uname invocation. (line 77)\n* -v <20>: chcon invocation. (line 61)\n* -v <21>: env invocation. (line 173)\n* -v <22>: timeout invocation. (line 54)\n* -w: nl invocation. (line 115)\n* -w <1>: od invocation. (line 157)\n* -w <2>: base64 invocation. (line 22)\n* -w <3>: fmt invocation. (line 59)\n* -w <4>: pr invocation. (line 229)\n* -W: pr invocation. (line 239)\n* -w <5>: fold invocation. (line 35)\n* -w <6>: wc invocation. (line 51)\n* -w <7>: md5sum invocation. (line 118)\n* -w <8>: uniq invocation. (line 133)\n* -W <1>: Input processing in ptx.\n(line 105)\n* -w <9>: Output formatting in ptx.\n(line 32)\n* -w <10>: General output formatting.\n(line 128)\n* -w <11>: Access permission tests.\n(line 21)\n* -w <12>: who invocation. (line 94)\n* -w <13>: seq invocation. (line 49)\n* -WIDTH: fmt invocation. (line 59)\n* -x: od invocation. (line 197)\n* -x <1>: split invocation. (line 131)\n* -X: Sorting the output. (line 74)\n* -x <2>: General output formatting.\n(line 113)\n* -x <3>: cp invocation. (line 378)\n* -x <4>: shred invocation. (line 164)\n* -x <5>: df invocation. (line 223)\n* -x <6>: du invocation. (line 263)\n* -x <7>: Access permission tests.\n(line 24)\n* -X FILE: du invocation. (line 252)\n* -z: head invocation. (line 55)\n* -z <1>: tail invocation. (line 188)\n* -z <2>: csplit invocation. (line 95)\n* -z <3>: md5sum invocation. (line 128)\n* -z <4>: sort invocation. (line 383)\n* -z <5>: shuf invocation. (line 55)\n* -z <6>: uniq invocation. (line 139)\n* -z <7>: comm invocation. (line 88)\n* -z <8>: cut invocation. (line 94)\n* -z <9>: paste invocation. (line 72)\n* -z <10>: General options in join.\n(line 93)\n* -Z: What information is listed.\n(line 259)\n* -Z <1>: cp invocation. (line 384)\n* -Z <2>: install invocation. (line 139)\n* -Z <3>: mv invocation. (line 117)\n* -z <11>: shred invocation. (line 175)\n* -Z <4>: mkdir invocation. (line 56)\n* -Z <5>: mkfifo invocation. (line 28)\n* -Z <6>: mknod invocation. (line 53)\n* -z <12>: readlink invocation. (line 65)\n* -z <13>: String tests. (line 15)\n* -z <14>: basename invocation. (line 42)\n* -z <15>: dirname invocation. (line 31)\n* -z <16>: realpath invocation. (line 71)\n* -Z <7>: id invocation. (line 51)\n* -z <17>: id invocation. (line 58)\n* -z <18>: numfmt invocation. (line 115)\n* /: Numeric expressions. (line 16)\n* 128-bit checksum: md5sum invocation. (line 6)\n* 16-bit checksum: sum invocation. (line 6)\n* 160-bit checksum: sha1sum invocation. (line 6)\n* 224-bit checksum: sha2 utilities. (line 6)\n* 256-bit checksum: sha2 utilities. (line 6)\n* 384-bit checksum: sha2 utilities. (line 6)\n* 512-bit checksum: b2sum invocation. (line 6)\n* 512-bit checksum <1>: sha2 utilities. (line 6)\n* <: Relations for expr. (line 22)\n* <=: Relations for expr. (line 22)\n* =: Relations for expr. (line 22)\n* = <1>: String tests. (line 22)\n* ==: Relations for expr. (line 22)\n* == <1>: String tests. (line 25)\n* >: Relations for expr. (line 22)\n* >=: Relations for expr. (line 22)\n* \\( regexp operator: String expressions. (line 24)\n* \\+ regexp operator: String expressions. (line 28)\n* \\? regexp operator: String expressions. (line 28)\n* \\c: printf invocation. (line 28)\n* \\OOO: printf invocation. (line 67)\n* \\uhhhh: printf invocation. (line 74)\n* \\Uhhhhhhhh: printf invocation. (line 74)\n* \\xHH: printf invocation. (line 67)\n* \\| regexp operator: String expressions. (line 28)\n* POSIX2VERSION: Standards conformance.\n(line 20)\n* POSIX2VERSION <1>: tail invocation. (line 203)\n* POSIX2VERSION <2>: sort invocation. (line 415)\n* POSIX2VERSION <3>: uniq invocation. (line 46)\n* POSIX2VERSION <4>: touch invocation. (line 107)\n* |: Relations for expr. (line 11)\n* abbreviations for months: Calendar date items. (line 38)\n* access permission tests: Access permission tests.\n(line 6)\n* access permissions, changing: chmod invocation. (line 6)\n* access time, changing: touch invocation. (line 48)\n* access timestamp: dd invocation. (line 278)\n* access timestamp, printing or sorting files by: Sorting the output.\n(line 44)\n* access timestamp, show the most recent: du invocation. (line 210)\n* across columns: pr invocation. (line 62)\n* across, listing files: General output formatting.\n(line 113)\n* adding permissions: Setting Permissions. (line 35)\n* addition: Numeric expressions. (line 12)\n* ago in date strings: Relative items in date strings.\n(line 23)\n* all lines, grouping: uniq invocation. (line 100)\n* all repeated lines, outputting: uniq invocation. (line 69)\n* alnum: Character sets. (line 88)\n* alpha: Character sets. (line 90)\n* alternate ebcdic, converting to: dd invocation. (line 117)\n* always color option: General output formatting.\n(line 26)\n* always hyperlink option: General output formatting.\n(line 65)\n* always interactive option: rm invocation. (line 59)\n* am i: who invocation. (line 21)\n* am in date strings: Time of day items. (line 21)\n* and operator: Connectives for test.\n(line 29)\n* and operator <1>: Relations for expr. (line 17)\n* append: dd invocation. (line 207)\n* appending to the output file: dd invocation. (line 207)\n* appropriate privileges: install invocation. (line 91)\n* appropriate privileges <1>: Setting the time. (line 6)\n* appropriate privileges <2>: hostname invocation. (line 6)\n* appropriate privileges <3>: nice invocation. (line 6)\n* arbitrary date strings, debugging: Options for date. (line 25)\n* arbitrary date strings, parsing: Options for date. (line 11)\n* arbitrary text, displaying: echo invocation. (line 6)\n* arch: arch invocation. (line 6)\n* arithmetic tests: Numeric tests. (line 6)\n* ASCII dump of files: od invocation. (line 6)\n* ascii, converting to: dd invocation. (line 106)\n* atime: File timestamps. (line 6)\n* atime, changing: touch invocation. (line 48)\n* atime, printing or sorting files by: Sorting the output. (line 44)\n* atime, show the most recent: du invocation. (line 210)\n* attribute caching: stat invocation. (line 33)\n* attributes, file: Changing file attributes.\n(line 6)\n* authors of parsedatetime: Authors of parsedatetime.\n(line 6)\n* auto color option: General output formatting.\n(line 25)\n* auto hyperlink option: General output formatting.\n(line 64)\n* b for block special file: mknod invocation. (line 31)\n* b2sum: b2sum invocation. (line 6)\n* background jobs, stopping at terminal write: Local. (line 41)\n* backslash escapes: Character sets. (line 14)\n* backslash escapes <1>: echo invocation. (line 25)\n* backslash escapes <2>: echo invocation. (line 61)\n* backslash sequences for file names: Formatting the file names.\n(line 11)\n* backup files, ignoring: Which files are listed.\n(line 23)\n* backup options: Backup options. (line 6)\n* backup suffix: Backup options. (line 49)\n* backups, making: Backup options. (line 13)\n* backups, making <1>: cp invocation. (line 79)\n* backups, making <2>: install invocation. (line 41)\n* backups, making <3>: mv invocation. (line 59)\n* backups, making <4>: ln invocation. (line 82)\n* backups, making only: cp invocation. (line 51)\n* base32: base32 invocation. (line 6)\n* base32 encoding: base32 invocation. (line 6)\n* base32 encoding <1>: basenc invocation. (line 6)\n* base64: base64 invocation. (line 6)\n* Base64 decoding: base64 invocation. (line 30)\n* base64 encoding: base64 invocation. (line 6)\n* basename: basename invocation. (line 6)\n* basenc: basenc invocation. (line 6)\n* baud rate, setting: Special. (line 52)\n* beeping at input buffer full: Input. (line 59)\n* beginning of time: Time conversion specifiers.\n(line 32)\n* beginning of time, for POSIX: Seconds since the Epoch.\n(line 13)\n* Bellovin, Steven M.: Authors of parsedatetime.\n(line 6)\n* Berets, Jim: Authors of parsedatetime.\n(line 6)\n* Berry, K.: Introduction. (line 29)\n* Berry, K. <1>: Authors of parsedatetime.\n(line 19)\n* binary: dd invocation. (line 295)\n* binary I/O: dd invocation. (line 295)\n* binary input files: md5sum invocation. (line 41)\n* bind mount: rm invocation. (line 67)\n* bind mount <1>: stat invocation. (line 192)\n* birth time, printing or sorting files by: Sorting the output.\n(line 52)\n* birthtime: File timestamps. (line 6)\n* BLAKE2: b2sum invocation. (line 6)\n* BLAKE2 hash length: b2sum invocation. (line 12)\n* blank: Character sets. (line 92)\n* blank lines, numbering: nl invocation. (line 82)\n* blanks, ignoring leading: sort invocation. (line 79)\n* block (space-padding): dd invocation. (line 127)\n* block size: Block size. (line 6)\n* block size <1>: dd invocation. (line 34)\n* block size of conversion: dd invocation. (line 41)\n* block size of input: dd invocation. (line 26)\n* block size of output: dd invocation. (line 30)\n* block special check: File type tests. (line 10)\n* block special files: mknod invocation. (line 11)\n* block special files, creating: mknod invocation. (line 6)\n* BLOCKSIZE: Block size. (line 12)\n* BLOCKSIZE: Block size. (line 12)\n* body, numbering: nl invocation. (line 17)\n* Bourne shell syntax for color setup: dircolors invocation.\n(line 34)\n* breaks, cause interrupts: Input. (line 12)\n* breaks, ignoring: Input. (line 9)\n* brkint: Input. (line 12)\n* bs: dd invocation. (line 34)\n* BSD output: md5sum invocation. (line 99)\n* BSD sum: sum invocation. (line 25)\n* BSD tail: tail invocation. (line 26)\n* BSD touch compatibility: touch invocation. (line 66)\n* bsN: Output. (line 55)\n* btrfs file system type: df invocation. (line 211)\n* bugs, reporting: Introduction. (line 12)\n* built-in shell commands, conflicts with: mknod invocation. (line 20)\n* built-in shell commands, conflicts with <1>: stat invocation.\n(line 15)\n* built-in shell commands, conflicts with <2>: echo invocation.\n(line 11)\n* built-in shell commands, conflicts with <3>: printf invocation.\n(line 16)\n* built-in shell commands, conflicts with <4>: test invocation.\n(line 28)\n* built-in shell commands, conflicts with <5>: pwd invocation.\n(line 30)\n* built-in shell commands, conflicts with <6>: nice invocation.\n(line 38)\n* built-in shell commands, conflicts with <7>: kill invocation.\n(line 13)\n* built-in shell commands, conflicts with <8>: sleep invocation.\n(line 36)\n* byte count: wc invocation. (line 6)\n* byte-swapping: od invocation. (line 51)\n* byte-swapping <1>: dd invocation. (line 159)\n* c for character special file: mknod invocation. (line 34)\n* C shell syntax for color setup: dircolors invocation.\n(line 40)\n* C-s/C-q flow control: Input. (line 40)\n* calendar date item: Calendar date items. (line 6)\n* calling combined multi-call program: Multi-call invocation.\n(line 6)\n* canonical file name: readlink invocation. (line 6)\n* canonical file name <1>: realpath invocation. (line 6)\n* canonicalize a file name: readlink invocation. (line 6)\n* canonicalize a file name <1>: realpath invocation. (line 6)\n* case folding: sort invocation. (line 94)\n* case translation: Local. (line 36)\n* case, ignored in dates: General date syntax. (line 60)\n* cat: cat invocation. (line 6)\n* cbreak: Combination. (line 52)\n* cbs: dd invocation. (line 41)\n* CD-ROM file system type: df invocation. (line 215)\n* cdfs file system type: df invocation. (line 215)\n* cdtrdsr: Control. (line 44)\n* change or print terminal settings: stty invocation. (line 6)\n* change SELinux context: chcon invocation. (line 6)\n* changed files, verbosely describing: chgrp invocation. (line 24)\n* changed owners, verbosely describing: chown invocation. (line 73)\n* changing access permissions: chmod invocation. (line 6)\n* changing file attributes: Changing file attributes.\n(line 6)\n* changing file ownership: chown invocation. (line 6)\n* changing file timestamps: touch invocation. (line 6)\n* changing group ownership: chown invocation. (line 6)\n* changing group ownership <1>: chgrp invocation. (line 6)\n* changing security context: chcon invocation. (line 6)\n* changing special mode bits: Changing Special Mode Bits.\n(line 6)\n* character classes: Character sets. (line 74)\n* character count: wc invocation. (line 6)\n* character size: Control. (line 24)\n* character special check: File type tests. (line 13)\n* character special files: mknod invocation. (line 11)\n* character special files, creating: mknod invocation. (line 6)\n* characters, special: Characters. (line 6)\n* chcon: chcon invocation. (line 6)\n* check file types: test invocation. (line 6)\n* checking for sortedness: sort invocation. (line 39)\n* checking for sortedness <1>: sort invocation. (line 47)\n* checksum, 128-bit: md5sum invocation. (line 6)\n* checksum, 16-bit: sum invocation. (line 6)\n* checksum, 160-bit: sha1sum invocation. (line 6)\n* checksum, 224-bit: sha2 utilities. (line 6)\n* checksum, 256-bit: sha2 utilities. (line 6)\n* checksum, 384-bit: sha2 utilities. (line 6)\n* checksum, 512-bit: b2sum invocation. (line 6)\n* checksum, 512-bit <1>: sha2 utilities. (line 6)\n* chgrp: chgrp invocation. (line 6)\n* chmod: chmod invocation. (line 6)\n* chown: chown invocation. (line 6)\n* chroot: chroot invocation. (line 6)\n* cio: dd invocation. (line 215)\n* cksum: cksum invocation. (line 6)\n* clocal: Control. (line 38)\n* clock skew: Formatting file timestamps.\n(line 11)\n* clock skew <1>: File timestamps. (line 39)\n* clone: cp invocation. (line 265)\n* cmspar: Control. (line 16)\n* cntrl: Character sets. (line 94)\n* color database, printing: dircolors invocation.\n(line 45)\n* color setup: dircolors invocation.\n(line 6)\n* color, distinguishing file types with: General output formatting.\n(line 22)\n* cols: Special. (line 27)\n* column to wrap data after: base64 invocation. (line 22)\n* COLUMNS: General output formatting.\n(line 128)\n* COLUMNS <1>: Special. (line 39)\n* columns: Special. (line 27)\n* combination settings: Combination. (line 6)\n* combined: Multi-call invocation.\n(line 6)\n* combined date and time of day item: Combined date and time of day items.\n(line 6)\n* comm: comm invocation. (line 6)\n* command-line operands to shuffle: shuf invocation. (line 19)\n* commands for controlling processes: Process control. (line 6)\n* commands for delaying: Delaying. (line 6)\n* commands for exit status: Conditions. (line 6)\n* commands for file name manipulation: File name manipulation.\n(line 6)\n* commands for invoking other commands: Modified command invocation.\n(line 6)\n* commands for printing text: Printing text. (line 6)\n* commands for printing the working context: Working context. (line 6)\n* commands for printing user information: User information. (line 6)\n* commands for redirection: Redirection. (line 6)\n* commands for SELinux context: SELinux context. (line 6)\n* commands for system context: System context. (line 6)\n* commas, outputting between files: General output formatting.\n(line 103)\n* comments, in dates: General date syntax. (line 60)\n* common field, joining on: join invocation. (line 6)\n* common lines: comm invocation. (line 18)\n* common options: Common options. (line 6)\n* compare values: test invocation. (line 6)\n* comparing sorted files: comm invocation. (line 6)\n* comparison operators: Relations for expr. (line 22)\n* concatenate and write files: cat invocation. (line 6)\n* concurrent I/O: dd invocation. (line 215)\n* conditional executability: Conditional Executability.\n(line 6)\n* conditions: Conditions. (line 6)\n* conflicts with shell built-ins: mknod invocation. (line 20)\n* conflicts with shell built-ins <1>: stat invocation. (line 15)\n* conflicts with shell built-ins <2>: echo invocation. (line 11)\n* conflicts with shell built-ins <3>: printf invocation. (line 16)\n* conflicts with shell built-ins <4>: test invocation. (line 28)\n* conflicts with shell built-ins <5>: pwd invocation. (line 30)\n* conflicts with shell built-ins <6>: nice invocation. (line 38)\n* conflicts with shell built-ins <7>: kill invocation. (line 13)\n* conflicts with shell built-ins <8>: sleep invocation. (line 36)\n* connectives, logical: Connectives for test.\n(line 6)\n* connectives, logical <1>: Relations for expr. (line 6)\n* constant parity: Control. (line 16)\n* context splitting: csplit invocation. (line 6)\n* context, system: System context. (line 6)\n* control characters, using ^C: Local. (line 51)\n* control settings: Control. (line 6)\n* controlling terminal: dd invocation. (line 284)\n* conv: dd invocation. (line 100)\n* conversion block size: dd invocation. (line 41)\n* conversion specifiers, date: Date conversion specifiers.\n(line 6)\n* conversion specifiers, literal: Literal conversion specifiers.\n(line 6)\n* conversion specifiers, time: Time conversion specifiers.\n(line 6)\n* converting tabs to spaces: expand invocation. (line 6)\n* converting while copying a file: dd invocation. (line 6)\n* cooked: Combination. (line 37)\n* Coordinated Universal Time: Options for date. (line 119)\n* copy on write: cp invocation. (line 265)\n* copying directories recursively: cp invocation. (line 96)\n* copying directories recursively <1>: cp invocation. (line 252)\n* copying existing permissions: Copying Permissions. (line 6)\n* copying files: cat invocation. (line 6)\n* copying files and directories: cp invocation. (line 6)\n* copying files and setting attributes: install invocation. (line 6)\n* core utilities: Top. (line 18)\n* count: dd invocation. (line 56)\n* countbytes: dd invocation. (line 313)\n* COW: cp invocation. (line 265)\n* cp: cp invocation. (line 6)\n* crashes and corruption: sync invocation. (line 17)\n* CRC checksum: cksum invocation. (line 6)\n* cread: Control. (line 35)\n* creating directories: mkdir invocation. (line 6)\n* creating FIFOs (named pipes): mkfifo invocation. (line 6)\n* creating links (hard only): link invocation. (line 6)\n* creating links (hard or soft): ln invocation. (line 6)\n* creating output file, avoiding: dd invocation. (line 176)\n* creating output file, requiring: dd invocation. (line 172)\n* creation timestamp, printing or sorting files by: Sorting the output.\n(line 52)\n* crN: Output. (line 45)\n* crown margin: fmt invocation. (line 34)\n* crt: Combination. (line 75)\n* crterase: Local. (line 22)\n* crtkill: Local. (line 56)\n* crtscts: Control. (line 41)\n* csh syntax for color setup: dircolors invocation.\n(line 40)\n* csN: Control. (line 24)\n* csplit: csplit invocation. (line 6)\n* cstopb: Control. (line 32)\n* ctime: File timestamps. (line 6)\n* ctime, printing or sorting by: Sorting the output. (line 13)\n* ctime, show the most recent: du invocation. (line 204)\n* ctlecho: Local. (line 51)\n* current working directory, printing: pwd invocation. (line 6)\n* cut: cut invocation. (line 6)\n* cyclic redundancy check: cksum invocation. (line 6)\n* data, erasing: shred invocation. (line 6)\n* database for color setup, printing: dircolors invocation.\n(line 45)\n* date: date invocation. (line 6)\n* date and time of day format, ISO 8601: Combined date and time of day items.\n(line 6)\n* date conversion specifiers: Date conversion specifiers.\n(line 6)\n* date format, ISO 8601: Calendar date items. (line 30)\n* date input formats: Date input formats. (line 6)\n* date options: Options for date. (line 6)\n* date strings, debugging: Options for date. (line 25)\n* date strings, parsing: Options for date. (line 11)\n* day in date strings: Relative items in date strings.\n(line 15)\n* day in date strings <1>: Relative items in date strings.\n(line 29)\n* day of week item: Day of week items. (line 6)\n* dd: dd invocation. (line 6)\n* ddrescue: dd invocation. (line 362)\n* debugging date strings: Options for date. (line 25)\n* debugging, env -S: env invocation. (line 273)\n* dec: Combination. (line 78)\n* decctlq: Combination. (line 63)\n* Decode base64 data: base64 invocation. (line 30)\n* delay for a specified time: sleep invocation. (line 6)\n* delaying commands: Delaying. (line 6)\n* deleting characters: Squeezing and deleting.\n(line 6)\n* dereferencing symbolic links: ln invocation. (line 42)\n* descriptor follow option: tail invocation. (line 56)\n* destination directory: Target directory. (line 15)\n* destination directory <1>: Target directory. (line 31)\n* destination directory <2>: cp invocation. (line 350)\n* destination directory <3>: cp invocation. (line 354)\n* destination directory <4>: install invocation. (line 125)\n* destination directory <5>: install invocation. (line 130)\n* destination directory <6>: mv invocation. (line 108)\n* destination directory <7>: mv invocation. (line 112)\n* destination directory <8>: ln invocation. (line 171)\n* destination directory <9>: ln invocation. (line 175)\n* destinations, multiple output: tee invocation. (line 6)\n* device file, disk: df invocation. (line 30)\n* df: df invocation. (line 6)\n* DFBLOCKSIZE: Block size. (line 12)\n* diagnostic: chcon invocation. (line 61)\n* dictionary order: sort invocation. (line 87)\n* differing lines: comm invocation. (line 18)\n* digit: Character sets. (line 96)\n* dir: dir invocation. (line 6)\n* dircolors: dircolors invocation.\n(line 6)\n* direct: dd invocation. (line 221)\n* direct I/O: dd invocation. (line 221)\n* directories, copying: cp invocation. (line 6)\n* directories, copying recursively: cp invocation. (line 96)\n* directories, copying recursively <1>: cp invocation. (line 252)\n* directories, creating: mkdir invocation. (line 6)\n* directories, creating with given attributes: install invocation.\n(line 67)\n* directories, removing: rm invocation. (line 35)\n* directories, removing (recursively): rm invocation. (line 95)\n* directories, removing empty: rmdir invocation. (line 6)\n* directory: dd invocation. (line 229)\n* directory check: File type tests. (line 16)\n* directory components, printing: dirname invocation. (line 6)\n* directory deletion, ignoring failures: rmdir invocation. (line 17)\n* directory deletion, reporting: rmdir invocation. (line 31)\n* directory I/O: dd invocation. (line 229)\n* directory listing: ls invocation. (line 6)\n* directory listing, brief: dir invocation. (line 6)\n* directory listing, recursive: Which files are listed.\n(line 90)\n* directory listing, verbose: vdir invocation. (line 6)\n* directory order, listing by: Sorting the output. (line 20)\n* directory, creating temporary: mktemp invocation. (line 6)\n* directory, stripping from file names: basename invocation. (line 6)\n* dired Emacs mode support: What information is listed.\n(line 16)\n* dirname: dirname invocation. (line 6)\n* disabling special characters: Characters. (line 12)\n* disambiguating group names and IDs: Disambiguating names and IDs.\n(line 6)\n* discard: Characters. (line 39)\n* discarding file cache: dd invocation. (line 246)\n* disk allocation: What information is listed.\n(line 236)\n* disk device file: df invocation. (line 30)\n* disk usage: Disk usage. (line 6)\n* disk usage by file system: df invocation. (line 6)\n* disk usage for files: du invocation. (line 6)\n* disks, failing: dd invocation. (line 362)\n* displacement of dates: Relative items in date strings.\n(line 6)\n* displaying text: echo invocation. (line 6)\n* displaying value of a symbolic link: readlink invocation. (line 6)\n* division: Numeric expressions. (line 16)\n* do nothing, successfully: true invocation. (line 6)\n* do nothing, unsuccessfully: false invocation. (line 6)\n* DOS file system: df invocation. (line 219)\n* double spacing: pr invocation. (line 74)\n* down columns: pr invocation. (line 49)\n* drain: Special. (line 30)\n* dsusp: Characters. (line 57)\n* dsync: dd invocation. (line 235)\n* DTR/DSR flow control: Control. (line 44)\n* du: du invocation. (line 6)\n* DUBLOCKSIZE: Block size. (line 12)\n* DVD file system type: df invocation. (line 215)\n* ebcdic, converting to: dd invocation. (line 112)\n* echo: echo invocation. (line 6)\n* echo <1>: Local. (line 18)\n* echoctl: Local. (line 51)\n* echoe: Local. (line 22)\n* echok: Local. (line 26)\n* echoke: Local. (line 56)\n* echonl: Local. (line 29)\n* echoprt: Local. (line 46)\n* effective user and group IDs, printing: id invocation. (line 6)\n* effective user ID, printing: whoami invocation. (line 6)\n* Eggert, Paul: Authors of parsedatetime.\n(line 6)\n* eight-bit characters: Control. (line 24)\n* eight-bit characters <1>: Combination. (line 55)\n* eight-bit input: Input. (line 25)\n* ek: Combination. (line 22)\n* empty files, creating: touch invocation. (line 11)\n* empty lines, numbering: nl invocation. (line 82)\n* endianness: od invocation. (line 51)\n* entire files, output of: Output of entire files.\n(line 6)\n* env: env invocation. (line 6)\n* env -S, and single quotes: env invocation. (line 264)\n* env -S, debugging: env invocation. (line 273)\n* env in scripts: env invocation. (line 188)\n* environment variables, printing: printenv invocation. (line 6)\n* environment, printing: env invocation. (line 50)\n* environment, running a program in a modified: env invocation.\n(line 6)\n* eof: Characters. (line 30)\n* eol: Characters. (line 33)\n* eol2: Characters. (line 36)\n* epoch, for POSIX: Seconds since the Epoch.\n(line 13)\n* epoch, seconds since: Time conversion specifiers.\n(line 32)\n* equal string check: String tests. (line 22)\n* equal string check <1>: String tests. (line 25)\n* equivalence classes: Character sets. (line 113)\n* erase: Characters. (line 24)\n* erasing data: shred invocation. (line 6)\n* error messages, omitting: chown invocation. (line 79)\n* error messages, omitting <1>: chgrp invocation. (line 30)\n* error messages, omitting <2>: chmod invocation. (line 49)\n* evaluation of expressions: expr invocation. (line 6)\n* even parity: Control. (line 13)\n* evenp: Combination. (line 9)\n* exabyte, definition of: Block size. (line 106)\n* examples of date: Examples of date. (line 6)\n* examples of expr: Examples of expr. (line 6)\n* exbibyte, definition of: Block size. (line 109)\n* excl: dd invocation. (line 172)\n* excluding files from du: du invocation. (line 252)\n* excluding files from du <1>: du invocation. (line 257)\n* executable file check: Access permission tests.\n(line 24)\n* executables and file type, marking: General output formatting.\n(line 46)\n* execute/search permission: Mode Structure. (line 16)\n* execute/search permission, symbolic: Setting Permissions. (line 56)\n* existence-of-file check: File characteristic tests.\n(line 9)\n* existing backup method: Backup options. (line 39)\n* exit status commands: Conditions. (line 6)\n* exit status of chroot: chroot invocation. (line 78)\n* exit status of env: env invocation. (line 193)\n* exit status of expr: expr invocation. (line 43)\n* exit status of false: false invocation. (line 6)\n* exit status of ls: ls invocation. (line 29)\n* exit status of mktemp: mktemp invocation. (line 128)\n* exit status of nice: nice invocation. (line 63)\n* exit status of nohup: nohup invocation. (line 48)\n* exit status of pathchk: pathchk invocation. (line 47)\n* exit status of printenv: printenv invocation. (line 23)\n* exit status of realpath: realpath invocation. (line 75)\n* exit status of runcon: runcon invocation. (line 50)\n* exit status of sort: sort invocation. (line 58)\n* exit status of stdbuf: stdbuf invocation. (line 70)\n* exit status of test: test invocation. (line 41)\n* exit status of timeout: timeout invocation. (line 66)\n* exit status of true: true invocation. (line 6)\n* exit status of tty: tty invocation. (line 20)\n* expand: expand invocation. (line 6)\n* expr: expr invocation. (line 6)\n* expression evaluation: test invocation. (line 6)\n* expression evaluation <1>: expr invocation. (line 6)\n* expressions, numeric: Numeric expressions. (line 6)\n* expressions, string: String expressions. (line 6)\n* ext2 file system type: df invocation. (line 211)\n* ext3 file system type: df invocation. (line 211)\n* ext4 file system type: df invocation. (line 211)\n* extended attributes, xattr: install invocation. (line 34)\n* extended attributes, xattr <1>: mv invocation. (line 33)\n* extension, sorting files by: Sorting the output. (line 74)\n* extproc: Local. (line 61)\n* factor: factor invocation. (line 6)\n* failure exit status: false invocation. (line 6)\n* false: false invocation. (line 6)\n* fat file system file: df invocation. (line 219)\n* fdatasync: dd invocation. (line 188)\n* ffN: Output. (line 63)\n* field separator character: sort invocation. (line 332)\n* fields, padding numeric: Padding and other flags.\n(line 6)\n* FIFOs, creating: mkfifo invocation. (line 6)\n* file attributes, changing: Changing file attributes.\n(line 6)\n* file characteristic tests: File characteristic tests.\n(line 6)\n* file contents, dumping unambiguously: od invocation. (line 6)\n* file information, preserving: cp invocation. (line 235)\n* file information, preserving, extended attributes, xattr: cp invocation.\n(line 169)\n* file mode bits, numeric: Numeric Modes. (line 6)\n* file name manipulation: File name manipulation.\n(line 6)\n* file names, canonicalization: realpath invocation. (line 6)\n* file names, checking validity and portability: pathchk invocation.\n(line 6)\n* file names, creating temporary: mktemp invocation. (line 6)\n* file names, stripping directory and suffix: basename invocation.\n(line 6)\n* file offset radix: od invocation. (line 36)\n* file ownership, changing: chown invocation. (line 6)\n* file sizes: du invocation. (line 52)\n* file space usage: du invocation. (line 6)\n* file status: stat invocation. (line 6)\n* file system disk usage: df invocation. (line 6)\n* file system sizes: df invocation. (line 54)\n* file system space, retrieving current data more slowly: df invocation.\n(line 174)\n* file system space, retrieving old data more quickly: df invocation.\n(line 84)\n* file system status: stat invocation. (line 6)\n* file system types, limiting output to certain: df invocation.\n(line 80)\n* file system types, limiting output to certain <1>: df invocation.\n(line 194)\n* file system types, printing: df invocation. (line 200)\n* file systems: stat invocation. (line 28)\n* file systems and hard links: ln invocation. (line 6)\n* file systems, omitting copying to different: cp invocation. (line 378)\n* file timestamp resolution: File timestamps. (line 45)\n* file timestamps, changing: touch invocation. (line 6)\n* file type and executables, marking: General output formatting.\n(line 46)\n* file type tests: File type tests. (line 6)\n* file type, marking: General output formatting.\n(line 57)\n* file type, marking <1>: General output formatting.\n(line 108)\n* file types: Special file types. (line 9)\n* file types, special: Special file types. (line 6)\n* file utilities: Top. (line 18)\n* files beginning with -, removing: rm invocation. (line 101)\n* files, copying: cp invocation. (line 6)\n* files, creating: truncate invocation. (line 11)\n* fingerprint, 128-bit: md5sum invocation. (line 6)\n* fingerprint, 160-bit: sha1sum invocation. (line 6)\n* fingerprint, 224-bit: sha2 utilities. (line 6)\n* fingerprint, 256-bit: sha2 utilities. (line 6)\n* fingerprint, 384-bit: sha2 utilities. (line 6)\n* fingerprint, 512-bit: b2sum invocation. (line 6)\n* fingerprint, 512-bit <1>: sha2 utilities. (line 6)\n* first in date strings: General date syntax. (line 22)\n* first part of files, outputting: head invocation. (line 6)\n* fixed-length records, converting to variable-length: dd invocation.\n(line 41)\n* floating point: Floating point. (line 6)\n* flow control, hardware: Control. (line 41)\n* flow control, hardware <1>: Control. (line 44)\n* flow control, software: Input. (line 45)\n* flush: Characters. (line 39)\n* flushing, disabling: Local. (line 32)\n* flusho: Local. (line 67)\n* fmt: fmt invocation. (line 6)\n* fold: fold invocation. (line 6)\n* folding long input lines: fold invocation. (line 6)\n* footers, numbering: nl invocation. (line 17)\n* force deletion: shred invocation. (line 123)\n* formatting file contents: Formatting file contents.\n(line 6)\n* formatting of numbers in seq: seq invocation. (line 28)\n* formatting times: pr invocation. (line 78)\n* formatting times <1>: date invocation. (line 20)\n* fortnight in date strings: Relative items in date strings.\n(line 15)\n* fsync: dd invocation. (line 192)\n* fullblock: dd invocation. (line 303)\n* general date syntax: General date syntax. (line 6)\n* general numeric sort: sort invocation. (line 105)\n* gibibyte, definition of: Block size. (line 94)\n* gigabyte, definition of: Block size. (line 91)\n* giving away permissions: Umask and Protection.\n(line 12)\n* GMT: Options for date. (line 119)\n* grand total of disk size, usage and available space: df invocation.\n(line 180)\n* grand total of disk space: du invocation. (line 61)\n* graph: Character sets. (line 98)\n* Greenwich Mean Time: Options for date. (line 119)\n* group IDs, disambiguating: Disambiguating names and IDs.\n(line 6)\n* group names, disambiguating: Disambiguating names and IDs.\n(line 6)\n* group owner, default: Mode Structure. (line 27)\n* group ownership of installed files, setting: install invocation.\n(line 73)\n* group ownership, changing: chown invocation. (line 6)\n* group ownership, changing <1>: chgrp invocation. (line 6)\n* group, permissions for: Setting Permissions. (line 25)\n* groups: groups invocation. (line 6)\n* growing files: tail invocation. (line 56)\n* hangups, immunity to: nohup invocation. (line 6)\n* hard link check: File characteristic tests.\n(line 23)\n* hard link, defined: ln invocation. (line 32)\n* hard links: dd invocation. (line 292)\n* hard links to directories: ln invocation. (line 88)\n* hard links to symbolic links: ln invocation. (line 182)\n* hard links, counting in du: du invocation. (line 123)\n* hard links, creating: link invocation. (line 6)\n* hard links, creating <1>: ln invocation. (line 6)\n* hard links, preserving: cp invocation. (line 109)\n* hardware class: uname invocation. (line 42)\n* hardware flow control: Control. (line 41)\n* hardware flow control <1>: Control. (line 44)\n* hardware platform: uname invocation. (line 35)\n* hardware type: uname invocation. (line 42)\n* hat notation for control characters: Local. (line 51)\n* head: head invocation. (line 6)\n* head of output: shuf invocation. (line 31)\n* headers, numbering: nl invocation. (line 17)\n* help, online: Common options. (line 36)\n* hex dump of files: od invocation. (line 6)\n* holes, copying files with: cp invocation. (line 299)\n* holes, creating files with: truncate invocation. (line 13)\n* horizontal, listing files: General output formatting.\n(line 113)\n* host processor type: uname invocation. (line 51)\n* hostid: hostid invocation. (line 6)\n* hostname: hostname invocation. (line 6)\n* hostname <1>: uname invocation. (line 47)\n* hour in date strings: Relative items in date strings.\n(line 15)\n* human numeric sort: sort invocation. (line 126)\n* human-readable output: Block size. (line 42)\n* human-readable output <1>: What information is listed.\n(line 116)\n* human-readable output <2>: df invocation. (line 59)\n* human-readable output <3>: du invocation. (line 96)\n* hup[cl]: Control. (line 28)\n* hurd, author, printing: What information is listed.\n(line 10)\n* hyperlink, linking to files: General output formatting.\n(line 61)\n* ibs: dd invocation. (line 26)\n* icanon: Local. (line 11)\n* icrnl: Input. (line 34)\n* id: id invocation. (line 6)\n* idle time: who invocation. (line 85)\n* IEEE floating point: Floating point. (line 6)\n* iexten: Local. (line 15)\n* if: dd invocation. (line 18)\n* iflag: dd invocation. (line 196)\n* ignbrk: Input. (line 9)\n* igncr: Input. (line 31)\n* ignore file systems: df invocation. (line 42)\n* Ignore garbage in base64 stream: base64 invocation. (line 36)\n* ignoring case: sort invocation. (line 94)\n* ignpar: Input. (line 15)\n* imaxbel: Input. (line 59)\n* immunity to hangups: nohup invocation. (line 6)\n* implementation, hardware: uname invocation. (line 35)\n* indenting lines: pr invocation. (line 180)\n* index: String expressions. (line 45)\n* information, about current users: who invocation. (line 6)\n* initial part of files, outputting: head invocation. (line 6)\n* initial tabs, converting: expand invocation. (line 46)\n* inlcr: Input. (line 28)\n* inode number, printing: What information is listed.\n(line 123)\n* inode usage: df invocation. (line 69)\n* inode usage, dereferencing in du: du invocation. (line 102)\n* inode, and hard links: ln invocation. (line 32)\n* inodes, written buffered: sync invocation. (line 11)\n* inpck: Input. (line 22)\n* input block size: dd invocation. (line 26)\n* input encoding, UTF-8: Input. (line 37)\n* input range to shuffle: shuf invocation. (line 23)\n* input settings: Input. (line 6)\n* input tabs: pr invocation. (line 98)\n* install: install invocation. (line 6)\n* intr: Characters. (line 18)\n* invocation of commands, modified: Modified command invocation.\n(line 6)\n* isig: Local. (line 7)\n* ISO 8601 date and time of day format: Combined date and time of day items.\n(line 6)\n* ISO 8601 date format: Calendar date items. (line 30)\n* ISO/IEC 10646: printf invocation. (line 74)\n* ISO9660 file system type: df invocation. (line 215)\n* iso9660 file system type: df invocation. (line 215)\n* ispeed: Special. (line 16)\n* istrip: Input. (line 25)\n* items in date strings: General date syntax. (line 6)\n* iterations, selecting the number of: shred invocation. (line 127)\n* iuclc: Input. (line 50)\n* iutf8: Input. (line 37)\n* ixany: Input. (line 55)\n* ixoff: Input. (line 45)\n* ixon: Input. (line 40)\n* join: join invocation. (line 6)\n* kernel name: uname invocation. (line 66)\n* kernel release: uname invocation. (line 62)\n* kernel version: uname invocation. (line 77)\n* kibibyte, definition of: Block size. (line 82)\n* kibibytes for file sizes: du invocation. (line 111)\n* kibibytes for file system sizes: df invocation. (line 74)\n* kill: kill invocation. (line 6)\n* kill <1>: Characters. (line 27)\n* kilobyte, definition of: Block size. (line 78)\n* Knuth, Donald E.: fmt invocation. (line 19)\n* language, in dates: General date syntax. (line 36)\n* language, in dates <1>: General date syntax. (line 40)\n* last DAY: Day of week items. (line 15)\n* last DAY <1>: Options for date. (line 11)\n* last in date strings: General date syntax. (line 22)\n* last modified dates, displaying in du: du invocation. (line 197)\n* last part of files, outputting: tail invocation. (line 6)\n* lcase: Combination. (line 71)\n* LCASE: Combination. (line 71)\n* lcase, converting to: dd invocation. (line 138)\n* lchown: chown invocation. (line 106)\n* lchown <1>: chown invocation. (line 118)\n* lchown <2>: chgrp invocation. (line 34)\n* lchown <3>: chgrp invocation. (line 46)\n* LCALL: sort invocation. (line 23)\n* LCALL <1>: ls invocation. (line 17)\n* LCCOLLATE: sort invocation. (line 23)\n* LCCOLLATE <1>: uniq invocation. (line 21)\n* LCCOLLATE <2>: comm invocation. (line 12)\n* LCCOLLATE <3>: Sorting files for join.\n(line 16)\n* LCCOLLATE <4>: Relations for expr. (line 22)\n* LCCTYPE: sort invocation. (line 79)\n* LCCTYPE <1>: sort invocation. (line 87)\n* LCCTYPE <2>: sort invocation. (line 94)\n* LCCTYPE <3>: sort invocation. (line 143)\n* LCCTYPE <4>: printf invocation. (line 74)\n* LCMESSAGES: pr invocation. (line 13)\n* LCNUMERIC: Block size. (line 57)\n* LCNUMERIC <1>: Floating point. (line 29)\n* LCNUMERIC <2>: sort invocation. (line 105)\n* LCNUMERIC <3>: sort invocation. (line 126)\n* LCNUMERIC <4>: sort invocation. (line 160)\n* LCNUMERIC <5>: printf invocation. (line 61)\n* LCTIME: pr invocation. (line 85)\n* LCTIME <1>: sort invocation. (line 150)\n* LCTIME <2>: Formatting file timestamps.\n(line 28)\n* LCTIME <3>: Formatting file timestamps.\n(line 73)\n* LCTIME <4>: Formatting file timestamps.\n(line 97)\n* LCTIME <5>: du invocation. (line 219)\n* LCTIME <6>: date invocation. (line 11)\n* leading directories, creating missing: install invocation. (line 67)\n* leading directory components, stripping: basename invocation.\n(line 6)\n* leap seconds: touch invocation. (line 99)\n* leap seconds <1>: Time conversion specifiers.\n(line 32)\n* leap seconds <2>: Time conversion specifiers.\n(line 36)\n* leap seconds <3>: Options for date. (line 119)\n* leap seconds <4>: Examples of date. (line 104)\n* leap seconds <5>: General date syntax. (line 65)\n* leap seconds <6>: Time of day items. (line 14)\n* leap seconds <7>: Seconds since the Epoch.\n(line 26)\n* left margin: pr invocation. (line 180)\n* length: String expressions. (line 50)\n* limiting output of du: du invocation. (line 74)\n* line: Special. (line 46)\n* line buffered: stdbuf invocation. (line 6)\n* line count: wc invocation. (line 6)\n* line numbering: nl invocation. (line 6)\n* line separator character: split invocation. (line 148)\n* line settings of terminal: stty invocation. (line 6)\n* line-breaking: fmt invocation. (line 19)\n* line-by-line comparison: comm invocation. (line 6)\n* LINES: Special. (line 39)\n* link: link invocation. (line 6)\n* links, creating: link invocation. (line 6)\n* links, creating <1>: ln invocation. (line 6)\n* Linux file system types: df invocation. (line 211)\n* literal conversion specifiers: Literal conversion specifiers.\n(line 6)\n* litout: Combination. (line 59)\n* ln: ln invocation. (line 6)\n* ln format for nl: nl invocation. (line 93)\n* lnext: Characters. (line 66)\n* local file system types: df invocation. (line 211)\n* local settings: Local. (line 6)\n* logging out and continuing to run: nohup invocation. (line 6)\n* logical and operator: Connectives for test.\n(line 29)\n* logical and operator <1>: Relations for expr. (line 17)\n* logical connectives: Connectives for test.\n(line 6)\n* logical connectives <1>: Relations for expr. (line 6)\n* logical or operator: Connectives for test.\n(line 33)\n* logical or operator <1>: Relations for expr. (line 11)\n* logical pages, numbering on: nl invocation. (line 12)\n* login name, printing: logname invocation. (line 6)\n* login sessions, printing users with: users invocation. (line 6)\n* login time: who invocation. (line 11)\n* logname: logname invocation. (line 6)\n* long ls format: What information is listed.\n(line 131)\n* lower: Character sets. (line 100)\n* lowercase, translating to output: Output. (line 12)\n* ls: ls invocation. (line 6)\n* LSBLOCKSIZE: Block size. (line 12)\n* LSCOLORS: General output formatting.\n(line 31)\n* LSCOLORS <1>: dircolors invocation.\n(line 23)\n* lutimes: touch invocation. (line 70)\n* machine type: uname invocation. (line 42)\n* machine-readable stty output: stty invocation. (line 41)\n* MacKenzie, D.: Introduction. (line 29)\n* MacKenzie, David: Authors of parsedatetime.\n(line 6)\n* Makefiles, installing programs in: install invocation. (line 29)\n* manipulating files: Basic operations. (line 6)\n* manipulation of file names: File name manipulation.\n(line 6)\n* mark parity: Control. (line 16)\n* match: String expressions. (line 36)\n* matching patterns: String expressions. (line 11)\n* MD5: md5sum invocation. (line 6)\n* md5sum: md5sum invocation. (line 6)\n* mebibyte, definition of: Block size. (line 89)\n* mebibytes for file sizes: du invocation. (line 127)\n* megabyte, definition of: Block size. (line 86)\n* merging files: paste invocation. (line 6)\n* merging files in parallel: pr invocation. (line 6)\n* merging sorted files: sort invocation. (line 53)\n* message status: who invocation. (line 94)\n* message-digest, 128-bit: md5sum invocation. (line 6)\n* message-digest, 160-bit: sha1sum invocation. (line 6)\n* message-digest, 224-bit: sha2 utilities. (line 6)\n* message-digest, 256-bit: sha2 utilities. (line 6)\n* message-digest, 384-bit: sha2 utilities. (line 6)\n* message-digest, 512-bit: b2sum invocation. (line 6)\n* message-digest, 512-bit <1>: sha2 utilities. (line 6)\n* Meyering, J.: Introduction. (line 29)\n* Meyering, Jim: Authors of parsedatetime.\n(line 6)\n* midnight in date strings: Time of day items. (line 21)\n* min: Special. (line 7)\n* minute in date strings: Relative items in date strings.\n(line 15)\n* minutes, time zone correction by: Time of day items. (line 29)\n* mkdir: mkdir invocation. (line 6)\n* mkfifo: mkfifo invocation. (line 6)\n* mknod: mknod invocation. (line 6)\n* mktemp: mktemp invocation. (line 6)\n* modem control: Control. (line 38)\n* modes and umask: Umask and Protection.\n(line 6)\n* modes of created directories, setting: mkdir invocation. (line 19)\n* modes of created FIFOs, setting: mkfifo invocation. (line 21)\n* modification timestamp, sorting files by: Sorting the output.\n(line 36)\n* modified command invocation: Modified command invocation.\n(line 6)\n* modified environment, running a program in a: env invocation.\n(line 6)\n* modify time, changing: touch invocation. (line 85)\n* month in date strings: Relative items in date strings.\n(line 15)\n* month names in date strings: Calendar date items. (line 38)\n* months, sorting by: sort invocation. (line 150)\n* months, written-out: General date syntax. (line 32)\n* MS-DOS file system: df invocation. (line 219)\n* MS-Windows file system: df invocation. (line 219)\n* mtime: File timestamps. (line 6)\n* mtime, changing: touch invocation. (line 85)\n* mtime-greater-atime file check: File characteristic tests.\n(line 27)\n* multicall: Multi-call invocation.\n(line 6)\n* multicolumn output, generating: pr invocation. (line 6)\n* multiple changes to permissions: Multiple Changes. (line 6)\n* multiplication: Numeric expressions. (line 16)\n* multipliers after numbers: dd invocation. (line 337)\n* multithreaded sort: sort invocation. (line 360)\n* mv: mv invocation. (line 6)\n* name follow option: tail invocation. (line 56)\n* name of kernel: uname invocation. (line 66)\n* named pipe check: File type tests. (line 28)\n* named pipes, creating: mkfifo invocation. (line 6)\n* network node name: uname invocation. (line 47)\n* never interactive option: rm invocation. (line 56)\n* newer files, copying only: cp invocation. (line 359)\n* newer files, moving only: mv invocation. (line 84)\n* newer-than file check: File characteristic tests.\n(line 15)\n* newline echoing after kill: Local. (line 26)\n* newline, echoing: Local. (line 29)\n* newline, translating to crlf: Output. (line 19)\n* newline, translating to return: Input. (line 28)\n* next DAY: Day of week items. (line 15)\n* next DAY <1>: Options for date. (line 11)\n* next in date strings: General date syntax. (line 22)\n* NFS file system type: df invocation. (line 206)\n* NFS mounts from BSD to HP-UX: What information is listed.\n(line 244)\n* NFS mounts from BSD to HP-UX <1>: du invocation. (line 266)\n* nice: nice invocation. (line 6)\n* niceness: nice invocation. (line 6)\n* nl: nl invocation. (line 6)\n* nl <1>: Combination. (line 18)\n* nlN: Output. (line 39)\n* no dereference: chcon invocation. (line 26)\n* no-op: true invocation. (line 6)\n* noatime: dd invocation. (line 278)\n* nocache: dd invocation. (line 246)\n* nocreat: dd invocation. (line 176)\n* noctty: dd invocation. (line 284)\n* node name: uname invocation. (line 47)\n* noerror: dd invocation. (line 185)\n* noflsh: Local. (line 32)\n* nofollow: dd invocation. (line 289)\n* nohup: nohup invocation. (line 6)\n* nohup.out: nohup invocation. (line 6)\n* nohup.out <1>: nohup invocation. (line 20)\n* nolinks: dd invocation. (line 292)\n* non-directories, copying as special files: cp invocation. (line 96)\n* non-directories, copying as special files <1>: cp invocation.\n(line 252)\n* non-directory suffix, stripping: dirname invocation. (line 6)\n* nonblock: dd invocation. (line 275)\n* nonblocking I/O: dd invocation. (line 275)\n* nonblocking stty setting: Special. (line 30)\n* none backup method: Backup options. (line 31)\n* none color option: General output formatting.\n(line 24)\n* none dd status=: dd invocation. (line 71)\n* none hyperlink option: General output formatting.\n(line 63)\n* none, sorting option for ls: Sorting the output. (line 60)\n* nonempty file check: File characteristic tests.\n(line 12)\n* nonprinting characters, ignoring: sort invocation. (line 143)\n* nonzero-length string check: String tests. (line 19)\n* noon in date strings: Time of day items. (line 21)\n* not-equal string check: String tests. (line 28)\n* notrunc: dd invocation. (line 182)\n* now in date strings: Relative items in date strings.\n(line 33)\n* noxfer dd status=: dd invocation. (line 75)\n* NONEWPRIVS: runcon invocation. (line 22)\n* nproc: nproc invocation. (line 6)\n* NTFS file system: df invocation. (line 219)\n* ntfs file system file: df invocation. (line 219)\n* number of inputs to merge, nmerge: sort invocation. (line 262)\n* numbered backup method: Backup options. (line 35)\n* numbering lines: nl invocation. (line 6)\n* numbers, written-out: General date syntax. (line 22)\n* numeric expressions: Numeric expressions. (line 6)\n* numeric field padding: Padding and other flags.\n(line 6)\n* numeric modes: Numeric Modes. (line 6)\n* numeric operations: Numeric operations. (line 6)\n* numeric sequences: seq invocation. (line 6)\n* numeric sort: sort invocation. (line 160)\n* numeric tests: Numeric tests. (line 6)\n* numeric uid and gid: What information is listed.\n(line 225)\n* numeric user and group IDs: What information is listed.\n(line 225)\n* numfmt: numfmt invocation. (line 6)\n* obs: dd invocation. (line 30)\n* ocrnl: Output. (line 16)\n* octal dump of files: od invocation. (line 6)\n* octal numbers for file modes: Numeric Modes. (line 6)\n* od: od invocation. (line 6)\n* odd parity: Control. (line 13)\n* oddp: Combination. (line 14)\n* of: dd invocation. (line 21)\n* ofdel: Output. (line 34)\n* ofill: Output. (line 30)\n* oflag: dd invocation. (line 200)\n* olcuc: Output. (line 12)\n* older-than file check: File characteristic tests.\n(line 19)\n* once interactive option: rm invocation. (line 57)\n* one file system, restricting du to: du invocation. (line 263)\n* one file system, restricting rm to: rm invocation. (line 65)\n* one-line output format: df invocation. (line 148)\n* onlcr: Output. (line 19)\n* onlret: Output. (line 27)\n* onocr: Output. (line 23)\n* operating on characters: Operating on characters.\n(line 6)\n* operating on sorted files: Operating on sorted files.\n(line 6)\n* operating system name: uname invocation. (line 58)\n* opost: Output. (line 9)\n* option delimiter: Common options. (line 43)\n* options for date: Options for date. (line 6)\n* or operator: Connectives for test.\n(line 33)\n* or operator <1>: Relations for expr. (line 11)\n* ordinal numbers: General date syntax. (line 22)\n* ospeed: Special. (line 19)\n* other permissions: Setting Permissions. (line 27)\n* output block size: dd invocation. (line 30)\n* output file name prefix: split invocation. (line 15)\n* output file name prefix <1>: csplit invocation. (line 63)\n* output file name suffix: csplit invocation. (line 67)\n* output format: stat invocation. (line 50)\n* output format <1>: stat invocation. (line 59)\n* output format, portable: df invocation. (line 148)\n* output NUL-byte-terminated lines: md5sum invocation. (line 128)\n* output NUL-byte-terminated lines <1>: readlink invocation. (line 65)\n* output NUL-byte-terminated lines <2>: du invocation. (line 26)\n* output NUL-byte-terminated lines <3>: basename invocation. (line 42)\n* output NUL-byte-terminated lines <4>: dirname invocation. (line 31)\n* output NUL-byte-terminated lines <5>: realpath invocation. (line 71)\n* output NUL-byte-terminated lines <6>: printenv invocation. (line 19)\n* output NUL-byte-terminated lines <7>: env invocation. (line 90)\n* output of entire files: Output of entire files.\n(line 6)\n* output of parts of files: Output of parts of files.\n(line 6)\n* output settings: Output. (line 6)\n* output tabs: pr invocation. (line 117)\n* overwriting of input, allowed: sort invocation. (line 288)\n* overwriting of input, allowed <1>: shuf invocation. (line 36)\n* owned by effective group ID check: Access permission tests.\n(line 31)\n* owned by effective user ID check: Access permission tests.\n(line 28)\n* owner of file, permissions for: Setting Permissions. (line 23)\n* owner, default: Mode Structure. (line 27)\n* ownership of installed files, setting: install invocation. (line 91)\n* p for FIFO file: mknod invocation. (line 28)\n* pad character: Output. (line 34)\n* pad instead of timing for delaying: Output. (line 30)\n* padding of numeric fields: Padding and other flags.\n(line 6)\n* paragraphs, reformatting: fmt invocation. (line 6)\n* parenb: Control. (line 9)\n* parent directories and cp: cp invocation. (line 239)\n* parent directories, creating: mkdir invocation. (line 34)\n* parent directories, creating missing: install invocation. (line 67)\n* parent directories, removing: rmdir invocation. (line 22)\n* parentheses for grouping: expr invocation. (line 31)\n* parity: Combination. (line 10)\n* parity errors, marking: Input. (line 18)\n* parity, ignoring: Input. (line 15)\n* parmrk: Input. (line 18)\n* parodd: Control. (line 13)\n* parsedatetime: Date input formats. (line 6)\n* parsing date strings: Options for date. (line 11)\n* parts of files, output of: Output of parts of files.\n(line 6)\n* pass8: Combination. (line 55)\n* paste: paste invocation. (line 6)\n* Paterson, R.: Introduction. (line 29)\n* PATH: env invocation. (line 28)\n* pathchk: pathchk invocation. (line 6)\n* pattern matching: String expressions. (line 11)\n* pebibyte, definition of: Block size. (line 104)\n* permission tests: Access permission tests.\n(line 6)\n* permissions of installed files, setting: install invocation.\n(line 79)\n* permissions, changing access: chmod invocation. (line 6)\n* permissions, copying existing: Copying Permissions. (line 6)\n* permissions, for changing file timestamps: touch invocation.\n(line 21)\n* permissions, output by ls: What information is listed.\n(line 182)\n* petabyte, definition of: Block size. (line 101)\n* phone directory order: sort invocation. (line 87)\n* pieces, splitting a file into: split invocation. (line 6)\n* Pinard, F.: Introduction. (line 29)\n* Pinard, F. <1>: Authors of parsedatetime.\n(line 19)\n* pipe fitting: tee invocation. (line 6)\n* Plass, Michael F.: fmt invocation. (line 19)\n* platform, hardware: uname invocation. (line 35)\n* pm in date strings: Time of day items. (line 21)\n* portable file names, checking for: pathchk invocation. (line 6)\n* portable output format: df invocation. (line 148)\n* POSIX: Introduction. (line 11)\n* POSIX output format: df invocation. (line 148)\n* POSIXLYCORRECT: Common options. (line 11)\n* POSIXLYCORRECT <1>: Standards conformance.\n(line 6)\n* POSIXLYCORRECT <2>: pr invocation. (line 85)\n* POSIXLYCORRECT <3>: sort invocation. (line 299)\n* POSIXLYCORRECT <4>: sort invocation. (line 415)\n* POSIXLYCORRECT <5>: dd invocation. (line 406)\n* POSIXLYCORRECT <6>: echo invocation. (line 65)\n* POSIXLYCORRECT <7>: printf invocation. (line 53)\n* POSIXLYCORRECT <8>: id invocation. (line 15)\n* POSIXLYCORRECT, and block size: Block size. (line 12)\n* pr: pr invocation. (line 6)\n* prime factors: factor invocation. (line 6)\n* print: Character sets. (line 102)\n* print machine hardware name: arch invocation. (line 6)\n* print name of current directory: pwd invocation. (line 6)\n* print system information: uname invocation. (line 6)\n* print terminal file name: tty invocation. (line 6)\n* Print the number of processors: nproc invocation. (line 6)\n* printenv: printenv invocation. (line 6)\n* printf: printf invocation. (line 6)\n* printing all or some environment variables: printenv invocation.\n(line 6)\n* printing color database: dircolors invocation.\n(line 45)\n* printing current user information: who invocation. (line 6)\n* printing current usernames: users invocation. (line 6)\n* printing groups a user is in: groups invocation. (line 6)\n* printing real and effective user and group IDs: id invocation.\n(line 6)\n* printing text: echo invocation. (line 6)\n* printing text, commands for: Printing text. (line 6)\n* printing the current time: date invocation. (line 6)\n* printing the effective user ID: whoami invocation. (line 6)\n* printing the host identifier: hostid invocation. (line 6)\n* printing the hostname: hostname invocation. (line 6)\n* printing the system uptime and load: uptime invocation. (line 6)\n* printing user's login name: logname invocation. (line 6)\n* printing, preparing files for: pr invocation. (line 6)\n* process zero-terminated items: head invocation. (line 55)\n* process zero-terminated items <1>: tail invocation. (line 188)\n* process zero-terminated items <2>: sort invocation. (line 383)\n* process zero-terminated items <3>: shuf invocation. (line 55)\n* process zero-terminated items <4>: uniq invocation. (line 139)\n* process zero-terminated items <5>: comm invocation. (line 88)\n* process zero-terminated items <6>: cut invocation. (line 94)\n* process zero-terminated items <7>: paste invocation. (line 72)\n* process zero-terminated items <8>: General options in join.\n(line 93)\n* process zero-terminated items <9>: numfmt invocation. (line 115)\n* processes, commands for controlling: Process control. (line 6)\n* progress dd status=: dd invocation. (line 79)\n* prompting, and ln: ln invocation. (line 98)\n* prompting, and mv: mv invocation. (line 37)\n* prompting, and rm: rm invocation. (line 11)\n* prompts, forcing: mv invocation. (line 70)\n* prompts, omitting: mv invocation. (line 64)\n* prompts, omitting <1>: mv invocation. (line 77)\n* prterase: Local. (line 46)\n* ptx: ptx invocation. (line 6)\n* punct: Character sets. (line 104)\n* pure numbers in date strings: Pure numbers in date strings.\n(line 6)\n* pwd: pwd invocation. (line 6)\n* quit: Characters. (line 21)\n* quoting style: Formatting the file names.\n(line 34)\n* radix for file offsets: od invocation. (line 36)\n* random seed: Random sources. (line 31)\n* random sort: sort invocation. (line 189)\n* random source for shredding: shred invocation. (line 133)\n* random source for shuffling: shuf invocation. (line 42)\n* random source for sorting: sort invocation. (line 304)\n* random sources: Random sources. (line 6)\n* ranges: Character sets. (line 44)\n* raw: Combination. (line 43)\n* read errors, ignoring: dd invocation. (line 185)\n* read from stdin and write to stdout and files: tee invocation.\n(line 6)\n* read permission: Mode Structure. (line 12)\n* read permission, symbolic: Setting Permissions. (line 52)\n* read system call, and holes: cp invocation. (line 299)\n* readable file check: Access permission tests.\n(line 15)\n* readlink: readlink invocation. (line 6)\n* real user and group IDs, printing: id invocation. (line 6)\n* realpath: realpath invocation. (line 6)\n* realpath <1>: realpath invocation. (line 6)\n* realpath <2>: realpath invocation. (line 6)\n* realpath <3>: readlink invocation. (line 6)\n* record separator character: split invocation. (line 148)\n* recursive directory listing: Which files are listed.\n(line 90)\n* recursively changing access permissions: chmod invocation. (line 73)\n* recursively changing file ownership: chown invocation. (line 150)\n* recursively changing group ownership: chgrp invocation. (line 77)\n* recursively copying directories: cp invocation. (line 96)\n* recursively copying directories <1>: cp invocation. (line 252)\n* redirection: Redirection. (line 6)\n* reference file: chcon invocation. (line 30)\n* reformatting paragraph text: fmt invocation. (line 6)\n* regular expression matching: String expressions. (line 11)\n* regular file check: File type tests. (line 19)\n* relations, numeric or string: Relations for expr. (line 6)\n* relative items in date strings: Relative items in date strings.\n(line 6)\n* release of kernel: uname invocation. (line 62)\n* relpath: realpath invocation. (line 49)\n* remainder: Numeric expressions. (line 16)\n* remote hostname: who invocation. (line 11)\n* removing characters: Squeezing and deleting.\n(line 6)\n* removing empty directories: rmdir invocation. (line 6)\n* removing files after shredding: shred invocation. (line 144)\n* removing files or directories: rm invocation. (line 6)\n* removing files or directories (via the unlink syscall): unlink invocation.\n(line 6)\n* removing permissions: Setting Permissions. (line 38)\n* repeat output values: shuf invocation. (line 47)\n* repeated characters: Character sets. (line 66)\n* repeated lines, outputting: uniq invocation. (line 63)\n* repeated output of a string: yes invocation. (line 6)\n* restricted deletion flag: Mode Structure. (line 52)\n* restricted security context: runcon invocation. (line 22)\n* return, ignoring: Input. (line 31)\n* return, translating to newline: Input. (line 34)\n* return, translating to newline <1>: Output. (line 16)\n* reverse sorting: sort invocation. (line 183)\n* reverse sorting <1>: Sorting the output. (line 27)\n* reversing files: tac invocation. (line 6)\n* rm: rm invocation. (line 6)\n* rmdir: rmdir invocation. (line 6)\n* rn format for nl: nl invocation. (line 95)\n* root as default owner: install invocation. (line 91)\n* root directory, allow recursive destruction: rm invocation. (line 88)\n* root directory, allow recursive modification: chown invocation.\n(line 131)\n* root directory, allow recursive modification <1>: chgrp invocation.\n(line 59)\n* root directory, allow recursive modification <2>: chmod invocation.\n(line 58)\n* root directory, disallow recursive destruction: rm invocation.\n(line 81)\n* root directory, disallow recursive modification: chown invocation.\n(line 126)\n* root directory, disallow recursive modification <1>: chgrp invocation.\n(line 54)\n* root directory, disallow recursive modification <2>: chmod invocation.\n(line 53)\n* root directory, running a program in a specified: chroot invocation.\n(line 6)\n* rows: Special. (line 22)\n* rprnt: Characters. (line 60)\n* RTS/CTS flow control: Control. (line 41)\n* run commands with bounded time: timeout invocation. (line 6)\n* run with security context: runcon invocation. (line 6)\n* runcon: runcon invocation. (line 6)\n* running a program in a modified environment: env invocation.\n(line 6)\n* running a program in a specified root directory: chroot invocation.\n(line 6)\n* rz format for nl: nl invocation. (line 97)\n* Salz, Rich: Authors of parsedatetime.\n(line 6)\n* same file check: File characteristic tests.\n(line 23)\n* sane: Combination. (line 26)\n* scheduling, affecting: nice invocation. (line 6)\n* screen columns: fold invocation. (line 14)\n* scripts arguments: env invocation. (line 188)\n* seconds since the epoch: Time conversion specifiers.\n(line 32)\n* section delimiters of pages: nl invocation. (line 63)\n* security context: What information is listed.\n(line 259)\n* security context <1>: cp invocation. (line 384)\n* security context <2>: install invocation. (line 96)\n* security context <3>: install invocation. (line 139)\n* security context <4>: mv invocation. (line 117)\n* security context <5>: mkdir invocation. (line 56)\n* security context <6>: mkfifo invocation. (line 28)\n* security context <7>: mknod invocation. (line 53)\n* security context <8>: id invocation. (line 51)\n* seek: dd invocation. (line 51)\n* seekbytes: dd invocation. (line 325)\n* self-backups: cp invocation. (line 51)\n* SELinux: What information is listed.\n(line 259)\n* SELinux <1>: install invocation. (line 96)\n* SELinux <2>: id invocation. (line 51)\n* SELinux context: SELinux context. (line 6)\n* SELinux, context: SELinux context. (line 6)\n* SELinux, restoring security context: mv invocation. (line 117)\n* SELinux, setting/restoring security context: cp invocation. (line 384)\n* SELinux, setting/restoring security context <1>: install invocation.\n(line 139)\n* SELinux, setting/restoring security context <2>: mkdir invocation.\n(line 56)\n* SELinux, setting/restoring security context <3>: mkfifo invocation.\n(line 28)\n* SELinux, setting/restoring security context <4>: mknod invocation.\n(line 53)\n* send a signal to processes: kill invocation. (line 6)\n* sentences and line-breaking: fmt invocation. (line 19)\n* separator for numbers in seq: seq invocation. (line 44)\n* seq: seq invocation. (line 6)\n* sequence of numbers: seq invocation. (line 6)\n* set-group-ID: Mode Structure. (line 45)\n* set-group-ID check: Access permission tests.\n(line 9)\n* set-user-ID: Mode Structure. (line 39)\n* set-user-ID check: Access permission tests.\n(line 18)\n* setgid: Mode Structure. (line 45)\n* setting permissions: Setting Permissions. (line 41)\n* setting the hostname: hostname invocation. (line 6)\n* setting the time: Setting the time. (line 6)\n* setuid: Mode Structure. (line 39)\n* setup for color: dircolors invocation.\n(line 6)\n* sh syntax for color setup: dircolors invocation.\n(line 34)\n* SHA-1: sha1sum invocation. (line 6)\n* SHA-2: sha2 utilities. (line 6)\n* sha1sum: sha1sum invocation. (line 6)\n* sha224sum: sha2 utilities. (line 6)\n* sha256sum: sha2 utilities. (line 6)\n* sha384sum: sha2 utilities. (line 6)\n* sha512sum: sha2 utilities. (line 6)\n* shebang arguments: env invocation. (line 188)\n* SHELL environment variable, and color: General output formatting.\n(line 31)\n* SHELL environment variable, and color <1>: dircolors invocation.\n(line 23)\n* shell utilities: Top. (line 18)\n* shred: shred invocation. (line 6)\n* shuf: shuf invocation. (line 6)\n* shuffling files: shuf invocation. (line 6)\n* SI output: Block size. (line 42)\n* SI output <1>: What information is listed.\n(line 251)\n* SI output <2>: df invocation. (line 167)\n* SI output <3>: du invocation. (line 145)\n* signals, specifying: Signal specifications.\n(line 6)\n* simple backup method: Backup options. (line 44)\n* SIMPLEBACKUPSUFFIX: Backup options. (line 49)\n* single quotes, and env -S: env invocation. (line 264)\n* single-column output of files: General output formatting.\n(line 10)\n* size: Special. (line 39)\n* size for main memory sorting: sort invocation. (line 316)\n* size of file to shred: shred invocation. (line 138)\n* size of files, reporting: What information is listed.\n(line 236)\n* size of files, sorting files by: Sorting the output. (line 32)\n* skip: dd invocation. (line 46)\n* skipbytes: dd invocation. (line 319)\n* sleep: sleep invocation. (line 6)\n* socket check: File type tests. (line 31)\n* software flow control: Input. (line 45)\n* sort: sort invocation. (line 6)\n* sort field: sort invocation. (line 231)\n* sort stability: sort invocation. (line 12)\n* sort stability <1>: sort invocation. (line 309)\n* sort's last-resort comparison: sort invocation. (line 12)\n* sort's last-resort comparison <1>: sort invocation. (line 309)\n* sorted files, operations on: Operating on sorted files.\n(line 6)\n* sorting files: sort invocation. (line 6)\n* sorting ls output: Sorting the output. (line 6)\n* space: Character sets. (line 106)\n* space parity: Control. (line 16)\n* sparse: dd invocation. (line 146)\n* sparse files, copying: cp invocation. (line 299)\n* sparse files, creating: truncate invocation. (line 13)\n* special characters: Characters. (line 6)\n* special file types: Special file types. (line 6)\n* special file types <1>: Special file types. (line 9)\n* special files: mknod invocation. (line 11)\n* special settings: Special. (line 6)\n* specifying sets of characters: Character sets. (line 6)\n* speed: Special. (line 49)\n* split: split invocation. (line 6)\n* splitting a file into pieces: split invocation. (line 6)\n* splitting a file into pieces by context: csplit invocation. (line 6)\n* squeezing blank lines: cat invocation. (line 36)\n* squeezing empty lines: cat invocation. (line 36)\n* squeezing repeat characters: Squeezing and deleting.\n(line 6)\n* Stallman, R.: Introduction. (line 29)\n* standard input: Common options. (line 47)\n* standard output: Common options. (line 47)\n* standard streams, buffering: stdbuf invocation. (line 6)\n* start: Characters. (line 48)\n* stat: stat invocation. (line 6)\n* status: dd invocation. (line 66)\n* status <1>: Characters. (line 45)\n* status time, printing or sorting by: Sorting the output. (line 13)\n* status time, show the most recent: du invocation. (line 204)\n* stdbuf: stdbuf invocation. (line 6)\n* stick parity: Control. (line 16)\n* sticky: Mode Structure. (line 52)\n* sticky bit check: Access permission tests.\n(line 12)\n* stop: Characters. (line 51)\n* stop bits: Control. (line 32)\n* strftime and date: date invocation. (line 20)\n* string constants, outputting: od invocation. (line 81)\n* string expressions: String expressions. (line 6)\n* string tests: String tests. (line 6)\n* strip directory and suffix from file names: basename invocation.\n(line 6)\n* stripping non-directory suffix: dirname invocation. (line 6)\n* stripping symbol table information: install invocation. (line 113)\n* stripping trailing slashes: cp invocation. (line 332)\n* stripping trailing slashes <1>: mv invocation. (line 98)\n* stty: stty invocation. (line 6)\n* substr: String expressions. (line 40)\n* subtracting permissions: Setting Permissions. (line 38)\n* subtraction: Numeric expressions. (line 12)\n* successful exit: true invocation. (line 6)\n* suffix, stripping from file names: basename invocation. (line 6)\n* sum: sum invocation. (line 6)\n* summarizing files: Summarizing files. (line 6)\n* superblock, writing: sync invocation. (line 11)\n* supplementary groups, printing: groups invocation. (line 6)\n* susp: Characters. (line 54)\n* swab (byte-swapping): dd invocation. (line 159)\n* swap space, saving text image in: Mode Structure. (line 52)\n* swtch: Characters. (line 42)\n* symbol table information, stripping: install invocation. (line 113)\n* symbol table information, stripping, program: install invocation.\n(line 116)\n* symbolic (soft) links, creating: ln invocation. (line 6)\n* symbolic link check: File type tests. (line 23)\n* symbolic link to directory, controlling traversal of: Traversing symlinks.\n(line 6)\n* symbolic link to directory, never traverse: Traversing symlinks.\n(line 26)\n* symbolic link to directory, never traverse <1>: chown invocation.\n(line 171)\n* symbolic link to directory, never traverse <2>: chgrp invocation.\n(line 99)\n* symbolic link to directory, never traverse <3>: chcon invocation.\n(line 56)\n* symbolic link to directory, traverse each that is encountered: Traversing symlinks.\n(line 22)\n* symbolic link to directory, traverse each that is encountered <1>: chown invocation.\n(line 158)\n* symbolic link to directory, traverse each that is encountered <2>: chgrp invocation.\n(line 86)\n* symbolic link to directory, traverse each that is encountered <3>: chcon invocation.\n(line 52)\n* symbolic link to directory, traverse if on the command line: Traversing symlinks.\n(line 18)\n* symbolic link to directory, traverse if on the command line <1>: chown invocation.\n(line 153)\n* symbolic link to directory, traverse if on the command line <2>: chgrp invocation.\n(line 81)\n* symbolic link to directory, traverse if on the command line <3>: chcon invocation.\n(line 47)\n* symbolic link, defined: ln invocation. (line 42)\n* symbolic links and ln: ln invocation. (line 182)\n* symbolic links and pwd: pwd invocation. (line 26)\n* symbolic links, changing group: chgrp invocation. (line 46)\n* symbolic links, changing owner: chown invocation. (line 83)\n* symbolic links, changing owner <1>: chown invocation. (line 106)\n* symbolic links, changing owner <2>: chown invocation. (line 118)\n* symbolic links, changing owner <3>: chgrp invocation. (line 34)\n* symbolic links, changing time: touch invocation. (line 70)\n* symbolic links, copying: cp invocation. (line 109)\n* symbolic links, copying <1>: cp invocation. (line 162)\n* symbolic links, copying with: cp invocation. (line 337)\n* symbolic links, dereferencing: Which files are listed.\n(line 36)\n* symbolic links, dereferencing <1>: Which files are listed.\n(line 41)\n* symbolic links, dereferencing <2>: Which files are listed.\n(line 83)\n* symbolic links, dereferencing in du: du invocation. (line 117)\n* symbolic links, dereferencing in du <1>: du invocation. (line 133)\n* symbolic links, dereferencing in stat: stat invocation. (line 22)\n* symbolic links, following: dd invocation. (line 289)\n* symbolic links, permissions of: chmod invocation. (line 10)\n* symbolic modes: Symbolic Modes. (line 6)\n* symlinks, resolution: realpath invocation. (line 6)\n* sync: sync invocation. (line 6)\n* sync <1>: dd invocation. (line 243)\n* sync (padding with ASCII NULs): dd invocation. (line 164)\n* Synchronize cached writes to persistent storage: sync invocation.\n(line 6)\n* synchronize disk and memory: sync invocation. (line 6)\n* synchronized data and metadata I/O: dd invocation. (line 243)\n* synchronized data and metadata writes, before finishing: dd invocation.\n(line 192)\n* synchronized data reads: dd invocation. (line 235)\n* synchronized data writes, before finishing: dd invocation. (line 188)\n* system context: System context. (line 6)\n* system information, printing: arch invocation. (line 6)\n* system information, printing <1>: nproc invocation. (line 6)\n* system information, printing <2>: uname invocation. (line 6)\n* system name, printing: hostname invocation. (line 6)\n* System V sum: sum invocation. (line 31)\n* tab stops, setting: expand invocation. (line 22)\n* tabN: Output. (line 51)\n* tabs: Combination. (line 66)\n* tabs to spaces, converting: expand invocation. (line 6)\n* tac: tac invocation. (line 6)\n* tagged paragraphs: fmt invocation. (line 40)\n* tail: tail invocation. (line 6)\n* tandem: Input. (line 45)\n* target directory: Target directory. (line 6)\n* target directory <1>: Target directory. (line 15)\n* target directory <2>: Target directory. (line 31)\n* target directory <3>: cp invocation. (line 350)\n* target directory <4>: cp invocation. (line 354)\n* target directory <5>: install invocation. (line 125)\n* target directory <6>: install invocation. (line 130)\n* target directory <7>: mv invocation. (line 108)\n* target directory <8>: mv invocation. (line 112)\n* target directory <9>: ln invocation. (line 171)\n* target directory <10>: ln invocation. (line 175)\n* tebibyte, definition of: Block size. (line 99)\n* tee: tee invocation. (line 6)\n* telephone directory order: sort invocation. (line 87)\n* temporary directory: sort invocation. (line 352)\n* temporary files and directories: mktemp invocation. (line 6)\n* terabyte, definition of: Block size. (line 96)\n* terminal check: File type tests. (line 34)\n* terminal file name, printing: tty invocation. (line 6)\n* terminal lines, currently used: who invocation. (line 11)\n* terminal settings: stty invocation. (line 6)\n* terminal, using color iff: General output formatting.\n(line 25)\n* terminal, using hyperlink iff: General output formatting.\n(line 64)\n* terse output: stat invocation. (line 70)\n* test: test invocation. (line 6)\n* text: dd invocation. (line 299)\n* text I/O: dd invocation. (line 299)\n* text image, saving in swap space: Mode Structure. (line 52)\n* text input files: md5sum invocation. (line 109)\n* text utilities: Top. (line 18)\n* text, displaying: echo invocation. (line 6)\n* text, reformatting: fmt invocation. (line 6)\n* this in date strings: Relative items in date strings.\n(line 33)\n* time: touch invocation. (line 56)\n* time <1>: Special. (line 11)\n* time conversion specifiers: Time conversion specifiers.\n(line 6)\n* time formats: pr invocation. (line 78)\n* time formats <1>: date invocation. (line 20)\n* time limit: timeout invocation. (line 6)\n* time of day item: Time of day items. (line 6)\n* time setting: Setting the time. (line 6)\n* time style: Formatting file timestamps.\n(line 24)\n* time style <1>: du invocation. (line 214)\n* time units: timeout invocation. (line 56)\n* time units <1>: sleep invocation. (line 11)\n* time zone correction: Time of day items. (line 29)\n* time zone item: General date syntax. (line 40)\n* time zone item <1>: Time zone items. (line 6)\n* time, printing or setting: date invocation. (line 6)\n* timeout: timeout invocation. (line 6)\n* timestamps of installed files, preserving: install invocation.\n(line 103)\n* timestamps, changing file: touch invocation. (line 6)\n* TIMESTYLE: Formatting file timestamps.\n(line 103)\n* TIMESTYLE <1>: du invocation. (line 242)\n* TMPDIR: sort invocation. (line 64)\n* TMPDIR <1>: sort invocation. (line 352)\n* today in date strings: Relative items in date strings.\n(line 33)\n* tomorrow: Options for date. (line 11)\n* tomorrow in date strings: Relative items in date strings.\n(line 29)\n* topological sort: tsort invocation. (line 6)\n* tostop: Local. (line 41)\n* total counts: wc invocation. (line 12)\n* touch: touch invocation. (line 6)\n* tr: tr invocation. (line 6)\n* trailing slashes: Trailing slashes. (line 6)\n* translating characters: Translating. (line 6)\n* true: true invocation. (line 6)\n* truncate: truncate invocation. (line 6)\n* truncating output file, avoiding: dd invocation. (line 182)\n* truncating, file sizes: truncate invocation. (line 6)\n* tsort: tsort invocation. (line 6)\n* tty: tty invocation. (line 6)\n* two-way parity: Control. (line 9)\n* type size: od invocation. (line 122)\n* TZ: pr invocation. (line 91)\n* TZ <1>: Formatting file timestamps.\n(line 17)\n* TZ <2>: touch invocation. (line 35)\n* TZ <3>: stat invocation. (line 213)\n* TZ <4>: who invocation. (line 26)\n* TZ <5>: date invocation. (line 16)\n* TZ <6>: Options for date. (line 119)\n* TZ <7>: Specifying time zone rules.\n(line 6)\n* u, and disabling special characters: Characters. (line 12)\n* ucase, converting to: dd invocation. (line 141)\n* umask and modes: Umask and Protection.\n(line 6)\n* uname: uname invocation. (line 6)\n* unblock: dd invocation. (line 132)\n* unexpand: unexpand invocation. (line 6)\n* Unicode: printf invocation. (line 74)\n* uniq: uniq invocation. (line 6)\n* unique lines, outputting: uniq invocation. (line 127)\n* uniquify files: uniq invocation. (line 6)\n* uniquifying output: sort invocation. (line 368)\n* Universal Time: Options for date. (line 119)\n* unlink: unlink invocation. (line 6)\n* unprintable characters, ignoring: sort invocation. (line 143)\n* unsorted directory listing: Sorting the output. (line 20)\n* upper: Character sets. (line 108)\n* uppercase, translating to lowercase: Input. (line 50)\n* uptime: uptime invocation. (line 6)\n* use time, changing: touch invocation. (line 48)\n* use time, printing or sorting files by: Sorting the output. (line 13)\n* use time, printing or sorting files by <1>: Sorting the output.\n(line 44)\n* use time, show the most recent: du invocation. (line 204)\n* user IDs, disambiguating: Disambiguating names and IDs.\n(line 6)\n* user information, commands for: User information. (line 6)\n* user name, printing: logname invocation. (line 6)\n* user names, disambiguating: Disambiguating names and IDs.\n(line 6)\n* usernames, printing current: users invocation. (line 6)\n* users: users invocation. (line 6)\n* UTC: Options for date. (line 119)\n* utmp: logname invocation. (line 6)\n* utmp <1>: users invocation. (line 14)\n* utmp <2>: who invocation. (line 15)\n* valid file names, checking for: pathchk invocation. (line 6)\n* variable-length records, converting to fixed-length: dd invocation.\n(line 41)\n* vdir: vdir invocation. (line 6)\n* verbose ls format: What information is listed.\n(line 131)\n* verifying MD5 checksums: md5sum invocation. (line 76)\n* verifying MD5 checksums <1>: md5sum invocation. (line 82)\n* verifying MD5 checksums <2>: md5sum invocation. (line 90)\n* verifying MD5 checksums <3>: md5sum invocation. (line 118)\n* verifying MD5 checksums <4>: md5sum invocation. (line 123)\n* version number sort: sort invocation. (line 177)\n* version number, finding: Common options. (line 40)\n* version of kernel: uname invocation. (line 77)\n* version, sorting option for ls: Sorting the output. (line 67)\n* version-control Emacs variable: Backup options. (line 24)\n* VERSIONCONTROL: Backup options. (line 13)\n* VERSIONCONTROL <1>: cp invocation. (line 79)\n* VERSIONCONTROL <2>: install invocation. (line 41)\n* VERSIONCONTROL <3>: mv invocation. (line 59)\n* VERSIONCONTROL <4>: ln invocation. (line 82)\n* vertical sorted files in columns: General output formatting.\n(line 16)\n* vtN: Output. (line 59)\n* wc: wc invocation. (line 6)\n* week in date strings: Relative items in date strings.\n(line 15)\n* werase: Characters. (line 63)\n* who: who invocation. (line 6)\n* who am i: who invocation. (line 21)\n* whoami: whoami invocation. (line 6)\n* word count: wc invocation. (line 6)\n* working context: Working context. (line 6)\n* working directory, printing: pwd invocation. (line 6)\n* wrap data: base64 invocation. (line 22)\n* wrapping long input lines: fold invocation. (line 6)\n* writable file check: Access permission tests.\n(line 21)\n* write permission: Mode Structure. (line 14)\n* write permission, symbolic: Setting Permissions. (line 54)\n* write, allowed: who invocation. (line 94)\n* wtmp: users invocation. (line 14)\n* wtmp <1>: who invocation. (line 15)\n* xcase: Local. (line 36)\n* xdigit: Character sets. (line 110)\n* xfs file system type: df invocation. (line 211)\n* XON/XOFF flow control: Input. (line 40)\n* year in date strings: Relative items in date strings.\n(line 15)\n* yes: yes invocation. (line 6)\n* yesterday: Options for date. (line 11)\n* yesterday in date strings: Relative items in date strings.\n(line 29)\n* yottabyte, definition of: Block size. (line 116)\n* Youmans, B.: Introduction. (line 29)\n* zero-length string check: String tests. (line 15)\n* zettabyte, definition of: Block size. (line 111)\n\n", "subsections": [] } }, "flags": [], "examples": [], "see_also": [] }