{ "content": [ { "type": "text", "text": "# ksh (man)\n\n## NAME\n\nksh, rksh - KornShell, a standard/restricted command and programming language\n\n## SYNOPSIS\n\nksh [ ±±abcefhiklmnprstuvxBCDEGH ] [ ±±o option ] ... [ - ] [ arg ... ]\nrksh [ ±±abcefhiklmnpstuvxBCDEGH ] [ ±±o option ] ... [ - ] [ arg ... ]\n\n## DESCRIPTION\n\nKsh is a command and programming language that executes commands read from a terminal or a\nfile. Rksh is a restricted version of the command interpreter ksh; it is used to set up lo‐\ngin names and execution environments whose capabilities are more controlled than those of the\nstandard shell. See Invocation below for the meaning of arguments to the shell.\n\n## TLDR\n\n> Korn Shell, a Bash-compatible command-line interpreter.\n\n- Start an interactive shell session:\n `ksh`\n- Execute specific [c]ommands:\n `ksh -c \"{{echo 'ksh is executed'}}\"`\n- Execute a specific script:\n `ksh {{path/to/script.ksh}}`\n- Check a specific script for syntax errors without executing it:\n `ksh -n {{path/to/script.ksh}}`\n- E[x]ecute a specific script, printing each command in the script before executing it:\n `ksh -x {{path/to/script.ksh}}`\n\n*Source: tldr-pages*\n\n## Sections\n\n- **NAME**\n- **SYNOPSIS**\n- **DESCRIPTION** (84 subsections)\n- **EXIT STATUS**\n- **FILES** (4 subsections)\n- **SEE ALSO**\n- **CAVEATS**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "ksh", "section": "", "mode": "man", "summary": "ksh, rksh - KornShell, a standard/restricted command and programming language", "synopsis": "ksh [ ±±abcefhiklmnprstuvxBCDEGH ] [ ±±o option ] ... [ - ] [ arg ... ]\nrksh [ ±±abcefhiklmnpstuvxBCDEGH ] [ ±±o option ] ... [ - ] [ arg ... ]", "tldr_summary": "Korn Shell, a Bash-compatible command-line interpreter.", "tldr_examples": [ { "description": "Start an interactive shell session", "command": "ksh" }, { "description": "Execute specific [c]ommands", "command": "ksh -c \"{{echo 'ksh is executed'}}\"" }, { "description": "Execute a specific script", "command": "ksh {{path/to/script.ksh}}" }, { "description": "Check a specific script for syntax errors without executing it", "command": "ksh -n {{path/to/script.ksh}}" }, { "description": "E[x]ecute a specific script, printing each command in the script before executing it", "command": "ksh -x {{path/to/script.ksh}}" } ], "tldr_source": "official", "flags": [ { "flag": "-E", "long": null, "arg": null, "description": "it is expanded. The optional option argument n defines the number of significant figures. The -F option causes the expansion to be represented as a floating decimal number when it is expanded. The -X option causes the expansion to be represented using the %a format defined by ISO C-99. The optional option argument n defines the number of places after the decimal (or radix) point in this case. An internal integer representation of a variable can be specified with the -i [n] option of the typeset special built-in command. The optional option argument n specifies an arithmetic base to be used when expanding the variable. If you do not specify an arithmetic base, base 10 will be used. Arithmetic evaluation is performed on the value of each assignment to a variable with the -E," }, { "flag": "-i", "long": null, "arg": null, "description": "integer causes the fractional part to be truncated." }, { "flag": "-a", "long": null, "arg": null, "description": "Same as -e below. This is obsolete." }, { "flag": "-b", "long": null, "arg": null, "description": "True, if file exists and is a block special file." }, { "flag": "-c", "long": null, "arg": null, "description": "True, if file exists and is a character special file." }, { "flag": "-d", "long": null, "arg": null, "description": "True, if file exists and is a directory." }, { "flag": "-e", "long": null, "arg": null, "description": "True, if file exists." }, { "flag": "-f", "long": null, "arg": null, "description": "True, if file exists and is an ordinary file." }, { "flag": "-g", "long": null, "arg": null, "description": "True, if file exists and it has its setgid bit set." }, { "flag": "-k", "long": null, "arg": null, "description": "True, if file exists and it has its sticky bit set." }, { "flag": "-n", "long": null, "arg": null, "description": "True, if length of string is non-zero." }, { "flag": "-o", "long": null, "arg": null, "description": "True, if option named option is a valid option name." }, { "flag": "-o", "long": null, "arg": null, "description": "True, if option named option is on." }, { "flag": "-p", "long": null, "arg": null, "description": "True, if file exists and is a fifo special file or a pipe." }, { "flag": "-r", "long": null, "arg": null, "description": "True, if file exists and is readable by current process." }, { "flag": "-s", "long": null, "arg": null, "description": "True, if file exists and has size greater than zero." }, { "flag": "-t", "long": null, "arg": null, "description": "True, if file descriptor number fildes is open and associated with a terminal device." }, { "flag": "-u", "long": null, "arg": null, "description": "True, if file exists and it has its setuid bit set." }, { "flag": "-v", "long": null, "arg": null, "description": "True, if variable name is a valid variable name and is set." }, { "flag": "-w", "long": null, "arg": null, "description": "True, if file exists and is writable by current process." }, { "flag": "-x", "long": null, "arg": null, "description": "True, if file exists and is executable by current process. If file exists and is a directory, then true if the current process has permission to search in the directory." }, { "flag": "-z", "long": null, "arg": null, "description": "True, if length of string is zero." }, { "flag": "-L", "long": null, "arg": null, "description": "True, if file exists and is a symbolic link." }, { "flag": "-h", "long": null, "arg": null, "description": "True, if file exists and is a symbolic link." }, { "flag": "-N", "long": null, "arg": null, "description": "True, if file exists and the modification time is greater than the last access time." }, { "flag": "-O", "long": null, "arg": null, "description": "True, if file exists and is owned by the effective user id of this process." }, { "flag": "-G", "long": null, "arg": null, "description": "True, if file exists and its group matches the effective group id of this process." }, { "flag": "-R", "long": null, "arg": null, "description": "True if variable name is a name reference." }, { "flag": "-S", "long": null, "arg": null, "description": "True, if file exists and is a socket. file1 -nt file2 True, if file1 exists and file2 does not, or file1 is newer than file2. file1 -ot file2 True, if file2 exists and file1 does not, or file1 is older than file2. file1 -ef file2 True, if file1 and file2 exist and refer to the same file. string == pattern True, if string matches pattern. Any part of pattern can be quoted to cause it to be matched as a string. With a successful match to a pattern, the .sh.match array vari‐ able will contain the match and subpattern matches. string = pattern Same as == above, but is obsolete. string != pattern True, if string does not match pattern. When the string matches the pattern the .sh.match array variable will contain the match and subpattern matches. string =∼∼ ere True if string matches the pattern ∼∼(E)ere where ere is an extended regular expres‐ sion. string1 < string2 True, if string1 comes before string2 based on ASCII value of their characters. string1 > string2 True, if string1 comes after string2 based on ASCII value of their characters. The following obsolete arithmetic comparisons are also permitted: exp1 -eq exp2 True, if exp1 is equal to exp2. exp1 -ne exp2 True, if exp1 is not equal to exp2. exp1 -lt exp2 True, if exp1 is less than exp2. exp1 -gt exp2 True, if exp1 is greater than exp2. exp1 -le exp2 True, if exp1 is less than or equal to exp2. exp1 -ge exp2 True, if exp1 is greater than or equal to exp2. In each of the above expressions, if file is of the form /dev/fd/n, where n is an integer, then the test is applied to the open file whose descriptor number is n. A compound expression can be constructed from these primitives by using any of the following, listed in decreasing order of precedence. (expression) True, if expression is true. Used to group expressions. ! expression True if expression is false. expression1 && expression2 True, if expression1 and expression2 are both true. expression1 || expression2 True, if either expression1 or expression2 is true." }, { "flag": "-T", "long": null, "arg": null, "description": "specified as an option argument to -T, is set with a compound variable assignment that de‐ fines the type. Function definitions can appear inside the compound variable assignment and these become discipline functions for this type and can be invoked or redefined by each in‐ stance of the type. The function name create is treated specially. It is invoked for each instance of the type that is created but is not inherited and cannot be redefined for each instance. When a type is defined a special built-in command of that name is added. These built-ins are declaration commands and follow the same expansion rules as the built-in commands described below that are marked with a ‡ symbol. These commands can subsequently be used inside further type definitions. The man page for these commands can be generated by using the --man option or any of the other -- options described with getopts. The -r, -a, -A, -h, and -S options of typeset are permitted with each of these new built-ins. An instance of a type is created by invoking the type name followed by one or more instance names. Each instance of the type is initialized with a copy of the subvariables except for subvariables that are defined with the -S option. Variables defined with the -S are shared by all instances of the type. Each instance can change the value of any subvariable and can also define new discipline functions of the same names as those defined by the type defini‐ tion as well as any standard discipline names. No additional subvariables can be defined for any instance. When defining a type, if the value of a subvariable is not set and the -r attribute is speci‐ fied, it causes the subvariable to be a required subvariable. Whenever an instance of a type is created, all required subvariables must be specified. These subvariables become read-only in each instance. When unset is invoked on a subvariable within a type, and the -r attribute has not been spec‐ ified for this field, the value is reset to the default value associative with the type. In‐ voking unset on a type instance not contained within another type deletes all subvariables and the variable itself. A type definition can be derived from another type definition by defining the first subvari‐ able name as and defining its type as the base type. Any remaining definitions will be ad‐ ditions and modifications that apply to the new type. If the new type name is the same as that of the base type, the type will be replaced and the original type will no longer be ac‐ cessible. The typeset command with the -T and no option argument or operands will write all the type definitions to standard output in a form that can be read in to create all they types." }, { "flag": "-o", "long": null, "arg": null, "description": "full POSIX compliance mode (see the set builtin command above for more information). After this, if the shell was assumed to be a login shell, commands are read from /etc/profile and then from $HOME/.profile if it exists. Alternatively, the option -l causes the shell to be treated as a login shell. Next, for interactive shells, commands are read from the file named by ENV if the file exists, its name being determined by performing parameter expansion, command substitution, and arithmetic expansion on the value of that environment variable. If the -s option is not present and arg and a file by the name of arg exists, then it reads and executes this script. Otherwise, if the first arg does not contain a /, a path search is performed on the first arg to determine the name of the script to execute. The script arg must have execute permission and any setuid and setgid settings will be ignored. If the script is not found on the path, arg is processed as if it named a built-in command or func‐ tion. Commands are then read as described below; the following options are interpreted by the shell when it is invoked:" }, { "flag": "-D", "long": null, "arg": null, "description": "dard output and the shell will exit. This set of strings will be subject to language translation when the locale is not C or POSIX. No commands will be executed." }, { "flag": "-o", "long": "--rc", "arg": null, "description": "Read the file named by the ENV variable or by $HOME/.kshrc if not defined after the profiles. On by default for interactive shells. Use +E, +o rc or --norc to turn off." }, { "flag": "-c", "long": null, "arg": null, "description": "present, becomes that script's command name ($0). Any third and further args become positional parameters starting at $1." }, { "flag": "-s", "long": null, "arg": null, "description": "($0) cannot be set. Any args become the positional parameters starting at $1. This option is forced on if no arg is given and is ignored if -c is also specified." }, { "flag": "-o", "long": "--interactive", "arg": null, "description": "If the -i option is present or if the shell's standard input and standard error are attached to a terminal (as told by tcgetattr(3)), then this shell is interactive. In this case TERM is ignored (so that kill 0 does not kill an interactive shell) and INTR is caught and ignored (so that wait is interruptible). In all cases, QUIT is ignored by the shell." }, { "flag": "-o", "long": "--restricted", "arg": null, "description": "If the -r option is present, the shell is a restricted shell. The remaining options and arguments are described under the set command above. An optional - as the first argument is ignored." } ], "examples": [], "see_also": [ { "name": "cat", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/cat/1/json" }, { "name": "cd", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/cd/1/json" }, { "name": "chmod", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/chmod/1/json" }, { "name": "cut", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/cut/1/json" }, { "name": "date", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/date/1/json" }, { "name": "egrep", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/egrep/1/json" }, { "name": "echo", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/echo/1/json" }, { "name": "emacs", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/emacs/1/json" }, { "name": "env", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/env/1/json" }, { "name": "fgrep", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/fgrep/1/json" }, { "name": "gmacs", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/gmacs/1/json" }, { "name": "grep", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/grep/1/json" }, { "name": "stty", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/stty/1/json" }, { "name": "test", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/test/1/json" }, { "name": "umask", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/umask/1/json" }, { "name": "vi", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/vi/1/json" }, { "name": "dup", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/dup/2/json" }, { "name": "exec", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/exec/2/json" }, { "name": "fork", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/fork/2/json" }, { "name": "getpwnam", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/getpwnam/3/json" }, { "name": "ioctl", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/ioctl/2/json" }, { "name": "lseek", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/lseek/2/json" }, { "name": "paste", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/paste/1/json" }, { "name": "pathconf", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/pathconf/2/json" }, { "name": "pipe", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/pipe/2/json" }, { "name": "sysconf", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/sysconf/3/json" }, { "name": "umask", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/umask/2/json" }, { "name": "ulimit", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/ulimit/2/json" }, { "name": "wait", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/wait/2/json" }, { "name": "strftime", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/strftime/3/json" }, { "name": "wctrans", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/wctrans/3/json" }, { "name": "rand", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/rand/3/json" }, { "name": "profile", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/profile/5/json" }, { "name": "environ", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/environ/7/json" } ], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "SYNOPSIS", "lines": 3, "subsections": [] }, { "name": "DESCRIPTION", "lines": 5, "subsections": [ { "name": "Definitions.", "lines": 19 }, { "name": "Commands.", "lines": 130 }, { "name": "if then else elif fi case esac for while until do done { } function select time [[ ]] !", "lines": 1 }, { "name": "Variable Assignments.", "lines": 45 }, { "name": "Comments.", "lines": 3 }, { "name": "Aliasing.", "lines": 21 }, { "name": "Tilde Expansion.", "lines": 25 }, { "name": "Command Substitution.", "lines": 12 }, { "name": "Arithmetic Expansion.", "lines": 3 }, { "name": "Process Substitution.", "lines": 17 }, { "name": "Parameter Expansion.", "lines": 159 }, { "name": "Shell Variables.", "lines": 262 }, { "name": "Field Splitting.", "lines": 6 }, { "name": "Brace Expansion.", "lines": 22 }, { "name": "Pathname Expansion.", "lines": 119 }, { "name": "Quoting.", "lines": 26 }, { "name": "Arithmetic Evaluation.", "lines": 27 }, { "name": "abs acos acosh asin asinh atan atan2 atanh cbrt ceil copysign cos cosh erf erfc exp exp10", "lines": 1 }, { "name": "exp2 expm1 fabs fdim finite float floor fma fmax fmin fmod fpclass fpclassify hypot ilogb int", "lines": 2 }, { "name": "byint nextafter nexttoward pow remainder rint round scalb scalbn signbit sin sinh sqrt tan", "lines": 1 }, { "name": "tanh tgamma trunc y0 y1 yn", "lines": 11 }, { "name": "-E", "lines": 12, "flag": "-E" }, { "name": "-F -X -i", "lines": 2, "flag": "-i" }, { "name": "Prompting.", "lines": 6 }, { "name": "Conditional Expressions.", "lines": 5 }, { "name": "-a", "lines": 1, "flag": "-a" }, { "name": "-b", "lines": 1, "flag": "-b" }, { "name": "-c", "lines": 1, "flag": "-c" }, { "name": "-d", "lines": 1, "flag": "-d" }, { "name": "-e", "lines": 1, "flag": "-e" }, { "name": "-f", "lines": 1, "flag": "-f" }, { "name": "-g", "lines": 1, "flag": "-g" }, { "name": "-k", "lines": 1, "flag": "-k" }, { "name": "-n", "lines": 1, "flag": "-n" }, { "name": "-o", "lines": 1, "flag": "-o" }, { "name": "-o", "lines": 1, "flag": "-o" }, { "name": "-p", "lines": 1, "flag": "-p" }, { "name": "-r", "lines": 1, "flag": "-r" }, { "name": "-s", "lines": 1, "flag": "-s" }, { "name": "-t", "lines": 1, "flag": "-t" }, { "name": "-u", "lines": 1, "flag": "-u" }, { "name": "-v", "lines": 1, "flag": "-v" }, { "name": "-w", "lines": 1, "flag": "-w" }, { "name": "-x", "lines": 2, "flag": "-x" }, { "name": "-z", "lines": 1, "flag": "-z" }, { "name": "-L", "lines": 1, "flag": "-L" }, { "name": "-h", "lines": 1, "flag": "-h" }, { "name": "-N", "lines": 1, "flag": "-N" }, { "name": "-O", "lines": 1, "flag": "-O" }, { "name": "-G", "lines": 1, "flag": "-G" }, { "name": "-R", "lines": 1, "flag": "-R" }, { "name": "-S", "lines": 51, "flag": "-S" }, { "name": "Input/Output.", "lines": 118 }, { "name": "Environment.", "lines": 31 }, { "name": "Functions.", "lines": 34 }, { "name": "Discipline Functions.", "lines": 25 }, { "name": "Name Spaces.", "lines": 16 }, { "name": "Type Variables.", "lines": 2 }, { "name": "-T -T", "lines": 41, "flag": "-T" }, { "name": "Jobs.", "lines": 57 }, { "name": "Signals.", "lines": 4 }, { "name": "Execution.", "lines": 50 }, { "name": "Command Re-entry.", "lines": 17 }, { "name": "In-line Editing Options.", "lines": 42 }, { "name": "Key Bindings.", "lines": 15 }, { "name": "Emacs Editing Mode.", "lines": 125 }, { "name": "Vi Editing Mode.", "lines": 16 }, { "name": "Input Edit Commands", "lines": 16 }, { "name": "Motion Edit Commands", "lines": 29 }, { "name": "Search Edit Commands", "lines": 23 }, { "name": "Text Modification Edit Commands", "lines": 38 }, { "name": "Other Edit Commands", "lines": 28 }, { "name": "Built-in Commands.", "lines": 441 }, { "name": "redirect", "lines": 213 }, { "name": "suspend", "lines": 253 }, { "name": "Invocation.", "lines": 4 }, { "name": "-o", "lines": 14, "flag": "-o" }, { "name": "-D", "lines": 3, "flag": "-D" }, { "name": "-E -o --rc", "lines": 3, "flag": "-o", "long": "--rc" }, { "name": "-c", "lines": 3, "flag": "-c" }, { "name": "-s", "lines": 3, "flag": "-s" }, { "name": "-i -o --interactive", "lines": 6, "flag": "-o", "long": "--interactive" }, { "name": "-r -o --restricted", "lines": 5, "flag": "-o", "long": "--restricted" }, { "name": "Rksh Only.", "lines": 25 } ] }, { "name": "EXIT STATUS", "lines": 9, "subsections": [] }, { "name": "FILES", "lines": 1, "subsections": [ { "name": "/etc/profile", "lines": 2 }, { "name": "$HOME/.profile", "lines": 2 }, { "name": "$HOME/.kshrc", "lines": 7 }, { "name": "/dev/null", "lines": 2 } ] }, { "name": "SEE ALSO", "lines": 10, "subsections": [] }, { "name": "CAVEATS", "lines": 23, "subsections": [] } ], "sections": { "NAME": { "content": "ksh, rksh - KornShell, a standard/restricted command and programming language\n", "subsections": [] }, "SYNOPSIS": { "content": "ksh [ ±±abcefhiklmnprstuvxBCDEGH ] [ ±±o option ] ... [ - ] [ arg ... ]\nrksh [ ±±abcefhiklmnpstuvxBCDEGH ] [ ±±o option ] ... [ - ] [ arg ... ]\n", "subsections": [] }, "DESCRIPTION": { "content": "Ksh is a command and programming language that executes commands read from a terminal or a\nfile. Rksh is a restricted version of the command interpreter ksh; it is used to set up lo‐\ngin names and execution environments whose capabilities are more controlled than those of the\nstandard shell. See Invocation below for the meaning of arguments to the shell.\n", "subsections": [ { "name": "Definitions.", "content": "A metacharacter is one of the following characters:\n\n; & ( ) | < > new-line space tab\n\nA blank is a tab or a space. An identifier is a sequence of letters, digits, or underscores\nstarting with a letter or underscore. Identifiers are used as components of variable names.\nA vname is a sequence of one or more identifiers separated by a . and optionally preceded by\na .. Vnames are used as function and variable names. A word is a sequence of characters\nfrom the character set defined by the current locale, excluding non-quoted metacharacters.\n\nA command is a sequence of characters in the syntax of the shell language. The shell reads\neach command and carries out the desired action either directly or by invoking separate util‐\nities. A built-in command is a command that is carried out by the shell itself without cre‐\nating a separate process. Some commands are built-in purely for convenience and are not doc‐\numented here. Built-ins that cause side effects in the shell environment and built-ins that\nare found before performing a path search (see Execution below) are documented here. For\nhistorical reasons, some of these built-ins behave differently than other built-ins and are\ncalled special built-ins.\n" }, { "name": "Commands.", "content": "A simple-command is a list of variable assignments (see Variable Assignments below) or a se‐\nquence of blank separated words which may be preceded by a list of variable assignments (see\nEnvironment below). The first word specifies the name of the command to be executed. Except\nas specified below, the remaining words are passed as arguments to the invoked command. The\ncommand name is passed as argument 0 (see exec(2)). The value of a simple-command is its\nexit status; 0-255 if it terminates normally; 256+signum if it terminates abnormally (the\nname of the signal corresponding to the exit status can be obtained via the -l option of the\nkill built-in utility).\n\nA pipeline is a sequence of one or more commands separated by |. The standard output of each\ncommand but the last is connected by a pipe(2) to the standard input of the next command.\nEach command, except possibly the last, is run as a separate process; the shell waits for the\nlast command to terminate. The exit status of a pipeline is the exit status of the last com‐\nmand unless the pipefail option is enabled. Each pipeline can be preceded by the reserved\nword ! which causes the exit status of the pipeline to become 0 if the exit status of the\nlast command is non-zero, and 1 if the exit status of the last command is 0.\n\nA list is a sequence of one or more pipelines separated by ;, &, |&, &&, or ||, and option‐\nally terminated by ;, &, or |&. Of these five symbols, ;, &, and |& have equal precedence,\nwhich is lower than that of && and ||. The symbols && and || also have equal precedence. A\nsemicolon (;) causes sequential execution of the preceding pipeline; an ampersand (&) causes\nasynchronous execution of the preceding pipeline (i.e., the shell does not wait for that\npipeline to finish). The symbol |& causes asynchronous execution of the preceding pipeline\nwith a two-way pipe established to the parent shell; the standard input and output of the\nspawned pipeline can be written to and read from by the parent shell by applying the redi‐\nrection operators <& and >& with arg p to commands and by using -p option of the built-in\ncommands read and print described later. The symbol && (||) causes the list following it to\nbe executed only if the preceding pipeline returns a zero (non-zero) value. One or more new-\nlines may appear in a list instead of a semicolon, to delimit a command. The first item of\nthe first pipeline of a list that is a simple command not beginning with a redirection, and\nnot occurring within a while, until, or if list, can be preceded by a semicolon. This semi‐\ncolon is ignored unless the showme option is enabled as described with the set built-in be‐\nlow.\n\nA command is either a simple-command or one of the following. Unless otherwise stated, the\nvalue returned by a command is that of the last simple-command executed in the command.\n\nfor vname [ in word ... ] ;do list ;done\nEach time a for command is executed, vname is set to the next word taken from the in\nword list. If in word ... is omitted, then the for command executes the do list once\nfor each positional parameter that is set starting from 1 (see Parameter Expansion be‐\nlow). Execution ends when there are no more words in the list.\n\nfor (( [expr1] ; [expr2] ; [expr3] )) ;do list ;done\nThe arithmetic expression expr1 is evaluated first (see Arithmetic Evaluation below).\nThe arithmetic expression expr2 is repeatedly evaluated until it evaluates to zero and\nwhen non-zero, list is executed and the arithmetic expression expr3 evaluated. If any\nexpression is omitted, then it behaves as if it evaluated to 1.\n\nselect vname [ in word ... ] ;do list ;done\nA select command prints on standard error (file descriptor 2) the set of words, each\npreceded by a number. If in word ... is omitted, then the positional parameters\nstarting from 1 are used instead (see Parameter Expansion below). The PS3 prompt is\nprinted and a line is read from the standard input. If this line consists of the num‐\nber of one of the listed words, then the value of the variable vname is set to the\nword corresponding to this number. If this line is empty, the selection list is\nprinted again. Otherwise the value of the variable vname is set to null. The con‐\ntents of the line read from standard input is saved in the variable REPLY. The list\nis executed for each selection until a break or end-of-file is encountered. If the\nREPLY variable is set to null by the execution of list, then the selection list is\nprinted before displaying the PS3 prompt for the next selection.\n\ncase word in [ [(]pattern [ | pattern ] ... ) list ;; ] ... esac\nA case command executes the list associated with the first pattern that matches word.\nThe form of the patterns is the same as that used for pathname expansion (see Pathname\nExpansion below). The ;; operator causes execution of case to terminate. If ;& is\nused in place of ;; the next subsequent list, if any, is executed.\n\nif list ;then list [ ;elif list ;then list ] ... [ ;else list ] ;fi\nThe list following if is executed and, if it returns a zero exit status, the list fol‐\nlowing the first then is executed. Otherwise, the list following elif is executed\nand, if its value is zero, the list following the next then is executed. Failing each\nsuccessive elif list, the else list is executed. If the if list has non-zero exit\nstatus and there is no else list, then the if command returns a zero exit status.\n\nwhile list ;do list ;done\nuntil list ;do list ;done\nA while command repeatedly executes the while list and, if the exit status of the last\ncommand in the list is zero, executes the do list; otherwise the loop terminates. If\nno commands in the do list are executed, then the while command returns a zero exit\nstatus; until may be used in place of while to negate the loop termination test.\n\n((expression))\nThe expression is evaluated using the rules for arithmetic evaluation described below.\nIf the value of the arithmetic expression is non-zero, the exit status is 0, otherwise\nthe exit status is 1.\n\n(list)\nExecute list in a separate environment. Note, that if two adjacent open parentheses\nare needed for nesting, a space must be inserted to avoid evaluation as an arithmetic\ncommand as described above.\n\n{ list;}\nlist is simply executed. Note that unlike the metacharacters ( and ), { and } are re‐\nserved words and must occur at the beginning of a line or after a ; in order to be\nrecognized.\n\n[[ expression ]]\nEvaluates expression and returns a zero exit status when expression is true. See Con‐\nditional Expressions below, for a description of expression.\n\nfunction varname { list ;}\nvarname () { list ;}\nDefine a function which is referenced by varname. A function whose varname contains a\n. is called a discipline function and the portion of the varname preceding the last .\nmust refer to an existing variable. The body of the function is the list of commands\nbetween { and }. A function defined with the function varname syntax can also be used\nas an argument to the . special built-in command to get the equivalent behavior as if\nthe varname() syntax were used to define it. (See Functions below.)\n\nnamespace identifier { list ;}\nDefines or uses the name space identifier and runs the commands in list in this name\nspace. (See Name Spaces below.)\n\n& [ name [ arg... ] ]\nCauses subsequent list commands terminated by & to be placed in the background job\npool name. If name is omitted a default unnamed pool is used. Commands in a named\nbackground pool may be executed remotely.\n\ntime [ pipeline ]\nIf pipeline is omitted the user and system time for the current shell and completed\nchild processes is printed on standard error. Otherwise, pipeline is executed and the\nelapsed time as well as the user and system time are printed on standard error. The\nTIMEFORMAT variable may be set to a format string that specifies how the timing infor‐\nmation should be displayed. See Shell Variables below for a description of the TIME‐‐\nFORMAT variable.\n\nThe following reserved words are recognized as reserved only when they are the first word of\na command and are not quoted:\n" }, { "name": "if then else elif fi case esac for while until do done { } function select time [[ ]] !", "content": "" }, { "name": "Variable Assignments.", "content": "One or more variable assignments can start a simple command or can be arguments to the type‐‐\nset, enum, export, or readonly special built-in commands as well as to other declaration com‐\nmands created as types. The syntax for an assignment is of the form:\n\nvarname=word\nvarname[word]=word\nNo space is permitted between varname and the = or between = and word.\n\nvarname=(assignlist)\nNo space is permitted between varname and the =. The variable varname is unset before\nthe assignment. An assignlist can be one of the following:\nword ...\nIndexed array assignment.\n[word]=word ...\nAssociative array assignment. If preceded by typeset -a this will cre‐\nate an indexed array instead.\nassignment ...\nCompound variable assignment. This creates a compound variable varname\nwith subvariables of the form varname.name, where name is the name por‐\ntion of assignment. The value of varname will contain all the assign‐\nment elements. Additional assignments made to subvariables of varname\nwill also be displayed as part of the value of varname. If no assign‐\nments are specified, varname will be a compound variable allowing sub‐\nsequence child elements to be defined.\ntypeset [options] assignment ...\nNested variable assignment. Multiple assignments can be specified by\nseparating each of them with a ;. The previous value is unset before\nthe assignment. Other declaration commands such as readonly, enum, and\nother declaration commands can be used in place of typeset.\n. filename\nInclude the assignment commands contained in filename.\n\nIn addition, a += can be used in place of the = to signify adding to or appending to the pre‐\nvious value. When += is applied to an arithmetic type, word is evaluated as an arithmetic\nexpression and added to the current value. When applied to a string variable, the value de‐\nfined by word is appended to the value. For compound assignments, the previous value is not\nunset and the new values are appended to the current ones provided that the types are compat‐\nible.\n\nThe right hand side of a variable assignment undergoes all the expansion listed below except\nword splitting, brace expansion, and pathname expansion. When the left hand side is an as‐\nsignment is a compound variable and the right hand is the name of a compound variable, the\ncompound variable on the right will be copied or appended to the compound variable on the\nleft.\n" }, { "name": "Comments.", "content": "A word beginning with # causes that word and all the following characters up to a new-line to\nbe ignored.\n" }, { "name": "Aliasing.", "content": "The first word of each command is replaced by the text of an alias if an alias for this word\nhas been defined. An alias name consists of any number of characters excluding metacharac‐\nters, quoting characters, file expansion characters, parameter expansion and command substi‐\ntution characters, the characters / and =. The replacement string can contain any valid\nshell script including the metacharacters listed above. The first word of each command in\nthe replaced text, other than any that are in the process of being replaced, will be tested\nfor aliases. If the last character of the alias value is a blank then the word following the\nalias will also be checked for alias substitution. Aliases can be used to redefine built-in\ncommands but cannot be used to redefine the reserved words listed above. Aliases can be cre‐\nated and listed with the alias command and can be removed with the unalias command.\n\nAliasing is performed when scripts are read, not while they are executed. Therefore, for an\nalias to take effect, the alias definition command has to be executed before the command\nwhich references the alias is read.\n\nThe following aliases are automatically preset when the shell is invoked as an interactive\nshell, unless invoked in POSIX compliance mode (see Invocation below). Preset aliases can be\nunset or redefined.\nhistory=′′hist -l′′\nr=′′hist -s′′\n" }, { "name": "Tilde Expansion.", "content": "After alias substitution is performed, each word is checked to see if it begins with an un‐\nquoted ∼∼. For tilde expansion, word also refers to the word portion of parameter expansion\n(see Parameter Expansion below). If a word is preceded by a tilde, then it is checked up to\na / to see if it matches a user name in the password database (see getpwname(3)). If a match\nis found, the ∼∼ and the matched login name are replaced by the login directory of the matched\nuser. If no match is found, the original text is left unchanged. A ∼∼ by itself, or in front\nof a /, is replaced by $HOME, unless the HOME variable is unset, in which case the current\nuser's home directory as configured in the operating system is used. A ∼∼ followed by a + or\n- is replaced by $PWD or $OLDPWD respectively.\n\nIn addition, when expanding a variable assignment (see Variable Assignments above), tilde ex‐\npansion is attempted when the value of the assignment begins with a ∼∼, and when a ∼∼ appears\nafter a :. A : also terminates a user name following a ∼∼.\n\nThe tilde expansion mechanism may be extended or modified by defining one of the discipline\nfunctions .sh.tilde.set or .sh.tilde.get (see Functions and Discipline Functions below). If\neither exists, then upon encountering a tilde word to expand, that function is called with\nthe tilde word assigned to either .sh.value (for the .sh.tilde.set function) or .sh.tilde\n(for the .sh.tilde.get function). Performing tilde expansion within a discipline function\nwill not recursively call that function, but default tilde expansion remains active, so lit‐\neral tildes should still be quoted where required. Either function may assign a replacement\nstring to .sh.value. If this value is non-empty and does not start with a ∼∼, it replaces the\ndefault tilde expansion when the function terminates. Otherwise, the tilde expansion is left\nunchanged.\n" }, { "name": "Command Substitution.", "content": "The standard output from a command list enclosed in parentheses preceded by a dollar sign (\n$(list) ), or in a brace group preceded by a dollar sign ( ${ list;} ), or in a pair of grave\naccents (``) may be used as part or all of a word; trailing new-lines are removed. In the\nsecond case, the { and } are treated as a reserved words so that { must be followed by a\nblank and } must appear at the beginning of the line or follow a ;. In the third (obsolete)\nform, the string between the quotes is processed for special quoting characters before the\ncommand is executed (see Quoting below). The command substitution $(cat file) can be re‐\nplaced by the equivalent but faster $((list) will run process list asynchronously\nconnected to some file in /dev/fd if this directory exists, or else a fifo a temporary direc‐\ntory. The name of this file will become the argument to the command. If the form with > is\nselected then writing on this file will provide input for list. If < is used, then the file\npassed as an argument will contain the output of the list process. For example,\n\npaste <(cut -f1 file1) <(cut -f3 file2) | tee >(process1) >(process2)\n\ncuts fields 1 and 3 from the files file1 and file2 respectively, pastes the results together,\nand sends it to the processes process1 and process2, as well as putting it onto the standard\noutput. Note that the file, which is passed as an argument to the command, is a UNIX pipe(2)\nso programs that expect to lseek(2) on the file will not work.\n\nProcess substitution of the form <(list) can also be used with the < redirection operator\nwhich causes the output of list to be standard input or the input for whatever file descrip‐\ntor is specified.\n" }, { "name": "Parameter Expansion.", "content": "A parameter is a variable, one or more digits, or any of the characters *, @, #, ?, -, $, and\n!. A variable is denoted by a vname. To create a variable whose vname contains a ., a vari‐\nable whose vname consists of everything before the last . must already exist. A variable has\na value and zero or more attributes. Variables can be assigned values and attributes by us‐\ning the typeset special built-in command. The attributes supported by the shell are de‐\nscribed later with the typeset special built-in command. Exported variables pass their at‐\ntributes to the environment so that a newly invoked ksh that is a child or exec'd process of\nthe current shell will automatically import them, unless the posix shell option is on.\n\nThe shell supports both indexed and associative arrays. An element of an array variable is\nreferenced by a subscript. A subscript for an indexed array is denoted by an arithmetic ex‐\npression (see Arithmetic Evaluation below) between a [ and a ]. To assign values to an in‐\ndexed array, use vname=(value ...) or set -A vname value ... . The value of all non-nega‐\ntive subscripts must be in the range of 0 through 4,194,303. A negative subscript is treated\nas an offset from the maximum current index +1 so that -1 refers to the last element. In‐\ndexed arrays can be declared with the -a option to typeset. Indexed arrays need not be de‐\nclared. Any reference to a variable with a valid subscript is legal and an array will be\ncreated if necessary.\n\nAn associative array is created with the -A option to typeset. A subscript for an associa‐\ntive array is denoted by a string enclosed between [ and ].\n\nReferencing any array without a subscript is equivalent to referencing the array with sub‐\nscript 0.\n\nThe value of a variable may be assigned by writing:\n\nvname=value [ vname=value ] ...\n\nor\nvname[subscript]=value [ vname[subscript]=value ] ...\nNote that no space is allowed before or after the =.\nAttributes assigned by the typeset special built-in command apply to all elements of the ar‐\nray. An array element can be a simple variable, a compound variable or an array variable.\nAn element of an indexed array can be either an indexed array or an associative array. An\nelement of an associative array can also be either. To refer to an array element that is\npart of an array element, concatenate the subscript in brackets. For example, to refer to\nthe foobar element of an associative array that is defined as the third element of the in‐\ndexed array, use ${vname[3][foobar]}\nA nameref is a variable that is a reference to another variable. A nameref is created with\nthe -n attribute of typeset. The value of the variable at the time of the typeset command\nbecomes the variable that will be referenced whenever the nameref variable is used. The name\nof a nameref cannot contain a .. When a variable or function name contains a ., and the por‐\ntion of the name up to the first . matches the name of a nameref, the variable referred to is\nobtained by replacing the nameref portion with the name of the variable referenced by the\nnameref. If a nameref is used as the index of a for loop, a name reference is established\nfor each item in the list. A nameref provides a convenient way to refer to the variable in‐\nside a function whose name is passed as an argument to a function. For example, if the name\nof a variable is passed as the first argument to a function, the command\ntypeset -n var=$1\ninside the function causes references and assignments to var to be references and assignments\nto the variable whose name has been passed to the function.\nIf any of the floating point attributes, -E, -F, or -X, or the integer attribute, -i, is set\nfor vname, then the value is subject to arithmetic evaluation as described below.\nPositional parameters, parameters denoted by a number, may be assigned values with the set\nspecial built-in command. Parameter $0 is set from argument zero when the shell is invoked.\nThe character $ is used to introduce substitutable parameters.\n${parameter}\nThe shell reads all the characters from ${ to the matching } as part of the same word\neven if it contains braces or metacharacters. The value, if any, of the parameter is\nsubstituted. The braces are required when parameter is followed by a letter, digit,\nor underscore that is not to be interpreted as part of its name, when the variable\nname contains a .. The braces are also required when a variable is subscripted unless\nit is part of an Arithmetic Expression or a Conditional Expression. If parameter is\none or more digits then it is a positional parameter. A positional parameter of more\nthan one digit must be enclosed in braces. If parameter is * or @, then all the posi‐\ntional parameters, starting with $1, are substituted (separated by a field separator\ncharacter). If an array vname with last subscript * @, or for indexed arrays of the\nform sub1 .. sub2. is used, then the value for each of the elements between sub1 and\nsub2 inclusive (or all elements for * and @) is substituted, separated by the first\ncharacter of the value of IFS.\n${#parameter}\nIf parameter is * or @, the number of positional parameters is substituted. Other‐\nwise, the length of the value of the parameter is substituted.\n${#vname[*]}\n${#vname[@]}\nThe number of elements in the array vname is substituted.\n\n${@vname}\nExpands to the type name (See Type Variables below) or attributes of the variable re‐\nferred to by vname.\n${!vname}\nExpands to the name of the variable referred to by vname. This will be vname except\nwhen vname is a name reference.\n${!vname[subscript]}\nExpands to name of the subscript unless subscript is *, @. or of the form sub1 ..\nsub2. When subscript is *, the list of array subscripts for vname is generated. For\na variable that is not an array, the value is 0 if the variable is set. Otherwise it\nis null. When subscript is @, same as above, except that when used in double quotes,\neach array subscript yields a separate argument. When subscript is of the form sub1\n.. sub2 it expands to the list of subscripts between sub1 and sub2 inclusive using\nthe same quoting rules as @.\n${!prefix@}\n${!prefix*}\nThese both expand to the names of the variables whose names begin with prefix. The\nexpansions otherwise work like $@ and $*, respectively (see under Quoting below).\n${parameter:-word}\nIf parameter is set and is non-null then substitute its value; otherwise substitute\nword.\n${parameter:=word}\nIf parameter is not set or is null then set it to word; the value of the parameter is\nthen substituted. Positional parameters may not be assigned to in this way.\n${parameter:?word}\nIf parameter is set and is non-null then substitute its value; otherwise, print word\nand exit from the shell (if not interactive). If word is omitted then a standard mes‐\nsage is printed.\n${parameter:+word}\nIf parameter is set and is non-null then substitute word; otherwise substitute noth‐\ning.\nIn the above, word is not evaluated unless it is to be used as the substituted string, so\nthat, in the following example, pwd is executed only if d is not set or is null:\nprint ${d:-$(pwd)}\nIf the colon ( : ) is omitted from the above expressions, then the shell only checks whether\nparameter is set or not.\n${parameter:offset:length}\n${parameter:offset}\nExpands to the portion of the value of parameter starting at the character (counting\nfrom 0) determined by expanding offset as an arithmetic expression and consisting of\nthe number of characters determined by the arithmetic expression defined by length.\nIn the second form, the remainder of the value is used. If A negative offset counts\nbackwards from the end of parameter. Note that one or more blanks is required in\nfront of a minus sign to prevent the shell from interpreting the operator as :-. If\nparameter is * or @, or is an array name indexed by * or @, then offset and length re‐\nfer to the array index and number of elements respectively. A negative offset is\ntaken relative to one greater than the highest subscript for indexed arrays. The or‐\nder for associative arrays is unspecified.\n${parameter#pattern}\n${parameter##pattern}\nIf the shell pattern matches the beginning of the value of parameter, then the value\nof this expansion is the value of the parameter with the matched portion deleted; oth‐\nerwise the value of this parameter is substituted. In the first form the smallest\nmatching pattern is deleted and in the second form the largest matching pattern is\ndeleted. When parameter is @, *, or an array variable with subscript @ or *, the sub‐\nstring operation is applied to each element in turn.\n\n${parameter%pattern}\n${parameter%%pattern}\nIf the shell pattern matches the end of the value of parameter, then the value of this\nexpansion is the value of the parameter with the matched part deleted; otherwise sub‐\nstitute the value of parameter. In the first form the smallest matching pattern is\ndeleted and in the second form the largest matching pattern is deleted. When parame‐\nter is @, *, or an array variable with subscript @ or *, the substring operation is\napplied to each element in turn.\n\n${parameter/pattern/string}\n${parameter//pattern/string}\n${parameter/#pattern/string}\n${parameter/%pattern/string}\nExpands parameter and replaces the longest match of pattern with the given string.\nEach occurrence of \\n in string is replaced by the portion of parameter that matches\nthe n-th subpattern. In the first form, only the first occurrence of pattern is re‐\nplaced. In the second form, each match for pattern is replaced by the given string.\nThe third form restricts the pattern match to the beginning of the string while the\nfourth form restricts the pattern match to the end of the string. When string is\nnull, the pattern will be deleted and the / in front of string may be omitted. When\nparameter is @, *, or an array variable with subscript @ or *, the substitution opera‐\ntion is applied to each element in turn. In this case, the string portion of word\nwill be re-evaluated for each element.\n" }, { "name": "Shell Variables.", "content": "The following parameters are automatically set by the shell:\n# The number of positional parameters in decimal.\n- Options supplied to the shell on invocation or by the set command.\n? The exit status returned by the last executed command. Its meaning depends on\nthe command or function that defines it, but there are conventions that other\ncommands often depend on: zero typically means 'success' or 'true', one typi‐\ncally means 'non-success' or 'false', and a value greater than one typically\nindicates some kind of error. Only the 8 least significant bits of $? (values 0\nto 255) are preserved when the exit status is passed on to a parent process,\nbut within the same (sub)shell environment, it is a signed integer value with a\nrange of possible values as shown by the commands getconf INTMIN and getconf\nINTMAX. Shell functions that run in the current environment may return status\nvalues in this range.\n$ The process ID of the main shell process. Note that this value will not change\nin a subshell, even if the subshell runs in a different process. See also\n.sh.pid.\nInitially, the value of is an absolute pathname of the shell or script being\nexecuted as passed in the environment. Subsequently it is assigned the last\nargument of the previous command. This parameter is not set for commands which\nare asynchronous. This parameter is also used to hold the name of the matching\nMAIL file when checking for mail. While defining a compound variable or a\ntype, is initialized as a reference to the compound variable or type. When a\ndiscipline function is invoked, is initialized as a reference to the variable\nassociated with the call to this function. Finally when is used as the name\nof the first variable of a type definition, the new type is derived from the\ntype of the first variable. (See Type Variables below.)\n! The process id or the pool name and job number of the last background command\ninvoked or the most recent job put in the background with the bg built-in com‐\nmand. Background jobs started in a named pool will be in the form pool.number\nwhere pool is the pool name and number is the job number within that pool.\n.sh.command\nWhen processing a DEBUG trap, this variable contains the current command line\nthat is about to run. The value is in the same format as the output generated\nby the xtrace option (minus the preceding PS4 prompt).\n.sh.edchar\nThis variable contains the value of the keyboard character (or sequence of\ncharacters if the first character is an ESC, ASCII 033) that has been entered\nwhen processing a KEYBD trap (see Key Bindings below). If the value is changed\nas part of the trap action, then the new value replaces the key (or key se‐\nquence) that caused the trap.\n.sh.edcol\nThe character position of the cursor at the time of the most recent KEYBD trap.\n.sh.edmode\nThe value is set to ESC when processing a KEYBD trap while in vi insert mode.\n(See Vi Editing Mode below.) Otherwise, .sh.edmode is null when processing a\nKEYBD trap.\n.sh.edtext\nThe characters in the input buffer at the time of the most recent KEYBD trap.\nThe value is null when not processing a KEYBD trap.\n.sh.file\nThe pathname of the file that contains the current command.\n.sh.fun\nThe name of the current function that is being executed.\n.sh.level\nSet to the current function depth. This can be changed inside a DEBUG trap and\nwill set the context to the specified level.\n.sh.lineno\nSet during a DEBUG trap to the line number for the caller of each function.\n.sh.match\nAn indexed array which stores the most recent match and subpattern matches af‐\nter conditional pattern matches that match and after variables expansions using\nthe operators #, %, or /. The 0-th element stores the complete match and the\ni-th. element stores the i-th submatch. The .sh.match variable becomes unset\nwhen the variable that has expanded is assigned a new value.\n.sh.math\nUsed for defining arithmetic functions (see Arithmetic Evaluation below) and\nstores the list of user defined arithmetic functions.\n.sh.name\nSet to the name of the variable at the time that a discipline function is in‐\nvoked.\n.sh.subscript\nSet to the name subscript of the variable at the time that a discipline func‐\ntion is invoked.\n.sh.subshell\nThe current depth for subshells and command substitution.\n.sh.pid\nSet to the process ID of the current shell. This is distinct from $$ as in\nforked subshells this is set to the process ID of the subshell instead of the\nparent shell's process ID. In virtual subshells .sh.pid retains its previous\nvalue.\n.sh.value\nSet to the value of the variable at the time that the set or append discipline\nfunction is invoked. When a user defined arithmetic function is invoked, the\nvalue of .sh.value is saved and .sh.value is set to long double precision\nfloating point. .sh.value is restored when the function returns.\n.sh.version\nSet to a value that identifies the version of this shell.\nKSHVERSION\nA name reference to .sh.version.\nLINENO The current line number within the script or function being executed.\nOLDPWD The previous working directory set by the cd command.\nOPTARG The value of the last option argument processed by the getopts built-in com‐\nmand.\nOPTIND The index of the last option argument processed by the getopts built-in com‐\nmand.\nPPID The process id of the parent of the shell.\nPWD The present working directory set by the cd command.\nRANDOM Each time this variable is referenced, a random integer, uniformly distributed\nbetween 0 and 32767, is generated. The sequence of random numbers can be ini‐\ntialized by assigning a numeric value to RANDOM.\nREPLY This variable is set by the select statement and by the read built-in command\nwhen no arguments are supplied.\nSECONDS\nEach time this variable is referenced, the number of seconds since shell invo‐\ncation is returned. If this variable is assigned a value, then the value re‐\nturned upon reference will be the value that was assigned plus the number of\nseconds since the assignment.\nSHLVL An integer variable that is incremented and exported each time the shell is in‐\nvoked. If SHLVL is not in the environment when the shell is invoked, it is set\nto 1.\n\nThe following variables are used by the shell:\nCDPATH The search path for the cd command.\nCOLUMNS\nIf this variable is set, the value is used to define the width of the edit win‐\ndow for the shell edit modes and for printing select lists.\nEDITOR If the VISUAL variable is not set, the value of this variable will be checked\nfor the patterns as described with VISUAL below and the corresponding editing\noption (see Special Command set below) will be turned on.\nENV If this variable is set, then parameter expansion, command substitution, and\narithmetic expansion are performed on the value to generate the pathname of the\nscript that will be executed when the shell is invoked interactively (see Invo‐\ncation below). This file is typically used for alias and function definitions.\nThe default value is $HOME/.kshrc. On systems that support a system wide\n/etc/ksh.kshrc initialization file, if the filename generated by the expansion\nof ENV begins with /./ or ././ the system wide initialization file will not be\nexecuted.\nFCEDIT Obsolete name for the default editor name for the hist command. FCEDIT is not\nused when HISTEDIT is set.\nFIGNORE\nA pattern that defines the set of filenames that will be ignored when perform‐\ning filename matching.\nFPATH The search path for function definitions. The directories in this path are\nsearched for a file with the same name as the function or command when a func‐\ntion with the -u attribute is referenced and when a command is not found. If\nan executable file with the name of that command is found, then it is read and\nexecuted in the current environment. Unlike PATH, the current directory must\nbe represented explicitly by . rather than by adjacent : characters or a be‐\nginning or ending :.\nHISTCMD\nNumber of the current command in the history file.\nHISTEDIT\nName for the default editor name for the hist command.\nHISTFILE\nIf this variable is set when the shell is invoked, then the value is the path‐\nname of the file that will be used to store the command history (see Command\nRe-entry below).\nHISTSIZE\nIf this variable is set when the shell is invoked, then the number of previ‐\nously entered commands that are accessible by this shell will be greater than\nor equal to this number. The default is 512.\nHOME The default argument (home directory) for the cd command.\nIFS Internal field separators, normally space, tab, and new-line that are used to\nseparate the results of command substitution or parameter expansion and to sep‐\narate fields with the built-in command read. The first character of the IFS\nvariable is used to separate arguments for the \"$*\" expansion (see Quoting be‐\nlow). Each single occurrence of an IFS character in the string to be split,\nthat is not in the isspace character class, and any adjacent characters in IFS\nthat are in the isspace character class, delimit a field. One or more charac‐\nters in IFS that belong to the isspace character class, delimit a field. In\naddition, if the same isspace character appears consecutively inside IFS, this\ncharacter is treated as if it were not in the isspace class, so that if IFS\nconsists of two tab characters, then two adjacent tab characters delimit a null\nfield.\nJOBMAX This variable defines the maximum number running background jobs that can run\nat a time. When this limit is reached, the shell will wait for a job to com‐\nplete before starting a new job.\nLANG This variable determines the locale category for any category not specifically\nselected with a variable starting with LC or LANG.\nLCALL This variable overrides the value of the LANG variable and any other LC vari‐\nable.\nLCCOLLATE\nThis variable determines the locale category for character collation informa‐\ntion.\nLCCTYPE\nThis variable determines the locale category for character handling functions.\nIt determines the character classes for pattern matching (see Pathname Expan‐\nsion below).\nLCNUMERIC\nThis variable determines the locale category for the decimal point character.\nLINES If this variable is set, the value is used to determine the column length for\nprinting select lists. Select lists will print vertically until about two-\nthirds of LINES lines are filled.\nMAIL If this variable is set to the name of a mail file and the MAILPATH variable is\nnot set, then the shell informs the user of arrival of mail in the specified\nfile.\nMAILCHECK\nThis variable specifies how often (in seconds) the shell will check for changes\nin the modification time of any of the files specified by the MAILPATH or MAIL\nvariables. The default value is 600 seconds. When the time has elapsed the\nshell will check before issuing the next prompt.\nMAILPATH\nA colon ( : ) separated list of file names. If this variable is set, then the\nshell informs the user of any modifications to the specified files that have\noccurred within the last MAILCHECK seconds. Each file name can be followed by\na ? and a message that will be printed. The message will undergo parameter\nexpansion, command substitution, and arithmetic expansion with the variable $\ndefined as the name of the file that has changed. The default message is you\nhave mail in $.\nPATH The search path for commands (see Execution below). The user may not change\nPATH if executing under rksh (except in .profile).\nPS1 Every time a new command line is started on an interactive shell, the value of\nthis variable is expanded to resolve backslash escaping, parameter expansion,\ncommand substitution, and arithmetic expansion. The result defines the primary\nprompt string for that command line. The default is ``$ ''. The character !\nin the primary prompt string is replaced by the command number (see Command Re-\nentry below). Two successive occurrences of ! will produce a single ! when\nthe prompt string is printed. Note that any terminal escape sequences used in\nthe PS1 prompt thus need every instance of ! in them to be changed to !!.\nPS2 Secondary prompt string, by default ``> ''.\nPS3 Selection prompt string used within a select loop, by default ``#? ''.\nPS4 The value of this variable is expanded for parameter evaluation, command sub‐\nstitution, and arithmetic expansion and precedes each line of an execution\ntrace. By default, PS4 is ``+ ''. In addition when PS4 is unset, the execu‐\ntion trace prompt is also ``+ ''.\nSHELL The pathname of the shell is kept in the environment. At invocation, if the\nbasename of this variable is rsh, rksh, or krsh, then the shell becomes re‐\nstricted.\nTIMEFORMAT\nThe value of this parameter is used as a format string specifying how the tim‐\ning information for pipelines prefixed with the time reserved word should be\ndisplayed. The % character introduces a format sequence that is expanded to a\ntime value or other information. The format sequences and their meanings are\nas follows.\n%% A literal %.\n%[p][l]R The elapsed time in seconds.\n%[p][l]U The number of CPU seconds spent in user mode.\n%[p][l]S The number of CPU seconds spent in system mode.\n%P The CPU percentage, computed as (U + S) / R.\n\nThe brackets denote optional portions. The optional p is a digit specifying\nthe precision, the number of fractional digits after a decimal point. A value\nof 0 causes no decimal point or fraction to be output. At most three places\nafter the decimal point can be displayed; values of p greater than 3 are\ntreated as 3. If p is not specified, the value 3 is used.\n\nThe optional l specifies a longer format, including hours if greater than zero,\nminutes, and seconds of the form HHhMMmSS.FFs. The value of p determines\nwhether or not the fraction is included.\n\nAll other characters are output without change and a trailing newline is added.\nIf unset, the default value, $'\\nreal\\t%2lR\\nuser\\t%2lU\\nsys\\t%2lS', is used.\nIf the value is null, no timing information is displayed.\n\nTMOUT Terminal read timeout. If set to a value greater than zero, the read built-in\ncommand and the select compound command time out after TMOUT seconds when input\nis from a terminal. An interactive shell will issue a warning and allow for an\nextra 60 second timeout grace period before terminating if a line is not en‐\ntered within the prescribed number of seconds while reading from a terminal.\n(Note that the shell can be compiled with a maximum bound for this value which\ncannot be exceeded.)\n\nVISUAL If the value of this variable matches the pattern *[Vv][Ii]*, then the vi op‐\ntion (see Special Command set below) is turned on. If the value matches the\npattern *gmacs* , the gmacs option is turned on. If the value matches the pat‐\ntern *macs*, then the emacs option will be turned on. The value of VISUAL\noverrides the value of EDITOR.\n\nThe shell gives default values to PATH, PS1, PS2, PS3, PS4, MAILCHECK, FCEDIT, TMOUT and IFS,\nwhile HOME, SHELL, ENV, and MAIL are not set at all by the shell (although HOME is set by lo‐\ngin(1)). On some systems MAIL and SHELL are also set by login(1).\n" }, { "name": "Field Splitting.", "content": "After parameter expansion and command substitution, the results of substitutions are scanned\nfor the field separator characters (those found in IFS) and split into distinct fields where\nsuch characters are found. Explicit null fields (\"\" or ′′′′) are retained. Implicit null\nfields (those resulting from parameters that have no values or command substitutions with no\noutput) are removed.\n" }, { "name": "Brace Expansion.", "content": "If the braceexpand (-B) option is set then each of the fields resulting from IFS are checked\nto see if they contain one or more of the brace patterns {*,*}, {l1..l2} , {n1..n2} ,\n{n1..n2% fmt} , {n1..n2 ..n3} , or {n1..n2 ..n3%fmt} , where * represents any character,\nl1,l2 are letters and n1,n2,n3 are signed numbers and fmt is a format specified as used by\nprintf. In each case, fields are created by prepending the characters before the { and ap‐\npending the characters after the } to each of the strings generated by the characters between\nthe { and }. The resulting fields are checked to see if they have any brace patterns.\n\nIn the first form, a field is created for each string between { and ,, between , and ,, and\nbetween , and }. The string represented by * can contain embedded matching { and } without\nquoting. Otherwise, each { and } with * must be quoted.\n\nIn the seconds form, l1 and l2 must both be either upper case or both be lower case charac‐\nters in the C locale. In this case a field is created for each character from l1 thru l2.\n\nIn the remaining forms, a field is created for each number starting at n1 and continuing un‐\ntil it reaches n2 incrementing n1 by n3. The cases where n3 is not specified behave as if n3\nwhere 1 if n1<=n2 and -1 otherwise. If forms which specify %fmt any format flags, widths and\nprecisions can be specified and fmt can end in any of the specifiers cdiouxX. For example,\n{a,z}{1..5..3%02d}{b..c}x expands to the 8 fields, a01bx, a01cx, a04bx, a04cx, z01bx, z01cx,\nz04bx and z04cx.\n" }, { "name": "Pathname Expansion.", "content": "This is also known as globbing or sometimes filename generation. Following splitting, each\nfield is scanned for the characters *, ?, (, and [ unless the -f option has been set. If one\nof these characters appears, then the word is regarded as a pattern. Each file name compo‐\nnent that contains any pattern character is replaced with a lexicographically sorted set of\nnames that matches the pattern from that directory. If no file name is found that matches\nthe pattern, then that component of the filename is left unchanged unless the pattern is pre‐\nfixed with ∼∼(N) in which case it is removed as described below. The special traversal names\n. and .. are never matched. If FIGNORE is set, then each file name component that matches\nthe pattern defined by the value of FIGNORE is ignored when generating the matching file‐\nnames. If FIGNORE is not set, the character . at the start of each file name component will\nbe ignored unless the first character of the pattern corresponding to this component is the\ncharacter . itself. Note, that for other uses of pattern matching the / and . are not\ntreated specially.\n\n* Matches any string, including the null string. When used for filename expan‐\nsion, if the globstar option is on, an isolated pattern of two adjacent *'s\nwill match all files and zero or more directories and subdirectories. If fol‐\nlowed by a / then only directories and subdirectories will match.\n? Matches any single character.\n[...] Matches any one of the enclosed characters. A pair of characters separated by\n- matches any character lexically between the pair, inclusive. If the first\ncharacter following the opening [ is a ! or ^ then any character not enclosed\nis matched. A - can be included in the character set by putting it as the\nfirst or last character.\nWithin [ and ], character classes can be specified with the syntax [:class:]\nwhere class is one of the following classes defined in the ANSI C standard:\n(Note that word is equivalent to alnum plus the character .)\nalnum alpha blank cntrl digit graph lower print punct space upper word xdigit\nWithin [ and ], an equivalence class can be specified with the syntax [=c=]\nwhich matches all characters with the same primary collation weight (as defined\nby the current locale) as the character c. Within [ and ], [.symbol.] matches\nthe collating symbol symbol.\nA pattern-list is a list of one or more patterns separated from each other with a & or |. A\n& signifies that all patterns must be matched whereas | requires that only one pattern be\nmatched. Composite patterns can be formed with one or more of the following subpatterns:\n?(pattern-list)\nOptionally matches any one of the given patterns.\n*(pattern-list)\nMatches zero or more occurrences of the given patterns.\n+(pattern-list)\nMatches one or more occurrences of the given patterns.\n{n}(pattern-list)\nMatches n occurrences of the given patterns.\n{m,n}(pattern-list)\nMatches from m to n occurrences of the given patterns. If m is omitted, 0 will\nbe used. If n is omitted at least m occurrences will be matched.\n@(pattern-list)\nMatches exactly one of the given patterns.\n!(pattern-list)\nMatches anything except one of the given patterns.\nBy default, each pattern, or subpattern will match the longest string possible consistent\nwith generating the longest overall match. If more than one match is possible, the one\nstarting closest to the beginning of the string will be chosen. However, for each of the\nabove compound patterns a - can be inserted in front of the ( to cause the shortest match to\nthe specified pattern-list to be used.\n\nWhen pattern-list is contained within parentheses, the backslash character \\ is treated spe‐\ncially even when inside a character class. All ANSI C character escapes are recognized and\nmatch the specified character. In addition the following escape sequences are recognized:\n\\d Matches any character in the digit class.\n\\D Matches any character not in the digit class.\n\\s Matches any character in the space class.\n\\S Matches any character not in the space class.\n\\w Matches any character in the word class.\n\\W Matches any character not in the word class.\n\nA pattern of the form %(pattern-pair(s)) is a subpattern that can be used to match nested\ncharacter expressions. Each pattern-pair is a two character sequence which cannot contain &\nor |. The first pattern-pair specifies the starting and ending characters for the match.\nEach subsequent pattern-pair represents the beginning and ending characters of a nested group\nthat will be skipped over when counting starting and ending character matches. The behavior\nis unspecified when the first character of a pattern-pair is alphanumeric except for the fol‐\nlowing:\nD Causes the ending character to terminate the search for this pattern without\nfinding a match.\nE Causes the ending character to be interpreted as an escape character.\nL Causes the ending character to be interpreted as a quote character causing all\ncharacters to be ignored when looking for a match.\nQ Causes the ending character to be interpreted as a quote character causing all\ncharacters other than any escape character to be ignored when looking for a\nmatch.\nThus, %({}Q\"E\\), matches characters starting at { until the matching } is found not counting\nany { or } that is inside a double quoted string or preceded by the escape character \\.\nWithout the {} this pattern matches any C language string.\n\nEach subpattern in a composite pattern is numbered, starting at 1, by the location of the (\nwithin the pattern. The sequence \\n, where n is a single digit and \\n comes after the n-th.\nsubpattern, matches the same string as the subpattern itself.\n\nFinally a pattern can contain subpatterns of the form ∼∼(options:pattern-list), where either\noptions or :pattern-list can be omitted. Unlike the other compound patterns, these subpat‐\nterns are not counted in the numbered subpatterns. :pattern-list must be omitted for options\nF, G, N , and V below. If options is present, it can consist of one or more of the follow‐\ning:\n+ Enable the following options. This is the default.\n- Disable the following options.\nE The remainder of the pattern uses extended regular expression syntax like the\negrep(1) command.\nF The remainder of the pattern uses fgrep(1) expression syntax.\nG The remainder of the pattern uses basic regular expression syntax like the\ngrep(1) command.\nK The remainder of the pattern uses shell pattern syntax. This is the default.\nN This is ignored. However, when it is the first letter and is used with path‐\nname expansion, and no matches occur, the file pattern expands to the empty\nstring.\nX The remainder of the pattern uses augmented regular expression syntax like the\nxgrep(1) command.\nP The remainder of the pattern uses perl(1) regular expression syntax. Not all\nperl regular expression syntax is currently implemented.\nV The remainder of the pattern uses System V regular expression syntax.\ni Always treat the match as case-insensitive, regardless of the globcasedetect\nshell option.\ng File the longest match (greedy). This is the default.\nl Left anchor the pattern. This is the default for K style patterns.\nr Right anchor the pattern. This is the default for K style patterns.\nIf both options and :pattern-list are specified, then the options apply only to pattern-\nlist. Otherwise, these options remain in effect until they are disabled by a subsequent\n∼∼(...) or at the end of the subpattern containing ∼∼(...).\n" }, { "name": "Quoting.", "content": "Each of the metacharacters listed earlier (see Definitions above) has a special meaning to\nthe shell and causes termination of a word unless quoted. A character may be quoted (i.e.,\nmade to stand for itself) by preceding it with a \\. The pair \\new-line is removed. All\ncharacters enclosed between a pair of single quote marks (′′′′) that is not preceded by a $ are\nquoted. A single quote cannot appear within the single quotes. A single quoted string pre‐\nceded by an unquoted $ is processed as an ANSI C string except for the following:\n\\0 Causes the remainder of the string to be ignored.\n\\E Equivalent to the escape character (ASCII 033),\n\\e Equivalent to the escape character (ASCII 033),\n\\cx Expands to the character control-x.\n\\C[.name.]\nExpands to the collating element name.\n\nInside double quote marks (\"\"), parameter and command substitution occur and \\ quotes the\ncharacters \\, `, \", and $. A $ in front of a double quoted string will be ignored in the \"C\"\nor \"POSIX\" locale, and may cause the string to be replaced by a locale specific string other‐\nwise. The meaning of $* and $@ is identical when not quoted or when used as a variable as‐\nsignment value or as a file name. However, when used as a command argument, \"$*\" is equiva‐\nlent to \"$1d$2d...\", where d is the first character of the IFS variable, whereas \"$@\" is\nequivalent to \"$1\" \"$2\" .... Inside grave quote marks (``), \\ quotes the characters \\, `,\nand $. If the grave quotes occur within double quotes, then \\ also quotes the character \".\n\nThe special meaning of reserved words or aliases can be removed by quoting any character of\nthe reserved word. The recognition of function names or built-in command names listed below\ncannot be altered by quoting them.\n" }, { "name": "Arithmetic Evaluation.", "content": "The shell performs arithmetic evaluation for arithmetic expansion, to evaluate an arithmetic\ncommand, to evaluate an indexed array subscript, and to evaluate arguments to the built-in\ncommands shift and let as well as arguments to numeric format specifiers given to print -f\nand printf. Evaluations are performed using double precision floating point arithmetic or\nlong double precision floating point for systems that provide this data type. Floating point\nconstants follow the ANSI C programming language floating point conventions. The case-insen‐\nsitive floating point constants NaN and Inf can be used to represent \"not a number\" and in‐\nfinity respectively, unless the posix shell option is on. Integer constants follow the ANSI\nC programming language integer constant conventions although only single byte character con‐\nstants are recognized and character casts are not recognized. In addition constants can be\nof the form [base#]n where base is a decimal number between two and sixty-four representing\nthe arithmetic base and n is a number in that base. The digits above 9 are represented by\nthe lower case letters, the upper case letters, @, and respectively. For bases less than\nor equal to 36, upper and lower case characters can be used interchangeably.\n\nAn arithmetic expression uses the same syntax, precedence, and associativity of expression as\nthe C language. All the C language operators that apply to floating point quantities can be\nused. In addition, the operator can be used for exponentiation. It has higher precedence\nthan multiplication and is left associative. In addition, when the value of an arithmetic\nvariable or subexpression can be represented as a long integer, all C language integer arith‐\nmetic operations can be performed. Variables can be referenced by name within an arithmetic\nexpression without using the parameter expansion syntax. When a variable is referenced, its\nvalue is evaluated as an arithmetic expression.\n\nAny of the following math library functions that are in the C math library can be used within\nan arithmetic expression:\n" }, { "name": "abs acos acosh asin asinh atan atan2 atanh cbrt ceil copysign cos cosh erf erfc exp exp10", "content": "" }, { "name": "exp2 expm1 fabs fdim finite float floor fma fmax fmin fmod fpclass fpclassify hypot ilogb int", "content": "isfinite isgreater isgreaterequal isinf isinfinite isless islessequal islessgreater isnan is‐‐\nnormal issubnormal isunordered iszero j0 j1 jn ldexp lgamma log log10 log1p log2 logb near‐‐" }, { "name": "byint nextafter nexttoward pow remainder rint round scalb scalbn signbit sin sinh sqrt tan", "content": "" }, { "name": "tanh tgamma trunc y0 y1 yn", "content": "In addition, arithmetic functions can be defined as shell functions with a variant of the\nfunction name syntax,\n\nfunction .sh.math.name ident ... { list ;}\nwhere name is the function name used in the arithmetic expression and each identifier,\nident is a name reference to the long double precision floating point argument. The\nvalue of .sh.value when the function returns is the value of this function. User de‐\nfined functions can take up to 3 arguments and override C math library functions.\n\nAn internal representation of a variable as a double precision floating point can be speci‐\nfied with the -E [n], -F [n], or -X [n] option of the typeset special built-in command. The" }, { "name": "-E", "content": "it is expanded. The optional option argument n defines the number of significant figures.\nThe -F option causes the expansion to be represented as a floating decimal number when it is\nexpanded. The -X option causes the expansion to be represented using the %a format defined\nby ISO C-99. The optional option argument n defines the number of places after the decimal\n(or radix) point in this case.\n\nAn internal integer representation of a variable can be specified with the -i [n] option of\nthe typeset special built-in command. The optional option argument n specifies an arithmetic\nbase to be used when expanding the variable. If you do not specify an arithmetic base, base\n10 will be used.\n\nArithmetic evaluation is performed on the value of each assignment to a variable with the -E,", "flag": "-E" }, { "name": "-F -X -i", "content": "integer causes the fractional part to be truncated.\n", "flag": "-i" }, { "name": "Prompting.", "content": "When used interactively, the shell prompts with the value of PS1 after expanding it for pa‐\nrameter expansion, command substitution, and arithmetic expansion, before reading a command.\nIn addition, each single ! in the prompt is replaced by the command number. A !! is re‐\nquired to place ! in the prompt. If at any time a new-line is typed and further input is\nneeded to complete a command, then the secondary prompt (i.e., the value of PS2) is issued.\n" }, { "name": "Conditional Expressions.", "content": "A conditional expression is used with the [[ compound command to test attributes of files and\nto compare strings. Field splitting and pathname expansion are not performed on the words\nbetween [[ and ]]. Each expression can be constructed from one or more of the following\nunary or binary expressions:\nstring True, if string is not null." }, { "name": "-a", "content": "Same as -e below. This is obsolete.", "flag": "-a" }, { "name": "-b", "content": "True, if file exists and is a block special file.", "flag": "-b" }, { "name": "-c", "content": "True, if file exists and is a character special file.", "flag": "-c" }, { "name": "-d", "content": "True, if file exists and is a directory.", "flag": "-d" }, { "name": "-e", "content": "True, if file exists.", "flag": "-e" }, { "name": "-f", "content": "True, if file exists and is an ordinary file.", "flag": "-f" }, { "name": "-g", "content": "True, if file exists and it has its setgid bit set.", "flag": "-g" }, { "name": "-k", "content": "True, if file exists and it has its sticky bit set.", "flag": "-k" }, { "name": "-n", "content": "True, if length of string is non-zero.", "flag": "-n" }, { "name": "-o", "content": "True, if option named option is a valid option name.", "flag": "-o" }, { "name": "-o", "content": "True, if option named option is on.", "flag": "-o" }, { "name": "-p", "content": "True, if file exists and is a fifo special file or a pipe.", "flag": "-p" }, { "name": "-r", "content": "True, if file exists and is readable by current process.", "flag": "-r" }, { "name": "-s", "content": "True, if file exists and has size greater than zero.", "flag": "-s" }, { "name": "-t", "content": "True, if file descriptor number fildes is open and associated with a terminal device.", "flag": "-t" }, { "name": "-u", "content": "True, if file exists and it has its setuid bit set.", "flag": "-u" }, { "name": "-v", "content": "True, if variable name is a valid variable name and is set.", "flag": "-v" }, { "name": "-w", "content": "True, if file exists and is writable by current process.", "flag": "-w" }, { "name": "-x", "content": "True, if file exists and is executable by current process. If file exists and is a\ndirectory, then true if the current process has permission to search in the directory.", "flag": "-x" }, { "name": "-z", "content": "True, if length of string is zero.", "flag": "-z" }, { "name": "-L", "content": "True, if file exists and is a symbolic link.", "flag": "-L" }, { "name": "-h", "content": "True, if file exists and is a symbolic link.", "flag": "-h" }, { "name": "-N", "content": "True, if file exists and the modification time is greater than the last access time.", "flag": "-N" }, { "name": "-O", "content": "True, if file exists and is owned by the effective user id of this process.", "flag": "-O" }, { "name": "-G", "content": "True, if file exists and its group matches the effective group id of this process.", "flag": "-G" }, { "name": "-R", "content": "True if variable name is a name reference.", "flag": "-R" }, { "name": "-S", "content": "True, if file exists and is a socket.\nfile1 -nt file2\nTrue, if file1 exists and file2 does not, or file1 is newer than file2.\nfile1 -ot file2\nTrue, if file2 exists and file1 does not, or file1 is older than file2.\nfile1 -ef file2\nTrue, if file1 and file2 exist and refer to the same file.\nstring == pattern\nTrue, if string matches pattern. Any part of pattern can be quoted to cause it to be\nmatched as a string. With a successful match to a pattern, the .sh.match array vari‐\nable will contain the match and subpattern matches.\nstring = pattern\nSame as == above, but is obsolete.\nstring != pattern\nTrue, if string does not match pattern. When the string matches the pattern the\n.sh.match array variable will contain the match and subpattern matches.\nstring =∼∼ ere\nTrue if string matches the pattern ∼∼(E)ere where ere is an extended regular expres‐\nsion.\nstring1 < string2\nTrue, if string1 comes before string2 based on ASCII value of their characters.\nstring1 > string2\nTrue, if string1 comes after string2 based on ASCII value of their characters.\nThe following obsolete arithmetic comparisons are also permitted:\nexp1 -eq exp2\nTrue, if exp1 is equal to exp2.\nexp1 -ne exp2\nTrue, if exp1 is not equal to exp2.\nexp1 -lt exp2\nTrue, if exp1 is less than exp2.\nexp1 -gt exp2\nTrue, if exp1 is greater than exp2.\nexp1 -le exp2\nTrue, if exp1 is less than or equal to exp2.\nexp1 -ge exp2\nTrue, if exp1 is greater than or equal to exp2.\n\nIn each of the above expressions, if file is of the form /dev/fd/n, where n is an integer,\nthen the test is applied to the open file whose descriptor number is n.\n\nA compound expression can be constructed from these primitives by using any of the following,\nlisted in decreasing order of precedence.\n(expression)\nTrue, if expression is true. Used to group expressions.\n! expression\nTrue if expression is false.\nexpression1 && expression2\nTrue, if expression1 and expression2 are both true.\nexpression1 || expression2\nTrue, if either expression1 or expression2 is true.\n", "flag": "-S" }, { "name": "Input/Output.", "content": "Before a command is executed, its input and output may be redirected using a special notation\ninterpreted by the shell. The following may appear anywhere in a simple-command or may pre‐\ncede or follow a command and are not passed on to the invoked command. Command substitution,\nparameter expansion, and arithmetic expansion occur before word or digit is used except as\nnoted below. Pathname expansion occurs only if the shell is interactive and the pattern\nmatches a single file. Field splitting is not performed.\n\nIn each of the following redirections, if file is of the form /dev/sctp/host/port,\n/dev/tcp/host/port, or /dev/udp/host/port, where host is a hostname or host address, and port\nis a service given by name or an integer port number, then the redirection attempts to make a\ntcp, sctp or udp connection to the corresponding socket.\n\nNo intervening space is allowed between the characters of redirection operators.\n\nword Use file word as standard output (file descriptor 1). If the file does not ex‐\nist then it is created. If the file exists, and the noclobber option is on,\nthis causes an error; otherwise, it is truncated to zero length.\n\n>|word Same as >, except that it overrides the noclobber option.\n\n>;word Write output to a temporary file. If the command completes successfully rename\nit to word, otherwise, delete the temporary file. >;word cannot be used with\nthe exec and redirect built-ins.\n\n>>word Use file word as standard output. If the file exists, then output is appended\nto it (by first seeking to the end-of-file); otherwise, the file is created.\n\n<>word Open file word for reading and writing as standard output. If the posix option\nis active, it defaults to standard input instead.\n\n<>;word The same as <>word except that if the command completes successfully, word is\ntruncated to the offset at command completion. <>;word cannot be used with the\nexec and redirect built-ins.\n\n<<[-]word The shell input is read up to a line that is the same as word after any quoting\nhas been removed, or to an end-of-file. No parameter expansion, command sub‐\nstitution, arithmetic expansion or pathname expansion is performed on word.\nThe resulting document, called a here-document, becomes the standard input. If\nany character of word is quoted, then no interpretation is placed upon the\ncharacters of the document; otherwise, parameter expansion, command substitu‐\ntion, and arithmetic expansion occur, \\new-line is ignored, and \\ must be used\nto quote the characters \\, $, `. If - is appended to <<, then all leading tabs\nare stripped from word and from the document. If # is appended to <<, then\nleading spaces and tabs will be stripped off the first line of the document and\nup to an equivalent indentation will be stripped from the remaining lines and\nfrom word. A tab stop is assumed to occur at every 8 columns for the purposes\nof determining the indentation.\n\n<<&digit The standard output is duplicated from file descriptor digit.\n\n<&digit- The file descriptor given by digit is moved to standard input.\n\n>&digit- The file descriptor given by digit is moved to standard output.\n\n<&- The standard input is closed.\n\n>&- The standard output is closed.\n\n<&p The input from the co-process is moved to standard input.\n\n>&p The output to the co-process is moved to standard output.\n\n<#((expr)) Evaluate arithmetic expression expr and position file descriptor 0 to the re‐\nsulting value bytes from the start of the file. The variables CUR and EOF\nevaluate to the current offset and end-of-file offset respectively when evalu‐\nating expr.\n\n>#((offset)) The same as <# except applies to file descriptor 1.\n\n<#pattern Seeks forward to the beginning of the next line containing pattern.\n\n<##pattern The same as <# except that the portion of the file that is skipped is copied to\nstandard output.\n\nIf one of the above is preceded by a digit, with no intervening space, then the file descrip‐\ntor number referred to is that specified by the digit (instead of the default 0 or 1). If\none of the above, other than >&- and the ># and <# forms, is preceded by {varname} with no\nintervening space, then a file descriptor number > 9 will be selected by the shell and stored\nin the variable varname, so it can be read from or written to with redirections like <& $var‐\nname or >& $varname. If >&- or the any of the ># and <# forms is preceded by {varname} the\nvalue of varname defines the file descriptor to close or position. For example:\n\n... 2>&1\n\nmeans file descriptor 2 is to be opened for writing as a duplicate of file descriptor 1 and\n\nexec {n}word is available; it is equivalent to >word 2>&1.\nIt cannot be preceded by any digit or variable name. This shorthand is disabled if the posix\nshell option is active.\n\nThe order in which redirections are specified is significant. The shell evaluates each redi‐\nrection in terms of the (file descriptor, file) association at the time of evaluation. For\nexample:\n\n... 1>fname 2>&1\n\nfirst associates file descriptor 1 with file fname. It then associates file descriptor 2\nwith the file associated with file descriptor 1 (i.e. fname). If the order of redirections\nwere reversed, file descriptor 2 would be associated with the terminal (assuming file de‐\nscriptor 1 had been) and then file descriptor 1 would be associated with file fname.\n\nIf a command is followed by & and job control is not active, then the default standard input\nfor the command is the empty file /dev/null. Otherwise, the environment for the execution of\na command contains the file descriptors of the invoking shell as modified by input/output\nspecifications.\n" }, { "name": "Environment.", "content": "The environment (see environ(7)) is a list of name-value pairs that is passed to an executed\nprogram in the same way as a normal argument list. The names must be identifiers and the\nvalues are character strings. The shell interacts with the environment in several ways. On\ninvocation, the shell scans the environment and creates a variable for each name found, giv‐\ning it the corresponding value and attributes and marking it export. Executed commands in‐\nherit the environment. If the user modifies the values of these variables or creates new\nones, using the export or typeset -x commands, they become part of the environment. The en‐\nvironment seen by any executed command is thus composed of any name-value pairs originally\ninherited by the shell, whose values may be modified by the current shell, plus any additions\nwhich must be noted in export or typeset -x commands.\n\nThe environment for any simple-command or function may be augmented by prefixing it with one\nor more variable assignments. A variable assignment argument is a word of the form identi‐\nfier=value. Thus:\n\nTERM=450 cmd args and\n(export TERM; TERM=450; cmd args)\n\nare equivalent (as far as the above execution of cmd is concerned except for special built-in\ncommands listed below - those that are marked with ††).\n\nIf the obsolete -k option is set, all variable assignment arguments are placed in the envi‐\nronment, even if they occur after the command name. The following first prints a=b c and\nthen c:\n\necho a=b c\nset -k\necho a=b c\nThis feature is intended for use with scripts written for early versions of the shell and its\nuse in new scripts is strongly discouraged. It is likely to disappear someday.\n" }, { "name": "Functions.", "content": "For historical reasons, there are two ways to define functions, the name() syntax and the\nfunction name syntax, described in the Commands section above. Shell functions are read in\nand stored internally. Alias names are resolved when the function is read. Functions are\nexecuted like commands with the arguments passed as positional parameters. (See Execution\nbelow.)\n\nFunctions defined by the function name syntax and called by name execute in the same process\nas the caller and share all files and present working directory with the caller. Traps\ncaught by the caller are reset to their default action inside the function. A trap condition\nthat is not caught or ignored by the function causes the function to terminate and the condi‐\ntion to be passed on to the caller. A trap on EXIT set inside a function is executed in the\nenvironment of the caller after the function completes. Ordinarily, variables are shared be‐\ntween the calling program and the function. However, the typeset special built-in command\nused within a function defines local variables whose scope includes the current function.\nThey can be passed to functions that they call in the variable assignment list that precedes\nthe call or as arguments passed as name references. Errors within functions return control\nto the caller.\n\nFunctions defined with the name() syntax and functions defined with the function name syntax\nthat are invoked with the . special built-in are executed in the caller's environment and\nshare all variables and traps with the caller. Errors within these function executions cause\nthe script that contains them to abort.\n\nThe special built-in command return is used to return from function calls.\n\nFunction names can be listed with the -f or +f option of the typeset special built-in com‐\nmand. The text of functions, when available, will also be listed with -f. Functions can be\nundefined with the -f option of the unset special built-in command.\n\nOrdinarily, functions are unset when the shell executes a shell script. Functions that need\nto be defined across separate invocations of the shell should be placed in a directory and\nthe FPATH variable should contain the name of this directory. They may also be specified in\nthe ENV file.\n" }, { "name": "Discipline Functions.", "content": "Each variable can have zero or more discipline functions associated with it. The shell ini‐\ntially understands the discipline names get, set, append, and unset but can be added when\ndefining new types. On most systems others can be added at run time via the C programming\ninterface extension provided by the builtin built-in utility. If the get discipline is de‐\nfined for a variable, it is invoked whenever the given variable is referenced. If the vari‐\nable .sh.value is assigned a value inside the discipline function, the referenced variable\nwill evaluate to this value instead. If the set discipline is defined for a variable, it is\ninvoked whenever the given variable is assigned a value. If the append discipline is defined\nfor a variable, it is invoked whenever a value is appended to the given variable. The vari‐\nable .sh.value is given the value of the variable before invoking the discipline, and the\nvariable will be assigned the value of .sh.value after the discipline completes. If\n.sh.value is unset inside the discipline, then that value is unchanged. If the unset disci‐\npline is defined for a variable, it is invoked whenever the given variable is unset. The\nvariable will not be unset unless it is unset explicitly from within this discipline func‐\ntion.\n\nThe variable .sh.name contains the name of the variable for which the discipline function is\ncalled, .sh.subscript is the subscript of the variable, and .sh.value will contain the value\nbeing assigned inside the set discipline function. The variable is a reference to the\nvariable including the subscript if any. For the set discipline, changing .sh.value will\nchange the value that gets assigned. Finally, the expansion ${var.name}, when name is the\nname of a discipline, and there is no variable of this name, is equivalent to the command\nsubstitution ${ var.name;}.\n\n" }, { "name": "Name Spaces.", "content": "Commands and functions that are executed as part of the list of a namespace command that mod‐\nify variables or create new ones, create a new variable whose name is the name of the name\nspace as given by identifier preceded by .. When a variable whose name is name is refer‐\nenced, it is first searched for using .identifier.name. Similarly, a function defined by a\ncommand in the namespace list is created using the name space name preceded by a ..\n\nWhen the list of a namespace command contains a namespace command, the names of variables\nand functions that are created consist of the variable or function name preceded by the list\nof identifiers each preceded by ..\n\nOutside of a name space, a variable or function created inside a name space can be referenced\nby preceding it with the name space name.\n\nBy default, variables starting with .sh are in the sh name space.\n\n" }, { "name": "Type Variables.", "content": "Typed variables provide a way to create data structure and objects. A type can be defined\neither by a shared library, by the enum built-in command described below, or by using the new" }, { "name": "-T -T", "content": "specified as an option argument to -T, is set with a compound variable assignment that de‐\nfines the type. Function definitions can appear inside the compound variable assignment and\nthese become discipline functions for this type and can be invoked or redefined by each in‐\nstance of the type. The function name create is treated specially. It is invoked for each\ninstance of the type that is created but is not inherited and cannot be redefined for each\ninstance.\n\nWhen a type is defined a special built-in command of that name is added. These built-ins are\ndeclaration commands and follow the same expansion rules as the built-in commands described\nbelow that are marked with a ‡ symbol. These commands can subsequently be used inside further\ntype definitions. The man page for these commands can be generated by using the --man option\nor any of the other -- options described with getopts. The -r, -a, -A, -h, and -S options of\ntypeset are permitted with each of these new built-ins.\n\nAn instance of a type is created by invoking the type name followed by one or more instance\nnames. Each instance of the type is initialized with a copy of the subvariables except for\nsubvariables that are defined with the -S option. Variables defined with the -S are shared\nby all instances of the type. Each instance can change the value of any subvariable and can\nalso define new discipline functions of the same names as those defined by the type defini‐\ntion as well as any standard discipline names. No additional subvariables can be defined for\nany instance.\n\nWhen defining a type, if the value of a subvariable is not set and the -r attribute is speci‐\nfied, it causes the subvariable to be a required subvariable. Whenever an instance of a type\nis created, all required subvariables must be specified. These subvariables become read-only\nin each instance.\n\nWhen unset is invoked on a subvariable within a type, and the -r attribute has not been spec‐\nified for this field, the value is reset to the default value associative with the type. In‐\nvoking unset on a type instance not contained within another type deletes all subvariables\nand the variable itself.\n\nA type definition can be derived from another type definition by defining the first subvari‐\nable name as and defining its type as the base type. Any remaining definitions will be ad‐\nditions and modifications that apply to the new type. If the new type name is the same as\nthat of the base type, the type will be replaced and the original type will no longer be ac‐\ncessible.\n\nThe typeset command with the -T and no option argument or operands will write all the type\ndefinitions to standard output in a form that can be read in to create all they types.\n", "flag": "-T" }, { "name": "Jobs.", "content": "If the monitor option of the set command is turned on, an interactive shell associates a job\nwith each pipeline. It keeps a table of current jobs, printed by the jobs command, and as‐\nsigns them small integer numbers. When a job is started asynchronously with &, the shell\nprints a line which looks like:\n\n[1] 1234\n\nindicating that the job which was started asynchronously was job number 1 and had one (top-\nlevel) process, whose process id was 1234.\n\nThis paragraph and the next require features that are not in all versions of UNIX and may not\napply. If you are running a job and wish to do something else you may hit the key ^Z (con‐\ntrol-Z) which sends a STOP signal to the current job. The shell will then normally indicate\nthat the job has been `Stopped', and print another prompt. You can then manipulate the state\nof this job, putting it in the background with the bg command, or run some other commands and\nthen eventually bring the job back into the foreground with the foreground command fg. A ^Z\ntakes effect immediately and is like an interrupt in that pending output and unread input are\ndiscarded when it is typed.\n\nA job being run in the background will stop if it tries to read from the terminal. Back‐\nground jobs are normally allowed to produce output, but this can be disabled by giving the\ncommand stty tostop. If you set this tty option, then background jobs will stop when they\ntry to produce output like they do when they try to read input.\n\nA job pool is a collection of jobs started with list & associated with a name.\n\nThere are several ways to refer to jobs in the shell. A job can be referred to by the\nprocess id of any process of the job or by one of the following:\n%number\nThe job with the given number.\npool All the jobs in the job pool named by pool.\npool.number\nThe job number number in the job pool named by pool.\n%string\nAny job whose command line begins with string.\n%?string\nAny job whose command line contains string.\n%% Current job.\n%+ Equivalent to %%.\n%- Previous job. In addition, unless noted otherwise, wherever a job can be specified,\nthe name of a background job pool can be used to represent all the jobs in that pool.\n\nThe shell learns immediately whenever a process changes state. It normally informs you when‐\never a job becomes blocked so that no further progress is possible, but only just before it\nprints a prompt. This is done so that it does not otherwise disturb your work. The notify\noption of the set command causes the shell to print these job change messages as soon as they\noccur.\n\nWhen the monitor option is on, each background job that completes triggers any trap set for\nCHLD.\n\nWhen you try to leave the shell while jobs are running or stopped, you will be warned that\n`You have stopped(running) jobs.' You may use the jobs command to see what they are. If you\nimmediately try to exit again, the shell will not warn you a second time, and the stopped\njobs will be terminated. When a login shell receives a HUP signal, it sends a HUP signal to\neach job that has not been disowned with the disown built-in command described below.\n" }, { "name": "Signals.", "content": "The INT and QUIT signals for an invoked command are ignored if the command is followed by &\nand the monitor option is not active. Otherwise, signals have the values inherited by the\nshell from its parent (but see also the trap built-in command below).\n" }, { "name": "Execution.", "content": "Each time a command is read, the above expansions and substitutions are carried out. If the\ncommand name matches one of the Special Built-in Commands listed below, it is executed within\nthe current shell process. Next, the command name is checked to see if it matches a user de‐\nfined function. If it does, the positional parameters are saved and then reset to the argu‐\nments of the function call. A function is also executed in the current shell process. When\nthe function completes or issues a return, the positional parameter list is restored. For\nfunctions defined with the function name syntax, any trap set on EXIT within the function is\nexecuted. The exit value of a function is the value of the last command executed. If a com‐\nmand name is not a special built-in command or a user defined function, but it is one of the\nbuilt-in commands listed below, it is executed in the current shell process.\n\nThe shell variables PATH followed by the variable FPATH defines the list of directories to\nsearch for the command name. Alternative directory names are separated by a colon (:). The\ndefault path is the value that was output by getconf PATH at the time ksh was compiled. The\ncurrent directory can be specified by two or more adjacent colons, or by a colon at the be‐\nginning or end of the path list. If the command name contains a /, then the search path is\nnot used. Otherwise, each directory in the list of directories defined by PATH and FPATH is\nchecked in order. If the directory being searched is contained in FPATH and contains a file\nwhose name matches the command being searched, then this file is loaded into the current\nshell environment as if it were the argument to the . command except that only preset aliases\nare expanded, and a function of the given name is executed as described above.\n\nIf this directory is not in FPATH the shell first determines whether there is a built-in ver‐\nsion of a command corresponding to a given pathname and if so it is invoked in the current\nprocess. If no built-in is found, the shell checks for a file named .paths in this direc‐\ntory. If found and there is a line of the form FPATH=path where path names an existing di‐\nrectory then that directory is searched immediately after the current directory as if it were\nfound in the FPATH variable. If path does not begin with /, it is checked for relative to\nthe directory being searched.\n\nThe .paths file is then checked for a line of the form PLUGINLIB=libname [ : libname ] ... .\nEach library named by libname will be searched for as if it were an option argument to\nbuiltin -f, and if it contains a built-in of the specified name this will be executed instead\nof a command by this name. Any built-in loaded from a library found this way will be associ‐\nated with the directory containing the .paths file so it will only execute if not found in an\nearlier directory.\n\nFinally, the directory will be checked for a file of the given name. If the file has execute\npermission but is not an a.out file, it is assumed to be a file containing shell commands. A\nseparate shell is spawned to read it. All non-exported variables are removed in this case.\nIf the shell command file doesn't have read permission, or if the setuid and/or setgid bits\nare set on the file, then the shell executes an agent whose job it is to set up the permis‐\nsions and execute the shell with the shell command file passed down as an open file. If the\n.paths contains a line of the form name=value in the first or second line, then the environ‐\nment variable name is modified by prepending the directory specified by value to the direc‐\ntory list. If value is not an absolute directory, then it specifies a directory relative to\nthe directory that the executable was found. If the environment variable name does not al‐\nready exist it will be added to the environment list for the specified command. A parenthe‐\nsized command is executed in a subshell without removing non-exported variables.\n" }, { "name": "Command Re-entry.", "content": "The text of the last HISTSIZE (default 512) commands entered from a terminal device is saved\nin a history file. The file $HOME/.shhistory is used if the HISTFILE variable is not set or\nif the file it names is not writable. A shell can access the commands of all interactive\nshells which use the same named HISTFILE. The built-in command hist is used to list or edit\na portion of this file. The portion of the file to be edited or listed can be selected by\nnumber or by giving the first character or characters of the command. A single command or\nrange of commands can be specified. If you do not specify an editor program as an argument\nto hist then the value of the variable HISTEDIT is used. If HISTEDIT is unset, the obsolete\nvariable FCEDIT is used. If FCEDIT is not defined, then /bin/ed is used. The edited com‐\nmand(s) is printed and re-executed upon leaving the editor unless you quit without writing.\nThe -s option (and in obsolete versions, the editor name -) is used to skip the editing phase\nand to re-execute the command. In this case a substitution parameter of the form old=new can\nbe used to modify the command before execution. For example, with the preset alias r, which\nis aliased to ′′hist -s′′, typing `r bad=good c' will re-execute the most recent command which\nstarts with the letter c, replacing the first occurrence of the string bad with the string\ngood.\n" }, { "name": "In-line Editing Options.", "content": "Normally, each command line entered from a terminal device is simply typed followed by a new-\nline (`RETURN' or `LINE FEED'). If either the emacs, gmacs, or vi option is active, the user\ncan edit the command line. To be in either of these edit modes set the corresponding option.\nAn editing option is automatically selected each time the VISUAL or EDITOR variable is as‐\nsigned a value ending in either of these option names.\n\nThe editing features require that the user's terminal accept `RETURN' as carriage return\nwithout line feed and that a space (` ') must overwrite the current character on the screen.\n\nUnless the multiline option is on, the editing modes implement a concept where the user is\nlooking through a window at the current line. The window width is the value of COLUMNS if it\nis defined, otherwise 80. If the window width is too small to display the prompt and leave\nat least 8 columns to enter input, the prompt is truncated from the left. If the line is\nlonger than the window width minus two, a mark is displayed at the end of the window to no‐\ntify the user. As the cursor moves and reaches the window boundaries the window will be cen‐\ntered about the cursor. The mark is a > (<, *) if the line extends on the right (left, both)\nside(s) of the window.\n\nThe search commands in each edit mode provide access to the history file. Only strings are\nmatched, not patterns, although a leading ^ in the string restricts the match to begin at the\nfirst character in the line.\n\nEach of the edit modes has an operation to list the files or commands that match a partially\nentered word. When applied to the first word on the line, or the first word after a ;, |, &,\nor (, and the word does not begin with ∼∼ or contain a /, the list of aliases, functions, and\nexecutable commands defined by the PATH variable that could match the partial word is dis‐\nplayed. Otherwise, the list of files that match the given word is displayed. If the par‐\ntially entered word does not contain any file expansion characters, a * is appended before\ngenerating these lists. After displaying the generated list, the input line is redrawn.\nThese operations are called command name listing and file name listing, respectively. There\nare additional operations, referred to as command name completion and file name completion,\nwhich compute the list of matching commands or files, but instead of printing the list, re‐\nplace the current word with a complete or partial match. For file name completion, if the\nmatch is unique, a / is appended if the file is a directory and a space is appended if the\nfile is not a directory. Otherwise, the longest common prefix for all the matching files re‐\nplaces the word. For command name completion, only the portion of the file names after the\nlast / are used to find the longest command prefix. If only a single name matches this pre‐\nfix, then the word is replaced with the command name followed by a space. When using a tab\nfor completion that does not yield a unique match, a subsequent tab will provide a numbered\nlist of matching alternatives. A specific selection can be made by entering the selection\nnumber followed by a tab.\n" }, { "name": "Key Bindings.", "content": "The KEYBD trap can be used to intercept keys as they are typed and change the characters that\nare actually seen by the shell. This trap is executed after each character (or sequence of\ncharacters when the first character is ESC) is entered while reading from a terminal. The\nvariable .sh.edchar contains the character or character sequence which generated the trap.\nChanging the value of .sh.edchar in the trap action causes the shell to behave as if the new\nvalue were entered from the keyboard rather than the original value.\n\nThe variable .sh.edcol is set to the input column number of the cursor at the time of the in‐\nput. The variable .sh.edmode is set to ESC when in vi insert mode (see below) and is null\notherwise. By prepending ${.sh.editmode} to a value assigned to .sh.edchar it will cause the\nshell to change to control mode if it is not already in this mode.\n\nThis trap is not invoked for characters entered as arguments to editing directives, or while\nreading input for a character search.\n" }, { "name": "Emacs Editing Mode.", "content": "This mode is entered by enabling either the emacs or gmacs option. The only difference be‐\ntween these two modes is the way they handle ^T. To edit, the user moves the cursor to the\npoint needing correction and then inserts or deletes characters or words as needed. All the\nediting commands are control characters or escape sequences. The notation for control char‐\nacters is caret (^) followed by the character. For example, ^F is the notation for control\nF. This is entered by depressing `f' while holding down the `CTRL' (control) key. The\n`SHIFT' key is not depressed. (The notation ^? indicates the DEL (delete) key.)\n\nThe notation for escape sequences is M- followed by a character. For example, M-f (pro‐\nnounced Meta f) is entered by depressing ESC (ASCII 033) followed by `f'. (M-F would be the\nnotation for ESC followed by `SHIFT' (capital) `F'.)\n\nAll edit commands operate from any place on the line (not just at the beginning). Neither\nthe `RETURN' nor the `LINE FEED' key is entered after edit commands except when noted.\n\nThe M-[ multi-character commands below are DEC VT220 escape sequences generated by special\nkeys on standard PC keyboards, such as the arrow keys. You could type them directly but they\nare meant to recognize the keys in question, which are indicated in parentheses.\n\n^F Move cursor forward (right) one character.\nM-[C (Right arrow) Same as ^F.\nM-f Move cursor forward one word. (The emacs editor's idea of a word is a string of\ncharacters consisting of only letters, digits and underscores.)\n^B Move cursor backward (left) one character.\nM-[D (Left arrow) Same as ^B.\nM-b Move cursor backward one word.\n^A Move cursor to start of line.\nM-[H (Home) Same as ^A.\n^E Move cursor to end of line.\nM-[F (End) Same as ^E.\nM-[Y Same as ^E.\n^]char Move cursor forward to character char on current line.\nM-^]char Move cursor backward to character char on current line.\n^X^X Interchange the cursor and mark.\nerase (User defined erase character as defined by the stty(1) command, usually ^H .)\nDelete previous character.\nlnext (User defined literal next character as defined by the stty(1) command, or ^V if\nnot defined.) Removes the next character's editing features (if any).\n^D Delete current character.\nM-[3~ (Forward delete) Same as ^D.\nM-d Delete current word.\nM-^H (Meta-backspace) Delete previous word.\nM-h Delete previous word.\nM-^? (Meta-DEL) Delete previous word (if your interrupt character is ^? (DEL, the de‐\nfault) then this command will not work).\n^T Transpose current character with previous character and advance the cursor in emacs\nmode. Transpose two previous characters in gmacs mode.\n^C Capitalize current character.\nM-c Capitalize current word.\nM-l Change the current word to lower case.\n^K Delete from the cursor to the end of the line. If preceded by a numerical parame‐\nter whose value is less than the current cursor position, then delete from given\nposition up to the cursor. If preceded by a numerical parameter whose value is\ngreater than the current cursor position, then delete from cursor up to given cur‐\nsor position.\n^W Kill from the cursor to the mark.\nM-p Push the region from the cursor to the mark on the stack.\nkill (User defined kill character as defined by the stty command, usually ^U .) Kill\nthe entire current line. If two kill characters are entered in succession, all\nkill characters from then on cause a line feed (useful when using paper terminals).\nA subsequent pair of kill characters undoes this change.\n^Y Restore last item removed from line. (Yank item back to the line.)\n^L Line feed and print current line.\nM-^L Clear the screen.\n^@ (Null character) Set mark.\nM-space (Meta space) Set mark.\n^J (New line) Execute the current line.\n^M (Return) Execute the current line.\neof End-of-file character, normally ^D, is processed as an End-of-file only if the cur‐\nrent line is null.\n^P Fetch previous command. Each time ^P is entered the previous command back in time\nis accessed. Moves back one line when not on the first line of a multi-line com‐\nmand.\nM-[A (Up arrow) If the cursor is at the end of the line, it is equivalent to ^R with\nstring set to the contents of the current line. Otherwise, it is equivalent to ^P.\nM-< Fetch the least recent (oldest) history line.\nM-> Fetch the most recent (youngest) history line.\n^N Fetch next command line. Each time ^N is entered the next command line forward in\ntime is accessed.\nM-[B (Down arrow) Equivalent to ^N.\n^Rstring Reverse search history for a previous command line containing string. If a parame‐\nter of zero is given, the search is forward. String is terminated by a `RETURN' or\n`NEW LINE'. If string is preceded by a ^, the matched line must begin with string.\nIf string is omitted, then the next command line containing the most recent string\nis accessed. In this case a parameter of zero reverses the direction of the\nsearch.\n^O Operate - Execute the current line and fetch the next line relative to current line\nfrom the history file.\nM-digits (Escape) Define numeric parameter, the digits are taken as a parameter to the next\ncommand. The commands that accept a parameter are ^F, ^B, erase, ^C, ^D, ^K, ^R,\n^P, ^N, ^], M-., M-^], M-, M-=, M-b, M-c, M-d, M-f, M-h, M-l, M-^H, and the arrow\nkeys and forward-delete key.\nM-letter Soft-key - Your alias list is searched for an alias by the name letter and if an\nalias of this name is defined, its value will be inserted on the input queue. The\nletter must not be one of the above meta-functions.\nM-[letter Soft-key - Your alias list is searched for an alias by the name letter and if an\nalias of this name is defined, its value will be inserted on the input queue. This\ncan be used to program function keys on many terminals.\nM-. The last word of the previous command is inserted on the line. If preceded by a\nnumeric parameter, the value of this parameter determines which word to insert\nrather than the last word.\nM- Same as M-..\nM-* Attempt pathname expansion on the current word. An asterisk is appended if the\nword doesn't match any file or contain any special pattern characters.\nM-ESC Command or file name completion as described above.\n^I tab Attempts command or file name completion as described above. If a partial comple‐\ntion occurs, repeating this will behave as if M-= were entered. If no match is\nfound or entered after space, a tab is inserted.\nM-= If not preceded by a numeric parameter, it generates the list of matching commands\nor file names as described above. Otherwise, the word under the cursor is replaced\nby the item corresponding to the value of the numeric parameter from the most re‐\ncently generated command or file list. If the cursor is not on a word, it is in‐\nserted instead.\n^U Multiply parameter of next command by 4.\n\\ If the backslashctrl shell option is on (which is the default setting), this es‐\ncapes the next character. Editing characters, the user's erase, kill and interrupt\n(normally ^C) characters may be entered in a command line or in a search string if\npreceded by a \\. The \\ removes the next character's editing features (if any).\nSee also lnext which is not subject to any shell option.\nM-^V Display version of the shell.\nM-# If the line does not begin with a #, a # is inserted at the beginning of the line\nand after each new-line, and the line is entered. This causes a comment to be in‐\nserted in the history file. If the line begins with a #, the # is deleted and one\n# after each new-line is also deleted.\n" }, { "name": "Vi Editing Mode.", "content": "There are two typing modes. Initially, when you enter a command you are in the input mode.\nTo edit, the user enters control mode by typing ESC (033) and moves the cursor to the point\nneeding correction and then inserts or deletes characters or words as needed. Most control\ncommands accept an optional repeat count prior to the command.\n\nThe notation for control characters used below is ^ followed by a character. For instance, ^H\nis entered by holding down the Control key and pressing H. ^[ (Control+[) is equivalent to\nthe ESC key. The notation for escape sequences is ^[ followed by one or more characters.\n\nThe ^[[ (ESC [) multi-character commands below are DEC VT220 escape sequences generated by\nspecial keys on standard PC keyboards, such as the arrow keys, which are indicated in paren‐\ntheses. When in input mode, these keys will switch you to control mode before performing the\nassociated action. These sequences can use preceding repeat count parameters, but only when\nthe ^[ and the subsequent [ are entered into the input buffer at the same time, such as when\npressing one of those keys.\n" }, { "name": "Input Edit Commands", "content": "By default the editor is in input mode.\nerase (User defined erase character as defined by the stty command, usually ^H or\n#.) Delete previous character.\n^W Delete the previous blank separated word. On some systems the viraw option\nmay be required for this to work.\neof As the first character of the line causes the shell to terminate unless the\nignoreeof option is set. Otherwise this character is ignored.\nlnext (User defined literal next character as defined by the stty(1) or ^V if not\ndefined.) Removes the next character's editing features (if any). On some\nsystems the viraw option may be required for this to work.\n\\ If the backslashctrl shell option is on (which is the default setting), this\nescapes the next erase or kill character.\n^I tab Attempts command or file name completion as described above and returns to\ninput mode. If a partial completion occurs, repeating this will behave as\nif = were entered from control mode. If no match is found or entered after\nspace, a tab is inserted." }, { "name": "Motion Edit Commands", "content": "These commands will move the cursor.\n[count]l Cursor forward (right) one character.\n[count]^[[C\n(Right arrow) Same as l.\n[count]w Cursor forward one alphanumeric word.\n[count]W Cursor to the beginning of the next word that follows a blank.\n[count]e Cursor to end of word.\n[count]E Cursor to end of the current blank delimited word.\n[count]h Cursor backward (left) one character.\n[count]^[[D\n(Left arrow) Same as h.\n[count]b Cursor backward one word.\n[count]B Cursor to preceding blank separated word.\n[count]| Cursor to column count.\n[count]fc Find the next character c in the current line.\n[count]Fc Find the previous character c in the current line.\n[count]tc Equivalent to f followed by h.\n[count]Tc Equivalent to F followed by l.\n[count]; Repeats count times, the last single character find command, f, F, t, or T.\n[count], Reverses the last single character find command count times.\n0 Cursor to start of line.\n^[[H (Home) Same as 0.\n^ Cursor to first non-blank character in line.\n$ Cursor to end of line.\n^[[F (End) Same as $.\n^[[Y Same as $.\n% Moves to balancing (, ), {, }, [, or ]. If cursor is not on one of the\nabove characters, the remainder of the line is searched for the first occur‐\nrence of one of the above characters first." }, { "name": "Search Edit Commands", "content": "These commands access your command history.\n[count]k Fetch previous command. Each time k is entered the previous command back in\ntime is accessed.\n[count]- Equivalent to k.\n[count]^[[A\n(Up arrow) If cursor is at the end of the line it is equivalent to / with\nstring set to the contents of the current line. Otherwise, it is equivalent\nto k.\n[count]j Fetch next command. Each time j is entered the next command forward in time\nis accessed.\n[count]+ Equivalent to j.\n[count]^[[B\n(Down arrow) Equivalent to j.\n[count]G The command number count is fetched. The default is the least recent his‐\ntory command.\n/string Search backward through history for a previous command containing string.\nString is terminated by a `RETURN' or `NEW LINE'. If string is preceded by\na ^, the matched line must begin with string. If string is null, the previ‐\nous string will be used.\n?string Same as / except that search will be in the forward direction.\nn Search for next match of the last pattern to / or ? commands.\nN Search for next match of the last pattern to / or ?, but in reverse direc‐\ntion." }, { "name": "Text Modification Edit Commands", "content": "These commands will modify the line.\na Enter input mode and enter text after the current character.\nA Append text to the end of the line. Equivalent to $a.\n[count]cmotion\nc[count]motion\nDelete current character through the character that motion would move the\ncursor to and enter input mode. If motion is c, the entire line will be\ndeleted and input mode entered.\nC Delete the current character through the end of line and enter input mode.\nEquivalent to c$.\nS Equivalent to cc.\n[count]s Replace characters under the cursor in input mode.\nD Delete the current character through the end of line. Equivalent to d$.\n[count]dmotion\nd[count]motion\nDelete current character through the character that motion would move to.\nIf motion is d , the entire line will be deleted.\ni Enter input mode and insert text before the current character.\nI Insert text before the beginning of the line. Equivalent to 0i.\n[count]P Place the previous text modification before the cursor.\n[count]p Place the previous text modification after the cursor.\nR Enter input mode and replace characters on the screen with characters you\ntype overlay fashion.\n[count]rc Replace the count character(s) starting at the current cursor position with\nc, and advance the cursor.\n[count]x Delete current character.\n[count]^[[3~\n(Forward delete) Same as x.\n[count]X Delete preceding character.\n[count]. Repeat the previous text modification command.\n[count]∼∼ Invert the case of the count character(s) starting at the current cursor po‐\nsition and advance the cursor.\n[count] Causes the count word of the previous command to be appended and input mode\nentered. The last word is used if count is omitted.\n* Causes an * to be appended to the current word and pathname expansion at‐\ntempted. If no match is found, it rings the bell. Otherwise, the word is\nreplaced by the matching pattern and input mode is entered.\n\\ Command or file name completion as described above." }, { "name": "Other Edit Commands", "content": "Miscellaneous commands.\n[count]ymotion\ny[count]motion\nYank current character through character that motion would move the cursor\nto and puts them into the delete buffer. The text and cursor are unchanged.\nyy Yanks the entire line.\nY Yanks from current position to end of line. Equivalent to y$.\nu Undo the last text modifying command.\nU Undo all the text modifying commands performed on the line.\n[count]v Returns the command hist -e ${VISUAL:-${EDITOR:-vi}} count in the input buf‐\nfer. If count is omitted, then the current line is used.\n^L Line feed and print current line. Has effect only in control mode.\n^J (New line) Execute the current line, regardless of mode.\n^M (Return) Execute the current line, regardless of mode.\n# If the first character of the command is a #, then this command deletes this\n# and each # that follows a newline. Otherwise, sends the line after in‐\nserting a # in front of each line in the command. Useful for causing the\ncurrent line to be inserted in the history as a comment and uncommenting\npreviously commented commands in the history file.\n[count]= If count is not specified, it generates the list of matching commands or\nfile names as described above. Otherwise, the word under the cursor is re‐\nplaced by the count item from the most recently generated command or file\nlist. If the cursor is not on a word, it is inserted instead.\n@letter Your alias list is searched for an alias by the name letter and if an alias\nof this name is defined, its value will be inserted on the input queue for\nprocessing.\n^V Display version of the shell.\n" }, { "name": "Built-in Commands.", "content": "The simple-commands listed below are built in to the shell and are executed in the same\nprocess as the shell. The effects of any added Input/Output redirections are local to the\ncommand, except for the exec and redirect commands. Unless otherwise indicated, the output\nis written on standard output (file descriptor 1) and the exit status, when there is no syn‐\ntax error, is zero. Except for :, true, false, and echo, all built-in commands accept -- to\nindicate end of options, and are self-documenting.\n\nThe self-documenting commands interpret the option --man as a request to display that com‐\nmand's own manual page, --help as a request to display the OPTIONS section from their manual\npage, and -? as a request to print a brief usage message. All these are processed as error\nmessages, so they are written on standard error (file descriptor 2) and to pipe them into a\npager such as more(1) you need to add a 2>&1 redirection before the |. The display of bold‐\nface text depends on whether standard error is on a terminal, so is disabled when using a\npager. Exporting the ERROROPTIONS environment variable with a value containing emphasis will\nforce this on; a value containing noemphasis forces it off. The test/[ command needs an ad‐\nditional -- argument to recognize self-documentation options, e.g. test --man --. The exec\nand redirect commands, as they make redirections permanent, should use self-documentation op‐\ntions in a subshell when redirecting, for example: (redirect --man) 2>&1. There are advanced\noutput options as well; see getopts --man for more information.\n\nCommands that are preceded by a † symbol below are special built-in commands and are treated\nspecially in the following ways:\n1. Variable assignment lists preceding the command remain in effect when the command com‐\npletes.\n2. I/O redirections are processed after variable assignments.\n3. Errors cause a script that contains them to abort.\n4. They are not valid function names.\nCommands that are preceded by a ‡ symbol below are declaration commands. Any following words\nthat are in the format of a variable assignment are expanded with the same rules as a vari‐\nable assignment. This means that tilde expansion is performed after the = sign, array as‐\nsignments of the form varname=(assignlist) are supported, and field splitting and pathname\nexpansion are not performed.\n\n† : [ arg ... ]\nThe command only expands parameters.\n\n† . name [ arg ... ]\nIf name is a function defined with the function name reserved word syntax, the func‐\ntion is executed in the current environment (as if it had been defined with the name()\nsyntax). Otherwise if name refers to a file, the file is read in its entirety and the\ncommands are executed in the current shell environment. The search path specified by\nPATH is used to find the directory containing the file. If any arguments arg are\ngiven, they become the positional parameters while processing the . command and the\noriginal positional parameters are restored upon completion. Otherwise the positional\nparameters are unchanged. The exit status is the exit status of the last command exe‐\ncuted.\n\n[ expression ]\nThe [ command is the same as test, with the exception that an additional closing ] ar‐\ngument is required. See test below.\n\nalias [ -ptx ] [ name[ =value ] ] ...\nalias with no arguments prints the list of aliases in the form name=value on standard\noutput. The -p option causes the word alias to be inserted before each one. When one\nor more arguments are given, an alias is defined for each name whose value is given.\nA trailing space in value causes the next word to be checked for alias substitution.\nWith the -t option, each name is looked up as a command in $PATH and its path is added\nto the hash table as a 'tracked alias'. If no name is given, this prints the hash ta‐\nble. See hash. Without the -t option, for each name in the argument list for which no\nvalue is given, the name and value of the alias is printed. The obsolete -x option\nhas no effect. The exit status is non-zero if a name is given, but no value, and no\nalias has been defined for the name.\n\nautoload name ...\nMarks each name undefined so that the FPATH variable will be searched to find the\nfunction definition when the function is referenced. The same as typeset -fu.\n\nbg [ job... ]\nThis command is only on systems that support job control. Puts each specified job\ninto the background. The current job is put in the background if job is not speci‐\nfied. See Jobs for a description of the format of job.\n\n† break [ n ]\nExit from the enclosing for, while, until, or select loop, if any. If n is specified,\nthen break n levels.\n\nbuiltin [ -ds ] [ -f file ] [ name ... ]\nIf name is not specified, and no -f option is specified, the built-ins are printed on\nstandard output. The -s option prints only the special built-ins. Otherwise, each\nname represents the pathname whose basename is the name of the built-in. The entry\npoint function name is determined by prepending b to the built-in name. A built-in\nspecified by a pathname will only be executed when that pathname would be found during\nthe path search. Built-ins found in libraries loaded via the .paths file will asso‐\nciate with the pathname of the directory containing the .paths file.\n\nThe ISO C/C++ prototype is bmycommand(int argc, char *argv[], void *context) for the\nbuiltin command mycommand where argv is array an of argc elements and context is an\noptional pointer to a Shellt structure as described in .\n\nSpecial built-ins cannot be bound to a pathname or deleted. The -d option deletes\neach of the given built-ins. On systems that support dynamic loading, the -f option\nnames a shared library containing the code for built-ins. The shared library prefix\nand/or suffix, which depend on the system, can be omitted. Once a library is loaded,\nits symbols become available for subsequent invocations of builtin. Multiple li‐\nbraries can be specified with separate invocations of the builtin command. Libraries\nare searched in the reverse order in which they are specified. When a library is\nloaded, it looks for a function in the library whose name is libinit() and invokes\nthis function with an argument of 0.\n\ncd [ -L ] [ -eP ] [ arg ]\ncd [ -L ] [ -eP ] old new\nThis command can be in either of two forms. In the first form it changes the current\ndirectory to arg. If arg is - the directory is changed to the previous directory.\nThe shell variable HOME is the default arg. The variable PWD is set to the current\ndirectory. The shell variable CDPATH defines the search path for the directory con‐\ntaining arg. Alternative directory names are separated by a colon (:). The default\npath is (specifying the current directory). Note that the current directory is\nspecified by a null path name, which can appear immediately after the equal sign or\nbetween the colon delimiters anywhere else in the path list. If arg begins with a /\nthen the search path is not used. Otherwise, each directory in the path is searched\nfor arg.\nThe second form of cd substitutes the string new for the string old in the current di‐\nrectory name, PWD, and tries to change to this new directory.\nBy default, symbolic link names are treated literally when finding the directory name.\nThis is equivalent to the -L option. The -P option causes symbolic links to be re‐\nsolved when determining the directory. The last instance of -L or -P on the command\nline determines which method is used.\nIf -e and -P are both in effect and the correct PWD could not be determined after suc‐\ncessfully changing the directory, cd will return with exit status one and produce no\noutput. If any other error occurs while both flags are active, the exit status is\ngreater than one.\nThe cd command may not be executed by rksh.\n\ncommand [ -pvxV ] name [ arg ... ]\nWith the -v option, command is equivalent to the built-in whence command described be‐\nlow. The -V option causes command to act like whence -v.\n\nWithout the -v or -V options, command executes name with the arguments given by arg.\nFunctions and aliases will not be searched for when finding name. If name refers to a\nspecial built-in, as marked with †† in this manual, command disables the special prop‐\nerties described above for that mark, executing the command as a regular built-in.\n(For example, using command set -o option-name prevents a script from terminating when\nan invalid option name is given.)\n\nThe -p option causes the operating system's standard utilities path (as output by get‐‐\nconf PATH) to be searched rather than the one defined by the value of PATH.\n\nThe -x option runs name as an external command, bypassing built-ins. If the arguments\ncontain at least one word that expands to multiple arguments, such as \"$@\" or *.txt,\nthen the -x option also allows executing external commands with argument lists that\nare longer than the operating system allows. This functionality is similar to xargs(1)\nbut is easier to use. The shell does this by invoking the external command multiple\ntimes if needed, dividing the expanded argument list over the invocations. Any argu‐\nments that come before the first word that expands to multiple arguments, as well as\nany that follow the last such word, are considered static arguments and are repeated\nfor each invocation. This allows each invocation to use the same command options, as\nwell as the same trailing destination arguments for commands like cp(1) or mv(1).\nWhen all invocations are completed, command -x exits with the status of the invocation\nthat had the highest exit status. (Note that command -x may still fail with an \"argu‐\nment list too long\" error if a single argument exceeds the maximum length of the argu‐\nment list, or if a long arguments list contains no word that expands to multiple argu‐\nments.)\n\n‡ compound vname[=value] ...\nCauses each vname to be a compound variable. The same as typeset -C.\n\n† continue [ n ]\nResume the next iteration of the enclosing for, while, until, or select loop. If n is\nspecified, then resume at the n-th enclosing loop.\n\ndisown [ job... ]\nCauses the shell not to send a HUP signal to each given job, or all active jobs if job\nis omitted, when a login shell terminates.\n\necho [ arg ... ]\nWhen the first arg does not begin with a -, and none of the arguments contain a \\,\nthen echo prints each of its arguments separated by a space and terminated by a new-\nline. Otherwise, the behavior of echo is system dependent and print or printf de‐\nscribed below should be used. See echo(1) for usage and description.\n\n‡ enum [ -i ] type[=(value ...) ]\nCreates a declaration command named type that allows one of the specified values as\nenumeration names. If =(value ...) is omitted, then type must be an indexed array\nvariable with at least two elements and the values are taken from this array variable.\nIf -i is specified the values are case-insensitive. Declaration commands are created\nas special builtins that cannot be removed or overridden by shell functions. Each\ncreated declaration command has a --man option that shows documentation on its type's\nbehavior and possible values.\n\nWithin arithmetic expressions (see Arithmetic Evaluation above), enumeration type val‐\nues translate to index numbers between 0 and the number of defined values minus 1. It\nis an error for an arithmetic expression to assign a value outside of that range. Dec‐\nimal fractions are ignored.\n\n† eval [ arg ... ]\nThe arguments are read as input to the shell and the resulting command(s) executed.\n\n† exec [ -c ] [ -a name ] [ arg ... ]\nIf arg is given, the command specified by the arguments is executed in place of this\nshell without creating a new process. The value of the SHLVL environment variable is\ndecreased by one, unless the shell replaced is a subshell. The -c option causes the\nenvironment to be cleared before applying variable assignments associated with the\nexec invocation. The -a option causes name rather than the first arg, to become\nargv[0] for the new process. If arg is not given and only I/O redirections are given,\nthen this command persistently modifies file descriptors as in redirect.\n\n† exit [ n ]\nCauses the shell to exit with the exit status specified by n. The value will be the\nleast significant 8 bits of n (if specified) or of the exit status of the last command\nexecuted. An end-of-file will also cause the shell to exit, except for an interactive\nshell that has the ignoreeof option turned on (see set below).\n\n†‡ export [ -p ] [ name[=value] ] ...\nIf name is not given, the names and values of each variable with the export attribute\nare printed with the values quoted in a manner that allows them to be re-input. The\nexport command is the same as typeset -x except that if you use export within a func‐\ntion, no local variable is created. The -p option causes the word export to be in‐\nserted before each one. Otherwise, the given names are marked for automatic export to\nthe environment of subsequently-executed commands.\n\nfalse Does nothing, and exits 1. Used with until for infinite loops.\n\nfc [ -e ename ] [ -N num ] [ -nlr ] [ first [ last ] ]\nfc -s [ old=new ] [ command ]\nThe same as hist.\n\nfg [ job... ]\nThis command is only on systems that support job control. Each job specified is\nbrought to the foreground and waited for in the specified order. Otherwise, the cur‐\nrent job is brought into the foreground. See Jobs for a description of the format of\njob.\n\n‡ float vname[=value] ...\nDeclares each vname to be a long floating point number. The same as typeset -lE.\n\nfunctions [ -Stux ] [ name ... ]\nLists functions. The same as typeset -f.\n\ngetconf [ name [ pathname ] ]\nPrints the current value of the configuration parameter given by name. The configura‐\ntion parameters are defined by the IEEE POSIX 1003.1 and IEEE POSIX 1003.2 standards.\n(See pathconf(2) and sysconf(3).) The pathname argument is required for parameters\nwhose value depends on the location in the file system. If no arguments are given,\ngetconf prints the names and values of the current configuration parameters. The\npathname / is used for each of the parameters that requires pathname.\n\ngetopts [ -a name ] optstring vname [ arg ... ]\nChecks arg for legal options. If arg is omitted, the positional parameters are used.\nAn option argument begins with a + or a -. An option not beginning with + or - or the\nargument -- ends the options. Options beginning with + are only recognized when opt‐\nstring begins with a +. optstring contains the letters that getopts recognizes. If a\nletter is followed by a :, that option is expected to have an argument. The options\ncan be separated from the argument by blanks. The option -? causes getopts to gener‐\nate a usage message on standard error. The -a argument can be used to specify the\nname to use for the usage message, which defaults to $0.\ngetopts places the next option letter it finds inside variable vname each time it is\ninvoked. The option letter will be prepended with a + when arg begins with a +. The\nindex of the next arg is stored in OPTIND. The option argument, if any, gets stored\nin OPTARG.\nA leading : in optstring causes getopts to store the letter of an invalid option in\nOPTARG, and to set vname to ? for an unknown option and to : when a required option\nargument is missing. Otherwise, getopts prints an error message. The exit status is\nnon-zero when there are no more options.\nThere is no way to specify any of the options :, +, -, ?, [, and ]. The option # can\nonly be specified as the first option.\n\nhash [ -r ] [ utility ]\nhash displays or modifies the hash table with the locations of recently used programs.\nIf given no arguments, it lists all command/path associations (a.k.a. 'tracked\naliases') in the hash table. Otherwise, hash performs a PATH search for each utility\nsupplied and adds the result to the hash table. The -r option empties the hash table.\nThis can also be achieved by resetting PATH.\n\nhist [ -e ename ] [ -N num ] [ -nlr ] [ first [ last ] ]\nhist -s [ old=new ] [ command ]\nIn the first form, a range of commands from first to last is selected from the last\nHISTSIZE commands that were typed at the terminal. The arguments first and last may\nbe specified as a number or as a string. A string is used to locate the most recent\ncommand starting with the given string. A negative number is used as an offset to the\ncurrent command number. If the -l option is selected, the commands are listed on\nstandard output. Otherwise, the editor program ename is invoked on a file containing\nthese keyboard commands. If ename is not supplied, then the value of the variable\nHISTEDIT is used. If HISTEDIT is not set, then FCEDIT (default /bin/ed) is used as\nthe editor. When editing is complete, the edited command(s) is executed if the\nchanges have been saved. If last is not specified, then it will be set to first. If\nfirst is not specified, the default is the previous command for editing and -16 for\nlisting. The option -r reverses the order of the commands and the option -n sup‐\npresses command numbers when listing. In the second form, command is interpreted as\nfirst described above and defaults to the last command executed. The resulting com‐\nmand is executed after the optional substitution old=new is performed. The option -N\ncauses hist to start num commands back.\n\n‡ integer vname[=value] ...\nDeclares each vname to be a long integer number. The same as typeset -li.\n\njobs [ -lnp ] [ job ... ]\nLists information about each given job; or all active jobs if job is omitted. The -l\noption lists process ids in addition to the normal information. The -n option only\ndisplays jobs that have stopped or exited since last notified. The -p option causes\nonly the process group to be listed. See Jobs for a description of the format of job.\n\nkill [ -s signame ] job ...\nkill [ -n signum ] job ...\nkill -Ll [ sig ... ]\nSends either the TERM (terminate) signal or the specified signal to the specified jobs\nor processes. Signals are either given by number with the -n option or by name with\nthe -s option (as given in , stripped of the prefix ``SIG'' with the excep‐\ntion that SIGCLD is named CHLD). For backward compatibility, the n and s can be omit‐\nted and the number or name placed immediately after the -. If the signal being sent\nis TERM (terminate) or HUP (hangup), then the job or process will be sent a CONT (con‐\ntinue) signal if it is stopped. The argument job can be the process id of a process\nthat is not a member of one of the active jobs. See Jobs for a description of the\nformat of job. In the third form, kill -l, or kill -L, if sig is not specified, the\nsignal names are listed. The -l option list only the signal names. -L options lists\neach signal name and corresponding number. Otherwise, for each sig that is a name,\nthe corresponding signal number is listed. For each sig that is a number, the signal\nname corresponding to the least significant 8 bits of sig is listed.\n\nlet arg ...\nEach arg is a separate arithmetic expression to be evaluated. let only recognizes oc‐\ntal numbers starting with 0 when the set option letoctal is on. See Arithmetic Evalu‐\nation above for a description of arithmetic expression evaluation.\nThe exit status is 0 if the value of the last expression is non-zero, and 1 otherwise.\n\n‡ nameref vname[=refname] ...\nDeclares each vname to be a variable name reference. The same as typeset -n.\n\nprint [ -CRenprsv ] [ -u unit ] [ -f format ] [ arg ... ]\nWith no options or with option - or --, each arg is printed on standard output. The\n-f option causes the arguments to be printed as described by printf. In this case,\nany e, n, r, R options are ignored. Otherwise, unless the -C, -R, -r, or -v are spec‐\nified, the following escape conventions will be applied:\n\\a The alert character (ASCII 07).\n\\b The backspace character (ASCII 010).\n\\c Causes print to end without processing more arguments and not adding a new-\nline.\n\\f The formfeed character (ASCII 014).\n\\n The newline character (ASCII 012).\n\\r The carriage return character (ASCII 015).\n\\t The tab character (ASCII 011).\n\\v The vertical tab character (ASCII 013).\n\\E The escape character (ASCII 033).\n\\\\ The backslash character \\.\n\\0x The character defined by the 1, 2, or 3-digit octal string given by x.\n\nThe -R option will print all subsequent arguments and options other than -n. The -e\ncauses the above escape conventions to be applied. This is the default behavior. It\nreverses the effect of an earlier -r. The -p option causes the arguments to be writ‐\nten onto the pipe of the process spawned with |& instead of standard output. The -v\noption treats each arg as a variable name and writes the value in the printf %B for‐\nmat. The -C option treats each arg as a variable name and writes the value in the\nprintf %#B format. The -s option causes the arguments to be written onto the history\nfile instead of standard output. The -u option can be used to specify a one digit\nfile descriptor unit number unit on which the output will be placed. The default is\n1. If the option -n is used, no new-line is added to the output.\n\nprintf [ -v vname ] format [ arg ... ]\nThe arguments arg are printed on standard output in accordance with the ANSI C format‐\nting rules associated with the format string format. If the number of arguments ex‐\nceeds the number of format specifications, the format string is reused to format re‐\nmaining arguments. The following extensions can also be used:\n%b A %b format can be used instead of %s to cause escape sequences in the corre‐\nsponding arg to be expanded as described in print.\n%B A %B option causes each of the arguments to be treated as variable names and\nthe binary value of variable will be printed. The alternate flag # causes a\ncompound variable to be output on a single line. This is most useful for com‐\npound variables and variables whose attribute is -b.\n%H A %H format can be used instead of %s to cause characters in arg that are spe‐\ncial in HTML and XML to be output as their entity name. The alternate flag #\nformats the output for use as a URI.\n%p A %p format will convert the given number to hexadecimal.\n%P A %P format can be used instead of %s to cause arg to be interpreted as an ex‐\ntended regular expression and be printed as a shell pattern.\n%q A %q format can be used instead of %s to cause the resulting string to be\nquoted in a manner than can be reinput to the shell. When q is preceded by the\nalternative format specifier, #, the string is quoted in manner suitable as a\nfield in a .csv format file.\n%(date-format)T\nA %(date-format)T format can be used to treat an argument as a date/time string\nand to format the date/time according to the date-format.\n%Q A %Q format will convert the given number of seconds to readable time.\n%R A %R format can be used instead of %s to cause arg to be interpreted as a shell\npattern and to be printed as an extended regular expression.\n%Z A %Z format will output a byte whose value is 0.\n%d The precision field of the %d format can be followed by a . and the output\nbase. In this case, the # flag character causes base# to be prepended.\n# The # flag, when used with the %d format without an output base, displays the\noutput in powers of 1000 indicated by one of the following suffixes: k M G T P\nE, and when used with the %i format displays the output in powers of 1024 indi‐\ncated by one of the following suffixes: Ki Mi Gi Ti Pi Ei.\n= The = flag centers the output within the specified field width.\nL The L flag, when used with the %c or %s formats, treats precision as character\nwidth instead of byte count.\n, The , flag, when used with the %d or %f formats, separates groups of digits\nwith the grouping delimiter (, on groups of 3 in the C locale).\n\nThe -v option assigns the output directly to a variable instead of\nwriting it to standard output. This is faster than capturing the output using a\ncommand substitution and avoids the latter's stripping of final linefeed char‐\nacters (\\n). The vname argument should be a valid variable name, optionally\nwith one or more array subscripts in square brackets. Note that square brack‐\nets should be quoted to avoid pathname expansion.\n\npwd [ -LP ]\nOutputs the value of the current working directory. The -L option is the default; it\nprints the logical name of the current directory. If the -P option is given, all sym‐\nbolic links are resolved from the name. The last instance of -L or -P on the command\nline determines which method is used.\n\nread [ -ACSprsv ] [ -d delim ] [ -n n ] [ [ -N n ] [ -t timeout ] [ -u unit ] [ vname?prompt\n] [ vname ... ]\nThe shell input mechanism. One line is read and is broken up into fields using the\ncharacters in IFS as separators. The escape character, \\, is used to remove any spe‐\ncial meaning for the next character and for line continuation. The -d option causes\nthe read to continue to the first character of delim rather than new-line. The -n op‐\ntion causes at most n bytes to read rather a full line but will return when reading\nfrom a slow device as soon as any characters have been read. The -N option causes ex‐\nactly n to be read unless an end-of-file has been encountered or the read times out\nbecause of the -t option. In raw mode, -r, the \\ character is not treated specially.\nThe first field is assigned to the first vname, the second field to the second vname,\netc., with leftover fields assigned to the last vname. When vname has the binary at‐\ntribute and -n or -N is specified, the bytes that are read are stored directly into\nthe variable. If the -v is specified, then the value of the first vname will be used\nas a default value when reading from a terminal device. The -A option causes the\nvariable vname to be unset and each field that is read to be stored in successive ele‐\nments of the indexed array vname. The -C option causes the variable vname to be read\nas a compound variable. Blanks will be ignored when finding the beginning open paren‐\nthesis. The -S option causes the line to be treated like a record in a .csv format\nfile so that double quotes can be used to allow the delimiter character and the new-\nline character to appear within a field. The -p option causes the input line to be\ntaken from the input pipe of a process spawned by the shell using |&. If the -s op‐\ntion is present, the input will be saved as a command in the history file. The option\n-u can be used to specify a one digit file descriptor unit unit to read from. The\nfile descriptor can be opened with the exec special built-in command. The default\nvalue of unit n is 0. The option -t is used to specify a timeout in seconds when\nreading from a terminal or pipe. If vname is omitted, then REPLY is used as the de‐\nfault vname. An end-of-file with the -p option causes cleanup for this process so\nthat another can be spawned. If the first argument contains a ?, the remainder of\nthis word is used as a prompt on standard error when the shell is interactive. The\nexit status is 0 unless an end-of-file is encountered or read has timed out.\n\n†‡ readonly [ -p ] [ vname[=value] ] ...\nIf vname is not given, the names and values of each variable with the read-only attri‐\nbute is printed with the values quoted in a manner that allows them to be re-input.\nThe -p option causes the word readonly to be inserted before each one. Otherwise, the\ngiven vnames are marked read-only and these names cannot be changed by subsequent as‐\nsignment. Unlike typeset -r , readonly does not create a function-local scope and the\ngiven vnames are marked globally read-only by default. When defining a type, if the\nvalue of a read-only subvariable is not defined, the value is required when creating\neach instance.\n" }, { "name": "redirect", "content": "This command only accepts input/output redirections. It can open and close files and\nmodify file descriptors from 0 to 9 as specified by the input/output redirection list\n(see the Input/Output section above), with the difference that the effect persists\npast the execution of the redirect command. When invoking another program, file de‐\nscriptors greater than 2 that were opened with this mechanism are only passed on if\nthey are explicitly redirected to themselves as part of the invocation (e.g. 4>&4) or\nif the posix option is set.\n\n† return [ n ]\nCauses a shell function, dot script (see . and source), or profile script to return to\nthe invoking shell environment with the exit status specified by n. This status value\ncan use the full signed integer range as shown by the commands getconf INTMIN and\ngetconf INTMAX. A value outside that range will produce a warning and an exit status\nof 128. If n is omitted, then the value of $? is assumed, i.e., the exit status of\nthe last command executed is passed on. If return is invoked while not in a function,\ndot script, or profile script, then it behaves the same as exit.\n\n† set [ ±±BCGHabefhkmnprstuvx ] [ ±±o [ option ] ] ... [ ±±A vname ] [ arg ... ]\nThe options for this command have meaning as follows:\n-A Array assignment. Unset the variable vname and assign values sequentially\nfrom the arg list. If +A is used, the variable vname is not unset first.\n-B Enable brace group expansion. On by default, except if ksh is invoked as sh or\nrsh.\n-C Prevents redirection > from truncating existing files. Files that are created\nare opened with the OEXCL mode. Requires >| to truncate a file when turned\non.\n-G Enables recursive pathname expansion. This adds the double-star pattern to\nthe pathname expansion (see Pathname Expansion above). By itself, it matches\nthe recursive contents of the current directory, which is to say, all files\nand directories in the current directory and in all its subdirectories, sub-\nsubdirectories, and so on. If the pathname pattern ends in /, only directo‐\nries and subdirectories are matched, including symbolic links that point to\ndirectories. A prefixed directory name is not included in the results unless\nthat directory was itself found by a pattern. For example, dir/ matches the\nrecursive contents of dir but not dir itself, whereas di[r]/ matches both\ndir itself and the recursive contents of dir. Symbolic links to non-directo‐\nries are not followed. Symbolic links to directories are followed if they are\nspecified literally or match a pattern as described under Pathname Expansion,\nbut not if they result from a double-star pattern.\n-H Enable !-style history expansion similar to csh(1).\n-a All subsequent variables that are defined are automatically exported.\n-b Prints job completion messages as soon as a background job changes state\nrather than waiting for the next prompt.\n-e Unless contained in a || or && command, or the command following an if while\nor until command or in the pipeline following !, if a command has a non-zero\nexit status, execute the ERR trap, if set, and exit. This mode is disabled\nwhile reading profiles.\n-f Disables pathname expansion.\n-h Each command becomes a tracked alias when first encountered.\n-k (Obsolete). All variable assignment arguments are placed in the environment\nfor a command, not just those that precede the command name.\n-m Background jobs will run in a separate process group and a line will print\nupon completion. The exit status of background jobs is reported in a comple‐\ntion message. On systems with job control, this option is turned on automati‐\ncally for interactive shells.\n-n Read commands and check them for syntax errors, but do not execute them. Ig‐\nnored for interactive shells.\n-o The following argument can be one of the following option names:\nallexport\nSame as -a.\nbackslashctrl\nThe backslash character \\ escapes the next control character in the\nemacs built-in editor and the next erase or kill character in the vi\nbuilt-in editor. On by default.\nbgnice All background jobs are run at a lower priority. This is the default\nmode.\nbraceexpand\nSame as -B.\nemacs Puts you in an emacs style in-line editor for command entry.\nerrexit Same as -e.\nglobcasedetect\nWhen this option is turned on, globbing (see Pathname Expansion above)\nand file name listing and completion (see In-line Editing Options\nabove) automatically become case-insensitive on file systems where the\ndifference between upper- and lowercase is ignored for file names.\nThis is transparently determined for each directory, so a path pattern\nthat spans multiple file systems can be part case-sensitive and part\ncase-insensitive. In more precise terms, each slash-separated path\nname component pattern p is treated as ~(i:p) if its parent directory\nexists on a case-insensitive file system. This option is only present\non operating systems that support case-insensitive file systems.\nglobstar\nSame as -G.\ngmacs Puts you in a gmacs style in-line editor for command entry.\nhistexpand\nSame as -H.\nignoreeof\nAn interactive shell will not exit on end-of-file. The command exit\nmust be used.\nkeyword Same as -k.\nletoctal\nThe let command allows octal numbers starting with 0. On by default\nif ksh is invoked as sh or rsh.\nmarkdirs\nAll directory names resulting from pathname expansion have a trailing\n/ appended.\nmonitor Same as -m.\nmultiline\nThe built-in editors will use multiple lines on the screen for lines\nthat are longer than the width of the screen. This may not work for\nall terminals.\nnoclobber\nSame as -C.\nnoexec Same as -n.\nnoglob Same as -f.\nnolog Obsolete; has no effect.\nnotify Same as -b.\nnounset Same as -u.\npipefail\nA pipeline will not complete until all components of the pipeline have\ncompleted, and the return value will be the value of the last non-zero\ncommand to fail or zero if no command has failed.\nposix Enables the POSIX standard mode for maximum compatibility with other\ncompliant shells. At the moment that the posix option is turned on, it\nalso turns on letoctal and turns off -B/braceexpand; the reverse is\ndone when posix is turned back off. (These options can still be con‐\ntrolled independently in between.) Furthermore, the posix option is\nautomatically turned on upon invocation if ksh is invoked as sh or\nrsh. In that case, or if the option is turned on by specifying -o\nposix on the invocation command line, the invoked shell will not set\nthe preset aliases even if interactive, and will not import type at‐\ntributes for variables (such as integer or left/right justify) from\nthe environment.\nIn addition, while on, the posix option\n• disables exporting variable type attributes to the environment for\nother ksh processes to import;\n• causes file descriptors > 2 to be left open when invoking another\nprogram;\n• disables the &> redirection shorthand;\n• makes the <> redirection operator default to redirecting standard\ninput if no file descriptor number precedes it;\n• disables the special floating point constants Inf and NaN in arith‐\nmetic evaluation so that, e.g., $((inf)) and $((nan)) refer to the\nvariables by those names;\n• enables the recognition of a leading zero as introducing an octal\nnumber in all arithmetic evaluation contexts, except in the let\nbuilt-in while letoctal is off;\n• stops the . command (but not source) from looking up functions de‐\nfined with the function syntax;\n• changes the test/[ built-in command to make its deprecated expr1 -a\nexpr2 and expr1 -o expr2 operators work even if expr1 equals \"!\" or\n\"(\" (which means the nonstandard unary -a file and -o option opera‐\ntors cannot be directly negated using ! or wrapped in parentheses);\nand\n• disables a hack that makes test -t ([ -t ]) equivalent to test -t 1\n([ -t 1 ]).\nprivileged\nSame as -p.\nshowme When enabled, simple commands or pipelines preceded by a semicolon (;)\nwill be displayed as if the xtrace option were enabled but will not be\nexecuted. Otherwise, the leading ; will be ignored.\ntrackall\nSame as -h.\nverbose Same as -v.\nvi Puts you in insert mode of a vi style in-line editor until you hit the\nescape character 033. This puts you in control mode. A return sends\nthe line.\nviraw Each character is processed as it is typed in vi mode. The shell may\nhave been compiled to force this option on at all times. Otherwise,\ncanonical processing (line-by-line input) is initially enabled and the\ncommand line will be echoed again if the speed is 1200 baud or greater\nand it contains any control characters or less than one second has\nelapsed since the prompt was printed. The ESC character terminates\ncanonical processing for the remainder of the command and the user can\nthen modify the command line. This scheme has the advantages of canon‐\nical processing with the type-ahead echoing of raw mode. If the viraw\noption is set, the terminal will always have canonical processing dis‐\nabled. This mode is implicit for systems that do not support two al‐\nternate end of line delimiters, and may be helpful for certain termi‐\nnals.\nxtrace Same as -x.\nIf no option name is supplied, then the current option settings are printed.\n-p Disables processing of the $HOME/.profile file and uses the file\n/etc/suidprofile instead of the ENV file. This mode is on whenever the ef‐\nfective uid (gid) is not equal to the real uid (gid). Turning this off causes\nthe effective uid and gid to be set to the real uid and gid.\n-r Enables the restricted shell. This option cannot be unset once set.\n-s Sort the positional parameters lexicographically.\n-t (Obsolete). Exit after reading and executing one command.\n-u Treat unset parameters as an error when substituting. $@ and $* are exempt.\n-v Print shell input lines as they are read.\n-x Print commands and their arguments as they are executed.\n-- Do not change any of the options; useful in setting $1 to a value beginning\nwith -. If no arguments follow this option then the positional parameters are\nunset.\n\nAs an obsolete feature, if the first arg is - then the -x and -v options are turned\noff and the next arg is treated as the first argument. Using + rather than - causes\nthese options to be turned off. These options can also be used upon invocation of the\nshell. The current set of options may be found in $-. Unless -A is specified, the\nremaining arguments are positional parameters and are assigned, in order, to $1 $2\n.... If no arguments are given, then the names and values of all variables are\nprinted on the standard output.\n\n† shift [ n ]\nThe positional parameters from $n+1 ... are renamed $1 ... , default n is 1. The pa‐\nrameter n can be any arithmetic expression that evaluates to a non-negative number\nless than or equal to $#.\n\nsleep [ -s ] duration\nSuspends execution for the number of decimal seconds or fractions of a second given by\nduration. duration can be an integer, floating point value or ISO 8601 duration spec‐\nifying the length of time to sleep. The option -s causes the sleep builtin to termi‐\nnate when it receives any signal. If duration is not specified in conjunction with\n-s, sleep will wait for a signal indefinitely.\n\nsource name [ arg ... ]\nSame as ., except it is not treated as a special built-in command.\n\nstop job ...\nSends a SIGSTOP signal to one or more processes specified by job, suspending them un‐\ntil they receive SIGCONT. The same as kill -s STOP.\n" }, { "name": "suspend", "content": "Sends a SIGSTOP signal to the main shell process, suspending the script or child shell\nsession until it receives SIGCONT (for instance, when typing fg in the parent shell).\nEquivalent to kill -s STOP \"$$\", except that it accepts no operands and refuses to\nsuspend a login shell.\n\ntest expression\nThe test and [ commands execute conditional expressions similar to those specified for\nthe [[ compound command under Conditional Expressions above, but with several impor‐\ntant differences. The =, == and != operators test for string (in)equality without pat‐\ntern matching; == is nonstandard and unportable. The f3&& and || operators are not\navailable. Instead, the -a and -o binary operators can be used, but they are fraught\nwith pitfalls due to grammatical ambiguities and therefore deprecated in favor of in‐‐\nvoking separate test commands. Most importantly, as test and [ are simple regular com‐‐\nmands, field splitting and pathname expansion are performed on all their arguments and\nall aspects of regular shell grammar (such as redirection) remain active. This is usu‐‐\nally harmful, so care must be taken to quote arguments and expansions to avoid this.\nTo avoid the many pitfalls arising from these issues, the [[ compound command should\nbe used instead. The primary purpose of the test and [ commands is compatibility with\nother shells that lack [[.\n\nThe test/[ command does not parse options except if there are two arguments and the\nsecond is --. To access the inline documentation with an option such as --man, you\nneed one of the forms test --man -- or [ --man -- ].\n\ntimes Displays the accumulated user and system CPU times, one line with the times used by\nthe shell and another with those used by all of the shell's child processes. No op‐\ntions are supported.\n\n† trap [ -p ] [ action ] [ sig ] ...\nThe -p option causes the trap action associated with each trap as specified by the ar‐\nguments to be printed with appropriate quoting. Otherwise, action will be processed\nas if it were an argument to eval when the shell receives signal(s) sig. Each sig can\nbe given as a number or as the name of the signal. Trap commands are executed in or‐\nder of signal number. Any attempt to set a trap on a signal that was ignored on entry\nto the current shell is ineffective. If action is omitted and the first sig is a num‐\nber, or if action is -, then the trap(s) for each sig are reset to their original val‐\nues. If action is the null string then this signal is ignored by the shell and by the\ncommands it invokes. If sig is ERR then action will be executed whenever a command\nhas a non-zero exit status. If sig is DEBUG then action will be executed before each\ncommand. The variable .sh.command will contain the current command line when action\nis running, in the same format as the output generated by the xtrace option (minus the\npreceding PS4 prompt). If the exit status of the trap is 2 the command will not be\nexecuted. If the exit status of the trap is 255 and inside a function or a dot\nscript, the function or dot script will return. If sig is 0 or EXIT and the trap\nstatement is executed inside the body of a function defined with the function name\nsyntax, then the command action is executed after the function completes. If sig is 0\nor EXIT for a trap set outside any function then the command action is executed on\nexit from the shell. If sig is KEYBD, then action will be executed whenever a key is\nread while in emacs, gmacs, or vi mode. The trap command with no arguments prints a\nlist of commands associated with each signal number.\n\nAn exit or return without an argument in a trap action will preserve the exit status of the\ncommand that invoked the trap.\n\ntrue Does nothing, and exits 0. Used with while for infinite loops.\n\ntype [ -afpq ] name ...\nThe same as whence -v.\n\n†‡ typeset [ ±±ACHSbflmnprstux ] [ ±±EFLRXZi[n] ] [ +-M [ mapname ] ] [ -T [ tname=(as‐\nsignlist) ] ] [ -h str ] [ -a [type] ] [ vname[=value ] ] ...\nSets attributes and values for shell variables and functions. When invoked inside a\nfunction defined with the function name syntax, a new instance of the variable vname\nis created, and the variable's value and type are restored when the function com‐\npletes. The following list of attributes may be specified:\n-A Declares vname to be an associative array. Subscripts are strings rather than\narithmetic expressions.\n-C Causes each vname to be a compound variable. If value names a compound vari‐\nable, it is copied into vname. Otherwise, the empty compound value is assigned\nto vname.\n-a Declares vname to be an indexed array. If type is specified, it must be the\nname of an enumeration type created with the enum command and it allows enumer‐\nation constants to be used as subscripts.\n-E Declares vname to be a double precision floating point number. If n is non-\nzero, it defines the number of significant figures that are used when expanding\nvname. Otherwise, ten significant figures will be used.\n-F Declares vname to be a double precision floating point number. If n is non-\nzero, it defines the number of places after the decimal point that are used\nwhen expanding vname. Otherwise ten places after the decimal point will be\nused.\n-H This option provides UNIX to host-name file mapping on non-UNIX machines.\n-L Left justify and remove leading blanks from value. If n is non-zero, it de‐\nfines the width of the field, otherwise it is determined by the width of the\nvalue of first assignment. When the variable is assigned to, it is filled on\nthe right with blanks or truncated, if necessary, to fit into the field. The\n-R option is turned off.\n-M Use the character mapping mapping defined by wctrans(3). such as tolower and\ntoupper when assigning a value to each of the specified operands. When mapping\nis specified and there are not operands, all variables that use this mapping\nare written to standard output. When mapping is omitted and there are no oper‐\nands, all mapped variables are written to standard output.\n-R Right justify and fill with leading blanks. If n is non-zero, it defines the\nwidth of the field, otherwise it is determined by the width of the value of\nfirst assignment. The field is left filled with blanks or truncated from the\nend if the variable is reassigned. The -L option is turned off.\n-S When used within the assignlist of a type definition, it causes the specified\nsubvariable to be shared by all instances of the type. When used inside a\nfunction defined with the function reserved word, the specified variables will\nhave function static scope. Otherwise, the variable is unset prior to process‐\ning the assignment list.\n-T If followed by tname, it creates a type named by tname using the compound as‐\nsignment assignlist to tname. Otherwise, it writes all the type definitions\nto standard output.\n-X Declares vname to be a double precision floating point number and expands using\nthe %a format of ISO-C99. If n is non-zero, it defines the number of hex dig‐\nits after the radix point that is used when expanding vname. The default is\n10.\n-Z Right justify and fill with leading zeros if the first non-blank character is a\ndigit and the -L option has not been set. Remove leading zeros if the -L op‐\ntion is also set. If n is non-zero, it defines the width of the field, other‐\nwise it is determined by the width of the value of first assignment.\n-f The names refer to function names rather than variable names. No assignments\ncan be made and the only other valid options are -S, -t, -u and -x. The -S can\nbe used with discipline functions defined in a type to indicate that the func‐\ntion is static. For a static function, the same method will be used by all in‐\nstances of that type no matter which instance references it. In addition, it\ncan only use value of variables from the original type definition. These dis‐\ncipline functions cannot be redefined in any type instance. The -t option\nturns on execution tracing for this function. The -u option causes this func‐\ntion to be marked undefined. The FPATH variable will be searched to find the\nfunction definition when the function is referenced. If no options other than\n-f is specified, then the function definition will be displayed on standard\noutput. If +f is specified, then a line containing the function name followed\nby a shell comment containing the line number and path name of the file where\nthis function was defined, if any, is displayed. The exit status can be used\nto determine whether the function is defined so that typeset -f .sh.math.name\nwill return 0 when math function name is defined and non-zero otherwise.\n-b The variable can hold any number of bytes of data. The data can be text or bi‐\nnary. The value is represented by the base64 encoding of the data. If -Z is\nalso specified, the size in bytes of the data in the buffer will be determined\nby the size associated with the -Z. If the base64 string assigned results in\nmore data, it will be truncated. Otherwise, it will be filled with bytes whose\nvalue is zero. The printf format %B can be used to output the actual data in\nthis buffer instead of the base64 encoding of the data.\n-h Used within type definitions to add information when generating information\nabout the subvariable on the man page. It is ignored when used outside of a\ntype definition. When used with -f the information is associated with the cor‐\nresponding discipline function.\n-i Declares vname to be represented internally as integer. The right hand side of\nan assignment is evaluated as an arithmetic expression when assigning to an in‐\nteger. If n is non-zero, it defines the output arithmetic base, otherwise the\noutput base will be ten.\n-l Used with -i, -E or -F, to indicate long integer, or long float. Otherwise,\nall uppercase characters are converted to lowercase. The uppercase option, -u,\nis turned off. Equivalent to -M tolower .\n-m moves or renames the variable. The value is the name of a variable whose value\nwill be moved to vname. The original variable will be unset. Cannot be used\nwith any other options.\n-n Declares vname to be a reference to the variable whose name is defined by the\nvalue of variable vname. This is usually used to reference a variable inside a\nfunction whose name has been passed as an argument. Cannot be used with any\nother options.\n-p The name, attributes and values for the given vnames are written on standard\noutput in a form that can be used as shell input. If +p is specified, then the\nvalues are not displayed.\n-r The given vnames are marked read-only and these names cannot be changed by sub‐\nsequent assignment.\n-s When given along with -i, restricts integer size to short.\n-t Tags the variables. Tags are user definable and have no special meaning to the\nshell.\n-u When given along with -i, specifies unsigned integer. Otherwise, all lowercase\ncharacters are converted to uppercase. The lowercase option, -l, is turned\noff. Equivalent to -M toupper .\n-x The given vnames are marked for automatic export to the environment of subse‐\nquently-executed commands. Variables whose names contain a . cannot be ex‐\nported.\n\nThe -i, -F, -E, and -X options cannot be specified along with -R, -L, or -Z. The -b\noption cannot be specified along with -L, -u, or -l. The -f, -m, -n, and -T options\ncannot be used together with any other option.\n\nUsing + rather than - causes these options to be turned off. If no vname arguments\nare given, a list of vnames (and optionally the values) of the variables is printed.\n(Using + rather than - keeps the values from being printed.) The -p option causes\ntypeset followed by the option letters to be printed before each name rather than the\nnames of the options. If any option other than -p is given, only those variables\nwhich have all of the given options are printed. Otherwise, the vnames and attributes\nof all variables that have attributes are printed.\n\nulimit [ -HSaMctdfxlqenupmrbiswTv ] [ limit ]\nSet or display a resource limit. The available resource limits are listed below.\nMany systems do not support one or more of these limits. The limit for a specified\nresource is set when limit is specified. The value of limit can be a number in the\nunit specified below with each resource, or the value unlimited. The -H and -S op‐\ntions specify whether the hard limit or the soft limit for the given resource is set.\nA hard limit cannot be increased once it is set. A soft limit can be increased up to\nthe value of the hard limit. If neither the H nor S option is specified, the limit\napplies to both. The current resource limit is printed when limit is omitted. In\nthis case, the soft limit is printed unless H is specified. When more than one re‐\nsource is specified, then the limit name and unit is printed before the value.\n-a Lists all of the current resource limits.\n-b The socket buffer size in bytes.\n-c The number of 512-byte blocks on the size of core dumps.\n-d The number of K-bytes on the size of the data area.\n-e The scheduling priority.\n-f The number of 512-byte blocks on files that can be written by the current\nprocess or by child processes (files of any size may be read).\n-i The signal queue size.\n-l The locked address space in K-bytes.\n-M The address space limit in K-bytes.\n-m The number of K-bytes on the size of physical memory.\n-n The number of file descriptors plus 1.\n-p The number of 512-byte blocks for pipe buffering.\n-q The message queue size in K-bytes.\n-r The max real-time priority.\n-s The number of K-bytes on the size of the stack area.\n-T The number of threads.\n-t The number of CPU seconds to be used by each process.\n-u The number of processes.\n-v The number of K-bytes for virtual memory.\n-w The swap size in K-bytes.\n-x The number of file locks.\n\nIf no option is given, -f is assumed.\n\numask [ -S ] [ mask ]\nThe user file-creation mask is set to mask (see umask(2)). mask can either be an oc‐\ntal number or a symbolic value as described in chmod(1). If a symbolic value is\ngiven, the new umask value is the complement of the result of applying mask to the\ncomplement of the previous umask value. If mask is omitted, the current value of the\nmask is printed. The -S option causes the mode to be printed as a symbolic value.\nOtherwise, the mask is printed in octal.\n\nunalias [ -a ] name ...\nThe aliases given by the list of names are removed from the alias list. The -a option\ncauses all the aliases to be unset.\n\n† unset [ -fnv ] vname ...\nThe variables given by the list of vnames are unassigned, i.e., except for subvari‐\nables within a type, their values and attributes are erased. For subvariables of a\ntype, the values are reset to the default value from the type definition. Readonly\nvariables cannot be unset. If the -f option is set, then the names refer to function\nnames. If the -v option is set, then the names refer to variable names. The -f op‐\ntion overrides -v. If -n is set and name is a name reference, then name will be unset\nrather than the variable that it references. The default is equivalent to -v. Unset‐\nting LINENO, MAILCHECK, OPTARG, OPTIND, RANDOM, SECONDS, TMOUT, and removes their\nspecial meaning even if they are subsequently assigned to.\n\nwait [ job ... ]\nWait for the specified job and report its termination status. If job is not given,\nthen all currently active child processes are waited for. The exit status from this\ncommand is that of the last process waited for if job is specified; otherwise it is\nzero. See Jobs for a description of the format of job.\n\nwhence [ -afpqv ] name ...\nFor each name, indicate how it would be interpreted if used as a command name.\nThe -v option produces a more verbose report. The -f option skips the search for\nfunctions. The -p option does a path search for name even if name is an alias, a\nfunction, or a reserved word. The -p option turns off the -v option. The -q option\ncauses whence to enter quiet mode. whence will return zero if all arguments are\nbuilt-ins, functions, or are programs found on the path. The -a option is similar to\nthe -v option but causes all interpretations of the given name to be reported.\n" }, { "name": "Invocation.", "content": "If the shell is invoked by exec(2), initialization depends on argument zero ($0) as follows.\nIf the first character of $0 is -, or the -l option is given on the invocation command line,\nthen the shell is assumed to be a login shell. If the basename of the command path in $0 is\nrsh, rksh, or krsh, then the shell becomes restricted. If the basename is sh or rsh, or the" }, { "name": "-o", "content": "full POSIX compliance mode (see the set builtin command above for more information). After\nthis, if the shell was assumed to be a login shell, commands are read from /etc/profile and\nthen from $HOME/.profile if it exists. Alternatively, the option -l causes the shell to be\ntreated as a login shell. Next, for interactive shells, commands are read from the file\nnamed by ENV if the file exists, its name being determined by performing parameter expansion,\ncommand substitution, and arithmetic expansion on the value of that environment variable. If\nthe -s option is not present and arg and a file by the name of arg exists, then it reads and\nexecutes this script. Otherwise, if the first arg does not contain a /, a path search is\nperformed on the first arg to determine the name of the script to execute. The script arg\nmust have execute permission and any setuid and setgid settings will be ignored. If the\nscript is not found on the path, arg is processed as if it named a built-in command or func‐\ntion. Commands are then read as described below; the following options are interpreted by\nthe shell when it is invoked:\n", "flag": "-o" }, { "name": "-D", "content": "dard output and the shell will exit. This set of strings will be subject to language\ntranslation when the locale is not C or POSIX. No commands will be executed.\n", "flag": "-D" }, { "name": "-E -o --rc", "content": "Read the file named by the ENV variable or by $HOME/.kshrc if not defined after the\nprofiles. On by default for interactive shells. Use +E, +o rc or --norc to turn off.\n", "flag": "-o", "long": "--rc" }, { "name": "-c", "content": "present, becomes that script's command name ($0). Any third and further args become\npositional parameters starting at $1.\n", "flag": "-c" }, { "name": "-s", "content": "($0) cannot be set. Any args become the positional parameters starting at $1. This\noption is forced on if no arg is given and is ignored if -c is also specified.\n", "flag": "-s" }, { "name": "-i -o --interactive", "content": "If the -i option is present or if the shell's standard input and standard error are\nattached to a terminal (as told by tcgetattr(3)), then this shell is interactive. In\nthis case TERM is ignored (so that kill 0 does not kill an interactive shell) and\nINTR is caught and ignored (so that wait is interruptible). In all cases, QUIT is\nignored by the shell.\n", "flag": "-o", "long": "--interactive" }, { "name": "-r -o --restricted", "content": "If the -r option is present, the shell is a restricted shell.\n\nThe remaining options and arguments are described under the set command above. An optional -\nas the first argument is ignored.\n", "flag": "-o", "long": "--restricted" }, { "name": "Rksh Only.", "content": "Rksh is used to set up login names and execution environments whose capabilities are more\ncontrolled than those of the standard shell. The actions of rksh are identical to those of\nksh, except that the following are disallowed:\nunsetting the restricted option,\nchanging directory (see cd(1)),\nsetting or unsetting the value or attributes of SHELL, ENV, FPATH, or PATH,\nspecifying path or command names containing /,\nredirecting output (>, >|, <>, and >>),\nadding or deleting built-in commands,\nusing command -p to invoke a command.\n\nThe restrictions above are enforced after .profile and the ENV files are interpreted.\n\nWhen a command to be executed is found to be a shell procedure, rksh invokes ksh to execute\nit. Thus, it is possible to provide to the end-user shell procedures that have access to the\nfull power of the standard shell, while imposing a limited menu of commands; this scheme as‐\nsumes that the end-user does not have write and execute permissions in the same directory.\n\nThe net effect of these rules is that the writer of the .profile has complete control over\nuser actions, by performing guaranteed setup actions and leaving the user in an appropriate\ndirectory (probably not the login directory).\n\nThe system administrator often sets up a directory of commands (e.g., /usr/rbin) that can be\nsafely invoked by rksh.\n" } ] }, "EXIT STATUS": { "content": "Errors detected by the shell, such as syntax errors, cause the shell to return a non-zero\nexit status. If the shell is being used non-interactively, then execution of the shell file\nis abandoned unless the error occurs inside a subshell in which case the subshell is aban‐\ndoned. Otherwise, the shell returns the exit status of the last command executed (see also\nthe exit command above). Run time errors detected by the shell are reported by printing the\ncommand or function name and the error condition. If the line number that the error occurred\non is greater than one, then the line number is also printed in square brackets ([]) after\nthe command or function name.\n", "subsections": [] }, "FILES": { "content": "", "subsections": [ { "name": "/etc/profile", "content": "The system wide initialization file, executed for login shells.\n" }, { "name": "$HOME/.profile", "content": "The personal initialization file, executed for login shells after /etc/profile.\n" }, { "name": "$HOME/.kshrc", "content": "Default personal initialization file, executed for interactive shells when ENV is not\nset.\n\n/etc/suidprofile\nAlternative initialization file, executed instead of the personal initialization file\nwhen the real and effective user or group id do not match.\n" }, { "name": "/dev/null", "content": "NULL device\n" } ] }, "SEE ALSO": { "content": "cat(1), cd(1), chmod(1), cut(1), date(1), egrep(1), echo(1), emacs(1), env(1), fgrep(1),\ngmacs(1), grep(1), stty(1), test(1), umask(1), vi(1), dup(2), exec(2), fork(2), getpwnam(3),\nioctl(2), lseek(2), paste(1), pathconf(2), pipe(2), sysconf(3), umask(2), ulimit(2), wait(2),\nstrftime(3), wctrans(3), rand(3), profile(5), environ(7).\n\nMorris I. Bolsky and David G. Korn, The New KornShell Command and Programming Language, Pren‐\ntice Hall, 1995.\n\nPOSIX - Part 2: Shell and Utilities, IEEE Std 1003.2-1992, ISO/IEC 9945-2, IEEE, 1993.\n", "subsections": [] }, "CAVEATS": { "content": "If a command is executed, and then a command with the same name is installed in a directory\nin the search path before the directory where the original command was found, the shell will\ncontinue to exec the original command. Use the hash command or the -t option of the alias\ncommand to correct this situation.\n\nSome very old shell scripts contain a ^ as a synonym for the pipe character |.\n\nUsing the hist built-in command within a compound command will cause the whole command to\ndisappear from the history file.\n\nThe built-in command . file reads the whole file before any commands are executed. There‐\nfore, alias and unalias commands in the file will not apply to any commands defined in the\nfile.\n\nTraps are not processed while a job is waiting for a foreground process. Thus, a trap on\nCHLD won't be executed until the foreground job terminates.\n\nIt is a good idea to leave a space after the comma operator in arithmetic expressions to pre‐\nvent the comma from being interpreted as the decimal point character in certain locales.\n\n\n\nKSH(1)", "subsections": [] } } } }