{ "mode": "info", "parameter": "egrep", "section": "", "url": "https://www.chedong.com/phpMan.php/info/egrep/json", "generated": "2026-07-29T01:25:31Z", "synopsis": "grep [OPTION...] PATTERNS [FILE...]\ngrep [OPTION...] -e PATTERNS ... [FILE...]\ngrep [OPTION...] -f PATTERNFILE ... [FILE...]", "sections": { "NAME": { "content": "grep, egrep, fgrep, rgrep - print lines that match patterns\n", "subsections": [] }, "SYNOPSIS": { "content": "grep [OPTION...] PATTERNS [FILE...]\ngrep [OPTION...] -e PATTERNS ... [FILE...]\ngrep [OPTION...] -f PATTERNFILE ... [FILE...]\n", "subsections": [] }, "DESCRIPTION": { "content": "grep searches for PATTERNS in each FILE. PATTERNS is one or more\npatterns separated by newline characters, and grep prints each line\nthat matches a pattern. Typically PATTERNS should be quoted when grep\nis used in a shell command.\n\nA FILE of \"-\" stands for standard input. If no FILE is given,\nrecursive searches examine the working directory, and nonrecursive\nsearches read standard input.\n\nIn addition, the variant programs egrep, fgrep and rgrep are the same\nas grep -E, grep -F, and grep -r, respectively. These variants are\ndeprecated, but are provided for backward compatibility.\n", "subsections": [] }, "OPTIONS": { "content": "Generic Program Information\n--help Output a usage message and exit.\n", "subsections": [ { "name": "-V, --version", "content": "Output the version number of grep and exit.\n\nPattern Syntax", "flag": "-V", "long": "--version" }, { "name": "-E, --extended-regexp", "content": "Interpret PATTERNS as extended regular expressions (EREs, see\nbelow).\n", "flag": "-E", "long": "--extended-regexp" }, { "name": "-F, --fixed-strings", "content": "Interpret PATTERNS as fixed strings, not regular expressions.\n", "flag": "-F", "long": "--fixed-strings" }, { "name": "-G, --basic-regexp", "content": "Interpret PATTERNS as basic regular expressions (BREs, see\nbelow). This is the default.\n", "flag": "-G", "long": "--basic-regexp" }, { "name": "-P, --perl-regexp", "content": "Interpret I as Perl-compatible regular expressions\n(PCREs). This option is experimental when combined with the -z\n(--null-data) option, and grep -P may warn of unimplemented\nfeatures.\n\nMatching Control\n-e PATTERNS, --regexp=PATTERNS\nUse PATTERNS as the patterns. If this option is used multiple\ntimes or is combined with the -f (--file) option, search for all\npatterns given. This option can be used to protect a pattern\nbeginning with \"-\".\n\n-f FILE, --file=FILE\nObtain patterns from FILE, one per line. If this option is used\nmultiple times or is combined with the -e (--regexp) option,\nsearch for all patterns given. The empty file contains zero\npatterns, and therefore matches nothing.\n", "flag": "-P", "long": "--perl-regexp" }, { "name": "-i, --ignore-case", "content": "Ignore case distinctions in patterns and input data, so that\ncharacters that differ only in case match each other.\n", "flag": "-i", "long": "--ignore-case" }, { "name": "--no-ignore-case", "content": "Do not ignore case distinctions in patterns and input data.\nThis is the default. This option is useful for passing to shell\nscripts that already use -i, to cancel its effects because the\ntwo options override each other.\n", "long": "--no-ignore-case" }, { "name": "-v, --invert-match", "content": "Invert the sense of matching, to select non-matching lines.\n", "flag": "-v", "long": "--invert-match" }, { "name": "-w, --word-regexp", "content": "Select only those lines containing matches that form whole\nwords. The test is that the matching substring must either be\nat the beginning of the line, or preceded by a non-word\nconstituent character. Similarly, it must be either at the end\nof the line or followed by a non-word constituent character.\nWord-constituent characters are letters, digits, and the\nunderscore. This option has no effect if -x is also specified.\n", "flag": "-w", "long": "--word-regexp" }, { "name": "-x, --line-regexp", "content": "Select only those matches that exactly match the whole line.\nFor a regular expression pattern, this is like parenthesizing\nthe pattern and then surrounding it with ^ and $.\n\n-y Obsolete synonym for -i.\n\nGeneral Output Control", "flag": "-x", "long": "--line-regexp" }, { "name": "-c, --count", "content": "Suppress normal output; instead print a count of matching lines\nfor each input file. With the -v, --invert-match option (see\nbelow), count non-matching lines.\n", "flag": "-c", "long": "--count" }, { "name": "--color[=WHEN], --colour[=WHEN]", "content": "Surround the matched (non-empty) strings, matching lines,\ncontext lines, file names, line numbers, byte offsets, and\nseparators (for fields and groups of context lines) with escape\nsequences to display them in color on the terminal. The colors\nare defined by the environment variable GREPCOLORS. The\ndeprecated environment variable GREPCOLOR is still supported,\nbut its setting does not have priority. WHEN is never, always,\nor auto.\n" }, { "name": "-L, --files-without-match", "content": "Suppress normal output; instead print the name of each input\nfile from which no output would normally have been printed.\n", "flag": "-L", "long": "--files-without-match" }, { "name": "-l, --files-with-matches", "content": "Suppress normal output; instead print the name of each input\nfile from which output would normally have been printed.\nScanning each input file stops upon first match.\n\n-m NUM, --max-count=NUM\nStop reading a file after NUM matching lines. If the input is\nstandard input from a regular file, and NUM matching lines are\noutput, grep ensures that the standard input is positioned to\njust after the last matching line before exiting, regardless of\nthe presence of trailing context lines. This enables a calling\nprocess to resume a search. When grep stops after NUM matching\nlines, it outputs any trailing context lines. When the -c or\n--count option is also used, grep does not output a count\ngreater than NUM. When the -v or --invert-match option is also\nused, grep stops after outputting NUM non-matching lines.\n", "flag": "-l", "long": "--files-with-matches" }, { "name": "-o, --only-matching", "content": "Print only the matched (non-empty) parts of a matching line,\nwith each such part on a separate output line.\n", "flag": "-o", "long": "--only-matching" }, { "name": "-q, --quiet, --silent", "content": "Quiet; do not write anything to standard output. Exit\nimmediately with zero status if any match is found, even if an\nerror was detected. Also see the -s or --no-messages option.\n", "flag": "-q", "long": "--silent" }, { "name": "-s, --no-messages", "content": "Suppress error messages about nonexistent or unreadable files.\n\nOutput Line Prefix Control", "flag": "-s", "long": "--no-messages" }, { "name": "-b, --byte-offset", "content": "Print the 0-based byte offset within the input file before each\nline of output. If -o (--only-matching) is specified, print the\noffset of the matching part itself.\n", "flag": "-b", "long": "--byte-offset" }, { "name": "-H, --with-filename", "content": "Print the file name for each match. This is the default when\nthere is more than one file to search. This is a GNU extension.\n", "flag": "-H", "long": "--with-filename" }, { "name": "-h, --no-filename", "content": "Suppress the prefixing of file names on output. This is the\ndefault when there is only one file (or only standard input) to\nsearch.\n\n--label=LABEL\nDisplay input actually coming from standard input as input\ncoming from file LABEL. This can be useful for commands that\ntransform a file's contents before searching, e.g., gzip -cd\nfoo.gz | grep --label=foo -H 'some pattern'. See also the -H\noption.\n", "flag": "-h", "long": "--no-filename" }, { "name": "-n, --line-number", "content": "Prefix each line of output with the 1-based line number within\nits input file.\n", "flag": "-n", "long": "--line-number" }, { "name": "-T, --initial-tab", "content": "Make sure that the first character of actual line content lies\non a tab stop, so that the alignment of tabs looks normal. This\nis useful with options that prefix their output to the actual\ncontent: -H,-n, and -b. In order to improve the probability\nthat lines from a single file will all start at the same column,\nthis also causes the line number and byte offset (if present) to\nbe printed in a minimum size field width.\n", "flag": "-T", "long": "--initial-tab" }, { "name": "-Z, --null", "content": "Output a zero byte (the ASCII NUL character) instead of the\ncharacter that normally follows a file name. For example, grep\n-lZ outputs a zero byte after each file name instead of the\nusual newline. This option makes the output unambiguous, even\nin the presence of file names containing unusual characters like\nnewlines. This option can be used with commands like find\n-print0, perl -0, sort -z, and xargs -0 to process arbitrary\nfile names, even those that contain newline characters.\n\nContext Line Control\n-A NUM, --after-context=NUM\nPrint NUM lines of trailing context after matching lines.\nPlaces a line containing a group separator (--) between\ncontiguous groups of matches. With the -o or --only-matching\noption, this has no effect and a warning is given.\n\n-B NUM, --before-context=NUM\nPrint NUM lines of leading context before matching lines.\nPlaces a line containing a group separator (--) between\ncontiguous groups of matches. With the -o or --only-matching\noption, this has no effect and a warning is given.\n\n-C NUM, -NUM, --context=NUM\nPrint NUM lines of output context. Places a line containing a\ngroup separator (--) between contiguous groups of matches. With\nthe -o or --only-matching option, this has no effect and a\nwarning is given.\n\n--group-separator=SEP\nWhen -A, -B, or -C are in use, print SEP instead of -- between\ngroups of lines.\n", "flag": "-Z", "long": "--null" }, { "name": "--no-group-separator", "content": "When -A, -B, or -C are in use, do not print a separator between\ngroups of lines.\n\nFile and Directory Selection", "long": "--no-group-separator" }, { "name": "-a, --text", "content": "Process a binary file as if it were text; this is equivalent to\nthe --binary-files=text option.\n\n--binary-files=TYPE\nIf a file's data or metadata indicate that the file contains\nbinary data, assume that the file is of type TYPE. Non-text\nbytes indicate binary data; these are either output bytes that\nare improperly encoded for the current locale, or null input\nbytes when the -z option is not given.\n\nBy default, TYPE is binary, and grep suppresses output after\nnull input binary data is discovered, and suppresses output\nlines that contain improperly encoded data. When some output is\nsuppressed, grep follows any output with a one-line message\nsaying that a binary file matches.\n\nIf TYPE is without-match, when grep discovers null input binary\ndata it assumes that the rest of the file does not match; this\nis equivalent to the -I option.\n\nIf TYPE is text, grep processes a binary file as if it were\ntext; this is equivalent to the -a option.\n\nWhen type is binary, grep may treat non-text bytes as line\nterminators even without the -z option. This means choosing\nbinary versus text can affect whether a pattern matches a file.\nFor example, when type is binary the pattern q$ might match q\nimmediately followed by a null byte, even though this is not\nmatched when type is text. Conversely, when type is binary the\npattern . (period) might not match a null byte.\n\nWarning: The -a option might output binary garbage, which can\nhave nasty side effects if the output is a terminal and if the\nterminal driver interprets some of it as commands. On the other\nhand, when reading files whose text encodings are unknown, it\ncan be helpful to use -a or to set LCALL='C' in the\nenvironment, in order to find more matches even if the matches\nare unsafe for direct display.\n\n-D ACTION, --devices=ACTION\nIf an input file is a device, FIFO or socket, use ACTION to\nprocess it. By default, ACTION is read, which means that\ndevices are read just as if they were ordinary files. If ACTION\nis skip, devices are silently skipped.\n\n-d ACTION, --directories=ACTION\nIf an input file is a directory, use ACTION to process it. By\ndefault, ACTION is read, i.e., read directories just as if they\nwere ordinary files. If ACTION is skip, silently skip\ndirectories. If ACTION is recurse, read all files under each\ndirectory, recursively, following symbolic links only if they\nare on the command line. This is equivalent to the -r option.\n\n--exclude=GLOB\nSkip any command-line file with a name suffix that matches the\npattern GLOB, using wildcard matching; a name suffix is either\nthe whole name, or a trailing part that starts with a non-slash\ncharacter immediately after a slash (/) in the name. When\nsearching recursively, skip any subfile whose base name matches\nGLOB; the base name is the part after the last slash. A pattern\ncan use *, ?, and [...] as wildcards, and \\ to quote a wildcard\nor backslash character literally.\n\n--exclude-from=FILE\nSkip files whose base name matches any of the file-name globs\nread from FILE (using wildcard matching as described under\n--exclude).\n\n--exclude-dir=GLOB\nSkip any command-line directory with a name suffix that matches\nthe pattern GLOB. When searching recursively, skip any\nsubdirectory whose base name matches GLOB. Ignore any redundant\ntrailing slashes in GLOB.\n\n-I Process a binary file as if it did not contain matching data;\nthis is equivalent to the --binary-files=without-match option.\n\n--include=GLOB\nSearch only files whose base name matches GLOB (using wildcard\nmatching as described under --exclude). If contradictory\n--include and --exclude options are given, the last matching one\nwins. If no --include or --exclude options match, a file is\nincluded unless the first such option is --include.\n", "flag": "-a", "long": "--text" }, { "name": "-r, --recursive", "content": "Read all files under each directory, recursively, following\nsymbolic links only if they are on the command line. Note that\nif no file operand is given, B searches the working\ndirectory. This is equivalent to the -d recurse option.\n", "flag": "-r", "long": "--recursive" }, { "name": "-R, --dereference-recursive", "content": "Read all files under each directory, recursively. Follow all\nsymbolic links, unlike -r.\n\nOther Options", "flag": "-R", "long": "--dereference-recursive" }, { "name": "--line-buffered", "content": "Use line buffering on output. This can cause a performance\npenalty.\n", "long": "--line-buffered" }, { "name": "-U, --binary", "content": "Treat the file(s) as binary. By default, under MS-DOS and MS-\nWindows, grep guesses whether a file is text or binary as\ndescribed for the --binary-files option. If grep decides the\nfile is a text file, it strips the CR characters from the\noriginal file contents (to make regular expressions with ^ and $\nwork correctly). Specifying -U overrules this guesswork,\ncausing all files to be read and passed to the matching\nmechanism verbatim; if the file is a text file with CR/LF pairs\nat the end of each line, this will cause some regular\nexpressions to fail. This option has no effect on platforms\nother than MS-DOS and MS-Windows.\n", "flag": "-U", "long": "--binary" }, { "name": "-z, --null-data", "content": "Treat input and output data as sequences of lines, each\nterminated by a zero byte (the ASCII NUL character) instead of a\nnewline. Like the -Z or --null option, this option can be used\nwith commands like sort -z to process arbitrary file names.\n", "flag": "-z", "long": "--null-data" } ] }, "REGULAR EXPRESSIONS": { "content": "A regular expression is a pattern that describes a set of strings.\nRegular expressions are constructed analogously to arithmetic\nexpressions, by using various operators to combine smaller expressions.\n\ngrep understands three different versions of regular expression syntax:\n\"basic\" (BRE), \"extended\" (ERE) and \"perl\" (PCRE). In GNU grep there\nis no difference in available functionality between basic and extended\nsyntaxes. In other implementations, basic regular expressions are less\npowerful. The following description applies to extended regular\nexpressions; differences for basic regular expressions are summarized\nafterwards. Perl-compatible regular expressions give additional\nfunctionality, and are documented in B(3) and\nB(3), but work only if PCRE support is enabled.\n\nThe fundamental building blocks are the regular expressions that match\na single character. Most characters, including all letters and digits,\nare regular expressions that match themselves. Any meta-character with\nspecial meaning may be quoted by preceding it with a backslash.\n\nThe period . matches any single character. It is unspecified whether\nit matches an encoding error.\n\nCharacter Classes and Bracket Expressions\nA bracket expression is a list of characters enclosed by [ and ]. It\nmatches any single character in that list. If the first character of\nthe list is the caret ^ then it matches any character not in the list;\nit is unspecified whether it matches an encoding error. For example,\nthe regular expression [0123456789] matches any single digit.\n\nWithin a bracket expression, a range expression consists of two\ncharacters separated by a hyphen. It matches any single character that\nsorts between the two characters, inclusive, using the locale's\ncollating sequence and character set. For example, in the default C\nlocale, [a-d] is equivalent to [abcd]. Many locales sort characters in\ndictionary order, and in these locales [a-d] is typically not\nequivalent to [abcd]; it might be equivalent to [aBbCcDd], for example.\nTo obtain the traditional interpretation of bracket expressions, you\ncan use the C locale by setting the LCALL environment variable to the\nvalue C.\n\nFinally, certain named classes of characters are predefined within\nbracket expressions, as follows. Their names are self explanatory, and\nthey are [:alnum:], [:alpha:], [:blank:], [:cntrl:], [:digit:],\n[:graph:], [:lower:], [:print:], [:punct:], [:space:], [:upper:], and\n[:xdigit:]. For example, [[:alnum:]] means the character class of\nnumbers and letters in the current locale. In the C locale and ASCII\ncharacter set encoding, this is the same as [0-9A-Za-z]. (Note that\nthe brackets in these class names are part of the symbolic names, and\nmust be included in addition to the brackets delimiting the bracket\nexpression.) Most meta-characters lose their special meaning inside\nbracket expressions. To include a literal ] place it first in the\nlist. Similarly, to include a literal ^ place it anywhere but first.\nFinally, to include a literal - place it last.\n\nAnchoring\nThe caret ^ and the dollar sign $ are meta-characters that respectively\nmatch the empty string at the beginning and end of a line.\n\nThe Backslash Character and Special Expressions\nThe symbols \\< and \\> respectively match the empty string at the\nbeginning and end of a word. The symbol \\b matches the empty string at\nthe edge of a word, and \\B matches the empty string provided it's not\nat the edge of a word. The symbol \\w is a synonym for [[:alnum:]] and\n\\W is a synonym for [^[:alnum:]].\n\nRepetition\nA regular expression may be followed by one of several repetition\noperators:\n? The preceding item is optional and matched at most once.\n* The preceding item will be matched zero or more times.\n+ The preceding item will be matched one or more times.\n{n} The preceding item is matched exactly n times.\n{n,} The preceding item is matched n or more times.\n{,m} The preceding item is matched at most m times. This is a GNU\nextension.\n{n,m} The preceding item is matched at least n times, but not more\nthan m times.\n\nConcatenation\nTwo regular expressions may be concatenated; the resulting regular\nexpression matches any string formed by concatenating two substrings\nthat respectively match the concatenated expressions.\n\nAlternation\nTwo regular expressions may be joined by the infix operator |; the\nresulting regular expression matches any string matching either\nalternate expression.\n\nPrecedence\nRepetition takes precedence over concatenation, which in turn takes\nprecedence over alternation. A whole expression may be enclosed in\nparentheses to override these precedence rules and form a\nsubexpression.\n\nBack-references and Subexpressions\nThe back-reference \\n, where n is a single digit, matches the substring\npreviously matched by the nth parenthesized subexpression of the\nregular expression.\n\nBasic vs Extended Regular Expressions\nIn basic regular expressions the meta-characters ?, +, {, |, (, and )\nlose their special meaning; instead use the backslashed versions \\?,\n\\+, \\{, \\|, \\(, and \\).\n", "subsections": [] }, "EXIT STATUS": { "content": "Normally the exit status is 0 if a line is selected, 1 if no lines were\nselected, and 2 if an error occurred. However, if the -q or --quiet or\n--silent is used and a line is selected, the exit status is 0 even if\nan error occurred.\n", "subsections": [] }, "ENVIRONMENT": { "content": "The behavior of grep is affected by the following environment\nvariables.\n\nThe locale for category LCfoo is specified by examining the three\nenvironment variables LCALL, LCfoo, LANG, in that order. The first\nof these variables that is set specifies the locale. For example, if\nLCALL is not set, but LCMESSAGES is set to ptBR, then the Brazilian\nPortuguese locale is used for the LCMESSAGES category. The C locale\nis used if none of these environment variables are set, if the locale\ncatalog is not installed, or if grep was not compiled with national\nlanguage support (NLS). The shell command locale -a lists locales that\nare currently available.\n\nGREPCOLOR\nThis variable specifies the color used to highlight matched\n(non-empty) text. It is deprecated in favor of GREPCOLORS, but\nstill supported. The mt, ms, and mc capabilities of GREPCOLORS\nhave priority over it. It can only specify the color used to\nhighlight the matching non-empty text in any matching line (a\nselected line when the -v command-line option is omitted, or a\ncontext line when -v is specified). The default is 01;31, which\nmeans a bold red foreground text on the terminal's default\nbackground.\n\nGREPCOLORS\nSpecifies the colors and other attributes used to highlight\nvarious parts of the output. Its value is a colon-separated\nlist of capabilities that defaults to\nms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36 with the rv\nand ne boolean capabilities omitted (i.e., false). Supported\ncapabilities are as follows.\n\nsl= SGR substring for whole selected lines (i.e., matching\nlines when the -v command-line option is omitted, or non-\nmatching lines when -v is specified). If however the\nboolean rv capability and the -v command-line option are\nboth specified, it applies to context matching lines\ninstead. The default is empty (i.e., the terminal's\ndefault color pair).\n\ncx= SGR substring for whole context lines (i.e., non-matching\nlines when the -v command-line option is omitted, or\nmatching lines when -v is specified). If however the\nboolean rv capability and the -v command-line option are\nboth specified, it applies to selected non-matching lines\ninstead. The default is empty (i.e., the terminal's\ndefault color pair).\n\nrv Boolean value that reverses (swaps) the meanings of the\nsl= and cx= capabilities when the -v command-line option\nis specified. The default is false (i.e., the capability\nis omitted).\n\nmt=01;31\nSGR substring for matching non-empty text in any matching\nline (i.e., a selected line when the -v command-line\noption is omitted, or a context line when -v is\nspecified). Setting this is equivalent to setting both\nms= and mc= at once to the same value. The default is a\nbold red text foreground over the current line\nbackground.\n\nms=01;31\nSGR substring for matching non-empty text in a selected\nline. (This is only used when the -v command-line option\nis omitted.) The effect of the sl= (or cx= if rv)\ncapability remains active when this kicks in. The\ndefault is a bold red text foreground over the current\nline background.\n\nmc=01;31\nSGR substring for matching non-empty text in a context\nline. (This is only used when the -v command-line option\nis specified.) The effect of the cx= (or sl= if rv)\ncapability remains active when this kicks in. The\ndefault is a bold red text foreground over the current\nline background.\n\nfn=35 SGR substring for file names prefixing any content line.\nThe default is a magenta text foreground over the\nterminal's default background.\n\nln=32 SGR substring for line numbers prefixing any content\nline. The default is a green text foreground over the\nterminal's default background.\n\nbn=32 SGR substring for byte offsets prefixing any content\nline. The default is a green text foreground over the\nterminal's default background.\n\nse=36 SGR substring for separators that are inserted between\nselected line fields (:), between context line fields,\n(-), and between groups of adjacent lines when nonzero\ncontext is specified (--). The default is a cyan text\nforeground over the terminal's default background.\n\nne Boolean value that prevents clearing to the end of line\nusing Erase in Line (EL) to Right (\\33[K) each time a\ncolorized item ends. This is needed on terminals on\nwhich EL is not supported. It is otherwise useful on\nterminals for which the backcolorerase (bce) boolean\nterminfo capability does not apply, when the chosen\nhighlight colors do not affect the background, or when EL\nis too slow or causes too much flicker. The default is\nfalse (i.e., the capability is omitted).\n\nNote that boolean capabilities have no =... part. They are\nomitted (i.e., false) by default and become true when specified.\n\nSee the Select Graphic Rendition (SGR) section in the\ndocumentation of the text terminal that is used for permitted\nvalues and their meaning as character attributes. These\nsubstring values are integers in decimal representation and can\nbe concatenated with semicolons. grep takes care of assembling\nthe result into a complete SGR sequence (\\33[...m). Common\nvalues to concatenate include 1 for bold, 4 for underline, 5 for\nblink, 7 for inverse, 39 for default foreground color, 30 to 37\nfor foreground colors, 90 to 97 for 16-color mode foreground\ncolors, 38;5;0 to 38;5;255 for 88-color and 256-color modes\nforeground colors, 49 for default background color, 40 to 47 for\nbackground colors, 100 to 107 for 16-color mode background\ncolors, and 48;5;0 to 48;5;255 for 88-color and 256-color modes\nbackground colors.\n\nLCALL, LCCOLLATE, LANG\nThese variables specify the locale for the LCCOLLATE category,\nwhich determines the collating sequence used to interpret range\nexpressions like [a-z].\n\nLCALL, LCCTYPE, LANG\nThese variables specify the locale for the LCCTYPE category,\nwhich determines the type of characters, e.g., which characters\nare whitespace. This category also determines the character\nencoding, that is, whether text is encoded in UTF-8, ASCII, or\nsome other encoding. In the C or POSIX locale, all characters\nare encoded as a single byte and every byte is a valid\ncharacter.\n\nLCALL, LCMESSAGES, LANG\nThese variables specify the locale for the LCMESSAGES category,\nwhich determines the language that grep uses for messages. The\ndefault C locale uses American English messages.\n\nPOSIXLYCORRECT\nIf set, grep behaves as POSIX requires; otherwise, grep behaves\nmore like other GNU programs. POSIX requires that options that\nfollow file names must be treated as file names; by default,\nsuch options are permuted to the front of the operand list and\nare treated as options. Also, POSIX requires that unrecognized\noptions be diagnosed as \"illegal\", but since they are not really\nagainst the law the default is to diagnose them as \"invalid\".\nPOSIXLYCORRECT also disables NGNUnonoptionargvflags,\ndescribed below.\n\nNGNUnonoptionargvflags\n(Here N is grep's numeric process ID.) If the ith character of\nthis environment variable's value is 1, do not consider the ith\noperand of grep to be an option, even if it appears to be one.\nA shell can put this variable in the environment for each\ncommand it runs, specifying which operands are the results of\nfile name wildcard expansion and therefore should not be treated\nas options. This behavior is available only with the GNU C\nlibrary, and only when POSIXLYCORRECT is not set.\n", "subsections": [] }, "NOTES": { "content": "This man page is maintained only fitfully; the full documentation is\noften more up-to-date.\n", "subsections": [] }, "COPYRIGHT": { "content": "Copyright 1998-2000, 2002, 2005-2021 Free Software Foundation, Inc.\n\nThis is free software; see the source for copying conditions. There is\nNO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR\nPURPOSE.\n", "subsections": [] }, "BUGS": { "content": "Reporting Bugs\nEmail bug reports to the bug-reporting address . An\nemail archive and a\nbug tracker \nare available.\n\nKnown Bugs\nLarge repetition counts in the {n,m} construct may cause grep to use\nlots of memory. In addition, certain other obscure regular expressions\nrequire exponential time and space, and may cause grep to run out of\nmemory.\n\nBack-references are very slow, and may require exponential time.\n", "subsections": [] }, "EXAMPLE": { "content": "The following example outputs the location and contents of any line\ncontaining \"f\" and ending in \".c\", within all files in the current di-\nrectory whose names contain \"g\" and end in \".h\". The -n option outputs\nline numbers, the -- argument treats expansions of \"*g*.h\" starting\nwith \"-\" as file names not options, and the empty file /dev/null causes\nfile names to be output even if only one file name happens to be of the\nform \"*g*.h\".\n\n$ grep -n -- 'f.*\\.c$' *g*.h /dev/null\nargmatch.h:1:/* definitions and prototypes for argmatch.c\n\nThe only line that matches is line 1 of argmatch.h. Note that the reg-\nular expression syntax used in the pattern differs from the globbing\nsyntax that the shell uses to match file names.\n", "subsections": [] }, "SEE ALSO": { "content": "Regular Manual Pages\nawk(1), cmp(1), diff(1), find(1), perl(1), sed(1), sort(1), xargs(1),\nread(2), pcre(3), pcresyntax(3), pcrepattern(3), terminfo(5), glob(7),\nregex(7)\n\nFull Documentation\nA complete manual is avail-\nable. If the info and grep programs are properly installed at your\nsite, the command\n\ninfo grep\n\nshould give you access to the complete manual.\n\nGNU grep 3.7 2019-12-29 GREP(1)", "subsections": [] } }, "summary": "grep, egrep, fgrep, rgrep - print lines that match patterns", "flags": [ { "flag": "-V", "long": "--version", "arg": null, "description": "Output the version number of grep and exit. Pattern Syntax" }, { "flag": "-E", "long": "--extended-regexp", "arg": null, "description": "Interpret PATTERNS as extended regular expressions (EREs, see below)." }, { "flag": "-F", "long": "--fixed-strings", "arg": null, "description": "Interpret PATTERNS as fixed strings, not regular expressions." }, { "flag": "-G", "long": "--basic-regexp", "arg": null, "description": "Interpret PATTERNS as basic regular expressions (BREs, see below). This is the default." }, { "flag": "-P", "long": "--perl-regexp", "arg": null, "description": "Interpret I as Perl-compatible regular expressions (PCREs). This option is experimental when combined with the -z (--null-data) option, and grep -P may warn of unimplemented features. Matching Control -e PATTERNS, --regexp=PATTERNS Use PATTERNS as the patterns. If this option is used multiple times or is combined with the -f (--file) option, search for all patterns given. This option can be used to protect a pattern beginning with \"-\". -f FILE, --file=FILE Obtain patterns from FILE, one per line. If this option is used multiple times or is combined with the -e (--regexp) option, search for all patterns given. The empty file contains zero patterns, and therefore matches nothing." }, { "flag": "-i", "long": "--ignore-case", "arg": null, "description": "Ignore case distinctions in patterns and input data, so that characters that differ only in case match each other." }, { "flag": "", "long": "--no-ignore-case", "arg": null, "description": "Do not ignore case distinctions in patterns and input data. This is the default. This option is useful for passing to shell scripts that already use -i, to cancel its effects because the two options override each other." }, { "flag": "-v", "long": "--invert-match", "arg": null, "description": "Invert the sense of matching, to select non-matching lines." }, { "flag": "-w", "long": "--word-regexp", "arg": null, "description": "Select only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word-constituent characters are letters, digits, and the underscore. This option has no effect if -x is also specified." }, { "flag": "-x", "long": "--line-regexp", "arg": null, "description": "Select only those matches that exactly match the whole line. For a regular expression pattern, this is like parenthesizing the pattern and then surrounding it with ^ and $. -y Obsolete synonym for -i. General Output Control" }, { "flag": "-c", "long": "--count", "arg": null, "description": "Suppress normal output; instead print a count of matching lines for each input file. With the -v, --invert-match option (see below), count non-matching lines." }, { "flag": "", "long": null, "arg": null, "description": "Surround the matched (non-empty) strings, matching lines, context lines, file names, line numbers, byte offsets, and separators (for fields and groups of context lines) with escape sequences to display them in color on the terminal. The colors are defined by the environment variable GREPCOLORS. The deprecated environment variable GREPCOLOR is still supported, but its setting does not have priority. WHEN is never, always, or auto." }, { "flag": "-L", "long": "--files-without-match", "arg": null, "description": "Suppress normal output; instead print the name of each input file from which no output would normally have been printed." }, { "flag": "-l", "long": "--files-with-matches", "arg": null, "description": "Suppress normal output; instead print the name of each input file from which output would normally have been printed. Scanning each input file stops upon first match. -m NUM, --max-count=NUM Stop reading a file after NUM matching lines. If the input is standard input from a regular file, and NUM matching lines are output, grep ensures that the standard input is positioned to just after the last matching line before exiting, regardless of the presence of trailing context lines. This enables a calling process to resume a search. When grep stops after NUM matching lines, it outputs any trailing context lines. When the -c or --count option is also used, grep does not output a count greater than NUM. When the -v or --invert-match option is also used, grep stops after outputting NUM non-matching lines." }, { "flag": "-o", "long": "--only-matching", "arg": null, "description": "Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line." }, { "flag": "-q", "long": "--silent", "arg": null, "description": "Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected. Also see the -s or --no-messages option." }, { "flag": "-s", "long": "--no-messages", "arg": null, "description": "Suppress error messages about nonexistent or unreadable files. Output Line Prefix Control" }, { "flag": "-b", "long": "--byte-offset", "arg": null, "description": "Print the 0-based byte offset within the input file before each line of output. If -o (--only-matching) is specified, print the offset of the matching part itself." }, { "flag": "-H", "long": "--with-filename", "arg": null, "description": "Print the file name for each match. This is the default when there is more than one file to search. This is a GNU extension." }, { "flag": "-h", "long": "--no-filename", "arg": null, "description": "Suppress the prefixing of file names on output. This is the default when there is only one file (or only standard input) to search. --label=LABEL Display input actually coming from standard input as input coming from file LABEL. This can be useful for commands that transform a file's contents before searching, e.g., gzip -cd foo.gz | grep --label=foo -H 'some pattern'. See also the -H option." }, { "flag": "-n", "long": "--line-number", "arg": null, "description": "Prefix each line of output with the 1-based line number within its input file." }, { "flag": "-T", "long": "--initial-tab", "arg": null, "description": "Make sure that the first character of actual line content lies on a tab stop, so that the alignment of tabs looks normal. This is useful with options that prefix their output to the actual content: -H,-n, and -b. In order to improve the probability that lines from a single file will all start at the same column, this also causes the line number and byte offset (if present) to be printed in a minimum size field width." }, { "flag": "-Z", "long": "--null", "arg": null, "description": "Output a zero byte (the ASCII NUL character) instead of the character that normally follows a file name. For example, grep -lZ outputs a zero byte after each file name instead of the usual newline. This option makes the output unambiguous, even in the presence of file names containing unusual characters like newlines. This option can be used with commands like find -print0, perl -0, sort -z, and xargs -0 to process arbitrary file names, even those that contain newline characters. Context Line Control -A NUM, --after-context=NUM Print NUM lines of trailing context after matching lines. Places a line containing a group separator (--) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given. -B NUM, --before-context=NUM Print NUM lines of leading context before matching lines. Places a line containing a group separator (--) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given. -C NUM, -NUM, --context=NUM Print NUM lines of output context. Places a line containing a group separator (--) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given. --group-separator=SEP When -A, -B, or -C are in use, print SEP instead of -- between groups of lines." }, { "flag": "", "long": "--no-group-separator", "arg": null, "description": "When -A, -B, or -C are in use, do not print a separator between groups of lines. File and Directory Selection" }, { "flag": "-a", "long": "--text", "arg": null, "description": "Process a binary file as if it were text; this is equivalent to the --binary-files=text option. --binary-files=TYPE If a file's data or metadata indicate that the file contains binary data, assume that the file is of type TYPE. Non-text bytes indicate binary data; these are either output bytes that are improperly encoded for the current locale, or null input bytes when the -z option is not given. By default, TYPE is binary, and grep suppresses output after null input binary data is discovered, and suppresses output lines that contain improperly encoded data. When some output is suppressed, grep follows any output with a one-line message saying that a binary file matches. If TYPE is without-match, when grep discovers null input binary data it assumes that the rest of the file does not match; this is equivalent to the -I option. If TYPE is text, grep processes a binary file as if it were text; this is equivalent to the -a option. When type is binary, grep may treat non-text bytes as line terminators even without the -z option. This means choosing binary versus text can affect whether a pattern matches a file. For example, when type is binary the pattern q$ might match q immediately followed by a null byte, even though this is not matched when type is text. Conversely, when type is binary the pattern . (period) might not match a null byte. Warning: The -a option might output binary garbage, which can have nasty side effects if the output is a terminal and if the terminal driver interprets some of it as commands. On the other hand, when reading files whose text encodings are unknown, it can be helpful to use -a or to set LCALL='C' in the environment, in order to find more matches even if the matches are unsafe for direct display. -D ACTION, --devices=ACTION If an input file is a device, FIFO or socket, use ACTION to process it. By default, ACTION is read, which means that devices are read just as if they were ordinary files. If ACTION is skip, devices are silently skipped. -d ACTION, --directories=ACTION If an input file is a directory, use ACTION to process it. By default, ACTION is read, i.e., read directories just as if they were ordinary files. If ACTION is skip, silently skip directories. If ACTION is recurse, read all files under each directory, recursively, following symbolic links only if they are on the command line. This is equivalent to the -r option. --exclude=GLOB Skip any command-line file with a name suffix that matches the pattern GLOB, using wildcard matching; a name suffix is either the whole name, or a trailing part that starts with a non-slash character immediately after a slash (/) in the name. When searching recursively, skip any subfile whose base name matches GLOB; the base name is the part after the last slash. A pattern can use *, ?, and [...] as wildcards, and \\ to quote a wildcard or backslash character literally. --exclude-from=FILE Skip files whose base name matches any of the file-name globs read from FILE (using wildcard matching as described under --exclude). --exclude-dir=GLOB Skip any command-line directory with a name suffix that matches the pattern GLOB. When searching recursively, skip any subdirectory whose base name matches GLOB. Ignore any redundant trailing slashes in GLOB. -I Process a binary file as if it did not contain matching data; this is equivalent to the --binary-files=without-match option. --include=GLOB Search only files whose base name matches GLOB (using wildcard matching as described under --exclude). If contradictory --include and --exclude options are given, the last matching one wins. If no --include or --exclude options match, a file is included unless the first such option is --include." }, { "flag": "-r", "long": "--recursive", "arg": null, "description": "Read all files under each directory, recursively, following symbolic links only if they are on the command line. Note that if no file operand is given, B searches the working directory. This is equivalent to the -d recurse option." }, { "flag": "-R", "long": "--dereference-recursive", "arg": null, "description": "Read all files under each directory, recursively. Follow all symbolic links, unlike -r. Other Options" }, { "flag": "", "long": "--line-buffered", "arg": null, "description": "Use line buffering on output. This can cause a performance penalty." }, { "flag": "-U", "long": "--binary", "arg": null, "description": "Treat the file(s) as binary. By default, under MS-DOS and MS- Windows, grep guesses whether a file is text or binary as described for the --binary-files option. If grep decides the file is a text file, it strips the CR characters from the original file contents (to make regular expressions with ^ and $ work correctly). Specifying -U overrules this guesswork, causing all files to be read and passed to the matching mechanism verbatim; if the file is a text file with CR/LF pairs at the end of each line, this will cause some regular expressions to fail. This option has no effect on platforms other than MS-DOS and MS-Windows." }, { "flag": "-z", "long": "--null-data", "arg": null, "description": "Treat input and output data as sequences of lines, each terminated by a zero byte (the ASCII NUL character) instead of a newline. Like the -Z or --null option, this option can be used with commands like sort -z to process arbitrary file names." } ], "examples": [ "The following example outputs the location and contents of any line", "containing \"f\" and ending in \".c\", within all files in the current di-", "rectory whose names contain \"g\" and end in \".h\". The -n option outputs", "line numbers, the -- argument treats expansions of \"*g*.h\" starting", "with \"-\" as file names not options, and the empty file /dev/null causes", "file names to be output even if only one file name happens to be of the", "form \"*g*.h\".", "$ grep -n -- 'f.*\\.c$' *g*.h /dev/null", "argmatch.h:1:/* definitions and prototypes for argmatch.c", "The only line that matches is line 1 of argmatch.h. Note that the reg-", "ular expression syntax used in the pattern differs from the globbing", "syntax that the shell uses to match file names." ], "see_also": [ { "name": "awk", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/awk/1/json" }, { "name": "cmp", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/cmp/1/json" }, { "name": "diff", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/diff/1/json" }, { "name": "find", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/find/1/json" }, { "name": "perl", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/perl/1/json" }, { "name": "sed", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/sed/1/json" }, { "name": "sort", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/sort/1/json" }, { "name": "xargs", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/xargs/1/json" }, { "name": "read", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/read/2/json" }, { "name": "pcre", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/pcre/3/json" }, { "name": "pcresyntax", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/pcresyntax/3/json" }, { "name": "pcrepattern", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/pcrepattern/3/json" }, { "name": "terminfo", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/terminfo/5/json" }, { "name": "glob", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/glob/7/json" }, { "name": "regex", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/regex/7/json" } ] }