PCREGREP(1)

📦 version 8.39, in debian bookworm, ubuntu jammy, ubuntu noble, ubuntu questing

💅 PCREGREP(1) — General Commands Manual 💅

okay bestie, welcome to the pcregrep page, this one lives in section 1 of the General Commands Manual and it is long, so buckle up 💖

✨ NAME ✨

pcregrep — it's a grep, but make it ✨Perl-compatible regular expressions✨. that's the whole vibe.

🌸 SYNOPSIS 🌸

pcregrep [options] [long options] [pattern] [path1 path2 ...]
zpcregrep [options] [long options] [pattern] [file1 file2 ...]

🦋 DESCRIPTION 🦋

so pcregrep searches files for character patterns, literally the same energy as every other grep command out there, BUT it uses the PCRE regular expression library so it can flex patterns that are compatible with the regular expressions of Perl 5. if you want the quick-and-dirty cheat sheet for pattern syntax, go read pcresyntax(3), and if you want the full tea on the syntax and semantics of the regexes PCRE supports, that's pcrepattern(3). 🫶

Patterns — whether you hand them over on the command line or pop them in a separate file — are given without delimiters. like, for example:

pcregrep Thursday /etc/motd

if you try to use delimiters anyway (say, wrapping your pattern in slashes the way Perl scripts love to do) they get interpreted as part of the pattern, not as delimiters. no cap. quotes can of course be used to delimit patterns on the command line, because the shell is the one interpreting those, and honestly quotes are required if your pattern has white space or shell metacharacters in it.

The first argument that follows any option settings is treated as the single pattern to be matched — but ONLY when neither -e nor -f is present. conversely, when one or both of those options are used to specify patterns, all the arguments are treated as path names. and you need at least one of -e, -f, or an argument pattern, periodt.

If no files are specified, pcregrep reads the standard input. and the standard input can also be referenced by a name consisting of a single hyphen. like:

pcregrep some-pattern /file1 - /file3

By default, each line that matches a pattern gets copied to the standard output, and if there's more than one file, the file name is output at the start of each line, followed by a colon. but there are options that can change how pcregrep behaves, obviously. in particular, the -M option makes it possible to search for patterns that span line boundaries. what actually defines a line boundary is controlled by the -N (--newline) option. 💫

The amount of memory used for buffering files that are being scanned is controlled by a parameter that can be set by the --buffer-size option. the default value for this parameter is specified when pcregrep is built, with the default default being 20K. a block of memory three times this size is used (to allow for buffering "before" and "after" lines). an error occurs if a line overflows the buffer. 🫠

Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the greater. BUFSIZ is defined in <stdio.h>. when there's more than one pattern (specified by the use of -e and/or -f), each pattern is applied to each line in the order in which they are defined, except that all the -e patterns are tried before the -f patterns.

By default, as soon as one pattern matches a line, no further patterns are considered. HOWEVER — if --colour (or --color) is used to colour the matching substrings, or if --only-matching, --file-offsets, or --line-offsets is used to output only the part of the line that matched (either shown literally, or as an offset), then scanning resumes immediately following the match, so that further matches on the same line can be found. if there are multiple patterns, they are all tried on the remainder of the line, but patterns that follow the one that matched are not tried on the earlier part of the line. iykyk 💅

This behaviour means that the order in which multiple patterns are specified can affect the output when one of the above options is used. this is no longer the same behaviour as GNU grep, which now manages to display earlier matches for later patterns (as long as there is no overlap).

Patterns that can match an empty string are accepted, but empty string matches are never recognized. an example is the pattern "(super)?(man)?", in which all components are optional. this pattern finds all occurrences of both "super" and "man"; the output differs from matching with "super|man" when only the matching substrings are being shown. 🙈

If the LC_ALL or LC_CTYPE environment variable is set, pcregrep uses the value to set a locale when calling the PCRE library. the --locale option can be used to override this.

zpcregrep is a wrapper script that allows pcregrep to work on gzip compressed files. cute right? 🎀

🗜️ SUPPORT FOR COMPRESSED FILES 🗜️

It is possible to compile pcregrep so that it uses libz or libbz2 to read files whose names end in .gz or .bz2, respectively. you can find out whether your binary has support for one or both of these file types by running it with the --help option. if the appropriate support is not present, files are treated as plain text. and the standard input is always so treated. 🌈

💀 BINARY FILES 💀

By default, a file that contains a binary zero byte within the first 1024 bytes is identified as a binary file, and is processed specially. (GNU grep also identifies binary files in this manner.) see the --binary-files option for a means of changing the way binary files are handled. 👑

👑 OPTIONS 👑

The order in which some of the options appear can affect the output. for example, both the -h and -l options affect the printing of file names. whichever comes later in the command line will be the one that takes effect. similarly, except where noted below, if an option is given twice, the later setting is used. numerical values for options may be followed by K or M, to signify multiplication by 1024 or 1024*1024 respectively. ⭐

  • -- — this terminates the list of options. it's useful if the next item on the command line starts with a hyphen but is not an option. this allows for the processing of patterns and filenames that start with hyphens.
  • -A number, --after-context=number — output number lines of context after each matching line. if filenames and/or line numbers are being output, a hyphen separator is used instead of a colon for the context lines. a line containing "--" is output between each group of lines, unless they are in fact contiguous in the input file. the value of number is expected to be relatively small. however, pcregrep guarantees to have up to 8K of following text available for context output.
  • -a, --text — treat binary files as text. this is equivalent to --binary-files=text.
  • -B number, --before-context=number — output number lines of context before each matching line. if filenames and/or line numbers are being output, a hyphen separator is used instead of a colon for the context lines. a line containing "--" is output between each group of lines, unless they are in fact contiguous in the input file. the value of number is expected to be relatively small. however, pcregrep guarantees to have up to 8K of preceding text available for context output.
  • --binary-files=word — specify how binary files are to be processed. if word is "binary" (the default), pattern matching is performed on binary files, but the only output is "Binary file <name> matches" when a match succeeds. if word is "text", which is equivalent to the -a or --text option, binary files are processed in the same way as any other file — and in this case, when a match succeeds, the output may be binary garbage, which can have nasty effects if sent to a terminal 😭. if word is "without-match", which is equivalent to the -I option, binary files are not processed at all; they are assumed not to be of interest.
  • --buffer-size=number — set the parameter that controls how much memory is used for buffering files that are being scanned.
  • -C number, --context=number — output number lines of context both before and after each matching line. this is equivalent to setting both -A and -B to the same value. 🫶
  • -c, --count — do not output individual lines from the files that are being scanned; instead output the number of lines that would otherwise have been shown. if no lines are selected, the number zero is output. if several files are being scanned, a count is output for each of them. however, if the --files-with-matches option is also used, only those files whose counts are greater than zero are listed. when -c is used, the -A, -B, and -C options are ignored. 💅
  • --colour, --color — if this option is given without any data, it is equivalent to "--colour=auto". if data is required, it must be given in the same shell item, separated by an equals sign.
  • --colour=value, --color=value — this option specifies under what circumstances the parts of a line that matched a pattern should be coloured in the output. by default, the output is not coloured. the value (which is optional, see above) may be "never", "always", or "auto". in the latter case, colouring happens only if the standard output is connected to a terminal. more resources are used when colouring is enabled, because pcregrep has to search for all possible matches in a line, not just one, in order to colour them all. 🌈

the colour that is used can be specified by setting the environment variable PCREGREP_COLOUR or PCREGREP_COLOR. the value of this variable should be a string of two numbers, separated by a semicolon. they are copied directly into the control string for setting colour on a terminal, so it is your responsibility to ensure that they make sense. if neither of the environment variables is set, the default is "1;31", which gives red. 🍓

  • -D action, --devices=action — if an input path is not a regular file or a directory, action specifies how it is to be processed. valid values are "read" (the default) or "skip" (silently skip the path). ✨
  • -d action, --directories=action — bestie, if an input path is a directory, action tells pcregrep how to deal with it. The valid values are read (the default in non-Windows environments, for compatibility with GNU grep), recurse (literally just the same thing as the -r option), or skip (silently skips the path — this one's the default in Windows environments 💅). In the read case, directories get read as if they were ordinary files. Ngl on some operating systems reading a directory like this gives you an immediate end-of-file; on others it may provoke an error 😭. So like, vibe check your OS first.
  • -e pattern, --regex=pattern, --regexp=pattern — ok so this specifies a pattern to be matched. You can use it multiple times to specify several patterns, no cap. It's also your go-to way of specifying a single pattern that starts with a hyphen (since otherwise pcregrep would think it's a flag 🙈). The moment you use -e, no argument pattern is taken from the command line anymore — all arguments are treated as file names, periodt. There is no limit to the number of patterns ✨. They get applied to each line in the order they were defined, until one matches.

If -f is used with -e, the command line patterns are matched first, followed by the patterns from the file(s) — independent of the order in which these options are specified. And heads up, queen: multiple use of -e is not the same as a single pattern with alternatives. For example, X|Y finds the first character in a line that is X or Y, whereas if the two patterns are given separately, with X first, pcregrep finds X if it is present, even if it follows Y in the line. It finds Y only if there is no X in the line. This matters only if you are using -o or --colo(u)r to show the part(s) of the line that matched. So like, only relevant in the showing-off era 💅.

  • --exclude=pattern — files (but not directories, ok?) whose names match the pattern get skipped without being processed. This applies to all files, whether listed on the command line, obtained from --file-list, or by scanning a directory. The pattern is a PCRE regular expression, and it's matched against the final component of the file name, not the entire path. The -F, -w, and -x options do not apply to this pattern. You can give this option any number of times to specify multiple patterns. If a file name matches both an --include and an --exclude pattern, it is excluded (exclude always wins, sorry 😔). There is no short form for this option.
  • --exclude-from=filename — treats each non-empty line of the file as the data for an --exclude option. What counts as a newline when reading the file is the operating system's default. The --newline option has no effect on this option. This option may be given more than once in order to specify a number of files to read.
  • --exclude-dir=pattern — directories whose names match the pattern get skipped without being processed, whatever the setting of the --recursive option. Applies to all directories, whether listed on the command line, obtained from --file-list, or by scanning a parent directory. The pattern is a PCRE regular expression, matched against the final component of the directory name, not the entire path. The -F, -w, and -x options do not apply to this pattern. Give it any number of times to specify more than one pattern. If a directory matches both --include-dir and --exclude-dir, it is excluded. There is no short form for this option.
  • -F, --fixed-strings — interprets each data-matching pattern as a list of fixed strings, separated by newlines, instead of as a regular expression. What counts as a newline for this purpose is controlled by the --newline option. The -w (match as a word) and -x (match whole line) options can be used with -F, and they apply to each of the fixed strings. A line is selected if any of the fixed strings are found in it (subject to -w or -x, if present). This option applies only to the patterns that are matched against the contents of files — it does not apply to patterns specified by any of the --include or --exclude options. Got it? 🫶
  • -f filename, --file=filename — reads patterns from the file, one per line, and matches them against each line of input. What counts as a newline when reading the file is the operating system's default. The --newline option has no effect on this option. Trailing white space is removed from each line, and blank lines are ignored. An empty file contains no patterns and therefore matches nothing 💀. See also the comments about multiple patterns versus a single pattern with alternatives in the description of -e above.

If this option is given more than once, all the specified files are read. A data line is output if any of the patterns match it. A filename can be given as - to refer to the standard input. When -f is used, patterns specified on the command line using -e may also be present; they are tested before the file's patterns. However, no other pattern is taken from the command line — all arguments are treated as the names of paths to be searched.

  • --file-list=filename — reads a list of files and/or directories that are to be scanned from the given file, one per line. Trailing white space is removed from each line, and blank lines are ignored. These paths are processed before any that are listed on the command line. The filename can be given as - to refer to the standard input. If --file and --file-list are both specified as -, patterns are read first. This is useful only when the standard input is a terminal, from which further lines (the list of files) can be read after an end-of-file indication. If this option is given more than once, all the specified files are read.
  • --file-offsets — instead of showing lines or parts of lines that match, show each match as an offset from the start of the file and a length, separated by a comma. In this mode, no context is shown — that is, the -A, -B, and -C options are ignored 🙈. If there is more than one match in a line, each of them is shown separately. This option is mutually exclusive with --line-offsets and --only-matching. Pick a lane, bestie.
  • -H, --with-filename — forces the inclusion of the filename at the start of output lines when searching a single file. By default, the filename is not shown in this case. For matching lines, the filename is followed by a colon; for context lines, a hyphen separator is used. If a line number is also being output, it follows the file name.
  • -h, --no-filename — suppresses the output filenames when searching multiple files. By default, filenames are shown when multiple files are searched. For matching lines, the filename is followed by a colon; for context lines, a hyphen separator is used. If a line number is also being output, it follows the file name.
  • --help — outputs a help message giving brief details of the command options and file type support, and then exits. Anything else on the command line is ignored. It's giving "I don't have time for your other flags" energy 💅.
  • -I — treats binary files as never matching. This is equivalent to --binary-files=without-match.
  • -i, --ignore-case — ignores upper/lower case distinctions during comparisons. Uppercase who? Never heard of her ✨.
  • --include=pattern — if any --include patterns are specified, the only files that get processed are those that match one of the patterns (and do not match an --exclude pattern). This option does not affect directories, but it applies to all files, whether listed on the command line, obtained from --file-list, or by scanning a directory. The pattern is a PCRE regular expression, matched against the final component of the file name, not the entire path. The -F, -w, and -x options do not apply to this pattern. The option may be given any number of times. If a file name matches both an --include and an --exclude pattern, it is excluded. There is no short form for this option.
  • --include-from=filename — treats each non-empty line of the file as the data for an --include option. What constitutes a newline for this purpose is the operating system's default. The --newline option has no effect on this option. This option may be given any number of times; all the files are read.
  • --include-dir=pattern — if any --include-dir patterns are specified, the only directories that get processed are those that match one of the patterns (and do not match an --exclude-dir pattern). This applies to all directories, whether listed on the command line, obtained from --file-list, or by scanning a parent directory. The pattern is a PCRE regular expression, matched against the final component of the directory name, not the entire path. The -F, -w, and -x options do not apply to this pattern. The option may be given any number of times. If a directory matches both --include-dir and --exclude-dir, it is excluded. There is no short form for this option.
  • -L, --files-without-match — instead of outputting lines from the files, just output the names of the files that do not contain any lines that would have been output. Each file name is output once, on a separate line. It's the anti-match era, and honestly? Iconic. 👑
  • -l, --files-with-matches — bestie, instead of spilling the actual lines, this just tells you which files had lines that would've been printed. Each file name shows up exactly once, on its own line, no repeats 💅. Normally the search dips the second it finds a matching line in a file — like, done, next. BUT if you also pass -c (count), it keeps going so the count is actually correct, and then those files with at least one match get listed with their counts. So using -l with -c? That's the lowkey genius way to hide all the files that had zero matches. Slay.
  • --label=name — gives a name to use for standard input whenever file names are being printed. Don't supply one and it defaults to "(standard input)". There's no short form for this one, so don't go looking 💀.
  • --line-buffered — with this on, input gets read and processed line by line, and output is flushed after every single write. By default, input is read in big chunky chunks, unless pcregrep can tell it's reading from a terminal (which rn is only possible in Unix-like environments). Output to a terminal is normally auto-flushed by the OS anyway. This option is your girl when the input or output is hooked up to a pipe and you do not want pcregrep hoarding huge amounts of data. The tradeoff? It affects performance, and the -M (multiline) option straight up stops working. 😭
  • --line-offsets — instead of showing lines or bits of lines that matched, show each match as a line number, the offset from the start of the line, and a length. The line number is terminated by a colon (as usual, see the -n option), and the offset and length are separated by a comma. In this mode, no context is shown — meaning the -A, -B, and -C options are ignored. More than one match in a line? Each one gets shown separately. This option is mutually exclusive with --file-offsets and --only-matching.
  • --locale=locale-name — sets the locale used for pattern matching. It overrides whatever's in the LC_ALL or LC_CTYPE environment variables. Don't specify one and the PCRE library's default kicks in (usually the "C" locale). No short form here either, sorry babe.
  • --match-limit=number — okay so some regex patterns are little monsters that need a ton of memory, and if there isn't enough, the program can literally crash. Others can take absolutely forever hunting for every possible matching string. The pcre_exec() function that pcregrep calls to do the matching has two parameters that can cap the resources it burns through.

The --match-limit option is your leash for patterns that aren't gonna match but have a huge number of possibilities in their search trees. The classic example? A pattern with nested unlimited repeats. Internally, PCRE uses a function called match() that it calls over and over (sometimes recursively). The limit set by --match-limit gets imposed on how many times this function is called during a match, which has the effect of capping the amount of backtracking that can happen. 🫶

The --recursion-limit option is similar to --match-limit, except instead of capping the total number of times match() is called, it caps the depth of recursive calls, which in turn caps the amount of memory that can be used. The recursion depth is a smaller number than the total number of calls, because not every call to match() is recursive. This limit only matters if you set it smaller than --match-limit.

There are no short forms for these options. The default settings are specified when the PCRE library is compiled, with the default default being 10 million. 💖

  • -M, --multiline — lets patterns match more than one line. With this on, patterns can usefully contain literal newline characters and internal ^ and $ characters. The output for a successful match might be more than one line, the last of which is the one where the match ended. If the matched string ends with a newline sequence, the output ends at the end of that line.

When this is set, the PCRE library gets called in "multiline" mode. There's a limit on how many lines can be matched, imposed by the way pcregrep buffers the input file while scanning it. That said, pcregrep makes sure at least 8K characters or the rest of the document (whichever is shorter) are available for forward matching, and similarly the previous 8K characters (or all the previous characters, if fewer than 8K) are guaranteed to be available for lookbehind assertions. Heads up: this option does not work when input is read line by line (see --line-buffered). 🙈

  • -N newline-type, --newline=newline-type — the PCRE library supports five different conventions for marking the ends of lines. They are: the single-character sequences CR (carriage return) and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention that recognizes any of the preceding three types, and an "any" convention where any Unicode line ending sequence is assumed to end a line. The Unicode sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029).

When the PCRE library is built, a default line-ending sequence is specified — normally the standard sequence for the operating system. Unless you say otherwise with this option, pcregrep uses the library's default. The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This makes it possible to use pcregrep to scan files that came from other environments without having to touch their line endings. If the data being scanned doesn't agree with the convention you set here, pcregrep may behave in strange ways 😳. Note that this option does not apply to files specified by the -f, --exclude-from, or --include-from options — those are expected to use the operating system's standard newline sequence.

  • -n, --line-number — puts each output line's line number in the file right before it, followed by a colon for matching lines or a hyphen for context lines. If the filename is also being output, it comes before the line number. This option is forced if --line-offsets is used. ⭐
  • --no-jit — if the PCRE library is built with support for just-in-time compiling (which speeds up matching), pcregrep automatically uses it, unless it was explicitly disabled at build time. This option disables the use of JIT at run time. It's provided for testing and working around problems. It should never be needed in normal use. Like, ever. 💀
  • -o, --only-matching — shows only the part of the line that matched a pattern, instead of the whole line. In this mode, no context is shown, so -A, -B, and -C get ignored. If there's more than one match in a line, each one is shown separately. If -o is combined with -v (which inverts the sense of the match to find non-matching lines), no output is generated, but the return code is still set appropriately. If the matched portion of the line is empty, nothing is output — unless the file name or line number is being printed, in which case they show up on an otherwise empty line. This option is mutually exclusive with --file-offsets and --line-offsets. ✨
  • -onumber, --only-matching=number — shows only the part of the line that matched the capturing parentheses of the given number. Up to 32 capturing parentheses are supported, and -o0 is equivalent to -o without a number. Because these options can be given without an argument (see above), if an argument is present it must be in the same shell item — for example, -o3 or --only-matching=2. The comments given for the non-argument case above also apply here. If the specified capturing parentheses don't exist in the pattern, or weren't set in the match, nothing is output unless the file name or line number is being printed.

If this option is given multiple times, multiple substrings get output, in the order the options were given. For example, -o3 -o1 -o3 causes the substrings matched by capturing parentheses 3 and 1 and then 3 again to be output. By default, there's no separator (but see the next option). 🎀

  • --om-separator=text — sets a separating string for multiple occurrences of -o. The default is an empty string. Separating strings are never coloured. 💅
  • -q, --quiet — work quietly, meaning display nothing except error messages. The exit status tells you whether or not any matches were found. Main character energy: says nothing, but you know. 👑
  • -r, --recursive — if any given path is a directory, recursively scan the files it contains, taking note of any --include and --exclude settings. By default, a directory is read as a normal file; in some operating systems this gives an immediate end-of-file. This option is a shorthand for setting the -d option to "recurse". 🦋
  • --recursion-limit=number — see --match-limit above. That's it, that's the whole thing. Go read it, bestie. 🌸
  • -s, --no-messages — suppresses error messages about non-existent or unreadable files. Those files just get quietly skipped. However, the return code is still 2, even if matches were found in other files. 🍓
  • -u, --utf-8 — okay so this one flips on UTF-8 mode, bestie. It's only available if PCRE has been compiled with UTF-8 support. Every pattern (including the ones for any --exclude and --include options) and every subject line that gets scanned has to be a valid string of UTF-8 characters. No fake UTF-8, periodt. 💅
  • -V, --version — this writes the version numbers of pcregrep and the PCRE library to the standard output, then exits. Anything else on the command line is ignored. It's giving "I only came here to say my name" energy. ✨
  • -v, --invert-match — inverts the sense of the match, so the lines that do not match any of the patterns are the ones that get found. Not me flipping the vibe check. 🔄
  • -w, --word-regex, --word-regexp — forces the patterns to match only whole words. This is equivalent to having \b at the start and end of the pattern. This option applies only to the patterns that are matched against the contents of files; it does not apply to patterns specified by any of the --include or --exclude options. So like, file-content patterns only, bestie. 🎀
  • -x, --line-regex, --line-regexp — forces the patterns to be anchored (each must start matching at the beginning of a line) and in addition, requires them to match entire lines. This is equivalent to having ^ and $ characters at the start and end of each alternative branch in every pattern. This option applies only to the patterns that are matched against the contents of files; it does not apply to patterns specified by any of the --include or --exclude options. Whole line or nothing, no cap. 💯

🌸 ENVIRONMENT VARIABLES 🌸

The environment variables LC_ALL and LC_CTYPE are examined, in that order, for a locale. The first one that is set is used. This can be overridden by the --locale option. If no locale is set, the PCRE library's default (usually the "C" locale) is used. So it's a little priority queue, and LC_ALL is first in line. 👑

✨ NEWLINES ✨

The -N (--newline) option allows pcregrep to scan files with different newline conventions from the default. Any parts of the input files that are written to the standard output are copied identically, with whatever newline sequences they have in the input. However, the setting of this option does not affect the interpretation of files specified by the -f, --exclude-from, or --include-from options, which are assumed to use the operating system's standard newline sequence, nor does it affect the way in which pcregrep writes informational messages to the standard error and output streams. For these it uses the string "\n" to indicate newlines, relying on the C I/O library to convert this to an appropriate sequence.

💖 OPTIONS COMPATIBILITY 💖

Many of the short and long forms of pcregrep's options are the same as in the GNU grep program. Any long option of the form --xxx-regexp (GNU terminology) is also available as --xxx-regex (PCRE terminology). However, the --file-list, --file-offsets, --include-dir, --line-offsets, --locale, --match-limit, -M, --multiline, -N, --newline, --om-separator, --recursion-limit, -u, and --utf-8 options are specific to pcregrep, as is the use of the --only-matching option with a capturing parentheses number.

Although most of the common options work the same way, a few are different in pcregrep. For example, the --include option's argument is a glob for GNU grep, but a regular expression for pcregrep. If both the -c and -l options are given, GNU grep lists only file names, without counts, but pcregrep gives the counts. So yeah, they're cousins, not twins. 👯

🎀 OPTIONS WITH DATA 🎀

There are four different ways in which an option with data can be specified. If a short form option is used, the data may follow immediately, or (with one exception) in the next command line item. For example:

-f/some/file
-f /some/file

The exception is the -o option, which may appear with or without data. Because of this, if data is present, it must follow immediately in the same item, for example -o3.

If a long form option is used, the data may appear in the same command line item, separated by an equals character, or (with two exceptions) it may appear in the next command line item. For example:

--file=/some/file
--file /some/file

Note, however, that if you want to supply a file name beginning with ~ as data in a shell command, and have the shell expand ~ to a home directory, you must separate the file name from the option, because the shell does not treat ~ specially unless it is at the start of an item.

The exceptions to the above are the --colour (or --color) and --only-matching options, for which the data is optional. If one of these options does have data, it must be given in the first form, using an equals character. Otherwise pcregrep will assume that it has no data. So don't be shy with that =, bestie. 💅

🔥 MATCHING ERRORS 🔥

It is possible to supply a regular expression that takes a very long time to fail to match certain lines. Such patterns normally involve nested indefinite repeats, for example: (a+)*\d when matched against a line of a's with no final digit. The PCRE matching function has a resource limit that causes it to abort in these circumstances. If this happens, pcregrep outputs an error message and the line that caused the problem to the standard error stream. If there are more than 20 such errors, pcregrep gives up. It's giving "I can't even" but in a stack-overflow way. 😭

The --match-limit option of pcregrep can be used to set the overall resource limit; there is a second option called --recursion-limit that sets a limit on the amount of memory (usually stack) that is used (see the discussion of these options above).

💅 DIAGNOSTICS 💅

Exit status is 0 if any matches were found, 1 if no matches were found, and 2 for syntax errors, overlong lines, non-existent or inaccessible files (even if matches were found in other files) or too many matching errors. Using the -s option to suppress error messages about inaccessible files does not affect the return code. So the exit code is the real main character here. 👑

🦋 SEE ALSO 🦋

pcrepattern(3), pcresyntax(3), pcretest(1).

👑 AUTHOR 👑

Philip Hazel University Computing Service Cambridge CB2 3QH, England.

🌈 REVISION 🌈

Last updated: 03 April 2014 Copyright (c) 1997-2014 University of Cambridge.

And that's a wrap on the PCREGREP(1) page, bestie! This one is from PCRE 8.35, dated 03 April 2014, and it's serving PCREGREP(1) energy. Go forth and grep slay. 💖✨

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