PCREGREP(1)

💖 PCREGREP(1) — General Commands Manual 💖

okay bestie, pull up a chair, because we're about to talk about pcregrep, and honestly? it's giving main character energy in the grep universe. ✨

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🌸 NAME 🌸

pcregrep — a grep with Perl-compatible regular expressions.

like. it's grep. but make it Perl. no cap. 💅

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🦋 SYNOPSIS 🦋

pcregrep [options] [long options] [pattern] [path1 path2 ...]

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✨ DESCRIPTION ✨

so here's the tea: pcregrep searches files for character patterns, exactly like all your other grep besties do, but it uses the PCRE regular expression library so it can support patterns that are compatible with Perl 5's regular expressions. iconic behaviour honestly.

if you want a quick-reference summary of pattern syntax, go peek at pcresyntax(3), or if you want the full lore — the whole description of the syntax and semantics of the regexes PCRE supports — that's pcrepattern(3). 🫶

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

pcregrep Thursday /etc/motd

now, if you try to use delimiters (like, say, wrapping your pattern in slashes the way Perl scripts love to do), they get interpreted as part of the pattern. 😭 quotes though? quotes are totally fine for delimiting patterns on the command line, because the shell handles them. and actually quotes are required if your pattern contains white space or shell metacharacters. periodt.

the first argument that follows any option settings is treated as the single pattern to be matched when neither -e nor -f is present. conversely, when one or both of these options are used to specify patterns, all arguments are treated as path names. and at least one of -e, -f, or an argument pattern must be provided. you can't just vibe in with nothing, babe. 🙈

if no files are specified, pcregrep reads the standard input. the standard input can also be referenced by a name consisting of a single hyphen. for example:

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 bestie, there are options that can change how pcregrep behaves. in particular, the -M option makes it possible to search for patterns that span line boundaries. what even 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 is 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), 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. 🧚

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

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. the way that it does that… 👑

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.

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🌸 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. the standard input is always so treated. 💅

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🦋 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. 🎀

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• -- — 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. lifesaver honestly 🫶
• -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 the 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 the word is "text", which is equivalent to the -a or --text option, binary files are processed in the same way as any other file. in this case, when a match succeeds, the output may be binary garbage, which can have nasty effects if sent to a terminal. ⚠️ if the 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 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. 💀 (also yes, the original really does say "are are", we're keeping it, it's iconic)
• --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 — if an input path is a directory, action specifies how it is to be processed. valid values are "read" (the default in non-Windows environments, for compatibility with GNU grep), "recurse" (equivalent to the -r option), or "skip" (silently skip the path, the default in Windows environments). in the "read" case, directories are read as if they were ordinary files. in some operating systems the effect of reading a directory like this is an immediate end-of-file; in others it may provoke an error. 🌀
• -e pattern, --regex=pattern, --regexp=pattern — bestie you can drop a pattern in here 💖 and it's the pattern that gets matched. Use it as many times as your heart desires to add multiple patterns. Also the ✨iconic✨ trick for a single pattern that starts with a hyphen (because otherwise the command line would be like “ma’am that’s a flag”). When -e is in play, no argument pattern is taken from the command line; every argument is treated as a file name. There’s literally no limit to the number of patterns. They get applied to each line in the order you defined them 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 real talk: multiple use of -e is not the same as a single pattern with alternatives. 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. 😭

• --exclude=pattern — files (but not directories) whose names match pattern get skipped without being processed. No thoughts, no processing, just ghosted 👻. This applies to all files, whether listed on the command line, obtained from --file-list, or by scanning a directory. 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 in order to specify multiple patterns. If a file name matches both an --include and an --exclude pattern, it is excluded. There is no short form for this option. 💅
• --exclude-from=filename — treat 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. You can give this more than once in order to specify a number of files to read. 🌸
• --exclude-dir=pattern — directories whose names match pattern are skipped without being processed, whatever the setting of the --recursive option. This applies to all directories, whether listed on the command line, obtained from --file-list, or by scanning a parent directory. pattern is a PCRE regular expression, and is 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 in order 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 — interpret 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. 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. ✨
• -f filename, --file=filename — read patterns from the file, one per line, and match 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 — read 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. 💀
• -H, --with-filename — force 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 — suppress 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 — output a help message, giving brief details of the command options and file type support, and then exit. Anything else on the command line is ignored. 🫶
• -I — treat binary files as never matching. This is equivalent to --binary-files=without-match. 🚫
• -i, --ignore-case — ignore upper/lower case distinctions during comparisons. No cap, case doesn’t matter. 💅
• --include=pattern — if any --include patterns are specified, the only files that are 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. pattern is a PCRE regular expression, and is 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 — treat 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 are 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. pattern is a PCRE regular expression, and is 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. 💔
• -l, --files-with-matches — instead of outputting lines from the files, just output the names of the files containing lines that would have been output. Each file name is output once, on a separate line. Searching normally stops as soon as a matching line is found in a file. However, if the -c (count) option is also used, matching continues in order to obtain the correct count, and those files that have at least one match are listed along with their counts. Using this option with -c is a way of suppressing the listing of files with no matches. 👑
• --label=name — this option supplies a name to be used for the standard input when file names are being output. If not supplied, "(standard input)" is used. There is no short form for this option. 🏷️
• --line-buffered — okay so bestie, when you turn this on, pcregrep reads and processes input line by line, and flushes the output after every single write. By default it reads in big chonky chunks instead, unless pcregrep can tell it's reading from a terminal (which, rn, is only a thing in Unix-like environments). Output to a terminal is normally auto-flushed by the OS anyway. This option is a whole vibe when your input or output is hooked up to a pipe and you do NOT want pcregrep buffering up massive amounts of data. BUT — and this is the tea — it will affect performance, and the -M (multiline) option stops working entirely. 💀
• --line-offsets — instead of showing you the lines or parts of lines that matched, this shows each match as a line number, the offset from the start of the line, and a length. The line number gets a colon after it (as usual, see -n), and the offset and length are separated by a comma. In this mode there's no context at all, meaning -A, -B, and -C are straight up ignored. If there's more than one match in a line, each one gets shown separately. Also, this option is mutually exclusive with --file-offsets and --only-matching — pick one bestie. 💅
• --locale=locale-name — this one picks a locale to use for pattern matching, and it overrides whatever's in the LC_ALL or LC_CTYPE environment variables. If you don't specify a locale, the PCRE library's default gets used (usually the "C" locale). Heads up: there is no short form for this option. 🎀
• --match-limit=number — so some regex patterns are lowkey menaces and can eat up an absolutely unhinged amount of memory, which can straight up crash your program if there isn't enough available. Other patterns might take forever trying to search 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 uses.

The --match-limit option is your little resource-usage seatbelt for patterns that aren't gonna match but have a huge number of possibilities in their search trees. The classic example? A pattern that uses nested unlimited repeats. Internally, PCRE uses a function called match() which it calls over and over (sometimes recursively). The limit you set with --match-limit gets imposed on how many times that function is called during a match, which limits how much backtracking can happen.

The --recursion-limit option is like --match-limit's sibling, but instead of capping the total number of times match() is called, it caps the depth of recursive calls, which limits how much memory can get used. Recursion depth is a smaller number than total calls, because not every call to match() is recursive. This limit only matters if you set it smaller than --match-limit.

No short forms for either of these, sorry bestie. The defaults get set when the PCRE library is compiled, and the default default is 10 million. ✨

• -M, --multiline — lets patterns match more than one line. When this is on, your patterns can actually make use of literal newline characters and internal ^ and $ characters. The output for a successful match might span more than one line, and the last of those is the one where the match ended. If the matched string ends with a newline sequence, the output ends right at the end of that line.

When this option is set, the PCRE library gets called in "multiline" mode. There's a limit to how many lines can be matched, imposed by the way pcregrep buffers the input file as it scans. However, 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 there are fewer than 8K) are guaranteed available for lookbehind assertions. 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, bestie. They are:
  • the single-character sequences CR (carriage return) and LF (linefeed)
  • the two-character sequence CRLF
  • an "anycrlf" convention, which recognizes any of the preceding three types
  • 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 gets specified — normally the standard one for your OS. 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 is what lets you use pcregrep to scan files that came from other environments without having to touch their line endings. If the data you're scanning doesn't agree with the convention you set here, pcregrep may behave in strange ways. Also note: 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 front of 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 gets forced on if --line-offsets is used. 👑
• --no-jit — if the PCRE library was 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 lets you disable JIT at run time instead. It exists for testing and working around problems. It should never be needed in normal use, fr fr. 🧚
• -o, --only-matching — shows only the part of the line that matched a pattern instead of the whole line. In this mode there's no context shown — that is, -A, -B, and -C are ignored. If there's more than one match in a line, each one gets 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 gets output — unless the file name or line number are 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 has to be in the same shell item, like -o3 or --only-matching=2. All the comments from 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 gets output — unless the file name or line number are being printed.

If you give this option multiple times, multiple substrings get output, in the order you gave the options. 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 — specifies 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. 🤫
• -r, --recursive — if any given path is a directory, recursively scan the files inside it, taking note of any --include and --exclude settings. By default, a directory is read as a normal file — and in some operating systems that just gives you an immediate end-of-file. This option is a shorthand for setting the -d option to "recurse". 🌸
• --recursion-limit=number — see --match-limit above, bestie. ⬆️
• -s, --no-messages — suppresses error messages about non-existent or unreadable files. Those files get quietly skipped. However, the return code is still 2, even if matches were found in other files. 💅
• -u, --utf-8 — operate in UTF-8 mode. This option is only available if PCRE was compiled with UTF-8 support. All patterns (including those for any --exclude and --include options) and all subject lines that get scanned must be valid strings of UTF-8 characters. ✨
• -V, --version — writes the version numbers of pcregrep and the PCRE library to the standard output, then exits. Anything else on the command line is ignored. 👑
• -v, --invert-match — inverts the sense of the match, so that lines which do not match any of the patterns are the ones that get found. 🔥
• -w, --word-regex, --word-regexp — okay so this one forces your patterns to match only whole words. It's literally the same as putting \b at the start and at the end of the pattern. Important bestie: this only applies to patterns matched against the contents of files. It does not apply to patterns specified by any of the --include or --exclude options. Periodt. 💅
• -x, --line-regex, --line-regexp — this one forces patterns to be anchored (each must start matching at the beginning of a line) and also requires them to match entire lines. Equivalent to having ^ and $ at the start and end of each alternative branch in every pattern. Same deal as above: applies only to patterns matched against contents of files, not to patterns from any --include or --exclude options. 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. It's giving "respect the locale order, bestie." 🌈

🦋 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. Lowkey iconic. ✨

💖 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, these are specific to pcregrep: --file-list, --file-offsets, --include-dir, --line-offsets, --locale, --match-limit, -M, --multiline, -N, --newline, --om-separator, --recursion-limit, -u, and --utf-8. Also specific to pcregrep: the use of the --only-matching option with a capturing parentheses number. Iykyk. 👑

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. Not me comparing them, but okay. 💀

🍓 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. Shell girlies know. 🐚

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. Periodt. 💅

😭 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 "runaway regex said no ma'am." 🚨

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). Keep that in mind, bestie. 🧠

🩺 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. The way that exit codes are literally the vibe check. ✅

🔗 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.

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And that's the whole PCRE 8.35 manual page, bestie! It's dated 03 April 2014, and the footer says PCREGREP(1). Copyright (c) 1997-2014 University of Cambridge, author Philip Hazel, University Computing Service, Cambridge CB2 3QH, England. Go slay those regexes. 💖✨🦋