PCREGREP(1)                                                        PCREGREP(1)



NAME
       pcregrep - a grep with Perl-compatible regular expressions.

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

DESCRIPTION

       pcregrep searches files for character patterns, in the same way as
       other grep commands do, but it uses the PCRE regular expression library
       to support patterns that are compatible with the regular expressions of
       Perl 5. See pcrepattern(3) for a full description of syntax and
       semantics of the regular expressions that PCRE supports.

       Patterns, whether supplied on the command line or in a separate file,
       are given without delimiters. For example:

         pcregrep Thursday /etc/motd

       If you attempt to use delimiters (for example, by surrounding a pattern
       with slashes, as is common in Perl scripts), they are interpreted as
       part of the pattern. Quotes can of course be used to delimit patterns
       on the command line because they are interpreted by the shell, and
       indeed they are required if a pattern contains white space or shell
       metacharacters.

       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. At least one of -e,
       -f, or an argument pattern must be provided.

       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 is copied to the standard
       output, and if there is more than one file, the file name is output at
       the start of each line, followed by a colon. However, 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 defines a line boundary is controlled by the -N (--newline)
       option.

       Patterns are limited to 8K or BUFSIZ characters, 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 (or fails to match when -v
       is used), 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 is the same behaviour as GNU grep, but it does mean that the order
       in which multiple patterns are specified can affect the output when one
       of the above options is used.

       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.

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.

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.

       --        This terminate the list of options. It is 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.

       -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.

       -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.

       --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),
                 "recurse" (equivalent to the -r option), or "skip" (silently
                 skip the path). In the default 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.

       -e pattern, --regex=pattern, --regexp=pattern
                 Specify a pattern to be matched. This option can be used
                 multiple times in order to specify several patterns. It can
                 also be used as a way of specifying a single pattern that
                 starts with a hyphen. When -e is used, no argument pattern is
                 taken from the command line; all arguments are treated as
                 file names. There is an overall maximum of 100 patterns. They
                 are applied to each line in the order in which they are
                 defined until one matches (or fails to match if -v is used).
                 If -f is used with -e, the command line patterns are matched
                 first, followed by the patterns from the file, independent of
                 the order in which these options are specified. Note that
                 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, 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 really matters only if you are using -o to
                 show the part(s) of the line that matched.

       --exclude=pattern
                 When pcregrep is searching the files in a directory as a
                 consequence of the -r (recursive search) option, any regular
                 files whose names match the pattern are excluded.
                 Subdirectories are not excluded by this option; they are
                 searched recursively, subject to the --exclude-dir and
                 --include_dir options. The pattern is a PCRE regular
                 expression, and is matched against the final component of the
                 file name (not the entire path). If a file name matches both
                 --include and --exclude, it is excluded.  There is no short
                 form for this option.

       --exclude-dir=pattern
                 When pcregrep is searching the contents of a directory as a
                 consequence of the -r (recursive search) option, any
                 subdirectories whose names match the pattern are excluded.
                 (Note that the --exclude option does not affect
                 subdirectories.) The pattern is a PCRE regular expression,
                 and is matched against the final component of the name (not
                 the entire path). If a subdirectory name matches both
                 --include-dir and --exclude-dir, it is excluded. There is no
                 short form for this option.

       -F, --fixed-strings
                 Interpret each pattern as a list of fixed strings, separated
                 by newlines, instead of as a regular expression. 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).

       -f filename, --file=filename
                 Read a number of patterns from the file, one per line, and
                 match them against each line of input. A data line is output
                 if any of the patterns match it. The 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 file names. There is an overall maximum of 100
                 patterns. 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.

       --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.

       -i, --ignore-case
                 Ignore upper/lower case distinctions during comparisons.

       --include=pattern
                 When pcregrep is searching the files in a directory as a
                 consequence of the -r (recursive search) option, only those
                 regular files whose names match the pattern are included.
                 Subdirectories are always included and searched recursively,
                 subject to the --include-dir and --exclude-dir options. The
                 pattern is a PCRE regular expression, and is matched against
                 the final component of the file name (not the entire path).
                 If a file name matches both --include and --exclude, it is
                 excluded. There is no short form for this option.

       --include-dir=pattern
                 When pcregrep is searching the contents of a directory as a
                 consequence of the -r (recursive search) option, only those
                 subdirectories whose names match the pattern are included.
                 (Note that the --include option does not affect
                 subdirectories.) The pattern is a PCRE regular expression,
                 and is matched against the final component of the name (not
                 the entire path). If a subdirectory name 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
                 When this option is given, input is read and processed line
                 by line, and the output is flushed after each write. By
                 default, input is read in large chunks, unless pcregrep can
                 determine that it is reading from a terminal (which is
                 currently possible only in Unix environments). Output to
                 terminal is normally automatically flushed by the operating
                 system. This option can be useful when the input or output is
                 attached to a pipe and you do not want pcregrep to buffer up
                 large amounts of data. However, its use will affect
                 performance, and the -M (multiline) option ceases to work.

       --line-offsets
                 Instead of showing lines or parts of lines that match, 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.
                 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 --file-
                 offsets and --only-matching.

       --locale=locale-name
                 This option specifies a locale to be used for pattern
                 matching. It overrides the value in the LC_ALL or LC_CTYPE
                 environment variables. If no locale is specified, the PCRE
                 library's default (usually the "C" locale) is used. There is
                 no short form for this option.

       --match-limit=number
                 Processing some regular expression patterns can require a
                 very large amount of memory, leading in some cases to a
                 program crash if not enough is available.  Other patterns may
                 take a very long time to search for all possible matching
                 strings. The pcre_exec() function that is called by pcregrep
                 to do the matching has two parameters that can limit the
                 resources that it uses.

                 The --match-limit option provides a means of limiting
                 resource usage when processing patterns that are not going to
                 match, but which have a very large number of possibilities in
                 their search trees. The classic example is a pattern that
                 uses nested unlimited repeats. Internally, PCRE uses a
                 function called match() which it calls repeatedly (sometimes
                 recursively). The limit set by --match-limit is imposed on
                 the number of times this function is called during a match,
                 which has the effect of limiting the amount of backtracking
                 that can take place.

                 The --recursion-limit option is similar to --match-limit, but
                 instead of limiting the total number of times that match() is
                 called, it limits the depth of recursive calls, which in turn
                 limits the amount of memory that can be used. The recursion
                 depth is a smaller number than the total number of calls,
                 because not all calls to match() are recursive. This limit is
                 of use only if it is set 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
                 Allow patterns to match more than one line. When this option
                 is given, patterns may usefully contain literal newline
                 characters and internal occurrences of ^ and $ characters.
                 The output for a successful match may consist of more than
                 one line, the last of which is the one in which the match
                 ended. If the matched string ends with a newline sequence the
                 output ends at the end of that line.

                 When this option is set, the PCRE library is called in
                 "multiline" mode.  There is a limit to the number of lines
                 that can be matched, imposed by the way that pcregrep buffers
                 the input file as it scans it. However, pcregrep ensures that
                 at least 8K characters or the rest of the document (whichever
                 is the 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. 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
                 indicating the ends of lines. 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, and an "any"
                 convention, in which 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 (formfeed,
                 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.  This is normally the standard
                 sequence for the operating system. Unless otherwise specified
                 by 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 on files that
                 have come from other environments without having to modify
                 their line endings. If the data that is being scanned does
                 not agree with the convention set by this option, pcregrep
                 may behave in strange ways.

       -n, --line-number
                 Precede each output line by its line number in the file,
                 followed by a colon for matching lines or a hyphen for
                 context lines. If the filename is also being output, it
                 precedes the line number. This option is forced if --line-
                 offsets is used.

       -o, --only-matching
                 Show only the part of the line that matched a pattern instead
                 of the whole line. 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.
                 If -o is combined with -v (invert the sense of the match to
                 find non-matching lines), no output is generated, but the
                 return code is set appropriately. If the matched portion of
                 the line is empty, nothing is output unless the file name or
                 line number are being printed, in which case they are shown
                 on an otherwise empty line. This option is mutually exclusive
                 with --file-offsets and --line-offsets.

       -onumber, --only-matching=number
                 Show only the part of the line that matched the capturing
                 parentheses of the given number. Up to 32 capturing
                 parentheses are supported. Because these options can be given
                 without an argument (see above), if an argument is present,
                 it must be given in the same shell item, for example, -o3 or
                 --only-matching=2. The comments given for the non-argument
                 case above also apply to this case. If the specified
                 capturing parentheses do not exist in the pattern, or were
                 not set in the match, nothing is output unless the file name
                 or line number are being printed.

       -q, --quiet
                 Work quietly, that is, display nothing except error messages.
                 The exit status indicates whether or not any matches were
                 found.

       -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.

       -s, --no-messages
                 Suppress error messages about non-existent or unreadable
                 files. Such files are 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 available only if PCRE
                 has been compiled with UTF-8 support. Both patterns and
                 subject lines must be valid strings of UTF-8 characters.

       -V, --version
                 Write the version numbers of pcregrep and the PCRE library
                 that is being used to the standard error stream.

       -v, --invert-match
                 Invert the sense of the match, so that lines which do not
                 match any of the patterns are the ones that are found.

       -w, --word-regex, --word-regexp
                 Force the patterns to match only whole words. This is
                 equivalent to having \b at the start and end of the pattern.

       -x, --line-regex, --line-regexp
                 Force the patterns to be anchored (each must start matching
                 at the beginning of a line) and in addition, require them to
                 match entire lines. This is equivalent to having ^ and $
                 characters at the start and end of each alternative branch in
                 every pattern.

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.

NEWLINES

       The -N (--newline) option allows pcregrep to scan files with different
       newline conventions from the default. However, the setting of this
       option does not affect the way in which pcregrep writes information to
       the standard error and output streams. It uses the string "\n" in C
       printf() calls to indicate newlines, relying on the C I/O library to
       convert this to an appropriate sequence if the output is sent to a
       file.

OPTIONS COMPATIBILITY

       Many of the short and long forms of pcregrep's options are the same as
       in the GNU grep program (version 2.5.4). Any long option of the form
       --xxx-regexp (GNU terminology) is also available as --xxx-regex (PCRE
       terminology). However, the --file-offsets, --include-dir, --line-
       offsets, --locale, --match-limit, -M, --multiline, -N, --newline,
       --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.

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.

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.

       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 and non-existent or inacessible files (even if
       matches were found in other files) or too many matching errors. Using
       the -s option to suppress error messages about inaccessble files does
       not affect the return code.

SEE ALSO

       pcrepattern(3), pcretest(1).

AUTHOR

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

REVISION

       Last updated: 14 January 2011
       Copyright (c) 1997-2011 University of Cambridge.



                                                                   PCREGREP(1)
