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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 exam-
       ple:

         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  argu-
       ments 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.

       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 are limited to 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 (or fails to match when -v is used), no further patterns are consid-
       ered.  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 liter-
       ally,  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  pat-
       terns 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 speci-
       fied 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.
       Numerical  values for options may be followed by K or M, to signify multiplication by 1024 or 1024*1024 respec-
       tively.

       --        This terminates 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.

       --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  set-
                 ting 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  stan-
                 dard  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 PCRE-
                 GREP_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  sepa-
                 rately. 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 fol-
                 lows 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, match-
                 ing  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 read-
                 ing 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.  How-
                 ever, 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 limit-
                 ing 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  success-
                 ful  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 charac-
                 ters (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 (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.  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.

       --no-jit  If  the  PCRE  library  is  built with support for just-in-time compiling (which speeds up matching),
                 pcregrep automatically makes use of this, unless it was  explicitly  disabled  at  build  time.  This
                 option  can  be  used  to  disable the use of JIT at run time. It is provided for testing and working
                 round problems.  It should never be needed in normal use.

       -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. How-
                 ever, 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  addi-
                 tion,  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 stan-
       dard 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 char-
       acter, 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 charac-
       ter. 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  circum-
       stances.  If  this happens, pcregrep outputs an error message and the line that caused the problem to the stan-
       dard 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 dis-
       cussion 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.

SEE ALSO

       pcrepattern(3), pcretest(1).

AUTHOR

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

REVISION

       Last updated: 06 September 2011
       Copyright (c) 1997-2011 University of Cambridge.



                                                                   PCREGREP(1)