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  seman-
       tics 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.   Con-
       versely,  when  one  or  both of these options are used to specify pat-
       terns, 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 stan-
       dard 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. As soon as one pat-
       tern matches (or fails to match when -v is used), no  further  patterns
       are considered.

       When  --only-matching,  --file-offsets,  or --line-offsets is used, the
       output is the part of the line that matched (either shown literally, or
       as an offset). In this case, 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.
       However, patterns that follow the one that matched are not tried on the
       earlier part of the line.

       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

       --        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  file-
                 names 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 sep-
                 arator  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 avail-
                 able 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 sep-
                 arator 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 avail-
                 able 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; instead just output a count
                 of the number of lines that would otherwise have been output.
                 If  several  files  are  given, a count is output for each of
                 them. In this mode, 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 part of  a
                 line that matched a pattern should be coloured in the output.
                 The value may be "never" (the default), "always", or  "auto".
                 In  the  latter  case, colouring happens only if the standard
                 output is connected to a terminal. The colour can  be  speci-
                 fied  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 ter-
                 minal,  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 mul-
                 tiple 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  multi-
                 ple use of -e is not the same as a single pattern with alter-
                 natives. For example, X|Y finds the first character in a line
                 that  is  X or Y, whereas if the two patterns are given sepa-
                 rately, 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 con-
                 sequence of the -r (recursive search) option, any files whose
                 names  match  the pattern are excluded. The pattern is a PCRE
                 regular expression. If a file name matches both --include and
                 --exclude,  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 (sub-
                 ject 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 and a  space;  for  context  lines,  a
                 hyphen separator is used. If a line number is also being out-
                 put, it follows the file name without a space.

       -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  and  a space; for context lines, a hyphen separator is
                 used. If a line number is also being output, it  follows  the
                 file name without a space.

       --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 con-
                 sequence  of  the  -r  (recursive  search) option, only those
                 files whose names match the pattern are included. The pattern
                 is  a  PCRE  regular  expression. If a file name matches both
                 --include and --exclude, 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 sepa-
                 rate 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 out-
                 put. Each file name is  output  once,  on  a  separate  line.
                 Searching  stops  as  soon  as  a matching line is found in a
                 file.

       --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-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  sepa-
                 rately. This option is mutually exclusive with --file-offsets
                 and --only-matching.

       --locale=locale-name
                 This option specifies a locale to be used for pattern  match-
                 ing.  It  overrides the value in the LC_ALL or LC_CTYPE envi-
                 ronment 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.

       -M, --multiline
                 Allow patterns to match more than one line. When this  option
                 is given, patterns may usefully contain literal newline char-
                 acters and internal occurrences of ^ and  $  characters.  The
                 output  for  any one match may consist of more than one line.
                 When this option is set, the PCRE library is called in  "mul-
                 tiline"  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 simi-
                 larly the previous 8K characters (or all the previous charac-
                 ters,  if  fewer  than 8K) are guaranteed to be available for
                 lookbehind assertions.

       -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 rec-
                 ognizes any of the preceding three types, and an  "any"  con-
                 vention, in which any Unicode line ending sequence is assumed
                 to end a line. The Unicode sequences are the three just  men-
                 tioned,   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, fol-
                 lowed  by  a colon and a space for matching lines or a hyphen
                 and a space 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.  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. This option is mutually exclusive with --file-
                 offsets and --line-offsets.

       -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  set-
                 tings.  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".

       -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 sub-
                 ject 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 equiva-
                 lent 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

       The majority of short and long forms of pcregrep's options are the same
       as  in  the  GNU grep program. Any long option of the form --xxx-regexp
       (GNU terminology) is also available as --xxx-regex (PCRE  terminology).
       However,  the  --locale,  -M,  --multiline, -u, and --utf-8 options are
       specific to pcregrep.


OPTIONS WITH DATA

       There are four different ways in which an option with data can be spec-
       ified.   If  a  short  form option is used, the data may follow immedi-
       ately, or in the next command line item. For example:

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

       If a long form option is used, the data may appear in the same  command
       line item, separated by an equals character, or (with one exception) 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 exception to the above is the --colour  (or  --color)  option,  for
       which  the  data is optional. If this option does have data, it must be
       given in the first form, using an equals character. Otherwise  it  will
       be assumed 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.


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: 17 December 2007
       Copyright (c) 1997-2007 University of Cambridge.
