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.

       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-match-
       ing, --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 fol-
       low 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  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 from the files that are being
                 scanned; instead output the number of lines that would other-
                 wise  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  out-
                 put  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 envi-
                 ronment 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 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 regular
                 files whose names match the pattern are excluded. Subdirecto-
                 ries  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  subdi-
                 rectories  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 (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; 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 con-
                 sequence of the -r (recursive search) option, only those reg-
                 ular files whose names match the pattern are included. Subdi-
                 rectories  are always included and searched recursively, sub-
                 ject to the --include-dir and --exclude-dir options. The pat-
                 tern 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 subdirecto-
                 ries.) 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  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 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 sup-
                 pressing 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  cur-
                 rently  possible only in Unix environments). Output to termi-
                 nal is normally automatically flushed by the  operating  sys-
                 tem.  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 perfor-
                 mance, 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  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.

       --match-limit=number
                 Processing some regular expression  patterns  can  require  a
                 very  large amount of memory, leading in some cases to a pro-
                 gram 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  func-
                 tion  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 set-
                 tings 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 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.  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 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 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 parenthe-
                 ses 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 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".

       --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  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

       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-off-
       sets, --locale, --match-limit, -M, --multiline, -N, --newline, --recur-
       sion-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 dif-
       ferent 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 spec-
       ified.  If a short form option is used, the  data  may  follow  immedi-
       ately, or (with one exception) in the next command line item. For exam-
       ple:

         -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: 16 November 2010
       Copyright (c) 1997-2010 University of Cambridge.
