path: root/libs/Pcre16/docs/doc/pcregrep.txt

PCREGREP(1)                 General Commands Manual                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 pcresyntax(3) for a quick-reference summary of pattern syn-
       tax,  or pcrepattern(3) for a full description of the 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  quotes  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.

       The amount of memory used for buffering files that are being scanned is
       controlled  by a parameter that can be set by the --buffer-size option.
       The default value for this parameter  is  specified  when  pcregrep  is
       built,  with  the  default  default  being 20K. A block of memory three
       times this size is used (to allow for buffering  "before"  and  "after"
       lines). An error occurs if a line overflows the buffer.

       Patterns  can  be  no  longer than 8K or BUFSIZ bytes, whichever is the
       greater.  BUFSIZ is defined in <stdio.h>. When there is more  than  one
       pattern (specified by the use of -e and/or -f), each pattern is applied
       to each line in the order in which they are defined,  except  that  all
       the -e patterns are tried before the -f patterns.

       By  default, as soon as one pattern matches a line, no further patterns
       are considered. However, if --colour (or --color) is used to colour the
       matching  substrings, or if --only-matching, --file-offsets, or --line-
       offsets is used to output only  the  part  of  the  line  that  matched
       (either shown literally, or as an offset), scanning resumes immediately
       following the match, so that further matches on the same  line  can  be
       found.  If  there  are  multiple  patterns,  they  are all tried on the
       remainder of the line, but patterns that follow the  one  that  matched
       are not tried on the earlier part of the line.

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

       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.


BINARY FILES

       By  default,  a  file that contains a binary zero byte within the first
       1024 bytes is identified as a binary file, and is processed  specially.
       (GNU  grep  also  identifies  binary  files  in  this  manner.) See the
       --binary-files option for a means of changing the way binary files  are
       handled.


OPTIONS

       The  order  in  which some of the options appear can affect the output.
       For example, both the -h and -l options affect  the  printing  of  file
       names.  Whichever  comes later in the command line will be the one that
       takes effect. Similarly, except where noted  below,  if  an  option  is
       given  twice,  the  later setting is used. Numerical values for options
       may be followed by K  or  M,  to  signify  multiplication  by  1024  or
       1024*1024 respectively.

       --        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 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.

       -a, --text
                 Treat  binary  files as text. This is equivalent to --binary-
                 files=text.

       -B number, --before-context=number
                 Output number lines of context before each matching line.  If
                 filenames and/or line numbers are being output, a hyphen 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.

       --binary-files=word
                 Specify  how binary files are to be processed. If the word is
                 "binary" (the default),  pattern  matching  is  performed  on
                 binary  files,  but  the  only  output is "Binary file <name>
                 matches" when a match succeeds. If the word is "text",  which
                 is  equivalent  to  the -a or --text option, binary files are
                 processed in the same way as any other file.  In  this  case,
                 when  a  match  succeeds,  the  output may be binary garbage,
                 which can have nasty effects if sent to a  terminal.  If  the
                 word  is  "without-match",  which  is  equivalent  to  the -I
                 option, binary files are  not  processed  at  all;  they  are
                 assumed not to be of interest.

       --buffer-size=number
                 Set  the  parameter that controls how much memory is used for
                 buffering files that are being scanned.

       -C number, --context=number
                 Output number lines of context both  before  and  after  each
                 matching  line.  This is equivalent to setting both -A and -B
                 to the same value.

       -c, --count
                 Do not output individual lines from the files that are  being
                 scanned; instead output the number of lines that would 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 in
                 non-Windows environments, for compatibility with  GNU  grep),
                 "recurse"  (equivalent to the -r option), or "skip" (silently
                 skip the path, the default in Windows environments).  In  the
                 "read"  case,  directories  are read as if they were ordinary
                 files. In some operating systems  the  effect  of  reading  a
                 directory like this is an immediate end-of-file; in others it
                 may provoke an error.

       -e pattern, --regex=pattern, --regexp=pattern
                 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 no limit to the number of patterns. They are
                 applied to each line in the order in which they  are  defined
                 until one matches.

                 If  -f is used with -e, the command line patterns are matched
                 first, followed by the patterns from the file(s), independent
                 of  the order in which these options are specified. 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,  with X first, pcregrep finds X if it is present,
                 even if it follows Y in the line. It finds Y only if there is
                 no  X  in  the line. This matters only if you are using -o or
                 --colo(u)r to show the part(s) of the line that matched.

       --exclude=pattern
                 Files (but not directories) whose names match the pattern are
                 skipped  without  being processed. This applies to all files,
                 whether listed on the command  line,  obtained  from  --file-
                 list, or by scanning a directory. The pattern is a PCRE regu-
                 lar expression, and is matched against the final component of
                 the  file  name,  not  the  entire  path.  The -F, -w, and -x
                 options do not apply to this pattern. The option may be given
                 any number of times in order to specify multiple patterns. If
                 a file name matches both an --include and an  --exclude  pat-
                 tern, it is excluded. There is no short form for this option.

       --exclude-from=filename
                 Treat  each  non-empty  line  of  the file as the data for an
                 --exclude option. What constitutes a newline when reading the
                 file  is the operating system's default. The --newline option
                 has no effect on this option. This option may be  given  more
                 than once in order to specify a number of files to read.

       --exclude-dir=pattern
                 Directories whose names match the pattern are skipped without
                 being processed, whatever  the  setting  of  the  --recursive
                 option.  This  applies  to all directories, whether listed on
                 the command line, obtained from --file-list, or by scanning a
                 parent  directory.  The pattern is a PCRE regular expression,
                 and is matched against the final component of  the  directory
                 name,  not the entire path. The -F, -w, and -x options do not
                 apply to this pattern. The option may be given any number  of
                 times  in order to specify more than one pattern. If a direc-
                 tory matches both  --include-dir  and  --exclude-dir,  it  is
                 excluded. There is no short form for this option.

       -F, --fixed-strings
                 Interpret  each  data-matching  pattern  as  a  list of fixed
                 strings, separated by  newlines,  instead  of  as  a  regular
                 expression.  What  constitutes  a newline for this purpose is
                 controlled by the --newline option. The -w (match as a  word)
                 and  -x (match whole line) options can be used with -F.  They
                 apply to each of the fixed strings. A line is selected if any
                 of the fixed strings are found in it (subject to -w or -x, if
                 present). This option applies only to the patterns  that  are
                 matched  against  the contents of files; it does not apply to
                 patterns specified by  any  of  the  --include  or  --exclude
                 options.

       -f filename, --file=filename
                 Read  patterns  from  the  file, one per line, and match them
                 against each line of input. What constitutes a  newline  when
                 reading  the  file  is  the  operating  system's default. The
                 --newline option has no effect on this option. Trailing white
                 space is removed from each line, and blank lines are ignored.
                 An empty file contains  no  patterns  and  therefore  matches
                 nothing. See also the comments about multiple patterns versus
                 a single pattern with alternatives in the description  of  -e
                 above.

                 If  this  option  is  given more than once, all the specified
                 files are read. A data line is output if any of the  patterns
                 match  it.  A  filename  can  be given as "-" to refer to the
                 standard input. When -f is used, patterns  specified  on  the
                 command  line  using  -e may also be present; they are tested
                 before the file's patterns.  However,  no  other  pattern  is
                 taken from the command line; all arguments are treated as the
                 names of paths to be searched.

       --file-list=filename
                 Read a list of  files  and/or  directories  that  are  to  be
                 scanned  from  the  given  file, one per line. Trailing white
                 space is removed from each line, and blank lines are ignored.
                 These  paths  are processed before any that are listed on the
                 command line. The filename can be given as "-"  to  refer  to
                 the standard input.  If --file and --file-list are both spec-
                 ified as "-", patterns are read first. This  is  useful  only
                 when  the  standard  input  is a terminal, from which further
                 lines (the list of files) can be read  after  an  end-of-file
                 indication.  If  this option is given more than once, all the
                 specified files are read.

       --file-offsets
                 Instead of showing lines or parts of lines that  match,  show
                 each  match  as  an  offset  from the start of the file and a
                 length, separated by a comma. In this  mode,  no  context  is
                 shown.  That  is,  the -A, -B, and -C options are ignored. If
                 there is more than one match in a line, each of them is shown
                 separately.  This  option  is mutually exclusive with --line-
                 offsets and --only-matching.

       -H, --with-filename
                 Force the inclusion of the filename at the  start  of  output
                 lines  when searching a single file. By default, the filename
                 is not shown in this case. For matching lines,  the  filename
                 is followed by a colon; for context lines, a hyphen separator
                 is used. If a line number is also being  output,  it  follows
                 the file name.

       -h, --no-filename
                 Suppress  the output filenames when searching multiple files.
                 By default, filenames  are  shown  when  multiple  files  are
                 searched.  For  matching lines, the filename is followed by a
                 colon; for context lines, a hyphen separator is used.   If  a
                 line number is also being output, it follows the file name.

       --help    Output  a  help  message, giving brief details of the command
                 options and file type support, and then exit.  Anything  else
                 on the command line is ignored.

       -I        Treat  binary  files as never matching. This is equivalent to
                 --binary-files=without-match.

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

       --include=pattern
                 If any --include patterns are specified, the only files  that
                 are  processed  are those that match one of the patterns (and
                 do not match an --exclude  pattern).  This  option  does  not
                 affect  directories,  but  it  applies  to all files, whether
                 listed on the command line, obtained from --file-list, or  by
                 scanning  a  directory. The pattern is a PCRE regular expres-
                 sion, and is matched against the final component of the  file
                 name,  not the entire path. The -F, -w, and -x options do not
                 apply to this pattern. The option may be given any number  of
                 times.  If  a  file  name  matches  both  an --include and an
                 --exclude pattern, it is excluded.  There is  no  short  form
                 for this option.

       --include-from=filename
                 Treat  each  non-empty  line  of  the file as the data for an
                 --include option. What constitutes a newline for this purpose
                 is  the  operating system's default. The --newline option has
                 no effect on this option. This option may be given any number
                 of times; all the files are read.

       --include-dir=pattern
                 If  any --include-dir patterns are specified, the only direc-
                 tories that are processed are those that  match  one  of  the
                 patterns  (and  do  not match an --exclude-dir pattern). This
                 applies to all directories, whether  listed  on  the  command
                 line,  obtained  from  --file-list,  or  by scanning a parent
                 directory. The pattern is a PCRE regular expression,  and  is
                 matched  against  the  final component of the directory name,
                 not the entire path. The -F, -w, and -x options do not  apply
                 to this pattern. The option may be given any number of times.
                 If a directory matches both --include-dir and  --exclude-dir,
                 it is excluded. There is no short form for this option.

       -L, --files-without-match
                 Instead  of  outputting lines from the files, just output the
                 names of the files that do not contain any lines  that  would
                 have  been  output. Each file name is output once, on a 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-like  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  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  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  "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  (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 to scan files
                 that have come from other environments without having to mod-
                 ify  their  line  endings.  If the data that is being scanned
                 does not agree with the convention set by this option,  pcre-
                 grep  may  behave in strange ways. Note that this option does
                 not apply to files specified by the  -f,  --exclude-from,  or
                 --include-from options, which are expected to use the operat-
                 ing system's standard newline sequence.

       -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.

       --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 prob-
                 lems.  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 parenthe-
                 ses are supported, and -o0 is equivalent to -o without a num-
                 ber.  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.

                 If this option is given multiple times,  multiple  substrings
                 are  output, in the order the options are given. For example,
                 -o3 -o1 -o3 causes the substrings matched by capturing paren-
                 theses  3  and  1  and then 3 again to be output. By default,
                 there is no separator (but see the next option).

       --om-separator=text
                 Specify a separating string for multiple occurrences  of  -o.
                 The  default is an empty string. Separating strings are never
                 coloured.

       -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. All patterns (including
                 those  for  any --exclude and --include options) and all sub-
                 ject lines that are scanned must be valid  strings  of  UTF-8
                 characters.

       -V, --version
                 Write the version numbers of pcregrep and the PCRE library to
                 the standard output and then exit. Anything else on the  com-
                 mand line is ignored.

       -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. This
                 option applies only to the patterns that are matched  against
                 the  contents  of files; it does not apply to patterns speci-
                 fied by any of the --include or --exclude options.

       -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. This option applies only to the patterns  that
                 are  matched against the contents of files; it does not apply
                 to patterns specified by any of the  --include  or  --exclude
                 options.


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. Any parts of the input files that
       are written to the standard output are copied identically,  with  what-
       ever  newline sequences they have in the input. However, the setting of
       this option does not affect the interpretation of  files  specified  by
       the -f, --exclude-from, or --include-from options, which are assumed to
       use the operating system's  standard  newline  sequence,  nor  does  it
       affect  the  way in which pcregrep writes informational messages to the
       standard error and output streams. For these it uses the string "\n" to
       indicate  newlines,  relying on the C I/O library to convert this to an
       appropriate sequence.


OPTIONS COMPATIBILITY

       Many of the short and long forms of pcregrep's options are the same  as
       in  the GNU grep program. Any long option of the form --xxx-regexp (GNU
       terminology) is also available as --xxx-regex (PCRE terminology).  How-
       ever,  the  --file-list, --file-offsets, --include-dir, --line-offsets,
       --locale, --match-limit, -M, --multiline, -N,  --newline,  --om-separa-
       tor,  --recursion-limit,  -u, and --utf-8 options are specific to pcre-
       grep, 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, 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 inaccessi-
       ble files does not affect the return code.


SEE ALSO

       pcrepattern(3), pcresyntax(3), pcretest(1).


AUTHOR

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


REVISION

       Last updated: 03 April 2014
       Copyright (c) 1997-2014 University of Cambridge.