trunk/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 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 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: 13 September 2012
       Copyright (c) 1997-2012 University of Cambridge.
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