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    1 PCREGREP(1)                 General Commands Manual                PCREGREP(1)
    2 
    3 
    4 
    5 NAME
    6        pcregrep - a grep with Perl-compatible regular expressions.
    7 
    8 SYNOPSIS
    9        pcregrep [options] [long options] [pattern] [path1 path2 ...]
   10 
   11 
   12 DESCRIPTION
   13 
   14        pcregrep  searches  files  for  character  patterns, in the same way as
   15        other grep commands do, but it uses the PCRE regular expression library
   16        to support patterns that are compatible with the regular expressions of
   17        Perl 5. See pcresyntax(3) for a quick-reference summary of pattern syn-
   18        tax,  or pcrepattern(3) for a full description of the syntax and seman-
   19        tics of the regular expressions that PCRE supports.
   20 
   21        Patterns, whether supplied on the command line or in a  separate  file,
   22        are given without delimiters. For example:
   23 
   24          pcregrep Thursday /etc/motd
   25 
   26        If you attempt to use delimiters (for example, by surrounding a pattern
   27        with slashes, as is common in Perl scripts), they  are  interpreted  as
   28        part  of  the pattern. Quotes can of course be used to delimit patterns
   29        on the command line because they are  interpreted  by  the  shell,  and
   30        indeed  quotes  are required if a pattern contains white space or shell
   31        metacharacters.
   32 
   33        The first argument that follows any option settings is treated  as  the
   34        single  pattern  to be matched when neither -e nor -f is present.  Con-
   35        versely, when one or both of these options are  used  to  specify  pat-
   36        terns, all arguments are treated as path names. At least one of -e, -f,
   37        or an argument pattern must be provided.
   38 
   39        If no files are specified, pcregrep reads the standard input. The stan-
   40        dard  input  can  also  be  referenced by a name consisting of a single
   41        hyphen.  For example:
   42 
   43          pcregrep some-pattern /file1 - /file3
   44 
   45        By default, each line that matches a pattern is copied to the  standard
   46        output,  and if there is more than one file, the file name is output at
   47        the start of each line, followed by a colon. However, there are options
   48        that  can  change  how  pcregrep  behaves. In particular, the -M option
   49        makes it possible to search for patterns  that  span  line  boundaries.
   50        What  defines  a  line  boundary  is  controlled  by the -N (--newline)
   51        option.
   52 
   53        The amount of memory used for buffering files that are being scanned is
   54        controlled  by a parameter that can be set by the --buffer-size option.
   55        The default value for this parameter  is  specified  when  pcregrep  is
   56        built,  with  the  default  default  being 20K. A block of memory three
   57        times this size is used (to allow for buffering  "before"  and  "after"
   58        lines). An error occurs if a line overflows the buffer.
   59 
   60        Patterns  can  be  no  longer than 8K or BUFSIZ bytes, whichever is the
   61        greater.  BUFSIZ is defined in <stdio.h>. When there is more  than  one
   62        pattern (specified by the use of -e and/or -f), each pattern is applied
   63        to each line in the order in which they are defined,  except  that  all
   64        the -e patterns are tried before the -f patterns.
   65 
   66        By  default, as soon as one pattern matches a line, no further patterns
   67        are considered. However, if --colour (or --color) is used to colour the
   68        matching  substrings, or if --only-matching, --file-offsets, or --line-
   69        offsets is used to output only  the  part  of  the  line  that  matched
   70        (either shown literally, or as an offset), scanning resumes immediately
   71        following the match, so that further matches on the same  line  can  be
   72        found.  If  there  are  multiple  patterns,  they  are all tried on the
   73        remainder of the line, but patterns that follow the  one  that  matched
   74        are not tried on the earlier part of the line.
   75 
   76        This  behaviour  means  that  the  order in which multiple patterns are
   77        specified can affect the output when one of the above options is  used.
   78        This  is no longer the same behaviour as GNU grep, which now manages to
   79        display earlier matches for later patterns (as  long  as  there  is  no
   80        overlap).
   81 
   82        Patterns  that can match an empty string are accepted, but empty string
   83        matches   are   never   recognized.   An   example   is   the   pattern
   84        "(super)?(man)?",  in  which  all components are optional. This pattern
   85        finds all occurrences of both "super" and  "man";  the  output  differs
   86        from  matching  with  "super|man" when only the matching substrings are
   87        being shown.
   88 
   89        If the LC_ALL or LC_CTYPE environment variable is  set,  pcregrep  uses
   90        the  value to set a locale when calling the PCRE library.  The --locale
   91        option can be used to override this.
   92 
   93 
   94 SUPPORT FOR COMPRESSED FILES
   95 
   96        It is possible to compile pcregrep so that it uses libz  or  libbz2  to
   97        read  files  whose names end in .gz or .bz2, respectively. You can find
   98        out whether your binary has support for one or both of these file types
   99        by running it with the --help option. If the appropriate support is not
  100        present, files are treated as plain text. The standard input is  always
  101        so treated.
  102 
  103 
  104 BINARY FILES
  105 
  106        By  default,  a  file that contains a binary zero byte within the first
  107        1024 bytes is identified as a binary file, and is processed  specially.
  108        (GNU  grep  also  identifies  binary  files  in  this  manner.) See the
  109        --binary-files option for a means of changing the way binary files  are
  110        handled.
  111 
  112 
  113 OPTIONS
  114 
  115        The  order  in  which some of the options appear can affect the output.
  116        For example, both the -h and -l options affect  the  printing  of  file
  117        names.  Whichever  comes later in the command line will be the one that
  118        takes effect. Similarly, except where noted  below,  if  an  option  is
  119        given  twice,  the  later setting is used. Numerical values for options
  120        may be followed by K  or  M,  to  signify  multiplication  by  1024  or
  121        1024*1024 respectively.
  122 
  123        --        This terminates the list of options. It is useful if the next
  124                  item on the command line starts with a hyphen but is  not  an
  125                  option.  This allows for the processing of patterns and file-
  126                  names that start with hyphens.
  127 
  128        -A number, --after-context=number
  129                  Output number lines of context after each matching  line.  If
  130                  filenames and/or line numbers are being output, a hyphen sep-
  131                  arator is used instead of a colon for the  context  lines.  A
  132                  line  containing  "--" is output between each group of lines,
  133                  unless they are in fact contiguous in  the  input  file.  The
  134                  value  of number is expected to be relatively small. However,
  135                  pcregrep guarantees to have up to 8K of following text avail-
  136                  able for context output.
  137 
  138        -a, --text
  139                  Treat  binary  files as text. This is equivalent to --binary-
  140                  files=text.
  141 
  142        -B number, --before-context=number
  143                  Output number lines of context before each matching line.  If
  144                  filenames and/or line numbers are being output, a hyphen sep-
  145                  arator is used instead of a colon for the  context  lines.  A
  146                  line  containing  "--" is output between each group of lines,
  147                  unless they are in fact contiguous in  the  input  file.  The
  148                  value  of number is expected to be relatively small. However,
  149                  pcregrep guarantees to have up to 8K of preceding text avail-
  150                  able for context output.
  151 
  152        --binary-files=word
  153                  Specify  how binary files are to be processed. If the word is
  154                  "binary" (the default),  pattern  matching  is  performed  on
  155                  binary  files,  but  the  only  output is "Binary file <name>
  156                  matches" when a match succeeds. If the word is "text",  which
  157                  is  equivalent  to  the -a or --text option, binary files are
  158                  processed in the same way as any other file.  In  this  case,
  159                  when  a  match  succeeds,  the  output may be binary garbage,
  160                  which can have nasty effects if sent to a  terminal.  If  the
  161                  word  is  "without-match",  which  is  equivalent  to  the -I
  162                  option, binary files are  not  processed  at  all;  they  are
  163                  assumed not to be of interest.
  164 
  165        --buffer-size=number
  166                  Set  the  parameter that controls how much memory is used for
  167                  buffering files that are being scanned.
  168 
  169        -C number, --context=number
  170                  Output number lines of context both  before  and  after  each
  171                  matching  line.  This is equivalent to setting both -A and -B
  172                  to the same value.
  173 
  174        -c, --count
  175                  Do not output individual lines from the files that are  being
  176                  scanned; instead output the number of lines that would other-
  177                  wise have been shown. If no lines are  selected,  the  number
  178                  zero  is  output.  If  several files are are being scanned, a
  179                  count is output for each of them. However,  if  the  --files-
  180                  with-matches  option  is  also  used,  only those files whose
  181                  counts are greater than zero are listed. When -c is used, the
  182                  -A, -B, and -C options are ignored.
  183 
  184        --colour, --color
  185                  If this option is given without any data, it is equivalent to
  186                  "--colour=auto".  If data is required, it must  be  given  in
  187                  the same shell item, separated by an equals sign.
  188 
  189        --colour=value, --color=value
  190                  This option specifies under what circumstances the parts of a
  191                  line that matched a pattern should be coloured in the output.
  192                  By  default,  the output is not coloured. The value (which is
  193                  optional, see above) may be "never", "always", or "auto".  In
  194                  the  latter case, colouring happens only if the standard out-
  195                  put is connected to a terminal. More resources are used  when
  196                  colouring  is enabled, because pcregrep has to search for all
  197                  possible matches in a line, not just one, in order to  colour
  198                  them all.
  199 
  200                  The colour that is used can be specified by setting the envi-
  201                  ronment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value
  202                  of this variable should be a string of two numbers, separated
  203                  by a semicolon. They are copied  directly  into  the  control
  204                  string  for  setting  colour  on  a  terminal,  so it is your
  205                  responsibility to ensure that they make sense. If neither  of
  206                  the  environment  variables  is  set,  the default is "1;31",
  207                  which gives red.
  208 
  209        -D action, --devices=action
  210                  If an input path is  not  a  regular  file  or  a  directory,
  211                  "action"  specifies  how  it is to be processed. Valid values
  212                  are "read" (the default) or "skip" (silently skip the path).
  213 
  214        -d action, --directories=action
  215                  If an input path is a directory, "action" specifies how it is
  216                  to  be  processed.   Valid  values are "read" (the default in
  217                  non-Windows environments, for compatibility with  GNU  grep),
  218                  "recurse"  (equivalent to the -r option), or "skip" (silently
  219                  skip the path, the default in Windows environments).  In  the
  220                  "read"  case,  directories  are read as if they were ordinary
  221                  files. In some operating systems  the  effect  of  reading  a
  222                  directory like this is an immediate end-of-file; in others it
  223                  may provoke an error.
  224 
  225        -e pattern, --regex=pattern, --regexp=pattern
  226                  Specify a pattern to be matched. This option can be used mul-
  227                  tiple times in order to specify several patterns. It can also
  228                  be used as a way of specifying a single pattern  that  starts
  229                  with  a hyphen. When -e is used, no argument pattern is taken
  230                  from the command line; all  arguments  are  treated  as  file
  231                  names.  There is no limit to the number of patterns. They are
  232                  applied to each line in the order in which they  are  defined
  233                  until one matches.
  234 
  235                  If  -f is used with -e, the command line patterns are matched
  236                  first, followed by the patterns from the file(s), independent
  237                  of  the order in which these options are specified. Note that
  238                  multiple use of -e is not the same as a single  pattern  with
  239                  alternatives. For example, X|Y finds the first character in a
  240                  line that is X or Y, whereas if the two  patterns  are  given
  241                  separately,  with X first, pcregrep finds X if it is present,
  242                  even if it follows Y in the line. It finds Y only if there is
  243                  no  X  in  the line. This matters only if you are using -o or
  244                  --colo(u)r to show the part(s) of the line that matched.
  245 
  246        --exclude=pattern
  247                  Files (but not directories) whose names match the pattern are
  248                  skipped  without  being processed. This applies to all files,
  249                  whether listed on the command  line,  obtained  from  --file-
  250                  list, or by scanning a directory. The pattern is a PCRE regu-
  251                  lar expression, and is matched against the final component of
  252                  the  file  name,  not  the  entire  path.  The -F, -w, and -x
  253                  options do not apply to this pattern. The option may be given
  254                  any number of times in order to specify multiple patterns. If
  255                  a file name matches both an --include and an  --exclude  pat-
  256                  tern, it is excluded. There is no short form for this option.
  257 
  258        --exclude-from=filename
  259                  Treat  each  non-empty  line  of  the file as the data for an
  260                  --exclude option. What constitutes a newline when reading the
  261                  file  is the operating system's default. The --newline option
  262                  has no effect on this option. This option may be  given  more
  263                  than once in order to specify a number of files to read.
  264 
  265        --exclude-dir=pattern
  266                  Directories whose names match the pattern are skipped without
  267                  being processed, whatever  the  setting  of  the  --recursive
  268                  option.  This  applies  to all directories, whether listed on
  269                  the command line, obtained from --file-list, or by scanning a
  270                  parent  directory.  The pattern is a PCRE regular expression,
  271                  and is matched against the final component of  the  directory
  272                  name,  not the entire path. The -F, -w, and -x options do not
  273                  apply to this pattern. The option may be given any number  of
  274                  times  in order to specify more than one pattern. If a direc-
  275                  tory matches both  --include-dir  and  --exclude-dir,  it  is
  276                  excluded. There is no short form for this option.
  277 
  278        -F, --fixed-strings
  279                  Interpret  each  data-matching  pattern  as  a  list of fixed
  280                  strings, separated by  newlines,  instead  of  as  a  regular
  281                  expression.  What  constitutes  a newline for this purpose is
  282                  controlled by the --newline option. The -w (match as a  word)
  283                  and  -x (match whole line) options can be used with -F.  They
  284                  apply to each of the fixed strings. A line is selected if any
  285                  of the fixed strings are found in it (subject to -w or -x, if
  286                  present). This option applies only to the patterns  that  are
  287                  matched  against  the contents of files; it does not apply to
  288                  patterns specified by  any  of  the  --include  or  --exclude
  289                  options.
  290 
  291        -f filename, --file=filename
  292                  Read  patterns  from  the  file, one per line, and match them
  293                  against each line of input. What constitutes a  newline  when
  294                  reading  the  file  is  the  operating  system's default. The
  295                  --newline option has no effect on this option. Trailing white
  296                  space is removed from each line, and blank lines are ignored.
  297                  An empty file contains  no  patterns  and  therefore  matches
  298                  nothing. See also the comments about multiple patterns versus
  299                  a single pattern with alternatives in the description  of  -e
  300                  above.
  301 
  302                  If  this  option  is  given more than once, all the specified
  303                  files are read. A data line is output if any of the  patterns
  304                  match  it.  A  filename  can  be given as "-" to refer to the
  305                  standard input. When -f is used, patterns  specified  on  the
  306                  command  line  using  -e may also be present; they are tested
  307                  before the file's patterns.  However,  no  other  pattern  is
  308                  taken from the command line; all arguments are treated as the
  309                  names of paths to be searched.
  310 
  311        --file-list=filename
  312                  Read a list of  files  and/or  directories  that  are  to  be
  313                  scanned  from  the  given  file, one per line. Trailing white
  314                  space is removed from each line, and blank lines are ignored.
  315                  These  paths  are processed before any that are listed on the
  316                  command line. The filename can be given as "-"  to  refer  to
  317                  the standard input.  If --file and --file-list are both spec-
  318                  ified as "-", patterns are read first. This  is  useful  only
  319                  when  the  standard  input  is a terminal, from which further
  320                  lines (the list of files) can be read  after  an  end-of-file
  321                  indication.  If  this option is given more than once, all the
  322                  specified files are read.
  323 
  324        --file-offsets
  325                  Instead of showing lines or parts of lines that  match,  show
  326                  each  match  as  an  offset  from the start of the file and a
  327                  length, separated by a comma. In this  mode,  no  context  is
  328                  shown.  That  is,  the -A, -B, and -C options are ignored. If
  329                  there is more than one match in a line, each of them is shown
  330                  separately.  This  option  is mutually exclusive with --line-
  331                  offsets and --only-matching.
  332 
  333        -H, --with-filename
  334                  Force the inclusion of the filename at the  start  of  output
  335                  lines  when searching a single file. By default, the filename
  336                  is not shown in this case. For matching lines,  the  filename
  337                  is followed by a colon; for context lines, a hyphen separator
  338                  is used. If a line number is also being  output,  it  follows
  339                  the file name.
  340 
  341        -h, --no-filename
  342                  Suppress  the output filenames when searching multiple files.
  343                  By default, filenames  are  shown  when  multiple  files  are
  344                  searched.  For  matching lines, the filename is followed by a
  345                  colon; for context lines, a hyphen separator is used.   If  a
  346                  line number is also being output, it follows the file name.
  347 
  348        --help    Output  a  help  message, giving brief details of the command
  349                  options and file type support, and then exit.  Anything  else
  350                  on the command line is ignored.
  351 
  352        -I        Treat  binary  files as never matching. This is equivalent to
  353                  --binary-files=without-match.
  354 
  355        -i, --ignore-case
  356                  Ignore upper/lower case distinctions during comparisons.
  357 
  358        --include=pattern
  359                  If any --include patterns are specified, the only files  that
  360                  are  processed  are those that match one of the patterns (and
  361                  do not match an --exclude  pattern).  This  option  does  not
  362                  affect  directories,  but  it  applies  to all files, whether
  363                  listed on the command line, obtained from --file-list, or  by
  364                  scanning  a  directory. The pattern is a PCRE regular expres-
  365                  sion, and is matched against the final component of the  file
  366                  name,  not the entire path. The -F, -w, and -x options do not
  367                  apply to this pattern. The option may be given any number  of
  368                  times.  If  a  file  name  matches  both  an --include and an
  369                  --exclude pattern, it is excluded.  There is  no  short  form
  370                  for this option.
  371 
  372        --include-from=filename
  373                  Treat  each  non-empty  line  of  the file as the data for an
  374                  --include option. What constitutes a newline for this purpose
  375                  is  the  operating system's default. The --newline option has
  376                  no effect on this option. This option may be given any number
  377                  of times; all the files are read.
  378 
  379        --include-dir=pattern
  380                  If  any --include-dir patterns are specified, the only direc-
  381                  tories that are processed are those that  match  one  of  the
  382                  patterns  (and  do  not match an --exclude-dir pattern). This
  383                  applies to all directories, whether  listed  on  the  command
  384                  line,  obtained  from  --file-list,  or  by scanning a parent
  385                  directory. The pattern is a PCRE regular expression,  and  is
  386                  matched  against  the  final component of the directory name,
  387                  not the entire path. The -F, -w, and -x options do not  apply
  388                  to this pattern. The option may be given any number of times.
  389                  If a directory matches both --include-dir and  --exclude-dir,
  390                  it is excluded. There is no short form for this option.
  391 
  392        -L, --files-without-match
  393                  Instead  of  outputting lines from the files, just output the
  394                  names of the files that do not contain any lines  that  would
  395                  have  been  output. Each file name is output once, on a sepa-
  396                  rate line.
  397 
  398        -l, --files-with-matches
  399                  Instead of outputting lines from the files, just  output  the
  400                  names of the files containing lines that would have been out-
  401                  put. Each file name is  output  once,  on  a  separate  line.
  402                  Searching  normally stops as soon as a matching line is found
  403                  in a file. However, if the -c (count) option  is  also  used,
  404                  matching  continues in order to obtain the correct count, and
  405                  those files that have at least one  match  are  listed  along
  406                  with their counts. Using this option with -c is a way of sup-
  407                  pressing the listing of files with no matches.
  408 
  409        --label=name
  410                  This option supplies a name to be used for the standard input
  411                  when file names are being output. If not supplied, "(standard
  412                  input)" is used. There is no short form for this option.
  413 
  414        --line-buffered
  415                  When this option is given, input is read and  processed  line
  416                  by  line,  and  the  output  is  flushed after each write. By
  417                  default, input is read in large chunks, unless  pcregrep  can
  418                  determine  that  it is reading from a terminal (which is cur-
  419                  rently possible only in Unix-like  environments).  Output  to
  420                  terminal  is  normally automatically flushed by the operating
  421                  system. This option can be useful when the input or output is
  422                  attached  to a pipe and you do not want pcregrep to buffer up
  423                  large amounts of data. However, its use will  affect  perfor-
  424                  mance, and the -M (multiline) option ceases to work.
  425 
  426        --line-offsets
  427                  Instead  of  showing lines or parts of lines that match, show
  428                  each match as a line number, the offset from the start of the
  429                  line,  and a length. The line number is terminated by a colon
  430                  (as usual; see the -n option), and the offset and length  are
  431                  separated  by  a  comma.  In  this mode, no context is shown.
  432                  That is, the -A, -B, and -C options are ignored. If there  is
  433                  more  than  one  match in a line, each of them is shown sepa-
  434                  rately. This option is mutually exclusive with --file-offsets
  435                  and --only-matching.
  436 
  437        --locale=locale-name
  438                  This  option specifies a locale to be used for pattern match-
  439                  ing. It overrides the value in the LC_ALL or  LC_CTYPE  envi-
  440                  ronment  variables.  If  no  locale  is  specified,  the PCRE
  441                  library's default (usually the "C" locale) is used. There  is
  442                  no short form for this option.
  443 
  444        --match-limit=number
  445                  Processing  some  regular  expression  patterns can require a
  446                  very large amount of memory, leading in some cases to a  pro-
  447                  gram  crash  if  not enough is available.  Other patterns may
  448                  take a very long time to search  for  all  possible  matching
  449                  strings.  The pcre_exec() function that is called by pcregrep
  450                  to do the matching has two  parameters  that  can  limit  the
  451                  resources that it uses.
  452 
  453                  The   --match-limit  option  provides  a  means  of  limiting
  454                  resource usage when processing patterns that are not going to
  455                  match, but which have a very large number of possibilities in
  456                  their search trees. The classic example  is  a  pattern  that
  457                  uses  nested unlimited repeats. Internally, PCRE uses a func-
  458                  tion called match()  which  it  calls  repeatedly  (sometimes
  459                  recursively).  The  limit  set by --match-limit is imposed on
  460                  the number of times this function is called during  a  match,
  461                  which  has  the effect of limiting the amount of backtracking
  462                  that can take place.
  463 
  464                  The --recursion-limit option is similar to --match-limit, but
  465                  instead of limiting the total number of times that match() is
  466                  called, it limits the depth of recursive calls, which in turn
  467                  limits  the  amount of memory that can be used. The recursion
  468                  depth is a smaller number than the  total  number  of  calls,
  469                  because not all calls to match() are recursive. This limit is
  470                  of use only if it is set smaller than --match-limit.
  471 
  472                  There are no short forms for these options. The default  set-
  473                  tings  are  specified when the PCRE library is compiled, with
  474                  the default default being 10 million.
  475 
  476        -M, --multiline
  477                  Allow patterns to match more than one line. When this  option
  478                  is given, patterns may usefully contain literal newline char-
  479                  acters and internal occurrences of ^ and  $  characters.  The
  480                  output  for  a  successful match may consist of more than one
  481                  line, the last of which is the one in which the match  ended.
  482                  If the matched string ends with a newline sequence the output
  483                  ends at the end of that line.
  484 
  485                  When this option is set, the PCRE library is called in  "mul-
  486                  tiline"  mode.   There is a limit to the number of lines that
  487                  can be matched, imposed by the way that pcregrep buffers  the
  488                  input  file as it scans it. However, pcregrep ensures that at
  489                  least 8K characters or the rest of the document (whichever is
  490                  the  shorter)  are  available for forward matching, and simi-
  491                  larly the previous 8K characters (or all the previous charac-
  492                  ters,  if  fewer  than 8K) are guaranteed to be available for
  493                  lookbehind assertions. This option does not work  when  input
  494                  is read line by line (see --line-buffered.)
  495 
  496        -N newline-type, --newline=newline-type
  497                  The  PCRE  library  supports  five  different conventions for
  498                  indicating the ends of lines. They are  the  single-character
  499                  sequences  CR  (carriage  return) and LF (linefeed), the two-
  500                  character sequence CRLF, an "anycrlf" convention, which  rec-
  501                  ognizes  any  of the preceding three types, and an "any" con-
  502                  vention, in which any Unicode line ending sequence is assumed
  503                  to  end a line. The Unicode sequences are the three just men-
  504                  tioned, plus  VT  (vertical  tab,  U+000B),  FF  (form  feed,
  505                  U+000C),   NEL  (next  line,  U+0085),  LS  (line  separator,
  506                  U+2028), and PS (paragraph separator, U+2029).
  507 
  508                  When  the  PCRE  library  is  built,  a  default  line-ending
  509                  sequence   is  specified.   This  is  normally  the  standard
  510                  sequence for the operating system. Unless otherwise specified
  511                  by  this  option,  pcregrep  uses the library's default.  The
  512                  possible values for this option are CR, LF, CRLF, ANYCRLF, or
  513                  ANY.  This  makes  it  possible to use pcregrep to scan files
  514                  that have come from other environments without having to mod-
  515                  ify  their  line  endings.  If the data that is being scanned
  516                  does not agree with the convention set by this option,  pcre-
  517                  grep  may  behave in strange ways. Note that this option does
  518                  not apply to files specified by the  -f,  --exclude-from,  or
  519                  --include-from options, which are expected to use the operat-
  520                  ing system's standard newline sequence.
  521 
  522        -n, --line-number
  523                  Precede each output line by its line number in the file, fol-
  524                  lowed  by  a colon for matching lines or a hyphen for context
  525                  lines. If the filename is also being output, it precedes  the
  526                  line number. This option is forced if --line-offsets is used.
  527 
  528        --no-jit  If  the  PCRE  library is built with support for just-in-time
  529                  compiling (which speeds up matching), pcregrep  automatically
  530                  makes use of this, unless it was explicitly disabled at build
  531                  time. This option can be used to disable the use  of  JIT  at
  532                  run  time. It is provided for testing and working round prob-
  533                  lems.  It should never be needed in normal use.
  534 
  535        -o, --only-matching
  536                  Show only the part of the line that matched a pattern instead
  537                  of  the  whole  line. In this mode, no context is shown. That
  538                  is, the -A, -B, and -C options are ignored. If there is  more
  539                  than  one  match in a line, each of them is shown separately.
  540                  If -o is combined with -v (invert the sense of the  match  to
  541                  find  non-matching  lines),  no  output is generated, but the
  542                  return code is set appropriately. If the matched  portion  of
  543                  the  line is empty, nothing is output unless the file name or
  544                  line number are being printed, in which case they  are  shown
  545                  on an otherwise empty line. This option is mutually exclusive
  546                  with --file-offsets and --line-offsets.
  547 
  548        -onumber, --only-matching=number
  549                  Show only the part of the line  that  matched  the  capturing
  550                  parentheses of the given number. Up to 32 capturing parenthe-
  551                  ses are supported, and -o0 is equivalent to -o without a num-
  552                  ber.  Because  these options can be given without an argument
  553                  (see above), if an argument is present, it must be  given  in
  554                  the  same  shell item, for example, -o3 or --only-matching=2.
  555                  The comments given for the non-argument case above also apply
  556                  to  this  case. If the specified capturing parentheses do not
  557                  exist in the pattern, or were not set in the  match,  nothing
  558                  is  output  unless  the  file  name  or line number are being
  559                  printed.
  560 
  561                  If this option is given multiple times,  multiple  substrings
  562                  are  output, in the order the options are given. For example,
  563                  -o3 -o1 -o3 causes the substrings matched by capturing paren-
  564                  theses  3  and  1  and then 3 again to be output. By default,
  565                  there is no separator (but see the next option).
  566 
  567        --om-separator=text
  568                  Specify a separating string for multiple occurrences  of  -o.
  569                  The  default is an empty string. Separating strings are never
  570                  coloured.
  571 
  572        -q, --quiet
  573                  Work quietly, that is, display nothing except error messages.
  574                  The  exit  status  indicates  whether or not any matches were
  575                  found.
  576 
  577        -r, --recursive
  578                  If any given path is a directory, recursively scan the  files
  579                  it  contains, taking note of any --include and --exclude set-
  580                  tings. By default, a directory is read as a normal  file;  in
  581                  some  operating  systems this gives an immediate end-of-file.
  582                  This option is a shorthand  for  setting  the  -d  option  to
  583                  "recurse".
  584 
  585        --recursion-limit=number
  586                  See --match-limit above.
  587 
  588        -s, --no-messages
  589                  Suppress  error  messages  about  non-existent  or unreadable
  590                  files. Such files are quietly skipped.  However,  the  return
  591                  code is still 2, even if matches were found in other files.
  592 
  593        -u, --utf-8
  594                  Operate  in UTF-8 mode. This option is available only if PCRE
  595                  has been compiled with UTF-8 support. All patterns (including
  596                  those  for  any --exclude and --include options) and all sub-
  597                  ject lines that are scanned must be valid  strings  of  UTF-8
  598                  characters.
  599 
  600        -V, --version
  601                  Write the version numbers of pcregrep and the PCRE library to
  602                  the standard output and then exit. Anything else on the  com-
  603                  mand line is ignored.
  604 
  605        -v, --invert-match
  606                  Invert  the  sense  of  the match, so that lines which do not
  607                  match any of the patterns are the ones that are found.
  608 
  609        -w, --word-regex, --word-regexp
  610                  Force the patterns to match only whole words. This is equiva-
  611                  lent  to  having \b at the start and end of the pattern. This
  612                  option applies only to the patterns that are matched  against
  613                  the  contents  of files; it does not apply to patterns speci-
  614                  fied by any of the --include or --exclude options.
  615 
  616        -x, --line-regex, --line-regexp
  617                  Force the patterns to be anchored (each must  start  matching
  618                  at  the beginning of a line) and in addition, require them to
  619                  match entire lines. This is equivalent  to  having  ^  and  $
  620                  characters at the start and end of each alternative branch in
  621                  every pattern. This option applies only to the patterns  that
  622                  are  matched against the contents of files; it does not apply
  623                  to patterns specified by any of the  --include  or  --exclude
  624                  options.
  625 
  626 
  627 ENVIRONMENT VARIABLES
  628 
  629        The  environment  variables  LC_ALL  and LC_CTYPE are examined, in that
  630        order, for a locale. The first one that is set is  used.  This  can  be
  631        overridden  by  the  --locale  option.  If  no  locale is set, the PCRE
  632        library's default (usually the "C" locale) is used.
  633 
  634 
  635 NEWLINES
  636 
  637        The -N (--newline) option allows pcregrep to scan files with  different
  638        newline conventions from the default. Any parts of the input files that
  639        are written to the standard output are copied identically,  with  what-
  640        ever  newline sequences they have in the input. However, the setting of
  641        this option does not affect the interpretation of  files  specified  by
  642        the -f, --exclude-from, or --include-from options, which are assumed to
  643        use the operating system's  standard  newline  sequence,  nor  does  it
  644        affect  the  way in which pcregrep writes informational messages to the
  645        standard error and output streams. For these it uses the string "\n" to
  646        indicate  newlines,  relying on the C I/O library to convert this to an
  647        appropriate sequence.
  648 
  649 
  650 OPTIONS COMPATIBILITY
  651 
  652        Many of the short and long forms of pcregrep's options are the same  as
  653        in  the GNU grep program. Any long option of the form --xxx-regexp (GNU
  654        terminology) is also available as --xxx-regex (PCRE terminology).  How-
  655        ever,  the  --file-list, --file-offsets, --include-dir, --line-offsets,
  656        --locale, --match-limit, -M, --multiline, -N,  --newline,  --om-separa-
  657        tor,  --recursion-limit,  -u, and --utf-8 options are specific to pcre-
  658        grep, as is the use of the  --only-matching  option  with  a  capturing
  659        parentheses number.
  660 
  661        Although  most  of the common options work the same way, a few are dif-
  662        ferent in pcregrep. For example, the --include option's argument  is  a
  663        glob  for  GNU grep, but a regular expression for pcregrep. If both the
  664        -c and -l options are given, GNU grep lists only  file  names,  without
  665        counts, but pcregrep gives the counts.
  666 
  667 
  668 OPTIONS WITH DATA
  669 
  670        There are four different ways in which an option with data can be spec-
  671        ified.  If a short form option is used, the  data  may  follow  immedi-
  672        ately, or (with one exception) in the next command line item. For exam-
  673        ple:
  674 
  675          -f/some/file
  676          -f /some/file
  677 
  678        The exception is the -o option, which may appear with or without  data.
  679        Because  of this, if data is present, it must follow immediately in the
  680        same item, for example -o3.
  681 
  682        If a long form option is used, the data may appear in the same  command
  683        line  item,  separated by an equals character, or (with two exceptions)
  684        it may appear in the next command line item. For example:
  685 
  686          --file=/some/file
  687          --file /some/file
  688 
  689        Note, however, that if you want to supply a file name beginning with  ~
  690        as  data  in  a  shell  command,  and have the shell expand ~ to a home
  691        directory, you must separate the file name from the option, because the
  692        shell does not treat ~ specially unless it is at the start of an item.
  693 
  694        The  exceptions  to the above are the --colour (or --color) and --only-
  695        matching options, for which the data  is  optional.  If  one  of  these
  696        options  does  have  data, it must be given in the first form, using an
  697        equals character. Otherwise pcregrep will assume that it has no data.
  698 
  699 
  700 MATCHING ERRORS
  701 
  702        It is possible to supply a regular expression that takes  a  very  long
  703        time  to  fail  to  match certain lines. Such patterns normally involve
  704        nested indefinite repeats, for example: (a+)*\d when matched against  a
  705        line  of  a's  with  no  final  digit. The PCRE matching function has a
  706        resource limit that causes it to abort in these circumstances. If  this
  707        happens, pcregrep outputs an error message and the line that caused the
  708        problem to the standard error stream. If there are more  than  20  such
  709        errors, pcregrep gives up.
  710 
  711        The  --match-limit  option  of  pcregrep can be used to set the overall
  712        resource limit; there is a second option called --recursion-limit  that
  713        sets  a limit on the amount of memory (usually stack) that is used (see
  714        the discussion of these options above).
  715 
  716 
  717 DIAGNOSTICS
  718 
  719        Exit status is 0 if any matches were found, 1 if no matches were found,
  720        and  2  for syntax errors, overlong lines, non-existent or inaccessible
  721        files (even if matches were found in other files) or too many  matching
  722        errors. Using the -s option to suppress error messages about inaccessi-
  723        ble files does not affect the return code.
  724 
  725 
  726 SEE ALSO
  727 
  728        pcrepattern(3), pcresyntax(3), pcretest(1).
  729 
  730 
  731 AUTHOR
  732 
  733        Philip Hazel
  734        University Computing Service
  735        Cambridge CB2 3QH, England.
  736 
  737 
  738 REVISION
  739 
  740        Last updated: 03 April 2014
  741        Copyright (c) 1997-2014 University of Cambridge.