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pcre2grep(1)                                                      pcre2grep(1)




NAME

       pcre2grep - a grep with Perl-compatible regular expressions.


SYNOPSIS

       pcre2grep [options] [long options] [pattern] [path1 path2 ...]


DESCRIPTION


       pcre2grep  searches  files  for  character patterns, in the same way as
       other grep commands do,  but  it  uses  the  PCRE2  regular  expression
       library  to  support  patterns  that  are  compatible  with the regular
       expressions of Perl 5. See pcre2syntax(3) for a quick-reference summary
       of  pattern  syntax,  or  pcre2pattern(3) for a full description of the
       syntax and semantics of the regular expressions that PCRE2 supports.

       Patterns, whether supplied on the command line or in a  separate  file,
       are given without delimiters. For example:

         pcre2grep 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, pcre2grep  reads  the  standard  input.  The
       standard  input can also be referenced by a name consisting of a single
       hyphen.  For example:

         pcre2grep some-pattern file1 - file3

       Input files are searched line by  line.  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
       pcre2grep behaves. In particular, the -M option makes  it  possible  to
       search  for  strings  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  parameters  that  can  be  set by the --buffer-size and
       --max-buffer-size options. The first of these sets the size  of  buffer
       that  is obtained at the start of processing. If an input file contains
       very long lines, a larger buffer may be  needed;  this  is  handled  by
       automatically extending the buffer, up to the limit specified by --max-
       buffer-size. The default values for these parameters can  be  set  when
       pcre2grep  is  built;  if nothing is specified, the defaults are set to
       20KiB and 1MiB respectively. An error occurs if a line is too long  and
       the buffer can no longer be expanded.

       The  block  of  memory that is actually used is three times the "buffer
       size", to allow for buffering "before" and "after" lines. If the buffer
       size  is too small, fewer than requested "before" and "after" lines may
       be output.

       Patterns can be no longer than 8KiB 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 matched 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, pcre2grep uses
       the value to set a locale when calling the PCRE2 library.  The --locale
       option can be used to override this.


SUPPORT FOR COMPRESSED FILES


       It  is  possible to compile pcre2grep so that it uses libz or libbz2 to
       read compressed files whose names end in .gz or .bz2, respectively. You
       can  find out whether your pcre2grep binary has support for one or both
       of these file types by running it with the --help option. If the appro-
       priate support is not present, all files are treated as plain text. The
       standard input is always so treated. When input is  from  a  compressed
       .gz or .bz2 file, the --line-buffered option is ignored.


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.
       However,  if  the  newline  type is specified as NUL, that is, the line
       terminator is a binary zero, the test for a binary file is not applied.
       See  the  --binary-files  option for a means of changing the way binary
       files are handled.


BINARY ZEROS IN PATTERNS


       Patterns passed from the command line are strings that  are  terminated
       by  a  binary zero, so cannot contain internal zeros. However, patterns
       that are read from a file via the -f option may contain binary zeros.


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  up  to  number  lines  of context after each matching
                 line. Fewer lines are output if the next match or the end  of
                 the  file  is  reached,  or if the processing buffer size has
                 been set too small. If file names  and/or  line  numbers  are
                 being  output,  a hyphen separator 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 contigu-
                 ous in the input file. The value of number is expected to  be
                 relatively small. When -c is used, -A is ignored.

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

       -B number, --before-context=number
                 Output up to number lines of  context  before  each  matching
                 line.  Fewer  lines  are  output if the previous match or the
                 start of the file is within number lines, or if the  process-
                 ing  buffer size has been set too small. If file names and/or
                 line numbers are being output, a  hyphen  separator  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.  When  -c  is  used,  -B  is
                 ignored.

       --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 and are skipped without causing
                 any output or affecting the return code.

       --buffer-size=number
                 Set the parameter that controls how much memory  is  obtained
                 at the start of processing for buffering files that are being
                 scanned. See also --max-buffer-size below.

       -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 lines from the files that  are  being  scanned;
                 instead  output  the  number  of  lines  that would have been
                 shown, either because they matched, or, if -v is set, because
                 they  failed  to match. By default, this count is exactly the
                 same as the number of lines that would have been output,  but
                 if  the -M (multiline) option is used (without -v), there may
                 be more suppressed lines than the count (that is, the  number
                 of matches).

                 If  no lines are selected, the number zero is output. If sev-
                 eral files are are being scanned, a count is output for  each
                 of  them and the -t option can be used to cause a total to be
                 output at  the  end.  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 pcre2grep 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 one of
                 the environment variables PCRE2GREP_COLOUR,  PCRE2GREP_COLOR,
                 PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that
                 order.  If  none  of  these  are  set,  pcre2grep  looks  for
                 GREP_COLORS  or  GREP_COLOR (in that order). The value of the
                 variable should be a string of two numbers,  separated  by  a
                 semicolon,  except  in  the  case  of GREP_COLORS, which must
                 start with "ms=" or "mt=" followed by two semicolon-separated
                 colours,  terminated  by the end of the string or by a colon.
                 If GREP_COLORS does not start  with  "ms="  or  "mt="  it  is
                 ignored, and GREP_COLOR is checked.

                 If  the  string obtained from one of the above variables con-
                 tains any characters other than semicolon or digits, the set-
                 ting is ignored and the default colour is used. The string is
                 copied directly into the control string for setting colour on
                 a  terminal,  so it is your responsibility to ensure that the
                 values make sense. If no  relevant  environment  variable  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.

       --depth-limit=number
                 See --match-limit below.

       -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, pcre2grep 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 PCRE2 reg-
                 ular 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 PCRE2 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. As is the case with patterns on
                 the command line, no delimiters should be used. What  consti-
                 tutes  a  newline when reading the file is the operating sys-
                 tem's default interpretation of \n. 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. Patterns
                 read from a file in this way may contain binary zeros,  which
                 are  treated  as  ordinary data characters. See also the com-
                 ments 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  file  name 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. What constitutes a
                 newline when reading  the  file  is  the  operating  system's
                 default.  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 file name can be
                 given as "-" to refer to the standard input.  If  --file  and
                 --file-list  are  both  specified  as  "-", patterns are read
                 first. This is useful only when the standard input is a  ter-
                 minal,  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  --output,
                 --line-offsets, and --only-matching.

       -H, --with-filename
                 Force  the  inclusion of the file name at the start of output
                 lines when searching a single file. By default, the file name
                 is not shown in this case.  For matching lines, the file name
                 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. When the -M option causes a pattern  to  match
                 more  than  one  line, only the first is preceded by the file
                 name. This option  overrides  any  previous  -h,  -l,  or  -L
                 options.

       -h, --no-filename
                 Suppress the output file names when searching multiple files.
                 By default, file names are  shown  when  multiple  files  are
                 searched.  For matching lines, the file name 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.
                 This option overrides any previous -H, -L, or -l options.

       --heap-limit=number
                 See --match-limit below.

       --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        Ignore  binary  files.  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 whose names 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 PCRE2 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 whose names 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 PCRE2 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.  This option overrides any previous -H, -h, or -l
                 options.

       -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  that  occurs
                 with  -c  on  its own. This option overrides any previous -H,
                 -h, or -L options.

       --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, non-compressed 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
                 pcre2grep  can  determine that it is reading from a terminal,
                 which is currently possible only in Unix-like environments or
                 Windows. 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
                 pcre2grep to buffer up large amounts of data.   However,  its
                 use  will  affect  performance, and the -M (multiline) option
                 ceases to work. When input is from a compressed .gz  or  .bz2
                 file, --line-buffered is ignored.

       --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  --output,
                 --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 PCRE2
                 library's default (usually the "C" locale) is used. There  is
                 no short form for this option.

       -M, --multiline
                 Allow  patterns to match more than one line. When this option
                 is set, the PCRE2 library is called in "multiline" mode. This
                 allows  a matched string to extend past the end of a line and
                 continue on one or more subsequent lines. Patterns used  with
                 -M may usefully contain literal newline characters and inter-
                 nal occurrences of ^ and $ characters. The output for a  suc-
                 cessful  match  may  consist of more than one line. The first
                 line is the line in which the match  started,  and  the  last
                 line  is  the  line  in which the match ended. If the matched
                 string ends with a newline sequence, the output ends  at  the
                 end  of  that  line.   If  -v  is set, none of the lines in a
                 multi-line match are output. Once a match has  been  handled,
                 scanning  restarts at the beginning of the line after the one
                 in which the match ended.

                 The newline sequence that separates multiple  lines  must  be
                 matched  as  part  of  the  pattern. For example, to find the
                 phrase "regular expression" in a file where  "regular"  might
                 be  at the end of a line and "expression" at the start of the
                 next line, you could use this command:

                   pcre2grep -M 'regular\s+expression' <file>

                 The \s escape sequence matches  any  white  space  character,
                 including  newlines,  and  is  followed  by  + so as to match
                 trailing white space on the first line as  well  as  possibly
                 handling a two-character newline sequence.

                 There  is a limit to the number of lines that can be matched,
                 imposed by the way that pcre2grep buffers the input  file  as
                 it  scans  it.  With  a sufficiently large processing buffer,
                 this should not be a problem, but the -M option does not work
                 when input is read line by line (see --line-buffered.)

       -m number, --max-count=number
                 Stop  processing after finding number matching lines, or non-
                 matching lines if -v is also set. Any trailing context  lines
                 are  output  after  the  final match. In multiline mode, each
                 multiline match counts as just one line for this purpose.  If
                 this  limit is reached when reading the standard input from a
                 regular file, the file is left positioned just after the last
                 matching  line.   If -c is also set, the count that is output
                 is never greater than number. This option has  no  effect  if
                 used with -L, -l, or -q, or when just checking for a match in
                 a binary file.

       --match-limit=number
                 Processing some regular expression patterns may take  a  very
                 long time to search for all possible matching strings. Others
                 may require a very large amount of memory.  There  are  three
                 options that set resource limits for matching.

                 The --match-limit option provides a means of limiting comput-
                 ing resource usage when  processing  patterns  that  are  not
                 going  to match, but which have a very large number of possi-
                 bilities in their search trees. The classic example is a pat-
                 tern  that  uses  nested unlimited repeats. Internally, PCRE2
                 has a counter that is incremented each time around  its  main
                 processing  loop.  If  the  value  set  by  --match-limit  is
                 reached, an error occurs.

                 The --heap-limit option specifies, as a number  of  kibibytes
                 (units  of 1024 bytes), the amount of heap memory that may be
                 used for matching. Heap memory is needed only if matching the
                 pattern  requires a significant number of nested backtracking
                 points to be remembered. This parameter can be set to zero to
                 forbid the use of heap memory altogether.

                 The  --depth-limit  option  limits  the depth of nested back-
                 tracking points, which indirectly limits the amount of memory
                 that is used. The amount of memory needed for each backtrack-
                 ing point depends on the number of capturing  parentheses  in
                 the pattern, so the amount of memory that is used before this
                 limit acts varies from pattern to pattern. This limit  is  of
                 use only if it is set smaller than --match-limit.

                 There  are no short forms for these options. The default lim-
                 its can be set when the PCRE2 library is  compiled;  if  they
                 are  not specified, the defaults are very large and so effec-
                 tively unlimited.

       --max-buffer-size=number
                 This limits the expansion of  the  processing  buffer,  whose
                 initial  size can be set by --buffer-size. The maximum buffer
                 size is silently forced to be no smaller  than  the  starting
                 buffer size.

       -N newline-type, --newline=newline-type
                 Six different conventions for indicating the ends of lines in
                 scanned files are supported. For example:

                   pcre2grep -N CRLF 'some pattern' <file>

                 The newline type may be specified in upper, lower,  or  mixed
                 case.  If  the  newline  type  is NUL, lines are separated by
                 binary zero characters. The other types are the  single-char-
                 acter  sequences  CR (carriage return) and LF (linefeed), the
                 two-character sequence CRLF, an "anycrlf" type, which  recog-
                 nizes  any  of  the preceding three types, and an "any" type,
                 for which any Unicode line ending sequence is assumed to  end
                 a  line.  The Unicode sequences are the three just mentioned,
                 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  PCRE2  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, pcre2grep uses the library's default.

                 This  option makes it possible to use pcre2grep 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,
                 pcre2grep  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
                 operating 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 file name is also being output, it precedes the
                 line  number.  When  the  -M option causes a pattern to match
                 more than one line, only the first is preceded  by  its  line
                 number. This option is forced if --line-offsets is used.

       --no-jit  If  the  PCRE2 library is built with support for just-in-time
                 compiling (which speeds up matching), pcre2grep 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 text, --output=text
                 When there is a match, instead of outputting  the  line  that
                 matched,  output just the text specified in this option, fol-
                 lowed by an operating-system standard newline. In this  mode,
                 no  context is shown. That is, the -A, -B, and -C options are
                 ignored. The --newline option has no effect on  this  option,
                 which is mutually exclusive with --only-matching, --file-off-
                 sets, and --line-offsets. However, like  --only-matching,  if
                 there is more than one match in a line, each of them causes a
                 line of output.

                 Escape sequences starting with a dollar character may be used
                 to insert the contents of the matched part of the line and/or
                 captured substrings into the text.

                 $<digits> or ${<digits>} is replaced  by  the  captured  sub-
                 string  of  the  given  decimal  number; zero substitutes the
                 whole match. If the number is greater than the number of cap-
                 turing  substrings,  or if the capture is unset, the replace-
                 ment is empty.

                 $a is replaced by bell; $b by backspace; $e by escape; $f  by
                 form  feed;  $n by newline; $r by carriage return; $t by tab;
                 $v by vertical tab.

                 $o<digits> or $o{<digits>} is replaced by the character whose
                 code  point  is the given octal number. In the first form, up
                 to three octal digits are processed.  When  more  digits  are
                 needed  in Unicode mode to specify a wide character, the sec-
                 ond form must be used.

                 $x<digits> or $x{<digits>} is replaced by the character  rep-
                 resented  by the given hexadecimal number. In the first form,
                 up to two hexadecimal digits are processed. When more  digits
                 are  needed  in Unicode mode to specify a wide character, the
                 second form must be used.

                 Any other character is substituted by itself. In  particular,
                 $$ is replaced by a single dollar.

       -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,
                 on  a  separate  line  of  output.  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 appropri-
                 ately. 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  --output,
                 --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 50 capturing parenthe-
                 ses are supported by default. This limit can be  changed  via
                 the  --om-capture option. A pattern may contain any number of
                 capturing parentheses, but only those whose number is  within
                 the  limit can be accessed by -o. An error occurs if the num-
                 ber specified by -o is greater than the limit.

                 -o0 is the same as -o without a number. 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  option.  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 output.

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

       --om-capture=number
                 Set the number of capturing parentheses that can be  accessed
                 by -o. The default is 50.

       --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
                 This is an obsolete synonym for --depth-limit.  See  --match-
                 limit above for details.

       -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.

       -t, --total-count
                 This  option  is  useful when scanning more than one file. If
                 used on its own, -t suppresses all output except for a  grand
                 total  number  of matching lines (or non-matching lines if -v
                 is used) in all the files. If -t is used  with  -c,  a  grand
                 total  is  output except when the previous output is just one
                 line. In other words, it is not output when just  one  file's
                 count  is  listed.  If file names are being output, the grand
                 total is preceded by "TOTAL:". Otherwise, it appears as  just
                 another  number.  The  -t option is ignored when used with -L
                 (list files without matches), because the grand  total  would
                 always be zero.

       -u, --utf Operate in UTF-8 mode. This option is available only if PCRE2
                 has been compiled with UTF-8 support. All patterns (including
                 those  for any --exclude and --include options) and all lines
                 that are scanned must be valid strings of  UTF-8  characters.
                 If an invalid UTF-8 string is encountered, an error occurs.

       -U, --utf-allow-invalid
                 As  --utf,  but in addition subject lines may contain invalid
                 UTF-8 code unit sequences. These can never form part  of  any
                 pattern  match.  Patterns  themselves, however, must still be
                 valid UTF-8 strings. This facility allows valid UTF-8 strings
                 to be sought within arbitrary byte sequences in executable or
                 other binary files. For more details about matching  in  non-
                 valid UTF-8 strings, see the pcre2unicode(3) documentation.

       -V, --version
                 Write  the version numbers of pcre2grep and the PCRE2 library
                 to the standard output and then exit. Anything  else  on  the
                 command 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.  When
                 this  option  is  set,  options  such  as --only-matching and
                 --output, which specify parts of a match that are to be  out-
                 put, are ignored.

       -w, --word-regex, --word-regexp
                 Force the patterns only to match "words". That is, there must
                 be a word boundary at the  start  and  end  of  each  matched
                 string.  This is equivalent to having "\b(?:" at the start of
                 each pattern, and ")\b" at the end. 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.

       -x, --line-regex, --line-regexp
                 Force  the  patterns to start matching only at the beginnings
                 of lines, and in  addition,  require  them  to  match  entire
                 lines. In multiline mode the match may be more than one line.
                 This is equivalent to having "^(?:" at the start of each pat-
                 tern  and  ")$"  at  the end. 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  PCRE2
       library's default (usually the "C" locale) is used.


NEWLINES


       The  -N  (--newline) option allows pcre2grep to scan files with newline
       conventions that differ from the default. This option affects only  the
       way  scanned files are processed. It does not affect the interpretation
       of  files  specified  by  the  -f,  --file-list,   --exclude-from,   or
       --include-from options.

       Any  parts  of the scanned input files that are written to the standard
       output are copied with whatever newline  sequences  they  have  in  the
       input.  However, if the final line of a file is output, and it does not
       end with a newline sequence, a newline sequence is added. If  the  new-
       line  setting  is  CR, LF, CRLF or NUL, that line ending is output; for
       the other settings (ANYCRLF or ANY) a single NL is used.

       The newline setting does not affect the way in which  pcre2grep  writes
       newlines  in  informational  messages  to the standard output and error
       streams.  Under Windows, the standard output is set to  be  binary,  so
       that  "\r\n" at the ends of output lines that are copied from the input
       is not converted to "\r\r\n" by the C I/O library. This means that  any
       messages  written  to the standard output must end with "\r\n". For all
       other operating systems, and for all messages  to  the  standard  error
       stream, "\n" is used.


OPTIONS COMPATIBILITY


       Many of the short and long forms of pcre2grep'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 (PCRE2 terminology). How-
       ever, the  --depth-limit,  --file-list,  --file-offsets,  --heap-limit,
       --include-dir,  --line-offsets,  --locale,  --match-limit, -M, --multi-
       line, -N, --newline,  --om-separator,  --output,  -u,  --utf,  -U,  and
       --utf-allow-invalid options are specific to pcre2grep, 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 pcre2grep. For example, the --include option's argument is a
       glob for GNU grep, but a regular expression for pcre2grep. If both  the
       -c  and  -l  options are given, GNU grep lists only file names, without
       counts, but pcre2grep gives the counts as well.


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 pcre2grep will assume that it has no  data.


USING PCRE2'S CALLOUT FACILITY


       pcre2grep  has,  by  default,  support for calling external programs or
       scripts or echoing specific strings during matching by  making  use  of
       PCRE2's  callout  facility.  However, this support can be completely or
       partially disabled when pcre2grep is built. You can  find  out  whether
       your  binary  has  support  for  callouts by running it with the --help
       option. If callout support is completely disabled, all callouts in pat-
       terns are ignored by pcre2grep.  If the facility is partially disabled,
       calling external programs is not supported, and callouts  that  request
       it are ignored.

       A  callout  in a PCRE2 pattern is of the form (?C<arg>) where the argu-
       ment is either a number or a quoted string (see the pcre2callout  docu-
       mentation  for  details).  Numbered  callouts are ignored by pcre2grep;
       only callouts with string arguments are useful.

   Echoing a specific string

       Starting the callout string with a pipe character  invokes  an  echoing
       facility that avoids calling an external program or script. This facil-
       ity is always available, provided that  callouts  were  not  completely
       disabled  when  pcre2grep  was built. The rest of the callout string is
       processed as a zero-terminated string, which means it should  not  con-
       tain  any  internal  binary  zeros. It is written to the output, having
       first been passed through the same escape processing as text  from  the
       --output  (-O) option (see above). However, $0 cannot be used to insert
       a matched substring because the match is still  in  progress.  Instead,
       the  single  character '0' is inserted. Any syntax errors in the string
       (for example, a dollar not followed by another  character)  causes  the
       callout  to be ignored. No terminator is added to the output string, so
       if you want a newline, you must include it explicitly using the  escape
       $n. For example:

         pcre2grep '(.)(..(.))(?C"|[$1] [$2] [$3]$n")' <some file>

       Matching  continues normally after the string is output. If you want to
       see only the callout output but not any output from  an  actual  match,
       you should end the pattern with (*FAIL).

   Calling external programs or scripts

       This facility can be independently disabled when pcre2grep is built. It
       is supported for Windows, where a call to _spawnvp() is used, for  VMS,
       where  lib$spawn()  is  used,  and  for any Unix-like environment where
       fork() and execv() are available.

       If the callout string does not start with a pipe (vertical bar) charac-
       ter,  it  is parsed into a list of substrings separated by pipe charac-
       ters. The first substring must be an executable name, with the  follow-
       ing substrings specifying arguments:

         executable_name|arg1|arg2|...

       Any  substring  (including  the  executable  name)  may  contain escape
       sequences started by a dollar character. These are the same as for  the
       --output (-O) option documented above, except that $0 cannot insert the
       matched string because the match is still  in  progress.  Instead,  the
       character '0' is inserted. If you need a literal dollar or pipe charac-
       ter in any substring, use $$ or $| respectively. Here is an example:

         echo -e "abcde\n12345" | pcre2grep \
           '(?x)(.)(..(.))
           (?C"/bin/echo|Arg1: [$1] [$2] [$3]|Arg2: $|${1}$| ($4)")()' -

         Output:

           Arg1: [a] [bcd] [d] Arg2: |a| ()
           abcde
           Arg1: [1] [234] [4] Arg2: |1| ()
           12345

       The parameters for the system call that is used to run the  program  or
       script are zero-terminated strings. This means that binary zero charac-
       ters in the callout argument will cause premature termination of  their
       substrings,  and  therefore should not be present. Any syntax errors in
       the string (for example, a dollar not followed  by  another  character)
       causes the callout to be ignored.  If running the program fails for any
       reason (including the non-existence of the executable), a local  match-
       ing failure occurs and the matcher backtracks in the normal way.


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  PCRE2  matching  function  has  a
       resource  limit that causes it to abort in these circumstances. If this
       happens, pcre2grep outputs an error message and the  line  that  caused
       the  problem  to  the  standard error stream. If there are more than 20
       such errors, pcre2grep gives up.

       The --match-limit option of pcre2grep can be used to  set  the  overall
       resource  limit.  There are also other limits that affect the amount of
       memory used during matching; see the  discussion  of  --heap-limit  and
       --depth-limit 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.

       When   run  under  VMS,  the  return  code  is  placed  in  the  symbol
       PCRE2GREP_RC because VMS  does  not  distinguish  between  exit(0)  and
       exit(1).


SEE ALSO


       pcre2pattern(3), pcre2syntax(3), pcre2callout(3), pcre2unicode(3).


AUTHOR


       Philip Hazel
       University Computing Service
       Cambridge, England.


REVISION


       Last updated: 04 October 2020
       Copyright (c) 1997-2020 University of Cambridge.



PCRE2 10.36                     04 October 2020                   pcre2grep(1)

pcre2 10.36 - Generated Thu Dec 24 09:30:59 CST 2020
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