Provided by: pcre2-utils_10.39-3ubuntu0.1_amd64 bug

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.  Conversely, when one or both of these options
       are used to specify patterns, 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 appropriate 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 contiguous 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.

       --allow-lookaround-bsk
                 PCRE2  now  forbids  the use of \K in lookarounds by default, in line with Perl.
                 This option causes pcre2grep to set the PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK option,
                 which enables this somewhat dangerous usage.

       -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 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 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 several 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  output  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 contains any characters
                 other than semicolon or digits, the setting 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 multiple 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
                 regular 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 pattern,  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  directory
                 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 constitutes a newline when reading the file is the operating system'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 comments about multiple patterns versus  a  single
                 pattern with alternatives in the description of -e above.

                 If this option is given more than once, all the specified files are read. A data
                 line is output if any of the patterns match it. A 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  terminal,  from  which
                 further  lines  (the list of files) can be read after an end-of-file indication.
                 If this option is given more than once, all the specified files are read.

       --file-offsets
                 Instead of showing lines or parts of lines that match, show  each  match  as  an
                 offset  from  the  start of the file and a length, separated by a comma. In this
                 mode, no context is shown. That is, the -A, -B, and -C options are  ignored.  If
                 there  is  more than one match in a line, each of them is shown separately. This
                 option is mutually exclusive with --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 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. 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  directories  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 separate 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 output. 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
                 suppressing 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 separately. 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 matching. It overrides the
                 value  in  the  LC_ALL  or  LC_CTYPE  environment  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  internal
                 occurrences of ^ and $ characters. The output for a successful 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 computing  resource  usage
                 when  processing  patterns  that  are  not going to match, but which have a very
                 large number of possibilities in their search trees. The classic  example  is  a
                 pattern that uses nested unlimited repeats. Internally, 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 backtracking points, which
                 indirectly limits the amount of memory that is used. The amount of memory needed
                 for  each  backtracking  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 limits can be  set  when
                 the  PCRE2 library is compiled; if they are not specified, the defaults are very
                 large and so effectively 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-character sequences CR (carriage return) and LF (linefeed), the two-
                 character sequence  CRLF,  an  "anycrlf"  type,  which  recognizes  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 modify 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, followed 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 problems.  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, followed 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-offsets,  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  substring  of  the  given
                 decimal  number; zero substitutes the whole match. If the number is greater than
                 the number of capturing substrings, or if the capture is unset, the  replacement
                 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
                 second form must be used.

                 $x<digits> or $x{<digits>} is replaced by the character represented 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 appropriately. If the matched portion of the line  is  empty,
                 nothing  is  output  unless  the  file name or line number are being printed, in
                 which case they are shown on an otherwise empty line. This  option  is  mutually
                 exclusive with --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 parentheses  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 number 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 settings. 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
                 output, 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
                 pattern 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 newline 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). However, the --depth-limit, --file-list,  --file-offsets,
       --heap-limit, --include-dir, --line-offsets, --locale, --match-limit, -M, --multiline, -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 different  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 specified.  If a short
       form option is used, the data may follow immediately, or (with one exception) in the  next
       command line item. For example:

         -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 patterns 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  argument  is  either  a
       number  or  a  quoted  string  (see  the pcre2callout documentation 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 facility 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 contain 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) character,  it  is  parsed
       into  a  list  of  substrings separated by pipe characters. The first substring must be an
       executable name, with the following 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 character 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 characters 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 matching 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 inaccessible 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
       Retired from University Computing Service
       Cambridge, England.

REVISION


       Last updated: 31 August 2021
       Copyright (c) 1997-2021 University of Cambridge.