pcre2grep(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | SUPPORT FOR COMPRESSED FILES | BINARY FILES | BINARY ZEROS IN PATTERNS | OPTIONS | ENVIRONMENT VARIABLES | NEWLINES | OPTIONS COMPATIBILITY WITH GNU GREP | OPTIONS WITH DATA | USING PCRE2'S CALLOUT FACILITY | MATCHING ERRORS | DIAGNOSTICS | SEE ALSO | AUTHOR | REVISION | COLOPHON

PCRE2GREP(1)             General Commands Manual            PCRE2GREP(1)

NAME         top

       pcre2grep - a grep with Perl-compatible regular expressions.

SYNOPSIS         top

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

DESCRIPTION         top


       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

       By default, input files are searched line by line, so pattern
       assertions about the beginning and end of a subject string (^, $,
       \A, \Z, and \z) match at the beginning and end of each line. When
       a line matches a pattern, it 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. For example, 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 -h and -H options control whether or not
       file names are shown, and the -Z option changes the file name
       terminator to a zero byte.

       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.

       When matching with a multiline pattern, the size of the buffer
       must be at least half of the maximum match expected or the
       pattern might fail to match.

       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, --line-offsets, or --output is used to output
       only the part of the line that matched (either shown literally,
       or as an offset), the behaviour is different. In this situation,
       all the patterns are applied to the line. If there is more than
       one match, the one that begins nearest to the start of the
       subject is processed; if there is more than one match at that
       position, the one with the longest matching substring is
       processed; if the matching substrings are equal, the first match
       found is processed.

       Scanning with all the patterns resumes immediately following the
       match, so that later matches on the same line can be found. Note,
       however, that an overlapping match that starts in the middle of
       another match will not be processed.

       The above behaviour was changed at release 10.41 to be more
       compatible with GNU grep. In earlier releases, pcre2grep did not
       recognize matches from later patterns that were earlier in the
       subject.

       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         top


       Compile-time options for pcre2grep can set it up to use libz or
       libbz2 for reading 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. If a file with a .gz or .bz2 extension is
       not in fact compressed, it is read as a plain text file. When
       input is from a compressed .gz or .bz2 file, the --line-buffered
       option is ignored.

BINARY FILES         top


       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         top


       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         top


       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 (the -Z option can be used to
              change the file name terminator to a zero byte). 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
              (the -Z option can be used to change the file name
              terminator to a zero byte). 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 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. It is ignored if --file-offsets, --line-offsets,
              or --output is set. By default, output is not coloured.
              The value for the --colour option (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, --case-restrict
              When case distinctions are being ignored in Unicode mode,
              two ASCII letters (K and S) will by default match Unicode
              characters U+212A (Kelvin sign) and U+017F (long S)
              respectively, as well as their lower case ASCII
              counterparts. When this option is set, case equivalences
              are restricted such that no ASCII character matches a non-
              ASCII character, and vice versa.

       -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.

              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.

       --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. 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.

              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 matched before the file's patterns.
              However, no 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, --colour
              has no effect, and 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.

       --group-separator=text
              Output this text string instead of two hyphens between
              groups of lines when -A, -B, or -C is in use. See also
              --no-group-separator.

       -H, --with-filename
              Force the inclusion of the file name at the start of
              output lines when searching a single file. The file name
              is not normally shown in this case.  By default, for
              matching lines, the file name is followed by a colon; for
              context lines, a hyphen separator is used. The -Z option
              can be used to change the terminator to a zero byte. 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. File names are normally shown when multiple files
              are searched. By default, for matching lines, the file
              name is followed by a colon; for context lines, a hyphen
              separator is used. The -Z option can be used to change the
              terminator to a zero byte. 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 when pattern
              matching. This applies when matching path names for
              inclusion or exclusion as well as when matching lines in
              files.

       --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 by default, but if the -Z option is set,
              they are separated by zero bytes instead of newlines. 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, but if the -Z option is set, they are separated by
              zero bytes instead of newlines. 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, --colour has no effect, and 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, and a match is allowed to continue past the end of
              the initial line and onto one or more subsequent lines.

              Patterns used with -M may usefully contain literal newline
              characters and internal occurrences of ^ and $ characters,
              because in multiline mode these can match at internal
              newlines. Because pcre2grep is scanning multiple lines,
              the \Z and \z assertions match only at the end of the last
              line in the file.  The \A assertion matches at the start
              of the first line of a match. This can be any line in the
              file; it is not anchored to the first line.

              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.

              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 maximum amount of
              heap memory that may be used for matching.

              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-group-separator
              Do not output a separator between groups of lines when -A,
              -B, or -C is in use. The default is to output a line
              containing two hyphens. See also --group-separator.

       --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 around 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, --colour has no effect, and 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.

       -P, --no-ucp
              Starting from release 10.43, when UTF/Unicode mode is
              specified with -u or -U, the PCRE2_UCP option is used by
              default. This means that the POSIX classes in patterns
              match more than just ASCII characters. For example,
              [:digit:] matches any Unicode decimal digit. The --no-ucp
              option suppresses PCRE2_UCP, thus restricting the POSIX
              classes to ASCII characters, as was the case in earlier
              releases. Note that there are now more fine-grained option
              settings within patterns that affect individual classes.
              For example, when in UCP mode, the sequence (?aP)
              restricts [:word:] to ASCII letters, while allowing \w to
              match Unicode letters and digits.

       -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/Unicode 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.

       -Z, --null
              Terminate files names in the regular output with a zero
              byte (the NUL character) instead of what would normally
              appear. This is useful when file names contain unusual
              characters such as colons, hyphens, or even newlines. The
              option does not apply to file names in error messages.

ENVIRONMENT VARIABLES         top


       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         top


       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 WITH GNU GREP         top


       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 --case-restrict, --depth-
       limit, -E, --file-list, --file-offsets, --heap-limit, --include-
       dir, --line-offsets, --locale, --match-limit, -M, --multiline,
       -N, --newline, --no-ucp, --om-separator, --output, -P, -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 in pcre2grep it is a regular
       expression to which the -i option applies. 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         top


       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         top


       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         top


       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         top


       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         top


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

AUTHOR         top


       Philip Hazel
       Retired from University Computing Service
       Cambridge, England.

REVISION         top


       Last updated: 22 December 2023
       Copyright (c) 1997-2023 University of Cambridge.

COLOPHON         top

       This page is part of the PCRE (Perl Compatible Regular
       Expressions) project.  Information about the project can be found
       at ⟨http://www.pcre.org/⟩.  If you have a bug report for this
       manual page, see
       ⟨http://bugs.exim.org/enter_bug.cgi?product=PCRE⟩.  This page was
       obtained from the tarball fetched from
       ⟨https://github.com/PhilipHazel/pcre2.git⟩ on 2024-06-14.  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to [email protected]

PCRE2 10.43                 22 December 2023                PCRE2GREP(1)