--- /dev/null
+PCRE2GREP(1) General Commands Manual PCRE2GREP(1)
+
+
+
+NAME
+ pcre2grep - a grep with Perl-compatible regular expressions.
+
+SYNOPSIS
+ pcre2grep [options] [long options] [pattern] [path1 path2 ...]
+
+
+DESCRIPTION
+
+ pcre2grep searches files for character patterns, in the same way as
+ other grep commands do, but it uses the PCRE2 regular expression
+ library to support patterns that are compatible with the regular
+ expressions of Perl 5. See pcre2syntax(3) for a quick-reference summary
+ of pattern syntax, or pcre2pattern(3) for a full description of the
+ syntax and semantics of the regular expressions that PCRE2 supports.
+
+ Patterns, whether supplied on the command line or in a separate file,
+ are given without delimiters. For example:
+
+ pcre2grep Thursday /etc/motd
+
+ If you attempt to use delimiters (for example, by surrounding a pattern
+ with slashes, as is common in Perl scripts), they are interpreted as
+ part of the pattern. Quotes can of course be used to delimit patterns
+ on the command line because they are interpreted by the shell, and
+ indeed quotes are required if a pattern contains white space or shell
+ metacharacters.
+
+ The first argument that follows any option settings is treated as the
+ single pattern to be matched when neither -e nor -f is present. Con-
+ versely, when one or both of these options are used to specify pat-
+ terns, all arguments are treated as path names. At least one of -e, -f,
+ or an argument pattern must be provided.
+
+ If no files are specified, pcre2grep reads the standard input. The
+ standard input can also be referenced by a name consisting of a single
+ hyphen. For example:
+
+ pcre2grep some-pattern file1 - file3
+
+ Input files are searched line by line. By default, each line that
+ matches a pattern is copied to the standard output, and if there is
+ more than one file, the file name is output at the start of each line,
+ followed by a colon. However, there are options that can change how
+ pcre2grep behaves. In particular, the -M option makes it possible to
+ search for strings that span line boundaries. What defines a line
+ boundary is controlled by the -N (--newline) option.
+
+ The amount of memory used for buffering files that are being scanned is
+ controlled by parameters that can be set by the --buffer-size and
+ --max-buffer-size options. The first of these sets the size of buffer
+ that is obtained at the start of processing. If an input file contains
+ very long lines, a larger buffer may be needed; this is handled by
+ automatically extending the buffer, up to the limit specified by --max-
+ buffer-size. The default values for these parameters can be set when
+ pcre2grep is built; if nothing is specified, the defaults are set to
+ 20KiB and 1MiB respectively. An error occurs if a line is too long and
+ the buffer can no longer be expanded.
+
+ The block of memory that is actually used is three times the "buffer
+ size", to allow for buffering "before" and "after" lines. If the buffer
+ size is too small, fewer than requested "before" and "after" lines may
+ be output.
+
+ Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the
+ greater. BUFSIZ is defined in <stdio.h>. When there is more than one
+ pattern (specified by the use of -e and/or -f), each pattern is applied
+ to each line in the order in which they are defined, except that all
+ the -e patterns are tried before the -f patterns.
+
+ By default, as soon as one pattern matches a line, no further patterns
+ are considered. However, if --colour (or --color) is used to colour the
+ matching substrings, or if --only-matching, --file-offsets, or --line-
+ offsets is used to output only the part of the line that matched
+ (either shown literally, or as an offset), scanning resumes immediately
+ following the match, so that further matches on the same line can be
+ found. If there are multiple patterns, they are all tried on the
+ remainder of the line, but patterns that follow the one that matched
+ are not tried on the earlier part of the line.
+
+ This behaviour means that the order in which multiple patterns are
+ specified can affect the output when one of the above options is used.
+ This is no longer the same behaviour as GNU grep, which now manages to
+ display earlier matches for later patterns (as long as there is no
+ overlap).
+
+ Patterns that can match an empty string are accepted, but empty string
+ matches are never recognized. An example is the pattern
+ "(super)?(man)?", in which all components are optional. This pattern
+ finds all occurrences of both "super" and "man"; the output differs
+ from matching with "super|man" when only the matching substrings are
+ being shown.
+
+ If the LC_ALL or LC_CTYPE environment variable is set, pcre2grep uses
+ the value to set a locale when calling the PCRE2 library. The --locale
+ option can be used to override this.
+
+
+SUPPORT FOR COMPRESSED FILES
+
+ It is possible to compile pcre2grep so that it uses libz or libbz2 to
+ read compressed files whose names end in .gz or .bz2, respectively. You
+ can find out whether your pcre2grep binary has support for one or both
+ of these file types by running it with the --help option. If the appro-
+ priate support is not present, all files are treated as plain text. The
+ standard input is always so treated. When input is from a compressed
+ .gz or .bz2 file, the --line-buffered option is ignored.
+
+
+BINARY FILES
+
+ By default, a file that contains a binary zero byte within the first
+ 1024 bytes is identified as a binary file, and is processed specially.
+ (GNU grep identifies binary files in this manner.) However, if the new-
+ line type is specified as "nul", that is, the line terminator is a
+ binary zero, the test for a binary file is not applied. See the
+ --binary-files option for a means of changing the way binary files are
+ handled.
+
+
+BINARY ZEROS IN PATTERNS
+
+ Patterns passed from the command line are strings that are terminated
+ by a binary zero, so cannot contain internal zeros. However, patterns
+ that are read from a file via the -f option may contain binary zeros.
+
+
+OPTIONS
+
+ The order in which some of the options appear can affect the output.
+ For example, both the -H and -l options affect the printing of file
+ names. Whichever comes later in the command line will be the one that
+ takes effect. Similarly, except where noted below, if an option is
+ given twice, the later setting is used. Numerical values for options
+ may be followed by K or M, to signify multiplication by 1024 or
+ 1024*1024 respectively.
+
+ -- This terminates the list of options. It is useful if the next
+ item on the command line starts with a hyphen but is not an
+ option. This allows for the processing of patterns and file
+ names that start with hyphens.
+
+ -A number, --after-context=number
+ Output up to number lines of context after each matching
+ line. Fewer lines are output if the next match or the end of
+ the file is reached, or if the processing buffer size has
+ been set too small. If file names and/or line numbers are
+ being output, a hyphen separator is used instead of a colon
+ for the context lines. A line containing "--" is output
+ between each group of lines, unless they are in fact contigu-
+ ous in the input file. The value of number is expected to be
+ relatively small. When -c is used, -A is ignored.
+
+ -a, --text
+ Treat binary files as text. This is equivalent to --binary-
+ files=text.
+
+ -B number, --before-context=number
+ Output up to number lines of context before each matching
+ line. Fewer lines are output if the previous match or the
+ start of the file is within number lines, or if the process-
+ ing buffer size has been set too small. If file names and/or
+ line numbers are being output, a hyphen separator is used
+ instead of a colon for the context lines. A line containing
+ "--" is output between each group of lines, unless they are
+ in fact contiguous in the input file. The value of number is
+ expected to be relatively small. When -c is used, -B is
+ ignored.
+
+ --binary-files=word
+ Specify how binary files are to be processed. If the word is
+ "binary" (the default), pattern matching is performed on
+ binary files, but the only output is "Binary file <name>
+ matches" when a match succeeds. If the word is "text", which
+ is equivalent to the -a or --text option, binary files are
+ processed in the same way as any other file. In this case,
+ when a match succeeds, the output may be binary garbage,
+ which can have nasty effects if sent to a terminal. If the
+ word is "without-match", which is equivalent to the -I
+ option, binary files are not processed at all; they are
+ assumed not to be of interest and are skipped without causing
+ any output or affecting the return code.
+
+ --buffer-size=number
+ Set the parameter that controls how much memory is obtained
+ at the start of processing for buffering files that are being
+ scanned. See also --max-buffer-size below.
+
+ -C number, --context=number
+ Output number lines of context both before and after each
+ matching line. This is equivalent to setting both -A and -B
+ to the same value.
+
+ -c, --count
+ Do not output lines from the files that are being scanned;
+ instead output the number of lines that would have been
+ shown, either because they matched, or, if -v is set, because
+ they failed to match. By default, this count is exactly the
+ same as the number of lines that would have been output, but
+ if the -M (multiline) option is used (without -v), there may
+ be more suppressed lines than the count (that is, the number
+ of matches).
+
+ If no lines are selected, the number zero is output. If sev-
+ eral files are are being scanned, a count is output for each
+ of them and the -t option can be used to cause a total to be
+ output at the end. However, if the --files-with-matches
+ option is also used, only those files whose counts are
+ greater than zero are listed. When -c is used, the -A, -B,
+ and -C options are ignored.
+
+ --colour, --color
+ If this option is given without any data, it is equivalent to
+ "--colour=auto". If data is required, it must be given in
+ the same shell item, separated by an equals sign.
+
+ --colour=value, --color=value
+ This option specifies under what circumstances the parts of a
+ line that matched a pattern should be coloured in the output.
+ By default, the output is not coloured. The value (which is
+ optional, see above) may be "never", "always", or "auto". In
+ the latter case, colouring happens only if the standard out-
+ put is connected to a terminal. More resources are used when
+ colouring is enabled, because pcre2grep has to search for all
+ possible matches in a line, not just one, in order to colour
+ them all.
+
+ The colour that is used can be specified by setting one of
+ the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR,
+ PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that
+ order. If none of these are set, pcre2grep looks for
+ GREP_COLORS or GREP_COLOR (in that order). The value of the
+ variable should be a string of two numbers, separated by a
+ semicolon, except in the case of GREP_COLORS, which must
+ start with "ms=" or "mt=" followed by two semicolon-separated
+ colours, terminated by the end of the string or by a colon.
+ If GREP_COLORS does not start with "ms=" or "mt=" it is
+ ignored, and GREP_COLOR is checked.
+
+ If the string obtained from one of the above variables con-
+ tains any characters other than semicolon or digits, the set-
+ ting is ignored and the default colour is used. The string is
+ copied directly into the control string for setting colour on
+ a terminal, so it is your responsibility to ensure that the
+ values make sense. If no relevant environment variable is
+ set, the default is "1;31", which gives red.
+
+ -D action, --devices=action
+ If an input path is not a regular file or a directory,
+ "action" specifies how it is to be processed. Valid values
+ are "read" (the default) or "skip" (silently skip the path).
+
+ -d action, --directories=action
+ If an input path is a directory, "action" specifies how it is
+ to be processed. Valid values are "read" (the default in
+ non-Windows environments, for compatibility with GNU grep),
+ "recurse" (equivalent to the -r option), or "skip" (silently
+ skip the path, the default in Windows environments). In the
+ "read" case, directories are read as if they were ordinary
+ files. In some operating systems the effect of reading a
+ directory like this is an immediate end-of-file; in others it
+ may provoke an error.
+
+ --depth-limit=number
+ See --match-limit below.
+
+ -e pattern, --regex=pattern, --regexp=pattern
+ Specify a pattern to be matched. This option can be used mul-
+ tiple times in order to specify several patterns. It can also
+ be used as a way of specifying a single pattern that starts
+ with a hyphen. When -e is used, no argument pattern is taken
+ from the command line; all arguments are treated as file
+ names. There is no limit to the number of patterns. They are
+ applied to each line in the order in which they are defined
+ until one matches.
+
+ If -f is used with -e, the command line patterns are matched
+ first, followed by the patterns from the file(s), independent
+ of the order in which these options are specified. Note that
+ multiple use of -e is not the same as a single pattern with
+ alternatives. For example, X|Y finds the first character in a
+ line that is X or Y, whereas if the two patterns are given
+ separately, with X first, pcre2grep finds X if it is present,
+ even if it follows Y in the line. It finds Y only if there is
+ no X in the line. This matters only if you are using -o or
+ --colo(u)r to show the part(s) of the line that matched.
+
+ --exclude=pattern
+ Files (but not directories) whose names match the pattern are
+ skipped without being processed. This applies to all files,
+ whether listed on the command line, obtained from --file-
+ list, or by scanning a directory. The pattern is a PCRE2 reg-
+ ular expression, and is matched against the final component
+ of the file name, not the entire path. The -F, -w, and -x
+ options do not apply to this pattern. The option may be given
+ any number of times in order to specify multiple patterns. If
+ a file name matches both an --include and an --exclude pat-
+ tern, it is excluded. There is no short form for this option.
+
+ --exclude-from=filename
+ Treat each non-empty line of the file as the data for an
+ --exclude option. What constitutes a newline when reading the
+ file is the operating system's default. The --newline option
+ has no effect on this option. This option may be given more
+ than once in order to specify a number of files to read.
+
+ --exclude-dir=pattern
+ Directories whose names match the pattern are skipped without
+ being processed, whatever the setting of the --recursive
+ option. This applies to all directories, whether listed on
+ the command line, obtained from --file-list, or by scanning a
+ parent directory. The pattern is a PCRE2 regular expression,
+ and is matched against the final component of the directory
+ name, not the entire path. The -F, -w, and -x options do not
+ apply to this pattern. The option may be given any number of
+ times in order to specify more than one pattern. If a direc-
+ tory matches both --include-dir and --exclude-dir, it is
+ excluded. There is no short form for this option.
+
+ -F, --fixed-strings
+ Interpret each data-matching pattern as a list of fixed
+ strings, separated by newlines, instead of as a regular
+ expression. What constitutes a newline for this purpose is
+ controlled by the --newline option. The -w (match as a word)
+ and -x (match whole line) options can be used with -F. They
+ apply to each of the fixed strings. A line is selected if any
+ of the fixed strings are found in it (subject to -w or -x, if
+ present). This option applies only to the patterns that are
+ matched against the contents of files; it does not apply to
+ patterns specified by any of the --include or --exclude
+ options.
+
+ -f filename, --file=filename
+ Read patterns from the file, one per line, and match them
+ against each line of input. As is the case with patterns on
+ the command line, no delimiters should be used. What consti-
+ tutes a newline when reading the file is the operating sys-
+ tem's default interpretation of \n. The --newline option has
+ no effect on this option. Trailing white space is removed
+ from each line, and blank lines are ignored. An empty file
+ contains no patterns and therefore matches nothing. Patterns
+ read from a file in this way may contain binary zeros, which
+ are treated as ordinary data characters. See also the com-
+ ments about multiple patterns versus a single pattern with
+ alternatives in the description of -e above.
+
+ If this option is given more than once, all the specified
+ files are read. A data line is output if any of the patterns
+ match it. A file name can be given as "-" to refer to the
+ standard input. When -f is used, patterns specified on the
+ command line using -e may also be present; they are tested
+ before the file's patterns. However, no other pattern is
+ taken from the command line; all arguments are treated as the
+ names of paths to be searched.
+
+ --file-list=filename
+ Read a list of files and/or directories that are to be
+ scanned from the given file, one per line. What constitutes a
+ newline when reading the file is the operating system's
+ default. Trailing white space is removed from each line, and
+ blank lines are ignored. These paths are processed before any
+ that are listed on the command line. The file name can be
+ given as "-" to refer to the standard input. If --file and
+ --file-list are both specified as "-", patterns are read
+ first. This is useful only when the standard input is a ter-
+ minal, from which further lines (the list of files) can be
+ read after an end-of-file indication. If this option is given
+ more than once, all the specified files are read.
+
+ --file-offsets
+ Instead of showing lines or parts of lines that match, show
+ each match as an offset from the start of the file and a
+ length, separated by a comma. In this mode, no context is
+ shown. That is, the -A, -B, and -C options are ignored. If
+ there is more than one match in a line, each of them is shown
+ separately. This option is mutually exclusive with --output,
+ --line-offsets, and --only-matching.
+
+ -H, --with-filename
+ Force the inclusion of the file name at the start of output
+ lines when searching a single file. By default, the file name
+ is not shown in this case. For matching lines, the file name
+ is followed by a colon; for context lines, a hyphen separator
+ is used. If a line number is also being output, it follows
+ the file name. When the -M option causes a pattern to match
+ more than one line, only the first is preceded by the file
+ name. This option overrides any previous -h, -l, or -L
+ options.
+
+ -h, --no-filename
+ Suppress the output file names when searching multiple files.
+ By default, file names are shown when multiple files are
+ searched. For matching lines, the file name is followed by a
+ colon; for context lines, a hyphen separator is used. If a
+ line number is also being output, it follows the file name.
+ This option overrides any previous -H, -L, or -l options.
+
+ --heap-limit=number
+ See --match-limit below.
+
+ --help Output a help message, giving brief details of the command
+ options and file type support, and then exit. Anything else
+ on the command line is ignored.
+
+ -I Ignore binary files. This is equivalent to --binary-
+ files=without-match.
+
+ -i, --ignore-case
+ Ignore upper/lower case distinctions during comparisons.
+
+ --include=pattern
+ If any --include patterns are specified, the only files that
+ are processed are those that match one of the patterns (and
+ do not match an --exclude pattern). This option does not
+ affect directories, but it applies to all files, whether
+ listed on the command line, obtained from --file-list, or by
+ scanning a directory. The pattern is a PCRE2 regular expres-
+ sion, and is matched against the final component of the file
+ name, not the entire path. The -F, -w, and -x options do not
+ apply to this pattern. The option may be given any number of
+ times. If a file name matches both an --include and an
+ --exclude pattern, it is excluded. There is no short form
+ for this option.
+
+ --include-from=filename
+ Treat each non-empty line of the file as the data for an
+ --include option. What constitutes a newline for this purpose
+ is the operating system's default. The --newline option has
+ no effect on this option. This option may be given any number
+ of times; all the files are read.
+
+ --include-dir=pattern
+ If any --include-dir patterns are specified, the only direc-
+ tories that are processed are those that match one of the
+ patterns (and do not match an --exclude-dir pattern). This
+ applies to all directories, whether listed on the command
+ line, obtained from --file-list, or by scanning a parent
+ directory. The pattern is a PCRE2 regular expression, and is
+ matched against the final component of the directory name,
+ not the entire path. The -F, -w, and -x options do not apply
+ to this pattern. The option may be given any number of times.
+ If a directory matches both --include-dir and --exclude-dir,
+ it is excluded. There is no short form for this option.
+
+ -L, --files-without-match
+ Instead of outputting lines from the files, just output the
+ names of the files that do not contain any lines that would
+ have been output. Each file name is output once, on a sepa-
+ rate line. This option overrides any previous -H, -h, or -l
+ options.
+
+ -l, --files-with-matches
+ Instead of outputting lines from the files, just output the
+ names of the files containing lines that would have been out-
+ put. Each file name is output once, on a separate line.
+ Searching normally stops as soon as a matching line is found
+ in a file. However, if the -c (count) option is also used,
+ matching continues in order to obtain the correct count, and
+ those files that have at least one match are listed along
+ with their counts. Using this option with -c is a way of sup-
+ pressing the listing of files with no matches. This opeion
+ overrides any previous -H, -h, or -L options.
+
+ --label=name
+ This option supplies a name to be used for the standard input
+ when file names are being output. If not supplied, "(standard
+ input)" is used. There is no short form for this option.
+
+ --line-buffered
+ When this option is given, non-compressed input is read and
+ processed line by line, and the output is flushed after each
+ write. By default, input is read in large chunks, unless
+ pcre2grep can determine that it is reading from a terminal
+ (which is currently possible only in Unix-like environments
+ or Windows). Output to terminal is normally automatically
+ flushed by the operating system. This option can be useful
+ when the input or output is attached to a pipe and you do not
+ want pcre2grep to buffer up large amounts of data. However,
+ its use will affect performance, and the -M (multiline)
+ option ceases to work. When input is from a compressed .gz or
+ .bz2 file, --line-buffered is ignored.
+
+ --line-offsets
+ Instead of showing lines or parts of lines that match, show
+ each match as a line number, the offset from the start of the
+ line, and a length. The line number is terminated by a colon
+ (as usual; see the -n option), and the offset and length are
+ separated by a comma. In this mode, no context is shown.
+ That is, the -A, -B, and -C options are ignored. If there is
+ more than one match in a line, each of them is shown sepa-
+ rately. This option is mutually exclusive with --output,
+ --file-offsets, and --only-matching.
+
+ --locale=locale-name
+ This option specifies a locale to be used for pattern match-
+ ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
+ ronment variables. If no locale is specified, the PCRE2
+ library's default (usually the "C" locale) is used. There is
+ no short form for this option.
+
+ --match-limit=number
+ Processing some regular expression patterns may take a very
+ long time to search for all possible matching strings. Others
+ may require a very large amount of memory. There are three
+ options that set resource limits for matching.
+
+ The --match-limit option provides a means of limiting comput-
+ ing resource usage when processing patterns that are not
+ going to match, but which have a very large number of possi-
+ bilities in their search trees. The classic example is a pat-
+ tern that uses nested unlimited repeats. Internally, PCRE2
+ has a counter that is incremented each time around its main
+ processing loop. If the value set by --match-limit is
+ reached, an error occurs.
+
+ The --heap-limit option specifies, as a number of kibibytes
+ (units of 1024 bytes), the amount of heap memory that may be
+ used for matching. Heap memory is needed only if matching the
+ pattern requires a significant number of nested backtracking
+ points to be remembered. This parameter can be set to zero to
+ forbid the use of heap memory altogether.
+
+ The --depth-limit option limits the depth of nested back-
+ tracking points, which indirectly limits the amount of memory
+ that is used. The amount of memory needed for each backtrack-
+ ing point depends on the number of capturing parentheses in
+ the pattern, so the amount of memory that is used before this
+ limit acts varies from pattern to pattern. This limit is of
+ use only if it is set smaller than --match-limit.
+
+ There are no short forms for these options. The default lim-
+ its can be set when the PCRE2 library is compiled; if they
+ are not specified, the defaults are very large and so effec-
+ tively unlimited.
+
+ --max-buffer-size=number
+ This limits the expansion of the processing buffer, whose
+ initial size can be set by --buffer-size. The maximum buffer
+ size is silently forced to be no smaller than the starting
+ buffer size.
+
+ -M, --multiline
+ Allow patterns to match more than one line. When this option
+ is set, the PCRE2 library is called in "multiline" mode. This
+ allows a matched string to extend past the end of a line and
+ continue on one or more subsequent lines. Patterns used with
+ -M may usefully contain literal newline characters and inter-
+ nal occurrences of ^ and $ characters. The output for a suc-
+ cessful match may consist of more than one line. The first
+ line is the line in which the match started, and the last
+ line is the line in which the match ended. If the matched
+ string ends with a newline sequence, the output ends at the
+ end of that line. If -v is set, none of the lines in a
+ multi-line match are output. Once a match has been handled,
+ scanning restarts at the beginning of the line after the one
+ in which the match ended.
+
+ The newline sequence that separates multiple lines must be
+ matched as part of the pattern. For example, to find the
+ phrase "regular expression" in a file where "regular" might
+ be at the end of a line and "expression" at the start of the
+ next line, you could use this command:
+
+ pcre2grep -M 'regular\s+expression' <file>
+
+ The \s escape sequence matches any white space character,
+ including newlines, and is followed by + so as to match
+ trailing white space on the first line as well as possibly
+ handling a two-character newline sequence.
+
+ There is a limit to the number of lines that can be matched,
+ imposed by the way that pcre2grep buffers the input file as
+ it scans it. With a sufficiently large processing buffer,
+ this should not be a problem, but the -M option does not work
+ when input is read line by line (see --line-buffered.)
+
+ -N newline-type, --newline=newline-type
+ The PCRE2 library supports five different conventions for
+ indicating the ends of lines. They are the single-character
+ sequences CR (carriage return) and LF (linefeed), the two-
+ character sequence CRLF, an "anycrlf" convention, which rec-
+ ognizes any of the preceding three types, and an "any" con-
+ vention, in which any Unicode line ending sequence is assumed
+ to end a line. The Unicode sequences are the three just men-
+ tioned, plus VT (vertical tab, U+000B), FF (form feed,
+ U+000C), NEL (next line, U+0085), LS (line separator,
+ U+2028), and PS (paragraph separator, U+2029).
+
+ When the 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. The
+ possible values for this option are CR, LF, CRLF, ANYCRLF, or
+ ANY. This makes it possible to use pcre2grep to scan files
+ that have come from other environments without having to mod-
+ ify their line endings. If the data that is being scanned
+ does not agree with the convention set by this option,
+ pcre2grep may behave in strange ways. Note that this option
+ does not apply to files specified by the -f, --exclude-from,
+ or --include-from options, which are expected to use the
+ operating system's standard newline sequence.
+
+ -n, --line-number
+ Precede each output line by its line number in the file, fol-
+ lowed by a colon for matching lines or a hyphen for context
+ lines. If the file name is also being output, it precedes the
+ line number. When the -M option causes a pattern to match
+ more than one line, only the first is preceded by its line
+ number. This option is forced if --line-offsets is used.
+
+ --no-jit If the PCRE2 library is built with support for just-in-time
+ compiling (which speeds up matching), pcre2grep automatically
+ makes use of this, unless it was explicitly disabled at build
+ time. This option can be used to disable the use of JIT at
+ run time. It is provided for testing and working round prob-
+ lems. It should never be needed in normal use.
+
+ -O text, --output=text
+ When there is a match, instead of outputting the whole line
+ that matched, output just the given text. This option is
+ mutually exclusive with --only-matching, --file-offsets, and
+ --line-offsets. Escape sequences starting with a dollar char-
+ acter may be used to insert the contents of the matched part
+ of the line and/or captured substrings into the text.
+
+ $<digits> or ${<digits>} is replaced by the captured sub-
+ string of the given decimal number; zero substitutes the
+ whole match. If the number is greater than the number of cap-
+ turing substrings, or if the capture is unset, the replace-
+ ment is empty.
+
+ $a is replaced by bell; $b by backspace; $e by escape; $f by
+ form feed; $n by newline; $r by carriage return; $t by tab;
+ $v by vertical tab.
+
+ $o<digits> is replaced by the character represented by the
+ given octal number; up to three digits are processed.
+
+ $x<digits> is replaced by the character represented by the
+ given hexadecimal number; up to two digits are processed.
+
+ Any other character is substituted by itself. In particular,
+ $$ is replaced by a single dollar.
+
+ -o, --only-matching
+ Show only the part of the line that matched a pattern instead
+ of the whole line. In this mode, no context is shown. That
+ is, the -A, -B, and -C options are ignored. If there is more
+ than one match in a line, each of them is shown separately,
+ on a separate line of output. If -o is combined with -v
+ (invert the sense of the match to find non-matching lines),
+ no output is generated, but the return code is set appropri-
+ ately. If the matched portion of the line is empty, nothing
+ is output unless the file name or line number are being
+ printed, in which case they are shown on an otherwise empty
+ line. This option is mutually exclusive with --output,
+ --file-offsets and --line-offsets.
+
+ -onumber, --only-matching=number
+ Show only the part of the line that matched the capturing
+ parentheses of the given number. Up to 32 capturing parenthe-
+ ses are supported, and -o0 is equivalent to -o without a num-
+ ber. Because these options can be given without an argument
+ (see above), if an argument is present, it must be given in
+ the same shell item, for example, -o3 or --only-matching=2.
+ The comments given for the non-argument case above also apply
+ to this 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 out-
+ put.
+
+ 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 option).
+
+ --om-separator=text
+ Specify a separating string for multiple occurrences of -o.
+ The default is an empty string. Separating strings are never
+ coloured.
+
+ -q, --quiet
+ Work quietly, that is, display nothing except error messages.
+ The exit status indicates whether or not any matches were
+ found.
+
+ -r, --recursive
+ If any given path is a directory, recursively scan the files
+ it contains, taking note of any --include and --exclude set-
+ tings. By default, a directory is read as a normal file; in
+ some operating systems this gives an immediate end-of-file.
+ This option is a shorthand for setting the -d option to
+ "recurse".
+
+ --recursion-limit=number
+ See --match-limit above.
+
+ -s, --no-messages
+ Suppress error messages about non-existent or unreadable
+ files. Such files are quietly skipped. However, the return
+ code is still 2, even if matches were found in other files.
+
+ -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-8
+ 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 sub-
+ ject lines that are scanned must be valid strings of UTF-8
+ characters.
+
+ -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.
+
+ -w, --word-regex, --word-regexp
+ Force the patterns only to match "words". That is, there must
+ be a word boundary at the start and end of each matched
+ string. This is equivalent to having "\b(?:" at the start of
+ each pattern, and ")\b" at the end. This option applies only
+ to the patterns that are matched against the contents of
+ files; it does not apply to patterns specified by any of the
+ --include or --exclude options.
+
+ -x, --line-regex, --line-regexp
+ Force the patterns to start matching only at the beginnings
+ of lines, and in addition, require them to match entire
+ lines. In multiline mode the match may be more than one line.
+ This is equivalent to having "^(?:" at the start of each pat-
+ tern and ")$" at the end. This option applies only to the
+ patterns that are matched against the contents of files; it
+ does not apply to patterns specified by any of the --include
+ or --exclude options.
+
+
+ENVIRONMENT VARIABLES
+
+ The environment variables LC_ALL and LC_CTYPE are examined, in that
+ order, for a locale. The first one that is set is used. This can be
+ overridden by the --locale option. If no locale is set, the PCRE2
+ library's default (usually the "C" locale) is used.
+
+
+NEWLINES
+
+ The -N (--newline) option allows pcre2grep to scan files with different
+ newline conventions from the default. Any parts of the input files that
+ are written to the standard output are copied identically, with what-
+ ever newline sequences they have in the input. However, the setting of
+ this option 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, nor does it affect the
+ way in which pcre2grep writes informational messages to the standard
+ error and output streams. For these it uses the string "\n" to indicate
+ newlines, relying on the C I/O library to convert this to an appropri-
+ ate sequence.
+
+
+OPTIONS COMPATIBILITY
+
+ Many of the short and long forms of pcre2grep's options are the same as
+ in the GNU grep program. Any long option of the form --xxx-regexp (GNU
+ terminology) is also available as --xxx-regex (PCRE2 terminology). How-
+ ever, the --depth-limit, --file-list, --file-offsets, --heap-limit,
+ --include-dir, --line-offsets, --locale, --match-limit, -M, --multi-
+ line, -N, --newline, --om-separator, --output, -u, and --utf-8 options
+ are specific to pcre2grep, as is the use of the --only-matching option
+ with a capturing parentheses number.
+
+ Although most of the common options work the same way, a few are dif-
+ ferent in pcre2grep. For example, the --include option's argument is a
+ glob for GNU grep, but a regular expression for pcre2grep. If both the
+ -c and -l options are given, GNU grep lists only file names, without
+ counts, but pcre2grep gives the counts as well.
+
+
+OPTIONS WITH DATA
+
+ There are four different ways in which an option with data can be spec-
+ ified. If a short form option is used, the data may follow immedi-
+ ately, or (with one exception) in the next command line item. For exam-
+ ple:
+
+ -f/some/file
+ -f /some/file
+
+ The exception is the -o option, which may appear with or without data.
+ Because of this, if data is present, it must follow immediately in the
+ same item, for example -o3.
+
+ If a long form option is used, the data may appear in the same command
+ line item, separated by an equals character, or (with two exceptions)
+ it may appear in the next command line item. For example:
+
+ --file=/some/file
+ --file /some/file
+
+ Note, however, that if you want to supply a file name beginning with ~
+ as data in a shell command, and have the shell expand ~ to a home
+ directory, you must separate the file name from the option, because the
+ shell does not treat ~ specially unless it is at the start of an item.
+
+ The exceptions to the above are the --colour (or --color) and --only-
+ matching options, for which the data is optional. If one of these
+ options does have data, it must be given in the first form, using an
+ equals character. Otherwise pcre2grep will assume that it has no data.
+
+
+USING PCRE2'S CALLOUT FACILITY
+
+ pcre2grep has, by default, support for calling external programs or
+ scripts or echoing specific strings during matching by making use of
+ PCRE2's callout facility. However, this support can be disabled when
+ pcre2grep is built. You can find out whether your binary has support
+ for callouts by running it with the --help option. If the support is
+ not enabled, all callouts in patterns are ignored by pcre2grep.
+
+ A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu-
+ ment is either a number or a quoted string (see the pcre2callout docu-
+ mentation for details). Numbered callouts are ignored by pcre2grep;
+ only callouts with string arguments are useful.
+
+ Calling external programs or scripts
+
+ If the callout string does not start with a pipe (vertical bar) charac-
+ ter, it is parsed into a list of substrings separated by pipe charac-
+ ters. The first substring must be an executable name, with the follow-
+ ing substrings specifying arguments:
+
+ executable_name|arg1|arg2|...
+
+ Any substring (including the executable name) may contain escape
+ sequences started by a dollar character: $<digits> or ${<digits>} is
+ replaced by the captured substring of the given decimal number, which
+ must be greater than zero. If the number is greater than the number of
+ capturing substrings, or if the capture is unset, the replacement is
+ empty.
+
+ Any other character is substituted by itself. In particular, $$ is
+ replaced by a single dollar and $| is replaced by a pipe character.
+ 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 execv() system call that is used to run the pro-
+ gram 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) cause 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.
+
+ Echoing a specific string
+
+ If the callout string starts with a pipe (vertical bar) character, the
+ rest of the string is written to the output, having been passed through
+ the same escape processing as text from the --output option. This pro-
+ vides a simple echoing facility that avoids calling an external program
+ or script. No terminator is added to the string, so if you want a new-
+ line, you must include it explicitly. 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 relevant
+ pattern with (*FAIL).
+
+
+MATCHING ERRORS
+
+ It is possible to supply a regular expression that takes a very long
+ time to fail to match certain lines. Such patterns normally involve
+ nested indefinite repeats, for example: (a+)*\d when matched against a
+ line of a's with no final digit. The PCRE2 matching function has a
+ resource limit that causes it to abort in these circumstances. If this
+ happens, pcre2grep outputs an error message and the line that caused
+ the problem to the standard error stream. If there are more than 20
+ such errors, pcre2grep gives up.
+
+ The --match-limit option of pcre2grep can be used to set the overall
+ resource limit. There are also other limits that affect the amount of
+ memory used during matching; see the discussion of --heap-limit and
+ --depth-limit above.
+
+
+DIAGNOSTICS
+
+ Exit status is 0 if any matches were found, 1 if no matches were found,
+ and 2 for syntax errors, overlong lines, non-existent or inaccessible
+ files (even if matches were found in other files) or too many matching
+ errors. Using the -s option to suppress error messages about inaccessi-
+ ble files does not affect the return code.
+
+ When run under VMS, the return code is placed in the symbol
+ PCRE2GREP_RC because VMS does not distinguish between exit(0) and
+ exit(1).
+
+
+SEE ALSO
+
+ pcre2pattern(3), pcre2syntax(3), pcre2callout(3).
+
+
+AUTHOR
+
+ Philip Hazel
+ University Computing Service
+ Cambridge, England.
+
+
+REVISION
+
+ Last updated: 24 February 2018
+ Copyright (c) 1997-2018 University of Cambridge.
projects / ossec-hids.git / blobdiff