--- /dev/null
+<html>
+<head>
+<title>pcre2grep specification</title>
+</head>
+<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
+<h1>pcre2grep man page</h1>
+<p>
+Return to the <a href="index.html">PCRE2 index page</a>.
+</p>
+<p>
+This page is part of the PCRE2 HTML documentation. It was generated
+automatically from the original man page. If there is any nonsense in it,
+please consult the man page, in case the conversion went wrong.
+<br>
+<ul>
+<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
+<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
+<li><a name="TOC3" href="#SEC3">SUPPORT FOR COMPRESSED FILES</a>
+<li><a name="TOC4" href="#SEC4">BINARY FILES</a>
+<li><a name="TOC5" href="#SEC5">BINARY ZEROS IN PATTERNS</a>
+<li><a name="TOC6" href="#SEC6">OPTIONS</a>
+<li><a name="TOC7" href="#SEC7">ENVIRONMENT VARIABLES</a>
+<li><a name="TOC8" href="#SEC8">NEWLINES</a>
+<li><a name="TOC9" href="#SEC9">OPTIONS COMPATIBILITY</a>
+<li><a name="TOC10" href="#SEC10">OPTIONS WITH DATA</a>
+<li><a name="TOC11" href="#SEC11">USING PCRE2'S CALLOUT FACILITY</a>
+<li><a name="TOC12" href="#SEC12">MATCHING ERRORS</a>
+<li><a name="TOC13" href="#SEC13">DIAGNOSTICS</a>
+<li><a name="TOC14" href="#SEC14">SEE ALSO</a>
+<li><a name="TOC15" href="#SEC15">AUTHOR</a>
+<li><a name="TOC16" href="#SEC16">REVISION</a>
+</ul>
+<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
+<P>
+<b>pcre2grep [options] [long options] [pattern] [path1 path2 ...]</b>
+</P>
+<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
+<P>
+<b>pcre2grep</b> 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
+<a href="pcre2syntax.html"><b>pcre2syntax</b>(3)</a>
+for a quick-reference summary of pattern syntax, or
+<a href="pcre2pattern.html"><b>pcre2pattern</b>(3)</a>
+for a full description of the syntax and semantics of the regular expressions
+that PCRE2 supports.
+</P>
+<P>
+Patterns, whether supplied on the command line or in a separate file, are given
+without delimiters. For example:
+<pre>
+ pcre2grep Thursday /etc/motd
+</pre>
+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.
+</P>
+<P>
+The first argument that follows any option settings is treated as the single
+pattern to be matched when neither <b>-e</b> nor <b>-f</b> 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 <b>-e</b>, <b>-f</b>, or an
+argument pattern must be provided.
+</P>
+<P>
+If no files are specified, <b>pcre2grep</b> reads the standard input. The
+standard input can also be referenced by a name consisting of a single hyphen.
+For example:
+<pre>
+ pcre2grep some-pattern file1 - file3
+</pre>
+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 <b>pcre2grep</b> behaves. In
+particular, the <b>-M</b> option makes it possible to search for strings that
+span line boundaries. What defines a line boundary is controlled by the
+<b>-N</b> (<b>--newline</b>) option.
+</P>
+<P>
+The amount of memory used for buffering files that are being scanned is
+controlled by parameters that can be set by the <b>--buffer-size</b> and
+<b>--max-buffer-size</b> 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 <b>--max-buffer-size</b>. The
+default values for these parameters can be set when <b>pcre2grep</b> 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.
+</P>
+<P>
+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.
+</P>
+<P>
+Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the greater.
+BUFSIZ is defined in <b><stdio.h></b>. When there is more than one pattern
+(specified by the use of <b>-e</b> and/or <b>-f</b>), each pattern is applied to
+each line in the order in which they are defined, except that all the <b>-e</b>
+patterns are tried before the <b>-f</b> patterns.
+</P>
+<P>
+By default, as soon as one pattern matches a line, no further patterns are
+considered. However, if <b>--colour</b> (or <b>--color</b>) is used to colour the
+matching substrings, or if <b>--only-matching</b>, <b>--file-offsets</b>, or
+<b>--line-offsets</b> 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.
+</P>
+<P>
+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).
+</P>
+<P>
+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.
+</P>
+<P>
+If the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variable is set,
+<b>pcre2grep</b> uses the value to set a locale when calling the PCRE2 library.
+The <b>--locale</b> option can be used to override this.
+</P>
+<br><a name="SEC3" href="#TOC1">SUPPORT FOR COMPRESSED FILES</a><br>
+<P>
+It is possible to compile <b>pcre2grep</b> so that it uses <b>libz</b> or
+<b>libbz2</b> to read compressed files whose names end in <b>.gz</b> or
+<b>.bz2</b>, respectively. You can find out whether your <b>pcre2grep</b> binary
+has support for one or both of these file types by running it with the
+<b>--help</b> option. If the appropriate support is not present, all files are
+treated as plain text. The standard input is always so treated. When input is
+from a compressed .gz or .bz2 file, the <b>--line-buffered</b> option is
+ignored.
+</P>
+<br><a name="SEC4" href="#TOC1">BINARY FILES</a><br>
+<P>
+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 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 <b>--binary-files</b> option for a means
+of changing the way binary files are handled.
+</P>
+<br><a name="SEC5" href="#TOC1">BINARY ZEROS IN PATTERNS</a><br>
+<P>
+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 <b>-f</b> option may contain binary zeros.
+</P>
+<br><a name="SEC6" href="#TOC1">OPTIONS</a><br>
+<P>
+The order in which some of the options appear can affect the output. For
+example, both the <b>-H</b> and <b>-l</b> 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.
+</P>
+<P>
+<b>--</b>
+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.
+</P>
+<P>
+<b>-A</b> <i>number</i>, <b>--after-context=</b><i>number</i>
+Output up to <i>number</i> lines of context after each matching line. Fewer
+lines are output if the next match or the end of the file is reached, or if the
+processing buffer size has been set too small. If file names and/or line
+numbers are being output, a hyphen separator is used instead of a colon for the
+context lines. A line containing "--" is output between each group of lines,
+unless they are in fact contiguous in the input file. The value of <i>number</i>
+is expected to be relatively small. When <b>-c</b> is used, <b>-A</b> is ignored.
+</P>
+<P>
+<b>-a</b>, <b>--text</b>
+Treat binary files as text. This is equivalent to
+<b>--binary-files</b>=<i>text</i>.
+</P>
+<P>
+<b>-B</b> <i>number</i>, <b>--before-context=</b><i>number</i>
+Output up to <i>number</i> lines of context before each matching line. Fewer
+lines are output if the previous match or the start of the file is within
+<i>number</i> lines, or if the processing buffer size has been set too small. If
+file names and/or line numbers are being output, a hyphen separator is used
+instead of a colon for the context lines. A line containing "--" is output
+between each group of lines, unless they are in fact contiguous in the input
+file. The value of <i>number</i> is expected to be relatively small. When
+<b>-c</b> is used, <b>-B</b> is ignored.
+</P>
+<P>
+<b>--binary-files=</b><i>word</i>
+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 <b>-a</b> or <b>--text</b> 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
+<b>-I</b> 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.
+</P>
+<P>
+<b>--buffer-size=</b><i>number</i>
+Set the parameter that controls how much memory is obtained at the start of
+processing for buffering files that are being scanned. See also
+<b>--max-buffer-size</b> below.
+</P>
+<P>
+<b>-C</b> <i>number</i>, <b>--context=</b><i>number</i>
+Output <i>number</i> lines of context both before and after each matching line.
+This is equivalent to setting both <b>-A</b> and <b>-B</b> to the same value.
+</P>
+<P>
+<b>-c</b>, <b>--count</b>
+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
+<b>-v</b> 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
+<b>-M</b> (multiline) option is used (without <b>-v</b>), there may be more
+suppressed lines than the count (that is, the number of matches).
+<br>
+<br>
+If no lines are selected, the number zero is output. If several files are are
+being scanned, a count is output for each of them and the <b>-t</b> option can
+be used to cause a total to be output at the end. However, if the
+<b>--files-with-matches</b> option is also used, only those files whose counts
+are greater than zero are listed. When <b>-c</b> is used, the <b>-A</b>,
+<b>-B</b>, and <b>-C</b> options are ignored.
+</P>
+<P>
+<b>--colour</b>, <b>--color</b>
+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.
+</P>
+<P>
+<b>--colour=</b><i>value</i>, <b>--color=</b><i>value</i>
+This option specifies under what circumstances the parts of a line that matched
+a pattern should be coloured in the output. By default, the output is not
+coloured. The value (which is optional, see above) may be "never", "always", or
+"auto". In the latter case, colouring happens only if the standard output is
+connected to a terminal. More resources are used when colouring is enabled,
+because <b>pcre2grep</b> has to search for all possible matches in a line, not
+just one, in order to colour them all.
+<br>
+<br>
+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,
+<b>pcre2grep</b> 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.
+<br>
+<br>
+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.
+</P>
+<P>
+<b>-D</b> <i>action</i>, <b>--devices=</b><i>action</i>
+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).
+</P>
+<P>
+<b>-d</b> <i>action</i>, <b>--directories=</b><i>action</i>
+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 <b>-r</b> 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.
+</P>
+<P>
+<b>--depth-limit</b>=<i>number</i>
+See <b>--match-limit</b> below.
+</P>
+<P>
+<b>-e</b> <i>pattern</i>, <b>--regex=</b><i>pattern</i>, <b>--regexp=</b><i>pattern</i>
+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 <b>-e</b> 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.
+<br>
+<br>
+If <b>-f</b> is used with <b>-e</b>, 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 <b>-e</b> 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, <b>pcre2grep</b> 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 <b>-o</b> or <b>--colo(u)r</b> to show the part(s)
+of the line that matched.
+</P>
+<P>
+<b>--exclude</b>=<i>pattern</i>
+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 <b>--file-list</b>, 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 <b>-F</b>, <b>-w</b>, and <b>-x</b> 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 <b>--include</b>
+and an <b>--exclude</b> pattern, it is excluded. There is no short form for this
+option.
+</P>
+<P>
+<b>--exclude-from=</b><i>filename</i>
+Treat each non-empty line of the file as the data for an <b>--exclude</b>
+option. What constitutes a newline when reading the file is the operating
+system's default. The <b>--newline</b> 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.
+</P>
+<P>
+<b>--exclude-dir</b>=<i>pattern</i>
+Directories whose names match the pattern are skipped without being processed,
+whatever the setting of the <b>--recursive</b> option. This applies to all
+directories, whether listed on the command line, obtained from
+<b>--file-list</b>, 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 <b>-F</b>, <b>-w</b>, and <b>-x</b> 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 <b>--include-dir</b>
+and <b>--exclude-dir</b>, it is excluded. There is no short form for this
+option.
+</P>
+<P>
+<b>-F</b>, <b>--fixed-strings</b>
+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 <b>--newline</b> option. The <b>-w</b> (match
+as a word) and <b>-x</b> (match whole line) options can be used with <b>-F</b>.
+They apply to each of the fixed strings. A line is selected if any of the fixed
+strings are found in it (subject to <b>-w</b> or <b>-x</b>, 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 <b>--include</b> or
+<b>--exclude</b> options.
+</P>
+<P>
+<b>-f</b> <i>filename</i>, <b>--file=</b><i>filename</i>
+Read patterns from the file, one per line, and match them against each line of
+input. As is the case with patterns on the command line, no delimiters should
+be used. What constitutes a newline when reading the file is the operating
+system's default interpretation of \n. The <b>--newline</b> option has no
+effect on this option. Trailing white space is removed from each line, and
+blank lines are ignored. An empty file contains no patterns and therefore
+matches nothing. Patterns read from a file in this way may contain binary
+zeros, which are treated as ordinary data characters. See also the comments
+about multiple patterns versus a single pattern with alternatives in the
+description of <b>-e</b> above.
+<br>
+<br>
+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 <b>-f</b> is used, patterns
+specified on the command line using <b>-e</b> 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.
+</P>
+<P>
+<b>--file-list</b>=<i>filename</i>
+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 <b>--file</b> and <b>--file-list</b> 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.
+</P>
+<P>
+<b>--file-offsets</b>
+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 <b>-A</b>, <b>-B</b>, and <b>-C</b>
+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 <b>--output</b>,
+<b>--line-offsets</b>, and <b>--only-matching</b>.
+</P>
+<P>
+<b>-H</b>, <b>--with-filename</b>
+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 <b>-M</b> option causes a pattern to match more than one
+line, only the first is preceded by the file name. This option overrides any
+previous <b>-h</b>, <b>-l</b>, or <b>-L</b> options.
+</P>
+<P>
+<b>-h</b>, <b>--no-filename</b>
+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 <b>-H</b>, <b>-L</b>, or <b>-l</b> options.
+</P>
+<P>
+<b>--heap-limit</b>=<i>number</i>
+See <b>--match-limit</b> below.
+</P>
+<P>
+<b>--help</b>
+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.
+</P>
+<P>
+<b>-I</b>
+Ignore binary files. This is equivalent to
+<b>--binary-files</b>=<i>without-match</i>.
+</P>
+<P>
+<b>-i</b>, <b>--ignore-case</b>
+Ignore upper/lower case distinctions during comparisons.
+</P>
+<P>
+<b>--include</b>=<i>pattern</i>
+If any <b>--include</b> patterns are specified, the only files that are
+processed are those that match one of the patterns (and do not match an
+<b>--exclude</b> pattern). This option does not affect directories, but it
+applies to all files, whether listed on the command line, obtained from
+<b>--file-list</b>, 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 <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not apply to
+this pattern. The option may be given any number of times. If a file name
+matches both an <b>--include</b> and an <b>--exclude</b> pattern, it is excluded.
+There is no short form for this option.
+</P>
+<P>
+<b>--include-from=</b><i>filename</i>
+Treat each non-empty line of the file as the data for an <b>--include</b>
+option. What constitutes a newline for this purpose is the operating system's
+default. The <b>--newline</b> option has no effect on this option. This option
+may be given any number of times; all the files are read.
+</P>
+<P>
+<b>--include-dir</b>=<i>pattern</i>
+If any <b>--include-dir</b> patterns are specified, the only directories that
+are processed are those that match one of the patterns (and do not match an
+<b>--exclude-dir</b> pattern). This applies to all directories, whether listed
+on the command line, obtained from <b>--file-list</b>, 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 <b>-F</b>,
+<b>-w</b>, and <b>-x</b> options do not apply to this pattern. The option may be
+given any number of times. If a directory matches both <b>--include-dir</b> and
+<b>--exclude-dir</b>, it is excluded. There is no short form for this option.
+</P>
+<P>
+<b>-L</b>, <b>--files-without-match</b>
+Instead of outputting lines from the files, just output the names of the files
+that do not contain any lines that would have been output. Each file name is
+output once, on a separate line. This option overrides any previous <b>-H</b>,
+<b>-h</b>, or <b>-l</b> options.
+</P>
+<P>
+<b>-l</b>, <b>--files-with-matches</b>
+Instead of outputting lines from the files, just output the names of the files
+containing lines that would have been output. Each file name is output once, on
+a separate line. Searching normally stops as soon as a matching line is found
+in a file. However, if the <b>-c</b> (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
+<b>-c</b> is a way of suppressing the listing of files with no matches. This
+opeion overrides any previous <b>-H</b>, <b>-h</b>, or <b>-L</b> options.
+</P>
+<P>
+<b>--label</b>=<i>name</i>
+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.
+</P>
+<P>
+<b>--line-buffered</b>
+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 <b>pcre2grep</b> 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 <b>pcre2grep</b> to buffer up large amounts of data.
+However, its use will affect performance, and the <b>-M</b> (multiline) option
+ceases to work. When input is from a compressed .gz or .bz2 file,
+<b>--line-buffered</b> is ignored.
+</P>
+<P>
+<b>--line-offsets</b>
+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 <b>-n</b> option), and the
+offset and length are separated by a comma. In this mode, no context is shown.
+That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b> 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 <b>--output</b>, <b>--file-offsets</b>, and
+<b>--only-matching</b>.
+</P>
+<P>
+<b>--locale</b>=<i>locale-name</i>
+This option specifies a locale to be used for pattern matching. It overrides
+the value in the <b>LC_ALL</b> or <b>LC_CTYPE</b> 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.
+</P>
+<P>
+<b>--match-limit</b>=<i>number</i>
+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.
+<br>
+<br>
+The <b>--match-limit</b> 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 <b>--match-limit</b> is reached, an error occurs.
+<br>
+<br>
+The <b>--heap-limit</b> 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.
+<br>
+<br>
+The <b>--depth-limit</b> 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 <b>--match-limit</b>.
+<br>
+<br>
+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.
+</P>
+<P>
+\fB--max-buffer-size=<i>number</i>
+This limits the expansion of the processing buffer, whose initial size can be
+set by <b>--buffer-size</b>. The maximum buffer size is silently forced to be no
+smaller than the starting buffer size.
+</P>
+<P>
+<b>-M</b>, <b>--multiline</b>
+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 <b>-M</b> may usefully contain literal newline characters and internal
+occurrences of ^ and $ characters. The output for a successful match may
+consist of more than one line. The first line is the line in which the match
+started, and the last line is the line in which the match ended. If the matched
+string ends with a newline sequence, the output ends at the end of that line.
+If <b>-v</b> 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.
+<br>
+<br>
+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:
+<pre>
+ pcre2grep -M 'regular\s+expression' <file>
+</pre>
+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.
+<br>
+<br>
+There is a limit to the number of lines that can be matched, imposed by the way
+that <b>pcre2grep</b> buffers the input file as it scans it. With a sufficiently
+large processing buffer, this should not be a problem, but the <b>-M</b> option
+does not work when input is read line by line (see \fP--line-buffered\fP.)
+</P>
+<P>
+<b>-N</b> <i>newline-type</i>, <b>--newline</b>=<i>newline-type</i>
+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 recognizes any of the preceding three types, and an "any" convention, in
+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).
+<br>
+<br>
+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, <b>pcre2grep</b> uses the library's default.
+The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
+makes it possible to use <b>pcre2grep</b> 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,
+<b>pcre2grep</b> may behave in strange ways. Note that this option does not
+apply to files specified by the <b>-f</b>, <b>--exclude-from</b>, or
+<b>--include-from</b> options, which are expected to use the operating system's
+standard newline sequence.
+</P>
+<P>
+<b>-n</b>, <b>--line-number</b>
+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 <b>-M</b> option causes a
+pattern to match more than one line, only the first is preceded by its line
+number. This option is forced if <b>--line-offsets</b> is used.
+</P>
+<P>
+<b>--no-jit</b>
+If the PCRE2 library is built with support for just-in-time compiling (which
+speeds up matching), <b>pcre2grep</b> automatically makes use of this, unless it
+was explicitly disabled at build time. This option can be used to disable the
+use of JIT at run time. It is provided for testing and working round problems.
+It should never be needed in normal use.
+</P>
+<P>
+<b>-O</b> <i>text</i>, <b>--output</b>=<i>text</i>
+When there is a match, instead of outputting the whole line that matched,
+output just the given text. This option is mutually exclusive with
+<b>--only-matching</b>, <b>--file-offsets</b>, and <b>--line-offsets</b>. 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.
+<br>
+<br>
+$<digits> or ${<digits>} is replaced by the captured
+substring of the given decimal number; zero substitutes the whole match. If
+the number is greater than the number of capturing substrings, or if the
+capture is unset, the replacement is empty.
+<br>
+<br>
+$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; $v by vertical tab.
+<br>
+<br>
+$o<digits> is replaced by the character represented by the given octal
+number; up to three digits are processed.
+<br>
+<br>
+$x<digits> is replaced by the character represented by the given hexadecimal
+number; up to two digits are processed.
+<br>
+<br>
+Any other character is substituted by itself. In particular, $$ is replaced by
+a single dollar.
+</P>
+<P>
+<b>-o</b>, <b>--only-matching</b>
+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 <b>-A</b>, <b>-B</b>, and
+<b>-C</b> 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 <b>-o</b> is
+combined with <b>-v</b> (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 <b>--output</b>,
+<b>--file-offsets</b> and <b>--line-offsets</b>.
+</P>
+<P>
+<b>-o</b><i>number</i>, <b>--only-matching</b>=<i>number</i>
+Show only the part of the line that matched the capturing parentheses of the
+given number. Up to 32 capturing parentheses are supported, and -o0 is
+equivalent to <b>-o</b> 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.
+<br>
+<br>
+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).
+</P>
+<P>
+<b>--om-separator</b>=<i>text</i>
+Specify a separating string for multiple occurrences of <b>-o</b>. The default
+is an empty string. Separating strings are never coloured.
+</P>
+<P>
+<b>-q</b>, <b>--quiet</b>
+Work quietly, that is, display nothing except error messages. The exit
+status indicates whether or not any matches were found.
+</P>
+<P>
+<b>-r</b>, <b>--recursive</b>
+If any given path is a directory, recursively scan the files it contains,
+taking note of any <b>--include</b> and <b>--exclude</b> 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 <b>-d</b>
+option to "recurse".
+</P>
+<P>
+<b>--recursion-limit</b>=<i>number</i>
+See <b>--match-limit</b> above.
+</P>
+<P>
+<b>-s</b>, <b>--no-messages</b>
+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.
+</P>
+<P>
+<b>-t</b>, <b>--total-count</b>
+This option is useful when scanning more than one file. If used on its own,
+<b>-t</b> suppresses all output except for a grand total number of matching
+lines (or non-matching lines if <b>-v</b> is used) in all the files. If <b>-t</b>
+is used with <b>-c</b>, 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 <b>-t</b> option is
+ignored when used with <b>-L</b> (list files without matches), because the grand
+total would always be zero.
+</P>
+<P>
+<b>-u</b>, <b>--utf-8</b>
+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 <b>--exclude</b> and
+<b>--include</b> options) and all subject lines that are scanned must be valid
+strings of UTF-8 characters.
+</P>
+<P>
+<b>-V</b>, <b>--version</b>
+Write the version numbers of <b>pcre2grep</b> and the PCRE2 library to the
+standard output and then exit. Anything else on the command line is
+ignored.
+</P>
+<P>
+<b>-v</b>, <b>--invert-match</b>
+Invert the sense of the match, so that lines which do <i>not</i> match any of
+the patterns are the ones that are found.
+</P>
+<P>
+<b>-w</b>, <b>--word-regex</b>, <b>--word-regexp</b>
+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 <b>--include</b> or
+<b>--exclude</b> options.
+</P>
+<P>
+<b>-x</b>, <b>--line-regex</b>, <b>--line-regexp</b>
+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 <b>--include</b> or <b>--exclude</b> options.
+</P>
+<br><a name="SEC7" href="#TOC1">ENVIRONMENT VARIABLES</a><br>
+<P>
+The environment variables <b>LC_ALL</b> and <b>LC_CTYPE</b> are examined, in that
+order, for a locale. The first one that is set is used. This can be overridden
+by the <b>--locale</b> option. If no locale is set, the PCRE2 library's default
+(usually the "C" locale) is used.
+</P>
+<br><a name="SEC8" href="#TOC1">NEWLINES</a><br>
+<P>
+The <b>-N</b> (<b>--newline</b>) option allows <b>pcre2grep</b> 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 whatever
+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 <b>-f</b>, <b>--file-list</b>,
+<b>--exclude-from</b>, or <b>--include-from</b> options, nor does it affect the
+way in which <b>pcre2grep</b> 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 appropriate
+sequence.
+</P>
+<br><a name="SEC9" href="#TOC1">OPTIONS COMPATIBILITY</a><br>
+<P>
+Many of the short and long forms of <b>pcre2grep</b>'s options are the same
+as in the GNU <b>grep</b> program. Any long option of the form
+<b>--xxx-regexp</b> (GNU terminology) is also available as <b>--xxx-regex</b>
+(PCRE2 terminology). However, the <b>--depth-limit</b>, <b>--file-list</b>,
+<b>--file-offsets</b>, <b>--heap-limit</b>, <b>--include-dir</b>,
+<b>--line-offsets</b>, <b>--locale</b>, <b>--match-limit</b>, <b>-M</b>,
+<b>--multiline</b>, <b>-N</b>, <b>--newline</b>, <b>--om-separator</b>,
+<b>--output</b>, <b>-u</b>, and <b>--utf-8</b> options are specific to
+<b>pcre2grep</b>, as is the use of the <b>--only-matching</b> option with a
+capturing parentheses number.
+</P>
+<P>
+Although most of the common options work the same way, a few are different in
+<b>pcre2grep</b>. For example, the <b>--include</b> option's argument is a glob
+for GNU <b>grep</b>, but a regular expression for <b>pcre2grep</b>. If both the
+<b>-c</b> and <b>-l</b> options are given, GNU grep lists only file names,
+without counts, but <b>pcre2grep</b> gives the counts as well.
+</P>
+<br><a name="SEC10" href="#TOC1">OPTIONS WITH DATA</a><br>
+<P>
+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:
+<pre>
+ -f/some/file
+ -f /some/file
+</pre>
+The exception is the <b>-o</b> 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.
+</P>
+<P>
+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:
+<pre>
+ --file=/some/file
+ --file /some/file
+</pre>
+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.
+</P>
+<P>
+The exceptions to the above are the <b>--colour</b> (or <b>--color</b>) and
+<b>--only-matching</b> 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 <b>pcre2grep</b> will assume that it has no data.
+</P>
+<br><a name="SEC11" href="#TOC1">USING PCRE2'S CALLOUT FACILITY</a><br>
+<P>
+<b>pcre2grep</b> 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 <b>pcre2grep</b> is
+built. You can find out whether your binary has support for callouts by running
+it with the <b>--help</b> option. If the support is not enabled, all callouts in
+patterns are ignored by <b>pcre2grep</b>.
+</P>
+<P>
+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
+<a href="pcre2callout.html"><b>pcre2callout</b></a>
+documentation for details). Numbered callouts are ignored by <b>pcre2grep</b>;
+only callouts with string arguments are useful.
+</P>
+<br><b>
+Calling external programs or scripts
+</b><br>
+<P>
+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:
+<pre>
+ executable_name|arg1|arg2|...
+</pre>
+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.
+</P>
+<P>
+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:
+<pre>
+ 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
+</pre>
+The parameters for the <b>execv()</b> 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) 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.
+</P>
+<br><b>
+Echoing a specific string
+</b><br>
+<P>
+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 provides a simple echoing
+facility that avoids calling an external program or script. No terminator is
+added to the string, so if you want a newline, 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).
+</P>
+<br><a name="SEC12" href="#TOC1">MATCHING ERRORS</a><br>
+<P>
+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, <b>pcre2grep</b> outputs an error
+message and the line that caused the problem to the standard error stream. If
+there are more than 20 such errors, <b>pcre2grep</b> gives up.
+</P>
+<P>
+The <b>--match-limit</b> option of <b>pcre2grep</b> 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 <b>--heap-limit</b> and
+<b>--depth-limit</b> above.
+</P>
+<br><a name="SEC13" href="#TOC1">DIAGNOSTICS</a><br>
+<P>
+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
+<b>-s</b> option to suppress error messages about inaccessible files does not
+affect the return code.
+</P>
+<P>
+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).
+</P>
+<br><a name="SEC14" href="#TOC1">SEE ALSO</a><br>
+<P>
+<b>pcre2pattern</b>(3), <b>pcre2syntax</b>(3), <b>pcre2callout</b>(3).
+</P>
+<br><a name="SEC15" href="#TOC1">AUTHOR</a><br>
+<P>
+Philip Hazel
+<br>
+University Computing Service
+<br>
+Cambridge, England.
+<br>
+</P>
+<br><a name="SEC16" href="#TOC1">REVISION</a><br>
+<P>
+Last updated: 24 February 2018
+<br>
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