3 <title>pcregrep specification</title>
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6 <h1>pcregrep man page</h1>
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16 <li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
17 <li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
18 <li><a name="TOC3" href="#SEC3">SUPPORT FOR COMPRESSED FILES</a>
19 <li><a name="TOC4" href="#SEC4">OPTIONS</a>
20 <li><a name="TOC5" href="#SEC5">ENVIRONMENT VARIABLES</a>
21 <li><a name="TOC6" href="#SEC6">NEWLINES</a>
22 <li><a name="TOC7" href="#SEC7">OPTIONS COMPATIBILITY</a>
23 <li><a name="TOC8" href="#SEC8">OPTIONS WITH DATA</a>
24 <li><a name="TOC9" href="#SEC9">MATCHING ERRORS</a>
25 <li><a name="TOC10" href="#SEC10">DIAGNOSTICS</a>
26 <li><a name="TOC11" href="#SEC11">SEE ALSO</a>
27 <li><a name="TOC12" href="#SEC12">AUTHOR</a>
28 <li><a name="TOC13" href="#SEC13">REVISION</a>
30 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
32 <b>pcregrep [options] [long options] [pattern] [path1 path2 ...]</b>
34 <br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
36 <b>pcregrep</b> searches files for character patterns, in the same way as other
37 grep commands do, but it uses the PCRE regular expression library to support
38 patterns that are compatible with the regular expressions of Perl 5. See
39 <a href="pcrepattern.html"><b>pcrepattern</b>(3)</a>
40 for a full description of syntax and semantics of the regular expressions
44 Patterns, whether supplied on the command line or in a separate file, are given
45 without delimiters. For example:
47 pcregrep Thursday /etc/motd
49 If you attempt to use delimiters (for example, by surrounding a pattern with
50 slashes, as is common in Perl scripts), they are interpreted as part of the
51 pattern. Quotes can of course be used to delimit patterns on the command line
52 because they are interpreted by the shell, and indeed they are required if a
53 pattern contains white space or shell metacharacters.
56 The first argument that follows any option settings is treated as the single
57 pattern to be matched when neither <b>-e</b> nor <b>-f</b> is present.
58 Conversely, when one or both of these options are used to specify patterns, all
59 arguments are treated as path names. At least one of <b>-e</b>, <b>-f</b>, or an
60 argument pattern must be provided.
63 If no files are specified, <b>pcregrep</b> reads the standard input. The
64 standard input can also be referenced by a name consisting of a single hyphen.
67 pcregrep some-pattern /file1 - /file3
69 By default, each line that matches a pattern is copied to the standard
70 output, and if there is more than one file, the file name is output at the
71 start of each line, followed by a colon. However, there are options that can
72 change how <b>pcregrep</b> behaves. In particular, the <b>-M</b> option makes it
73 possible to search for patterns that span line boundaries. What defines a line
74 boundary is controlled by the <b>-N</b> (<b>--newline</b>) option.
77 The amount of memory used for buffering files that are being scanned is
78 controlled by a parameter that can be set by the <b>--buffer-size</b> option.
79 The default value for this parameter is specified when <b>pcregrep</b> is built,
80 with the default default being 20K. A block of memory three times this size is
81 used (to allow for buffering "before" and "after" lines). An error occurs if a
82 line overflows the buffer.
85 Patterns are limited to 8K or BUFSIZ bytes, whichever is the greater. BUFSIZ is
86 defined in <b><stdio.h></b>. When there is more than one pattern (specified by
87 the use of <b>-e</b> and/or <b>-f</b>), each pattern is applied to each line in
88 the order in which they are defined, except that all the <b>-e</b> patterns are
89 tried before the <b>-f</b> patterns.
92 By default, as soon as one pattern matches (or fails to match when <b>-v</b> is
93 used), no further patterns are considered. However, if <b>--colour</b> (or
94 <b>--color</b>) is used to colour the matching substrings, or if
95 <b>--only-matching</b>, <b>--file-offsets</b>, or <b>--line-offsets</b> is used to
96 output only the part of the line that matched (either shown literally, or as an
97 offset), scanning resumes immediately following the match, so that further
98 matches on the same line can be found. If there are multiple patterns, they are
99 all tried on the remainder of the line, but patterns that follow the one that
100 matched are not tried on the earlier part of the line.
103 This is the same behaviour as GNU grep, but it does mean that the order in
104 which multiple patterns are specified can affect the output when one of the
105 above options is used.
108 Patterns that can match an empty string are accepted, but empty string
109 matches are never recognized. An example is the pattern "(super)?(man)?", in
110 which all components are optional. This pattern finds all occurrences of both
111 "super" and "man"; the output differs from matching with "super|man" when only
112 the matching substrings are being shown.
115 If the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variable is set,
116 <b>pcregrep</b> uses the value to set a locale when calling the PCRE library.
117 The <b>--locale</b> option can be used to override this.
119 <br><a name="SEC3" href="#TOC1">SUPPORT FOR COMPRESSED FILES</a><br>
121 It is possible to compile <b>pcregrep</b> so that it uses <b>libz</b> or
122 <b>libbz2</b> to read files whose names end in <b>.gz</b> or <b>.bz2</b>,
123 respectively. You can find out whether your binary has support for one or both
124 of these file types by running it with the <b>--help</b> option. If the
125 appropriate support is not present, files are treated as plain text. The
126 standard input is always so treated.
128 <br><a name="SEC4" href="#TOC1">OPTIONS</a><br>
130 The order in which some of the options appear can affect the output. For
131 example, both the <b>-h</b> and <b>-l</b> options affect the printing of file
132 names. Whichever comes later in the command line will be the one that takes
133 effect. Numerical values for options may be followed by K or M, to signify
134 multiplication by 1024 or 1024*1024 respectively.
138 This terminates the list of options. It is useful if the next item on the
139 command line starts with a hyphen but is not an option. This allows for the
140 processing of patterns and filenames that start with hyphens.
143 <b>-A</b> <i>number</i>, <b>--after-context=</b><i>number</i>
144 Output <i>number</i> lines of context after each matching line. If filenames
145 and/or line numbers are being output, a hyphen separator is used instead of a
146 colon for the context lines. A line containing "--" is output between each
147 group of lines, unless they are in fact contiguous in the input file. The value
148 of <i>number</i> is expected to be relatively small. However, <b>pcregrep</b>
149 guarantees to have up to 8K of following text available for context output.
152 <b>-B</b> <i>number</i>, <b>--before-context=</b><i>number</i>
153 Output <i>number</i> lines of context before each matching line. If filenames
154 and/or line numbers are being output, a hyphen separator is used instead of a
155 colon for the context lines. A line containing "--" is output between each
156 group of lines, unless they are in fact contiguous in the input file. The value
157 of <i>number</i> is expected to be relatively small. However, <b>pcregrep</b>
158 guarantees to have up to 8K of preceding text available for context output.
161 <b>--buffer-size=</b><i>number</i>
162 Set the parameter that controls how much memory is used for buffering files
163 that are being scanned.
166 <b>-C</b> <i>number</i>, <b>--context=</b><i>number</i>
167 Output <i>number</i> lines of context both before and after each matching line.
168 This is equivalent to setting both <b>-A</b> and <b>-B</b> to the same value.
171 <b>-c</b>, <b>--count</b>
172 Do not output individual lines from the files that are being scanned; instead
173 output the number of lines that would otherwise have been shown. If no lines
174 are selected, the number zero is output. If several files are are being
175 scanned, a count is output for each of them. However, if the
176 <b>--files-with-matches</b> option is also used, only those files whose counts
177 are greater than zero are listed. When <b>-c</b> is used, the <b>-A</b>,
178 <b>-B</b>, and <b>-C</b> options are ignored.
181 <b>--colour</b>, <b>--color</b>
182 If this option is given without any data, it is equivalent to "--colour=auto".
183 If data is required, it must be given in the same shell item, separated by an
187 <b>--colour=</b><i>value</i>, <b>--color=</b><i>value</i>
188 This option specifies under what circumstances the parts of a line that matched
189 a pattern should be coloured in the output. By default, the output is not
190 coloured. The value (which is optional, see above) may be "never", "always", or
191 "auto". In the latter case, colouring happens only if the standard output is
192 connected to a terminal. More resources are used when colouring is enabled,
193 because <b>pcregrep</b> has to search for all possible matches in a line, not
194 just one, in order to colour them all.
197 The colour that is used can be specified by setting the environment variable
198 PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
199 string of two numbers, separated by a semicolon. They are copied directly into
200 the control string for setting colour on a terminal, so it is your
201 responsibility to ensure that they make sense. If neither of the environment
202 variables is set, the default is "1;31", which gives red.
205 <b>-D</b> <i>action</i>, <b>--devices=</b><i>action</i>
206 If an input path is not a regular file or a directory, "action" specifies how
207 it is to be processed. Valid values are "read" (the default) or "skip"
208 (silently skip the path).
211 <b>-d</b> <i>action</i>, <b>--directories=</b><i>action</i>
212 If an input path is a directory, "action" specifies how it is to be processed.
213 Valid values are "read" (the default), "recurse" (equivalent to the <b>-r</b>
214 option), or "skip" (silently skip the path). In the default case, directories
215 are read as if they were ordinary files. In some operating systems the effect
216 of reading a directory like this is an immediate end-of-file.
219 <b>-e</b> <i>pattern</i>, <b>--regex=</b><i>pattern</i>, <b>--regexp=</b><i>pattern</i>
220 Specify a pattern to be matched. This option can be used multiple times in
221 order to specify several patterns. It can also be used as a way of specifying a
222 single pattern that starts with a hyphen. When <b>-e</b> is used, no argument
223 pattern is taken from the command line; all arguments are treated as file
224 names. There is an overall maximum of 100 patterns. They are applied to each
225 line in the order in which they are defined until one matches (or fails to
226 match if <b>-v</b> is used). If <b>-f</b> is used with <b>-e</b>, the command line
227 patterns are matched first, followed by the patterns from the file, independent
228 of the order in which these options are specified. Note that multiple use of
229 <b>-e</b> is not the same as a single pattern with alternatives. For example,
230 X|Y finds the first character in a line that is X or Y, whereas if the two
231 patterns are given separately, <b>pcregrep</b> finds X if it is present, even if
232 it follows Y in the line. It finds Y only if there is no X in the line. This
233 really matters only if you are using <b>-o</b> to show the part(s) of the line
237 <b>--exclude</b>=<i>pattern</i>
238 When <b>pcregrep</b> is searching the files in a directory as a consequence of
239 the <b>-r</b> (recursive search) option, any regular files whose names match the
240 pattern are excluded. Subdirectories are not excluded by this option; they are
241 searched recursively, subject to the <b>--exclude-dir</b> and
242 <b>--include_dir</b> options. The pattern is a PCRE regular expression, and is
243 matched against the final component of the file name (not the entire path). If
244 a file name matches both <b>--include</b> and <b>--exclude</b>, it is excluded.
245 There is no short form for this option.
248 <b>--exclude-dir</b>=<i>pattern</i>
249 When <b>pcregrep</b> is searching the contents of a directory as a consequence
250 of the <b>-r</b> (recursive search) option, any subdirectories whose names match
251 the pattern are excluded. (Note that the \fP--exclude\fP option does not affect
252 subdirectories.) The pattern is a PCRE regular expression, and is matched
253 against the final component of the name (not the entire path). If a
254 subdirectory name matches both <b>--include-dir</b> and <b>--exclude-dir</b>, it
255 is excluded. There is no short form for this option.
258 <b>-F</b>, <b>--fixed-strings</b>
259 Interpret each pattern as a list of fixed strings, separated by newlines,
260 instead of as a regular expression. The <b>-w</b> (match as a word) and <b>-x</b>
261 (match whole line) options can be used with <b>-F</b>. They apply to each of the
262 fixed strings. A line is selected if any of the fixed strings are found in it
263 (subject to <b>-w</b> or <b>-x</b>, if present).
266 <b>-f</b> <i>filename</i>, <b>--file=</b><i>filename</i>
267 Read a number of patterns from the file, one per line, and match them against
268 each line of input. A data line is output if any of the patterns match it. The
269 filename can be given as "-" to refer to the standard input. When <b>-f</b> is
270 used, patterns specified on the command line using <b>-e</b> may also be
271 present; they are tested before the file's patterns. However, no other pattern
272 is taken from the command line; all arguments are treated as file names. There
273 is an overall maximum of 100 patterns. Trailing white space is removed from
274 each line, and blank lines are ignored. An empty file contains no patterns and
275 therefore matches nothing. See also the comments about multiple patterns versus
276 a single pattern with alternatives in the description of <b>-e</b> above.
279 <b>--file-offsets</b>
280 Instead of showing lines or parts of lines that match, show each match as an
281 offset from the start of the file and a length, separated by a comma. In this
282 mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b>
283 options are ignored. If there is more than one match in a line, each of them is
284 shown separately. This option is mutually exclusive with <b>--line-offsets</b>
285 and <b>--only-matching</b>.
288 <b>-H</b>, <b>--with-filename</b>
289 Force the inclusion of the filename at the start of output lines when searching
290 a single file. By default, the filename is not shown in this case. For matching
291 lines, the filename is followed by a colon; for context lines, a hyphen
292 separator is used. If a line number is also being output, it follows the file
296 <b>-h</b>, <b>--no-filename</b>
297 Suppress the output filenames when searching multiple files. By default,
298 filenames are shown when multiple files are searched. For matching lines, the
299 filename is followed by a colon; for context lines, a hyphen separator is used.
300 If a line number is also being output, it follows the file name.
304 Output a help message, giving brief details of the command options and file
305 type support, and then exit.
308 <b>-i</b>, <b>--ignore-case</b>
309 Ignore upper/lower case distinctions during comparisons.
312 <b>--include</b>=<i>pattern</i>
313 When <b>pcregrep</b> is searching the files in a directory as a consequence of
314 the <b>-r</b> (recursive search) option, only those regular files whose names
315 match the pattern are included. Subdirectories are always included and searched
316 recursively, subject to the \fP--include-dir\fP and <b>--exclude-dir</b>
317 options. The pattern is a PCRE regular expression, and is matched against the
318 final component of the file name (not the entire path). If a file name matches
319 both <b>--include</b> and <b>--exclude</b>, it is excluded. There is no short
320 form for this option.
323 <b>--include-dir</b>=<i>pattern</i>
324 When <b>pcregrep</b> is searching the contents of a directory as a consequence
325 of the <b>-r</b> (recursive search) option, only those subdirectories whose
326 names match the pattern are included. (Note that the <b>--include</b> option
327 does not affect subdirectories.) The pattern is a PCRE regular expression, and
328 is matched against the final component of the name (not the entire path). If a
329 subdirectory name matches both <b>--include-dir</b> and <b>--exclude-dir</b>, it
330 is excluded. There is no short form for this option.
333 <b>-L</b>, <b>--files-without-match</b>
334 Instead of outputting lines from the files, just output the names of the files
335 that do not contain any lines that would have been output. Each file name is
336 output once, on a separate line.
339 <b>-l</b>, <b>--files-with-matches</b>
340 Instead of outputting lines from the files, just output the names of the files
341 containing lines that would have been output. Each file name is output
342 once, on a separate line. Searching normally stops as soon as a matching line
343 is found in a file. However, if the <b>-c</b> (count) option is also used,
344 matching continues in order to obtain the correct count, and those files that
345 have at least one match are listed along with their counts. Using this option
346 with <b>-c</b> is a way of suppressing the listing of files with no matches.
349 <b>--label</b>=<i>name</i>
350 This option supplies a name to be used for the standard input when file names
351 are being output. If not supplied, "(standard input)" is used. There is no
352 short form for this option.
355 <b>--line-buffered</b>
356 When this option is given, input is read and processed line by line, and the
357 output is flushed after each write. By default, input is read in large chunks,
358 unless <b>pcregrep</b> can determine that it is reading from a terminal (which
359 is currently possible only in Unix environments). Output to terminal is
360 normally automatically flushed by the operating system. This option can be
361 useful when the input or output is attached to a pipe and you do not want
362 <b>pcregrep</b> to buffer up large amounts of data. However, its use will affect
363 performance, and the <b>-M</b> (multiline) option ceases to work.
366 <b>--line-offsets</b>
367 Instead of showing lines or parts of lines that match, show each match as a
368 line number, the offset from the start of the line, and a length. The line
369 number is terminated by a colon (as usual; see the <b>-n</b> option), and the
370 offset and length are separated by a comma. In this mode, no context is shown.
371 That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b> options are ignored. If there is
372 more than one match in a line, each of them is shown separately. This option is
373 mutually exclusive with <b>--file-offsets</b> and <b>--only-matching</b>.
376 <b>--locale</b>=<i>locale-name</i>
377 This option specifies a locale to be used for pattern matching. It overrides
378 the value in the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variables. If no
379 locale is specified, the PCRE library's default (usually the "C" locale) is
380 used. There is no short form for this option.
383 <b>--match-limit</b>=<i>number</i>
384 Processing some regular expression patterns can require a very large amount of
385 memory, leading in some cases to a program crash if not enough is available.
386 Other patterns may take a very long time to search for all possible matching
387 strings. The <b>pcre_exec()</b> function that is called by <b>pcregrep</b> to do
388 the matching has two parameters that can limit the resources that it uses.
391 The <b>--match-limit</b> option provides a means of limiting resource usage
392 when processing patterns that are not going to match, but which have a very
393 large number of possibilities in their search trees. The classic example is a
394 pattern that uses nested unlimited repeats. Internally, PCRE uses a function
395 called <b>match()</b> which it calls repeatedly (sometimes recursively). The
396 limit set by <b>--match-limit</b> is imposed on the number of times this
397 function is called during a match, which has the effect of limiting the amount
398 of backtracking that can take place.
401 The <b>--recursion-limit</b> option is similar to <b>--match-limit</b>, but
402 instead of limiting the total number of times that <b>match()</b> is called, it
403 limits the depth of recursive calls, which in turn limits the amount of memory
404 that can be used. The recursion depth is a smaller number than the total number
405 of calls, because not all calls to <b>match()</b> are recursive. This limit is
406 of use only if it is set smaller than <b>--match-limit</b>.
409 There are no short forms for these options. The default settings are specified
410 when the PCRE library is compiled, with the default default being 10 million.
413 <b>-M</b>, <b>--multiline</b>
414 Allow patterns to match more than one line. When this option is given, patterns
415 may usefully contain literal newline characters and internal occurrences of ^
416 and $ characters. The output for a successful match may consist of more than
417 one line, the last of which is the one in which the match ended. If the matched
418 string ends with a newline sequence the output ends at the end of that line.
421 When this option is set, the PCRE library is called in "multiline" mode.
422 There is a limit to the number of lines that can be matched, imposed by the way
423 that <b>pcregrep</b> buffers the input file as it scans it. However,
424 <b>pcregrep</b> ensures that at least 8K characters or the rest of the document
425 (whichever is the shorter) are available for forward matching, and similarly
426 the previous 8K characters (or all the previous characters, if fewer than 8K)
427 are guaranteed to be available for lookbehind assertions. This option does not
428 work when input is read line by line (see \fP--line-buffered\fP.)
431 <b>-N</b> <i>newline-type</i>, <b>--newline</b>=<i>newline-type</i>
432 The PCRE library supports five different conventions for indicating
433 the ends of lines. They are the single-character sequences CR (carriage return)
434 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
435 which recognizes any of the preceding three types, and an "any" convention, in
436 which any Unicode line ending sequence is assumed to end a line. The Unicode
437 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
438 (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
439 PS (paragraph separator, U+2029).
442 When the PCRE library is built, a default line-ending sequence is specified.
443 This is normally the standard sequence for the operating system. Unless
444 otherwise specified by this option, <b>pcregrep</b> uses the library's default.
445 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
446 makes it possible to use <b>pcregrep</b> on files that have come from other
447 environments without having to modify their line endings. If the data that is
448 being scanned does not agree with the convention set by this option,
449 <b>pcregrep</b> may behave in strange ways.
452 <b>-n</b>, <b>--line-number</b>
453 Precede each output line by its line number in the file, followed by a colon
454 for matching lines or a hyphen for context lines. If the filename is also being
455 output, it precedes the line number. This option is forced if
456 <b>--line-offsets</b> is used.
460 If the PCRE library is built with support for just-in-time compiling (which
461 speeds up matching), <b>pcregrep</b> automatically makes use of this, unless it
462 was explicitly disabled at build time. This option can be used to disable the
463 use of JIT at run time. It is provided for testing and working round problems.
464 It should never be needed in normal use.
467 <b>-o</b>, <b>--only-matching</b>
468 Show only the part of the line that matched a pattern instead of the whole
469 line. In this mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and
470 <b>-C</b> options are ignored. If there is more than one match in a line, each
471 of them is shown separately. If <b>-o</b> is combined with <b>-v</b> (invert the
472 sense of the match to find non-matching lines), no output is generated, but the
473 return code is set appropriately. If the matched portion of the line is empty,
474 nothing is output unless the file name or line number are being printed, in
475 which case they are shown on an otherwise empty line. This option is mutually
476 exclusive with <b>--file-offsets</b> and <b>--line-offsets</b>.
479 <b>-o</b><i>number</i>, <b>--only-matching</b>=<i>number</i>
480 Show only the part of the line that matched the capturing parentheses of the
481 given number. Up to 32 capturing parentheses are supported. Because these
482 options can be given without an argument (see above), if an argument is
483 present, it must be given in the same shell item, for example, -o3 or
484 --only-matching=2. The comments given for the non-argument case above also
485 apply to this case. If the specified capturing parentheses do not exist in the
486 pattern, or were not set in the match, nothing is output unless the file name
487 or line number are being printed.
490 <b>-q</b>, <b>--quiet</b>
491 Work quietly, that is, display nothing except error messages. The exit
492 status indicates whether or not any matches were found.
495 <b>-r</b>, <b>--recursive</b>
496 If any given path is a directory, recursively scan the files it contains,
497 taking note of any <b>--include</b> and <b>--exclude</b> settings. By default, a
498 directory is read as a normal file; in some operating systems this gives an
499 immediate end-of-file. This option is a shorthand for setting the <b>-d</b>
503 <b>--recursion-limit</b>=<i>number</i>
504 See <b>--match-limit</b> above.
507 <b>-s</b>, <b>--no-messages</b>
508 Suppress error messages about non-existent or unreadable files. Such files are
509 quietly skipped. However, the return code is still 2, even if matches were
510 found in other files.
513 <b>-u</b>, <b>--utf-8</b>
514 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
515 with UTF-8 support. Both patterns and subject lines must be valid strings of
519 <b>-V</b>, <b>--version</b>
520 Write the version numbers of <b>pcregrep</b> and the PCRE library that is being
521 used to the standard error stream.
524 <b>-v</b>, <b>--invert-match</b>
525 Invert the sense of the match, so that lines which do <i>not</i> match any of
526 the patterns are the ones that are found.
529 <b>-w</b>, <b>--word-regex</b>, <b>--word-regexp</b>
530 Force the patterns to match only whole words. This is equivalent to having \b
531 at the start and end of the pattern.
534 <b>-x</b>, <b>--line-regex</b>, <b>--line-regexp</b>
535 Force the patterns to be anchored (each must start matching at the beginning of
536 a line) and in addition, require them to match entire lines. This is
537 equivalent to having ^ and $ characters at the start and end of each
538 alternative branch in every pattern.
540 <br><a name="SEC5" href="#TOC1">ENVIRONMENT VARIABLES</a><br>
542 The environment variables <b>LC_ALL</b> and <b>LC_CTYPE</b> are examined, in that
543 order, for a locale. The first one that is set is used. This can be overridden
544 by the <b>--locale</b> option. If no locale is set, the PCRE library's default
545 (usually the "C" locale) is used.
547 <br><a name="SEC6" href="#TOC1">NEWLINES</a><br>
549 The <b>-N</b> (<b>--newline</b>) option allows <b>pcregrep</b> to scan files with
550 different newline conventions from the default. However, the setting of this
551 option does not affect the way in which <b>pcregrep</b> writes information to
552 the standard error and output streams. It uses the string "\n" in C
553 <b>printf()</b> calls to indicate newlines, relying on the C I/O library to
554 convert this to an appropriate sequence if the output is sent to a file.
556 <br><a name="SEC7" href="#TOC1">OPTIONS COMPATIBILITY</a><br>
558 Many of the short and long forms of <b>pcregrep</b>'s options are the same
559 as in the GNU <b>grep</b> program (version 2.5.4). Any long option of the form
560 <b>--xxx-regexp</b> (GNU terminology) is also available as <b>--xxx-regex</b>
561 (PCRE terminology). However, the <b>--file-offsets</b>, <b>--include-dir</b>,
562 <b>--line-offsets</b>, <b>--locale</b>, <b>--match-limit</b>, <b>-M</b>,
563 <b>--multiline</b>, <b>-N</b>, <b>--newline</b>, <b>--recursion-limit</b>,
564 <b>-u</b>, and <b>--utf-8</b> options are specific to <b>pcregrep</b>, as is the
565 use of the <b>--only-matching</b> option with a capturing parentheses number.
568 Although most of the common options work the same way, a few are different in
569 <b>pcregrep</b>. For example, the <b>--include</b> option's argument is a glob
570 for GNU <b>grep</b>, but a regular expression for <b>pcregrep</b>. If both the
571 <b>-c</b> and <b>-l</b> options are given, GNU grep lists only file names,
572 without counts, but <b>pcregrep</b> gives the counts.
574 <br><a name="SEC8" href="#TOC1">OPTIONS WITH DATA</a><br>
576 There are four different ways in which an option with data can be specified.
577 If a short form option is used, the data may follow immediately, or (with one
578 exception) in the next command line item. For example:
583 The exception is the <b>-o</b> option, which may appear with or without data.
584 Because of this, if data is present, it must follow immediately in the same
585 item, for example -o3.
588 If a long form option is used, the data may appear in the same command line
589 item, separated by an equals character, or (with two exceptions) it may appear
590 in the next command line item. For example:
595 Note, however, that if you want to supply a file name beginning with ~ as data
596 in a shell command, and have the shell expand ~ to a home directory, you must
597 separate the file name from the option, because the shell does not treat ~
598 specially unless it is at the start of an item.
601 The exceptions to the above are the <b>--colour</b> (or <b>--color</b>) and
602 <b>--only-matching</b> options, for which the data is optional. If one of these
603 options does have data, it must be given in the first form, using an equals
604 character. Otherwise <b>pcregrep</b> will assume that it has no data.
606 <br><a name="SEC9" href="#TOC1">MATCHING ERRORS</a><br>
608 It is possible to supply a regular expression that takes a very long time to
609 fail to match certain lines. Such patterns normally involve nested indefinite
610 repeats, for example: (a+)*\d when matched against a line of a's with no final
611 digit. The PCRE matching function has a resource limit that causes it to abort
612 in these circumstances. If this happens, <b>pcregrep</b> outputs an error
613 message and the line that caused the problem to the standard error stream. If
614 there are more than 20 such errors, <b>pcregrep</b> gives up.
617 The <b>--match-limit</b> option of <b>pcregrep</b> can be used to set the overall
618 resource limit; there is a second option called <b>--recursion-limit</b> that
619 sets a limit on the amount of memory (usually stack) that is used (see the
620 discussion of these options above).
622 <br><a name="SEC10" href="#TOC1">DIAGNOSTICS</a><br>
624 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
625 for syntax errors, overlong lines, non-existent or inaccessible files (even if
626 matches were found in other files) or too many matching errors. Using the
627 <b>-s</b> option to suppress error messages about inaccessible files does not
628 affect the return code.
630 <br><a name="SEC11" href="#TOC1">SEE ALSO</a><br>
632 <b>pcrepattern</b>(3), <b>pcretest</b>(1).
634 <br><a name="SEC12" href="#TOC1">AUTHOR</a><br>
638 University Computing Service
640 Cambridge CB2 3QH, England.
643 <br><a name="SEC13" href="#TOC1">REVISION</a><br>
645 Last updated: 06 September 2011
647 Copyright © 1997-2011 University of Cambridge.
650 Return to the <a href="index.html">PCRE index page</a>.
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