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Add more explanation about recursive subpatterns, and make it possible to 
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1 <html>
2 <head>
3 <title>pcregrep specification</title>
4 </head>
5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 <h1>pcregrep man page</h1>
7 <p>
8 Return to the <a href="index.html">PCRE index page</a>.
9 </p>
10 <p>
11 This page is part of the PCRE HTML documentation. It was generated automatically
12 from the original man page. If there is any nonsense in it, please consult the
13 man page, in case the conversion went wrong.
14 <br>
15 <ul>
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>
29 </ul>
30 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
31 <P>
32 <b>pcregrep [options] [long options] [pattern] [path1 path2 ...]</b>
33 </P>
34 <br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
35 <P>
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
41 that PCRE supports.
42 </P>
43 <P>
44 Patterns, whether supplied on the command line or in a separate file, are given
45 without delimiters. For example:
46 <pre>
47 pcregrep Thursday /etc/motd
48 </pre>
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.
54 </P>
55 <P>
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.
61 </P>
62 <P>
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.
65 For example:
66 <pre>
67 pcregrep some-pattern /file1 - /file3
68 </pre>
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.
75 </P>
76 <P>
77 Patterns are limited to 8K or BUFSIZ characters, whichever is the greater.
78 BUFSIZ is defined in <b>&#60;stdio.h&#62;</b>. When there is more than one pattern
79 (specified by the use of <b>-e</b> and/or <b>-f</b>), each pattern is applied to
80 each line in the order in which they are defined, except that all the <b>-e</b>
81 patterns are tried before the <b>-f</b> patterns.
82 </P>
83 <P>
84 By default, as soon as one pattern matches (or fails to match when <b>-v</b> is
85 used), no further patterns are considered. However, if <b>--colour</b> (or
86 <b>--color</b>) is used to colour the matching substrings, or if
87 <b>--only-matching</b>, <b>--file-offsets</b>, or <b>--line-offsets</b> is used to
88 output only the part of the line that matched (either shown literally, or as an
89 offset), scanning resumes immediately following the match, so that further
90 matches on the same line can be found. If there are multiple patterns, they are
91 all tried on the remainder of the line, but patterns that follow the one that
92 matched are not tried on the earlier part of the line.
93 </P>
94 <P>
95 This is the same behaviour as GNU grep, but it does mean that the order in
96 which multiple patterns are specified can affect the output when one of the
97 above options is used.
98 </P>
99 <P>
100 Patterns that can match an empty string are accepted, but empty string
101 matches are never recognized. An example is the pattern "(super)?(man)?", in
102 which all components are optional. This pattern finds all occurrences of both
103 "super" and "man"; the output differs from matching with "super|man" when only
104 the matching substrings are being shown.
105 </P>
106 <P>
107 If the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variable is set,
108 <b>pcregrep</b> uses the value to set a locale when calling the PCRE library.
109 The <b>--locale</b> option can be used to override this.
110 </P>
111 <br><a name="SEC3" href="#TOC1">SUPPORT FOR COMPRESSED FILES</a><br>
112 <P>
113 It is possible to compile <b>pcregrep</b> so that it uses <b>libz</b> or
114 <b>libbz2</b> to read files whose names end in <b>.gz</b> or <b>.bz2</b>,
115 respectively. You can find out whether your binary has support for one or both
116 of these file types by running it with the <b>--help</b> option. If the
117 appropriate support is not present, files are treated as plain text. The
118 standard input is always so treated.
119 </P>
120 <br><a name="SEC4" href="#TOC1">OPTIONS</a><br>
121 <P>
122 The order in which some of the options appear can affect the output. For
123 example, both the <b>-h</b> and <b>-l</b> options affect the printing of file
124 names. Whichever comes later in the command line will be the one that takes
125 effect.
126 </P>
127 <P>
128 <b>--</b>
129 This terminate the list of options. It is useful if the next item on the
130 command line starts with a hyphen but is not an option. This allows for the
131 processing of patterns and filenames that start with hyphens.
132 </P>
133 <P>
134 <b>-A</b> <i>number</i>, <b>--after-context=</b><i>number</i>
135 Output <i>number</i> lines of context after each matching line. If filenames
136 and/or line numbers are being output, a hyphen separator is used instead of a
137 colon for the context lines. A line containing "--" is output between each
138 group of lines, unless they are in fact contiguous in the input file. The value
139 of <i>number</i> is expected to be relatively small. However, <b>pcregrep</b>
140 guarantees to have up to 8K of following text available for context output.
141 </P>
142 <P>
143 <b>-B</b> <i>number</i>, <b>--before-context=</b><i>number</i>
144 Output <i>number</i> lines of context before 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 preceding text available for context output.
150 </P>
151 <P>
152 <b>-C</b> <i>number</i>, <b>--context=</b><i>number</i>
153 Output <i>number</i> lines of context both before and after each matching line.
154 This is equivalent to setting both <b>-A</b> and <b>-B</b> to the same value.
155 </P>
156 <P>
157 <b>-c</b>, <b>--count</b>
158 Do not output individual lines from the files that are being scanned; instead
159 output the number of lines that would otherwise have been shown. If no lines
160 are selected, the number zero is output. If several files are are being
161 scanned, a count is output for each of them. However, if the
162 <b>--files-with-matches</b> option is also used, only those files whose counts
163 are greater than zero are listed. When <b>-c</b> is used, the <b>-A</b>,
164 <b>-B</b>, and <b>-C</b> options are ignored.
165 </P>
166 <P>
167 <b>--colour</b>, <b>--color</b>
168 If this option is given without any data, it is equivalent to "--colour=auto".
169 If data is required, it must be given in the same shell item, separated by an
170 equals sign.
171 </P>
172 <P>
173 <b>--colour=</b><i>value</i>, <b>--color=</b><i>value</i>
174 This option specifies under what circumstances the parts of a line that matched
175 a pattern should be coloured in the output. By default, the output is not
176 coloured. The value (which is optional, see above) may be "never", "always", or
177 "auto". In the latter case, colouring happens only if the standard output is
178 connected to a terminal. More resources are used when colouring is enabled,
179 because <b>pcregrep</b> has to search for all possible matches in a line, not
180 just one, in order to colour them all.
181 </P>
182 <P>
183 The colour that is used can be specified by setting the environment variable
184 PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
185 string of two numbers, separated by a semicolon. They are copied directly into
186 the control string for setting colour on a terminal, so it is your
187 responsibility to ensure that they make sense. If neither of the environment
188 variables is set, the default is "1;31", which gives red.
189 </P>
190 <P>
191 <b>-D</b> <i>action</i>, <b>--devices=</b><i>action</i>
192 If an input path is not a regular file or a directory, "action" specifies how
193 it is to be processed. Valid values are "read" (the default) or "skip"
194 (silently skip the path).
195 </P>
196 <P>
197 <b>-d</b> <i>action</i>, <b>--directories=</b><i>action</i>
198 If an input path is a directory, "action" specifies how it is to be processed.
199 Valid values are "read" (the default), "recurse" (equivalent to the <b>-r</b>
200 option), or "skip" (silently skip the path). In the default case, directories
201 are read as if they were ordinary files. In some operating systems the effect
202 of reading a directory like this is an immediate end-of-file.
203 </P>
204 <P>
205 <b>-e</b> <i>pattern</i>, <b>--regex=</b><i>pattern</i>, <b>--regexp=</b><i>pattern</i>
206 Specify a pattern to be matched. This option can be used multiple times in
207 order to specify several patterns. It can also be used as a way of specifying a
208 single pattern that starts with a hyphen. When <b>-e</b> is used, no argument
209 pattern is taken from the command line; all arguments are treated as file
210 names. There is an overall maximum of 100 patterns. They are applied to each
211 line in the order in which they are defined until one matches (or fails to
212 match if <b>-v</b> is used). If <b>-f</b> is used with <b>-e</b>, the command line
213 patterns are matched first, followed by the patterns from the file, independent
214 of the order in which these options are specified. Note that multiple use of
215 <b>-e</b> is not the same as a single pattern with alternatives. For example,
216 X|Y finds the first character in a line that is X or Y, whereas if the two
217 patterns are given separately, <b>pcregrep</b> finds X if it is present, even if
218 it follows Y in the line. It finds Y only if there is no X in the line. This
219 really matters only if you are using <b>-o</b> to show the part(s) of the line
220 that matched.
221 </P>
222 <P>
223 <b>--exclude</b>=<i>pattern</i>
224 When <b>pcregrep</b> is searching the files in a directory as a consequence of
225 the <b>-r</b> (recursive search) option, any regular files whose names match the
226 pattern are excluded. Subdirectories are not excluded by this option; they are
227 searched recursively, subject to the <b>--exclude_dir</b> and
228 <b>--include_dir</b> options. The pattern is a PCRE regular expression, and is
229 matched against the final component of the file name (not the entire path). If
230 a file name matches both <b>--include</b> and <b>--exclude</b>, it is excluded.
231 There is no short form for this option.
232 </P>
233 <P>
234 <b>--exclude_dir</b>=<i>pattern</i>
235 When <b>pcregrep</b> is searching the contents of a directory as a consequence
236 of the <b>-r</b> (recursive search) option, any subdirectories whose names match
237 the pattern are excluded. (Note that the \fP--exclude\fP option does not affect
238 subdirectories.) The pattern is a PCRE regular expression, and is matched
239 against the final component of the name (not the entire path). If a
240 subdirectory name matches both <b>--include_dir</b> and <b>--exclude_dir</b>, it
241 is excluded. There is no short form for this option.
242 </P>
243 <P>
244 <b>-F</b>, <b>--fixed-strings</b>
245 Interpret each pattern as a list of fixed strings, separated by newlines,
246 instead of as a regular expression. The <b>-w</b> (match as a word) and <b>-x</b>
247 (match whole line) options can be used with <b>-F</b>. They apply to each of the
248 fixed strings. A line is selected if any of the fixed strings are found in it
249 (subject to <b>-w</b> or <b>-x</b>, if present).
250 </P>
251 <P>
252 <b>-f</b> <i>filename</i>, <b>--file=</b><i>filename</i>
253 Read a number of patterns from the file, one per line, and match them against
254 each line of input. A data line is output if any of the patterns match it. The
255 filename can be given as "-" to refer to the standard input. When <b>-f</b> is
256 used, patterns specified on the command line using <b>-e</b> may also be
257 present; they are tested before the file's patterns. However, no other pattern
258 is taken from the command line; all arguments are treated as file names. There
259 is an overall maximum of 100 patterns. Trailing white space is removed from
260 each line, and blank lines are ignored. An empty file contains no patterns and
261 therefore matches nothing. See also the comments about multiple patterns versus
262 a single pattern with alternatives in the description of <b>-e</b> above.
263 </P>
264 <P>
265 <b>--file-offsets</b>
266 Instead of showing lines or parts of lines that match, show each match as an
267 offset from the start of the file and a length, separated by a comma. In this
268 mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b>
269 options are ignored. If there is more than one match in a line, each of them is
270 shown separately. This option is mutually exclusive with <b>--line-offsets</b>
271 and <b>--only-matching</b>.
272 </P>
273 <P>
274 <b>-H</b>, <b>--with-filename</b>
275 Force the inclusion of the filename at the start of output lines when searching
276 a single file. By default, the filename is not shown in this case. For matching
277 lines, the filename is followed by a colon; for context lines, a hyphen
278 separator is used. If a line number is also being output, it follows the file
279 name.
280 </P>
281 <P>
282 <b>-h</b>, <b>--no-filename</b>
283 Suppress the output filenames when searching multiple files. By default,
284 filenames are shown when multiple files are searched. For matching lines, the
285 filename is followed by a colon; for context lines, a hyphen separator is used.
286 If a line number is also being output, it follows the file name.
287 </P>
288 <P>
289 <b>--help</b>
290 Output a help message, giving brief details of the command options and file
291 type support, and then exit.
292 </P>
293 <P>
294 <b>-i</b>, <b>--ignore-case</b>
295 Ignore upper/lower case distinctions during comparisons.
296 </P>
297 <P>
298 <b>--include</b>=<i>pattern</i>
299 When <b>pcregrep</b> is searching the files in a directory as a consequence of
300 the <b>-r</b> (recursive search) option, only those regular files whose names
301 match the pattern are included. Subdirectories are always included and searched
302 recursively, subject to the \fP--include_dir\fP and <b>--exclude_dir</b>
303 options. The pattern is a PCRE regular expression, and is matched against the
304 final component of the file name (not the entire path). If a file name matches
305 both <b>--include</b> and <b>--exclude</b>, it is excluded. There is no short
306 form for this option.
307 </P>
308 <P>
309 <b>--include_dir</b>=<i>pattern</i>
310 When <b>pcregrep</b> is searching the contents of a directory as a consequence
311 of the <b>-r</b> (recursive search) option, only those subdirectories whose
312 names match the pattern are included. (Note that the <b>--include</b> option
313 does not affect subdirectories.) The pattern is a PCRE regular expression, and
314 is matched against the final component of the name (not the entire path). If a
315 subdirectory name matches both <b>--include_dir</b> and <b>--exclude_dir</b>, it
316 is excluded. There is no short form for this option.
317 </P>
318 <P>
319 <b>-L</b>, <b>--files-without-match</b>
320 Instead of outputting lines from the files, just output the names of the files
321 that do not contain any lines that would have been output. Each file name is
322 output once, on a separate line.
323 </P>
324 <P>
325 <b>-l</b>, <b>--files-with-matches</b>
326 Instead of outputting lines from the files, just output the names of the files
327 containing lines that would have been output. Each file name is output
328 once, on a separate line. Searching normally stops as soon as a matching line
329 is found in a file. However, if the <b>-c</b> (count) option is also used,
330 matching continues in order to obtain the correct count, and those files that
331 have at least one match are listed along with their counts. Using this option
332 with <b>-c</b> is a way of suppressing the listing of files with no matches.
333 </P>
334 <P>
335 <b>--label</b>=<i>name</i>
336 This option supplies a name to be used for the standard input when file names
337 are being output. If not supplied, "(standard input)" is used. There is no
338 short form for this option.
339 </P>
340 <P>
341 <b>--line-offsets</b>
342 Instead of showing lines or parts of lines that match, show each match as a
343 line number, the offset from the start of the line, and a length. The line
344 number is terminated by a colon (as usual; see the <b>-n</b> option), and the
345 offset and length are separated by a comma. In this mode, no context is shown.
346 That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b> options are ignored. If there is
347 more than one match in a line, each of them is shown separately. This option is
348 mutually exclusive with <b>--file-offsets</b> and <b>--only-matching</b>.
349 </P>
350 <P>
351 <b>--locale</b>=<i>locale-name</i>
352 This option specifies a locale to be used for pattern matching. It overrides
353 the value in the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variables. If no
354 locale is specified, the PCRE library's default (usually the "C" locale) is
355 used. There is no short form for this option.
356 </P>
357 <P>
358 <b>-M</b>, <b>--multiline</b>
359 Allow patterns to match more than one line. When this option is given, patterns
360 may usefully contain literal newline characters and internal occurrences of ^
361 and $ characters. The output for any one match may consist of more than one
362 line. When this option is set, the PCRE library is called in "multiline" mode.
363 There is a limit to the number of lines that can be matched, imposed by the way
364 that <b>pcregrep</b> buffers the input file as it scans it. However,
365 <b>pcregrep</b> ensures that at least 8K characters or the rest of the document
366 (whichever is the shorter) are available for forward matching, and similarly
367 the previous 8K characters (or all the previous characters, if fewer than 8K)
368 are guaranteed to be available for lookbehind assertions.
369 </P>
370 <P>
371 <b>-N</b> <i>newline-type</i>, <b>--newline=</b><i>newline-type</i>
372 The PCRE library supports five different conventions for indicating
373 the ends of lines. They are the single-character sequences CR (carriage return)
374 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
375 which recognizes any of the preceding three types, and an "any" convention, in
376 which any Unicode line ending sequence is assumed to end a line. The Unicode
377 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
378 (formfeed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
379 PS (paragraph separator, U+2029).
380 <br>
381 <br>
382 When the PCRE library is built, a default line-ending sequence is specified.
383 This is normally the standard sequence for the operating system. Unless
384 otherwise specified by this option, <b>pcregrep</b> uses the library's default.
385 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
386 makes it possible to use <b>pcregrep</b> on files that have come from other
387 environments without having to modify their line endings. If the data that is
388 being scanned does not agree with the convention set by this option,
389 <b>pcregrep</b> may behave in strange ways.
390 </P>
391 <P>
392 <b>-n</b>, <b>--line-number</b>
393 Precede each output line by its line number in the file, followed by a colon
394 for matching lines or a hyphen for context lines. If the filename is also being
395 output, it precedes the line number. This option is forced if
396 <b>--line-offsets</b> is used.
397 </P>
398 <P>
399 <b>-o</b>, <b>--only-matching</b>
400 Show only the part of the line that matched a pattern. In this mode, no
401 context is shown. That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b> options are
402 ignored. If there is more than one match in a line, each of them is shown
403 separately. If <b>-o</b> is combined with <b>-v</b> (invert the sense of the
404 match to find non-matching lines), no output is generated, but the return code
405 is set appropriately. This option is mutually exclusive with
406 <b>--file-offsets</b> and <b>--line-offsets</b>.
407 </P>
408 <P>
409 <b>-q</b>, <b>--quiet</b>
410 Work quietly, that is, display nothing except error messages. The exit
411 status indicates whether or not any matches were found.
412 </P>
413 <P>
414 <b>-r</b>, <b>--recursive</b>
415 If any given path is a directory, recursively scan the files it contains,
416 taking note of any <b>--include</b> and <b>--exclude</b> settings. By default, a
417 directory is read as a normal file; in some operating systems this gives an
418 immediate end-of-file. This option is a shorthand for setting the <b>-d</b>
419 option to "recurse".
420 </P>
421 <P>
422 <b>-s</b>, <b>--no-messages</b>
423 Suppress error messages about non-existent or unreadable files. Such files are
424 quietly skipped. However, the return code is still 2, even if matches were
425 found in other files.
426 </P>
427 <P>
428 <b>-u</b>, <b>--utf-8</b>
429 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
430 with UTF-8 support. Both patterns and subject lines must be valid strings of
431 UTF-8 characters.
432 </P>
433 <P>
434 <b>-V</b>, <b>--version</b>
435 Write the version numbers of <b>pcregrep</b> and the PCRE library that is being
436 used to the standard error stream.
437 </P>
438 <P>
439 <b>-v</b>, <b>--invert-match</b>
440 Invert the sense of the match, so that lines which do <i>not</i> match any of
441 the patterns are the ones that are found.
442 </P>
443 <P>
444 <b>-w</b>, <b>--word-regex</b>, <b>--word-regexp</b>
445 Force the patterns to match only whole words. This is equivalent to having \b
446 at the start and end of the pattern.
447 </P>
448 <P>
449 <b>-x</b>, <b>--line-regex</b>, <b>--line-regexp</b>
450 Force the patterns to be anchored (each must start matching at the beginning of
451 a line) and in addition, require them to match entire lines. This is
452 equivalent to having ^ and $ characters at the start and end of each
453 alternative branch in every pattern.
454 </P>
455 <br><a name="SEC5" href="#TOC1">ENVIRONMENT VARIABLES</a><br>
456 <P>
457 The environment variables <b>LC_ALL</b> and <b>LC_CTYPE</b> are examined, in that
458 order, for a locale. The first one that is set is used. This can be overridden
459 by the <b>--locale</b> option. If no locale is set, the PCRE library's default
460 (usually the "C" locale) is used.
461 </P>
462 <br><a name="SEC6" href="#TOC1">NEWLINES</a><br>
463 <P>
464 The <b>-N</b> (<b>--newline</b>) option allows <b>pcregrep</b> to scan files with
465 different newline conventions from the default. However, the setting of this
466 option does not affect the way in which <b>pcregrep</b> writes information to
467 the standard error and output streams. It uses the string "\n" in C
468 <b>printf()</b> calls to indicate newlines, relying on the C I/O library to
469 convert this to an appropriate sequence if the output is sent to a file.
470 </P>
471 <br><a name="SEC7" href="#TOC1">OPTIONS COMPATIBILITY</a><br>
472 <P>
473 The majority of short and long forms of <b>pcregrep</b>'s options are the same
474 as in the GNU <b>grep</b> program. Any long option of the form
475 <b>--xxx-regexp</b> (GNU terminology) is also available as <b>--xxx-regex</b>
476 (PCRE terminology). However, the <b>--locale</b>, <b>-M</b>, <b>--multiline</b>,
477 <b>-u</b>, and <b>--utf-8</b> options are specific to <b>pcregrep</b>. If both the
478 <b>-c</b> and <b>-l</b> options are given, GNU grep lists only file names,
479 without counts, but <b>pcregrep</b> gives the counts.
480 </P>
481 <br><a name="SEC8" href="#TOC1">OPTIONS WITH DATA</a><br>
482 <P>
483 There are four different ways in which an option with data can be specified.
484 If a short form option is used, the data may follow immediately, or in the next
485 command line item. For example:
486 <pre>
487 -f/some/file
488 -f /some/file
489 </pre>
490 If a long form option is used, the data may appear in the same command line
491 item, separated by an equals character, or (with one exception) it may appear
492 in the next command line item. For example:
493 <pre>
494 --file=/some/file
495 --file /some/file
496 </pre>
497 Note, however, that if you want to supply a file name beginning with ~ as data
498 in a shell command, and have the shell expand ~ to a home directory, you must
499 separate the file name from the option, because the shell does not treat ~
500 specially unless it is at the start of an item.
501 </P>
502 <P>
503 The exception to the above is the <b>--colour</b> (or <b>--color</b>) option,
504 for which the data is optional. If this option does have data, it must be given
505 in the first form, using an equals character. Otherwise it will be assumed that
506 it has no data.
507 </P>
508 <br><a name="SEC9" href="#TOC1">MATCHING ERRORS</a><br>
509 <P>
510 It is possible to supply a regular expression that takes a very long time to
511 fail to match certain lines. Such patterns normally involve nested indefinite
512 repeats, for example: (a+)*\d when matched against a line of a's with no final
513 digit. The PCRE matching function has a resource limit that causes it to abort
514 in these circumstances. If this happens, <b>pcregrep</b> outputs an error
515 message and the line that caused the problem to the standard error stream. If
516 there are more than 20 such errors, <b>pcregrep</b> gives up.
517 </P>
518 <br><a name="SEC10" href="#TOC1">DIAGNOSTICS</a><br>
519 <P>
520 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
521 for syntax errors and non-existent or inacessible files (even if matches were
522 found in other files) or too many matching errors. Using the <b>-s</b> option to
523 suppress error messages about inaccessble files does not affect the return
524 code.
525 </P>
526 <br><a name="SEC11" href="#TOC1">SEE ALSO</a><br>
527 <P>
528 <b>pcrepattern</b>(3), <b>pcretest</b>(1).
529 </P>
530 <br><a name="SEC12" href="#TOC1">AUTHOR</a><br>
531 <P>
532 Philip Hazel
533 <br>
534 University Computing Service
535 <br>
536 Cambridge CB2 3QH, England.
537 <br>
538 </P>
539 <br><a name="SEC13" href="#TOC1">REVISION</a><br>
540 <P>
541 Last updated: 13 September 2009
542 <br>
543 Copyright &copy; 1997-2009 University of Cambridge.
544 <br>
545 <p>
546 Return to the <a href="index.html">PCRE index page</a>.
547 </p>

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