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1 PCREGREP(1) PCREGREP(1)
2
3
4 NAME
5 pcregrep - a grep with Perl-compatible regular expressions.
6
7
8 SYNOPSIS
9 pcregrep [options] [long options] [pattern] [path1 path2 ...]
10
11
12 DESCRIPTION
13
14 pcregrep searches files for character patterns, in the same way as
15 other grep commands do, but it uses the PCRE regular expression library
16 to support patterns that are compatible with the regular expressions of
17 Perl 5. See pcrepattern(3) for a full description of syntax and seman-
18 tics of the regular expressions that PCRE supports.
19
20 Patterns, whether supplied on the command line or in a separate file,
21 are given without delimiters. For example:
22
23 pcregrep Thursday /etc/motd
24
25 If you attempt to use delimiters (for example, by surrounding a pattern
26 with slashes, as is common in Perl scripts), they are interpreted as
27 part of the pattern. Quotes can of course be used to delimit patterns
28 on the command line because they are interpreted by the shell, and
29 indeed they are required if a pattern contains white space or shell
30 metacharacters.
31
32 The first argument that follows any option settings is treated as the
33 single pattern to be matched when neither -e nor -f is present. Con-
34 versely, when one or both of these options are used to specify pat-
35 terns, all arguments are treated as path names. At least one of -e, -f,
36 or an argument pattern must be provided.
37
38 If no files are specified, pcregrep reads the standard input. The stan-
39 dard input can also be referenced by a name consisting of a single
40 hyphen. For example:
41
42 pcregrep some-pattern /file1 - /file3
43
44 By default, each line that matches a pattern is copied to the standard
45 output, and if there is more than one file, the file name is output at
46 the start of each line, followed by a colon. However, there are options
47 that can change how pcregrep behaves. In particular, the -M option
48 makes it possible to search for patterns that span line boundaries.
49 What defines a line boundary is controlled by the -N (--newline)
50 option.
51
52 Patterns are limited to 8K or BUFSIZ characters, whichever is the
53 greater. BUFSIZ is defined in <stdio.h>. When there is more than one
54 pattern (specified by the use of -e and/or -f), each pattern is applied
55 to each line in the order in which they are defined, except that all
56 the -e patterns are tried before the -f patterns.
57
58 By default, as soon as one pattern matches (or fails to match when -v
59 is used), no further patterns are considered. However, if --colour (or
60 --color) is used to colour the matching substrings, or if --only-match-
61 ing, --file-offsets, or --line-offsets is used to output only the part
62 of the line that matched (either shown literally, or as an offset),
63 scanning resumes immediately following the match, so that further
64 matches on the same line can be found. If there are multiple patterns,
65 they are all tried on the remainder of the line, but patterns that fol-
66 low the one that matched are not tried on the earlier part of the line.
67
68 This is the same behaviour as GNU grep, but it does mean that the order
69 in which multiple patterns are specified can affect the output when one
70 of the above options is used.
71
72 Patterns that can match an empty string are accepted, but empty string
73 matches are not recognized. An example is the pattern "(super)?(man)?",
74 in which all components are optional. This pattern finds all occur-
75 rences of both "super" and "man"; the output differs from matching with
76 "super|man" when only the matching substrings are being shown.
77
78 If the LC_ALL or LC_CTYPE environment variable is set, pcregrep uses
79 the value to set a locale when calling the PCRE library. The --locale
80 option can be used to override this.
81
82
83 SUPPORT FOR COMPRESSED FILES
84
85 It is possible to compile pcregrep so that it uses libz or libbz2 to
86 read files whose names end in .gz or .bz2, respectively. You can find
87 out whether your binary has support for one or both of these file types
88 by running it with the --help option. If the appropriate support is not
89 present, files are treated as plain text. The standard input is always
90 so treated.
91
92
93 OPTIONS
94
95 -- This terminate the list of options. It is useful if the next
96 item on the command line starts with a hyphen but is not an
97 option. This allows for the processing of patterns and file-
98 names that start with hyphens.
99
100 -A number, --after-context=number
101 Output number lines of context after each matching line. If
102 filenames and/or line numbers are being output, a hyphen sep-
103 arator is used instead of a colon for the context lines. A
104 line containing "--" is output between each group of lines,
105 unless they are in fact contiguous in the input file. The
106 value of number is expected to be relatively small. However,
107 pcregrep guarantees to have up to 8K of following text avail-
108 able for context output.
109
110 -B number, --before-context=number
111 Output number lines of context before each matching line. If
112 filenames and/or line numbers are being output, a hyphen sep-
113 arator is used instead of a colon for the context lines. A
114 line containing "--" is output between each group of lines,
115 unless they are in fact contiguous in the input file. The
116 value of number is expected to be relatively small. However,
117 pcregrep guarantees to have up to 8K of preceding text avail-
118 able for context output.
119
120 -C number, --context=number
121 Output number lines of context both before and after each
122 matching line. This is equivalent to setting both -A and -B
123 to the same value.
124
125 -c, --count
126 Do not output individual lines; instead just output a count
127 of the number of lines that would otherwise have been output.
128 If several files are given, a count is output for each of
129 them. In this mode, the -A, -B, and -C options are ignored.
130
131 --colour, --color
132 If this option is given without any data, it is equivalent to
133 "--colour=auto". If data is required, it must be given in
134 the same shell item, separated by an equals sign.
135
136 --colour=value, --color=value
137 This option specifies under what circumstances the parts of a
138 line that matched a pattern should be coloured in the output.
139 By default, the output is not coloured. The value (which is
140 optional, see above) may be "never", "always", or "auto". In
141 the latter case, colouring happens only if the standard out-
142 put is connected to a terminal. More resources are used when
143 colouring is enabled, because pcregrep has to search for all
144 possible matches in a line, not just one, in order to colour
145 them all.
146
147 The colour that is used can be specified by setting the envi-
148 ronment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value
149 of this variable should be a string of two numbers, separated
150 by a semicolon. They are copied directly into the control
151 string for setting colour on a terminal, so it is your
152 responsibility to ensure that they make sense. If neither of
153 the environment variables is set, the default is "1;31",
154 which gives red.
155
156 -D action, --devices=action
157 If an input path is not a regular file or a directory,
158 "action" specifies how it is to be processed. Valid values
159 are "read" (the default) or "skip" (silently skip the path).
160
161 -d action, --directories=action
162 If an input path is a directory, "action" specifies how it is
163 to be processed. Valid values are "read" (the default),
164 "recurse" (equivalent to the -r option), or "skip" (silently
165 skip the path). In the default case, directories are read as
166 if they were ordinary files. In some operating systems the
167 effect of reading a directory like this is an immediate end-
168 of-file.
169
170 -e pattern, --regex=pattern, --regexp=pattern
171 Specify a pattern to be matched. This option can be used mul-
172 tiple times in order to specify several patterns. It can also
173 be used as a way of specifying a single pattern that starts
174 with a hyphen. When -e is used, no argument pattern is taken
175 from the command line; all arguments are treated as file
176 names. There is an overall maximum of 100 patterns. They are
177 applied to each line in the order in which they are defined
178 until one matches (or fails to match if -v is used). If -f is
179 used with -e, the command line patterns are matched first,
180 followed by the patterns from the file, independent of the
181 order in which these options are specified. Note that multi-
182 ple use of -e is not the same as a single pattern with alter-
183 natives. For example, X|Y finds the first character in a line
184 that is X or Y, whereas if the two patterns are given sepa-
185 rately, pcregrep finds X if it is present, even if it follows
186 Y in the line. It finds Y only if there is no X in the line.
187 This really matters only if you are using -o to show the
188 part(s) of the line that matched.
189
190 --exclude=pattern
191 When pcregrep is searching the files in a directory as a con-
192 sequence of the -r (recursive search) option, any regular
193 files whose names match the pattern are excluded. Subdirecto-
194 ries are not excluded by this option; they are searched
195 recursively, subject to the --exclude_dir and --include_dir
196 options. The pattern is a PCRE regular expression, and is
197 matched against the final component of the file name (not the
198 entire path). If a file name matches both --include and
199 --exclude, it is excluded. There is no short form for this
200 option.
201
202 --exclude_dir=pattern
203 When pcregrep is searching the contents of a directory as a
204 consequence of the -r (recursive search) option, any subdi-
205 rectories whose names match the pattern are excluded. (Note
206 that the --exclude option does not affect subdirectories.)
207 The pattern is a PCRE regular expression, and is matched
208 against the final component of the name (not the entire
209 path). If a subdirectory name matches both --include_dir and
210 --exclude_dir, it is excluded. There is no short form for
211 this option.
212
213 -F, --fixed-strings
214 Interpret each pattern as a list of fixed strings, separated
215 by newlines, instead of as a regular expression. The -w
216 (match as a word) and -x (match whole line) options can be
217 used with -F. They apply to each of the fixed strings. A line
218 is selected if any of the fixed strings are found in it (sub-
219 ject to -w or -x, if present).
220
221 -f filename, --file=filename
222 Read a number of patterns from the file, one per line, and
223 match them against each line of input. A data line is output
224 if any of the patterns match it. The filename can be given as
225 "-" to refer to the standard input. When -f is used, patterns
226 specified on the command line using -e may also be present;
227 they are tested before the file's patterns. However, no other
228 pattern is taken from the command line; all arguments are
229 treated as file names. There is an overall maximum of 100
230 patterns. Trailing white space is removed from each line, and
231 blank lines are ignored. An empty file contains no patterns
232 and therefore matches nothing. See also the comments about
233 multiple patterns versus a single pattern with alternatives
234 in the description of -e above.
235
236 --file-offsets
237 Instead of showing lines or parts of lines that match, show
238 each match as an offset from the start of the file and a
239 length, separated by a comma. In this mode, no context is
240 shown. That is, the -A, -B, and -C options are ignored. If
241 there is more than one match in a line, each of them is shown
242 separately. This option is mutually exclusive with --line-
243 offsets and --only-matching.
244
245 -H, --with-filename
246 Force the inclusion of the filename at the start of output
247 lines when searching a single file. By default, the filename
248 is not shown in this case. For matching lines, the filename
249 is followed by a colon; for context lines, a hyphen separator
250 is used. If a line number is also being output, it follows
251 the file name.
252
253 -h, --no-filename
254 Suppress the output filenames when searching multiple files.
255 By default, filenames are shown when multiple files are
256 searched. For matching lines, the filename is followed by a
257 colon; for context lines, a hyphen separator is used. If a
258 line number is also being output, it follows the file name.
259
260 --help Output a help message, giving brief details of the command
261 options and file type support, and then exit.
262
263 -i, --ignore-case
264 Ignore upper/lower case distinctions during comparisons.
265
266 --include=pattern
267 When pcregrep is searching the files in a directory as a con-
268 sequence of the -r (recursive search) option, only those reg-
269 ular files whose names match the pattern are included. Subdi-
270 rectories are always included and searched recursively, sub-
271 ject to the --include_dir and --exclude_dir options. The pat-
272 tern is a PCRE regular expression, and is matched against the
273 final component of the file name (not the entire path). If a
274 file name matches both --include and --exclude, it is
275 excluded. There is no short form for this option.
276
277 --include_dir=pattern
278 When pcregrep is searching the contents of a directory as a
279 consequence of the -r (recursive search) option, only those
280 subdirectories whose names match the pattern are included.
281 (Note that the --include option does not affect subdirecto-
282 ries.) The pattern is a PCRE regular expression, and is
283 matched against the final component of the name (not the
284 entire path). If a subdirectory name matches both
285 --include_dir and --exclude_dir, it is excluded. There is no
286 short form for this option.
287
288 -L, --files-without-match
289 Instead of outputting lines from the files, just output the
290 names of the files that do not contain any lines that would
291 have been output. Each file name is output once, on a sepa-
292 rate line.
293
294 -l, --files-with-matches
295 Instead of outputting lines from the files, just output the
296 names of the files containing lines that would have been out-
297 put. Each file name is output once, on a separate line.
298 Searching stops as soon as a matching line is found in a
299 file.
300
301 --label=name
302 This option supplies a name to be used for the standard input
303 when file names are being output. If not supplied, "(standard
304 input)" is used. There is no short form for this option.
305
306 --line-offsets
307 Instead of showing lines or parts of lines that match, show
308 each match as a line number, the offset from the start of the
309 line, and a length. The line number is terminated by a colon
310 (as usual; see the -n option), and the offset and length are
311 separated by a comma. In this mode, no context is shown.
312 That is, the -A, -B, and -C options are ignored. If there is
313 more than one match in a line, each of them is shown sepa-
314 rately. This option is mutually exclusive with --file-offsets
315 and --only-matching.
316
317 --locale=locale-name
318 This option specifies a locale to be used for pattern match-
319 ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
320 ronment variables. If no locale is specified, the PCRE
321 library's default (usually the "C" locale) is used. There is
322 no short form for this option.
323
324 -M, --multiline
325 Allow patterns to match more than one line. When this option
326 is given, patterns may usefully contain literal newline char-
327 acters and internal occurrences of ^ and $ characters. The
328 output for any one match may consist of more than one line.
329 When this option is set, the PCRE library is called in "mul-
330 tiline" mode. There is a limit to the number of lines that
331 can be matched, imposed by the way that pcregrep buffers the
332 input file as it scans it. However, pcregrep ensures that at
333 least 8K characters or the rest of the document (whichever is
334 the shorter) are available for forward matching, and simi-
335 larly the previous 8K characters (or all the previous charac-
336 ters, if fewer than 8K) are guaranteed to be available for
337 lookbehind assertions.
338
339 -N newline-type, --newline=newline-type
340 The PCRE library supports five different conventions for
341 indicating the ends of lines. They are the single-character
342 sequences CR (carriage return) and LF (linefeed), the two-
343 character sequence CRLF, an "anycrlf" convention, which rec-
344 ognizes any of the preceding three types, and an "any" con-
345 vention, in which any Unicode line ending sequence is assumed
346 to end a line. The Unicode sequences are the three just men-
347 tioned, plus VT (vertical tab, U+000B), FF (formfeed,
348 U+000C), NEL (next line, U+0085), LS (line separator,
349 U+2028), and PS (paragraph separator, U+2029).
350
351 When the PCRE library is built, a default line-ending
352 sequence is specified. This is normally the standard
353 sequence for the operating system. Unless otherwise specified
354 by this option, pcregrep uses the library's default. The
355 possible values for this option are CR, LF, CRLF, ANYCRLF, or
356 ANY. This makes it possible to use pcregrep on files that
357 have come from other environments without having to modify
358 their line endings. If the data that is being scanned does
359 not agree with the convention set by this option, pcregrep
360 may behave in strange ways.
361
362 -n, --line-number
363 Precede each output line by its line number in the file, fol-
364 lowed by a colon for matching lines or a hyphen for context
365 lines. If the filename is also being output, it precedes the
366 line number. This option is forced if --line-offsets is used.
367
368 -o, --only-matching
369 Show only the part of the line that matched a pattern. In
370 this mode, no context is shown. That is, the -A, -B, and -C
371 options are ignored. If there is more than one match in a
372 line, each of them is shown separately. If -o is combined
373 with -v (invert the sense of the match to find non-matching
374 lines), no output is generated, but the return code is set
375 appropriately. This option is mutually exclusive with --file-
376 offsets and --line-offsets.
377
378 -q, --quiet
379 Work quietly, that is, display nothing except error messages.
380 The exit status indicates whether or not any matches were
381 found.
382
383 -r, --recursive
384 If any given path is a directory, recursively scan the files
385 it contains, taking note of any --include and --exclude set-
386 tings. By default, a directory is read as a normal file; in
387 some operating systems this gives an immediate end-of-file.
388 This option is a shorthand for setting the -d option to
389 "recurse".
390
391 -s, --no-messages
392 Suppress error messages about non-existent or unreadable
393 files. Such files are quietly skipped. However, the return
394 code is still 2, even if matches were found in other files.
395
396 -u, --utf-8
397 Operate in UTF-8 mode. This option is available only if PCRE
398 has been compiled with UTF-8 support. Both patterns and sub-
399 ject lines must be valid strings of UTF-8 characters.
400
401 -V, --version
402 Write the version numbers of pcregrep and the PCRE library
403 that is being used to the standard error stream.
404
405 -v, --invert-match
406 Invert the sense of the match, so that lines which do not
407 match any of the patterns are the ones that are found.
408
409 -w, --word-regex, --word-regexp
410 Force the patterns to match only whole words. This is equiva-
411 lent to having \b at the start and end of the pattern.
412
413 -x, --line-regex, --line-regexp
414 Force the patterns to be anchored (each must start matching
415 at the beginning of a line) and in addition, require them to
416 match entire lines. This is equivalent to having ^ and $
417 characters at the start and end of each alternative branch in
418 every pattern.
419
420
421 ENVIRONMENT VARIABLES
422
423 The environment variables LC_ALL and LC_CTYPE are examined, in that
424 order, for a locale. The first one that is set is used. This can be
425 overridden by the --locale option. If no locale is set, the PCRE
426 library's default (usually the "C" locale) is used.
427
428
429 NEWLINES
430
431 The -N (--newline) option allows pcregrep to scan files with different
432 newline conventions from the default. However, the setting of this
433 option does not affect the way in which pcregrep writes information to
434 the standard error and output streams. It uses the string "\n" in C
435 printf() calls to indicate newlines, relying on the C I/O library to
436 convert this to an appropriate sequence if the output is sent to a
437 file.
438
439
440 OPTIONS COMPATIBILITY
441
442 The majority of short and long forms of pcregrep's options are the same
443 as in the GNU grep program. Any long option of the form --xxx-regexp
444 (GNU terminology) is also available as --xxx-regex (PCRE terminology).
445 However, the --locale, -M, --multiline, -u, and --utf-8 options are
446 specific to pcregrep.
447
448
449 OPTIONS WITH DATA
450
451 There are four different ways in which an option with data can be spec-
452 ified. If a short form option is used, the data may follow immedi-
453 ately, or in the next command line item. For example:
454
455 -f/some/file
456 -f /some/file
457
458 If a long form option is used, the data may appear in the same command
459 line item, separated by an equals character, or (with one exception) it
460 may appear in the next command line item. For example:
461
462 --file=/some/file
463 --file /some/file
464
465 Note, however, that if you want to supply a file name beginning with ~
466 as data in a shell command, and have the shell expand ~ to a home
467 directory, you must separate the file name from the option, because the
468 shell does not treat ~ specially unless it is at the start of an item.
469
470 The exception to the above is the --colour (or --color) option, for
471 which the data is optional. If this option does have data, it must be
472 given in the first form, using an equals character. Otherwise it will
473 be assumed that it has no data.
474
475
476 MATCHING ERRORS
477
478 It is possible to supply a regular expression that takes a very long
479 time to fail to match certain lines. Such patterns normally involve
480 nested indefinite repeats, for example: (a+)*\d when matched against a
481 line of a's with no final digit. The PCRE matching function has a
482 resource limit that causes it to abort in these circumstances. If this
483 happens, pcregrep outputs an error message and the line that caused the
484 problem to the standard error stream. If there are more than 20 such
485 errors, pcregrep gives up.
486
487
488 DIAGNOSTICS
489
490 Exit status is 0 if any matches were found, 1 if no matches were found,
491 and 2 for syntax errors and non-existent or inacessible files (even if
492 matches were found in other files) or too many matching errors. Using
493 the -s option to suppress error messages about inaccessble files does
494 not affect the return code.
495
496
497 SEE ALSO
498
499 pcrepattern(3), pcretest(1).
500
501
502 AUTHOR
503
504 Philip Hazel
505 University Computing Service
506 Cambridge CB2 3QH, England.
507
508
509 REVISION
510
511 Last updated: 01 March 2009
512 Copyright (c) 1997-2009 University of Cambridge.

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