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

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