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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. As soon as one pat-
57 tern matches (or fails to match when -v is used), no further patterns
58 are considered.
59
60 When --only-matching, --file-offsets, or --line-offsets is used, the
61 output is the part of the line that matched (either shown literally, or
62 as an offset). In this case, scanning resumes immediately following the
63 match, so that further matches on the same line can be found. If there
64 are multiple patterns, they are all tried on the remainder of the line.
65 However, patterns that follow the one that matched are not tried on the
66 earlier part of the line.
67
68 If the LC_ALL or LC_CTYPE environment variable is set, pcregrep uses
69 the value to set a locale when calling the PCRE library. The --locale
70 option can be used to override this.
71
72
73 SUPPORT FOR COMPRESSED FILES
74
75 It is possible to compile pcregrep so that it uses libz or libbz2 to
76 read files whose names end in .gz or .bz2, respectively. You can find
77 out whether your binary has support for one or both of these file types
78 by running it with the --help option. If the appropriate support is not
79 present, files are treated as plain text. The standard input is always
80 so treated.
81
82
83 OPTIONS
84
85 -- This terminate the list of options. It is useful if the next
86 item on the command line starts with a hyphen but is not an
87 option. This allows for the processing of patterns and file-
88 names that start with hyphens.
89
90 -A number, --after-context=number
91 Output number lines of context after each matching line. If
92 filenames and/or line numbers are being output, a hyphen sep-
93 arator is used instead of a colon for the context lines. A
94 line containing "--" is output between each group of lines,
95 unless they are in fact contiguous in the input file. The
96 value of number is expected to be relatively small. However,
97 pcregrep guarantees to have up to 8K of following text avail-
98 able for context output.
99
100 -B number, --before-context=number
101 Output number lines of context before 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 preceding text avail-
108 able for context output.
109
110 -C number, --context=number
111 Output number lines of context both before and after each
112 matching line. This is equivalent to setting both -A and -B
113 to the same value.
114
115 -c, --count
116 Do not output individual lines; instead just output a count
117 of the number of lines that would otherwise have been output.
118 If several files are given, a count is output for each of
119 them. In this mode, the -A, -B, and -C options are ignored.
120
121 --colour, --color
122 If this option is given without any data, it is equivalent to
123 "--colour=auto". If data is required, it must be given in
124 the same shell item, separated by an equals sign.
125
126 --colour=value, --color=value
127 This option specifies under what circumstances the part of a
128 line that matched a pattern should be coloured in the output.
129 The value may be "never" (the default), "always", or "auto".
130 In the latter case, colouring happens only if the standard
131 output is connected to a terminal. The colour can be speci-
132 fied by setting the environment variable PCREGREP_COLOUR or
133 PCREGREP_COLOR. The value of this variable should be a string
134 of two numbers, separated by a semicolon. They are copied
135 directly into the control string for setting colour on a ter-
136 minal, so it is your responsibility to ensure that they make
137 sense. If neither of the environment variables is set, the
138 default is "1;31", which gives red.
139
140 -D action, --devices=action
141 If an input path is not a regular file or a directory,
142 "action" specifies how it is to be processed. Valid values
143 are "read" (the default) or "skip" (silently skip the path).
144
145 -d action, --directories=action
146 If an input path is a directory, "action" specifies how it is
147 to be processed. Valid values are "read" (the default),
148 "recurse" (equivalent to the -r option), or "skip" (silently
149 skip the path). In the default case, directories are read as
150 if they were ordinary files. In some operating systems the
151 effect of reading a directory like this is an immediate end-
152 of-file.
153
154 -e pattern, --regex=pattern, --regexp=pattern
155 Specify a pattern to be matched. This option can be used mul-
156 tiple times in order to specify several patterns. It can also
157 be used as a way of specifying a single pattern that starts
158 with a hyphen. When -e is used, no argument pattern is taken
159 from the command line; all arguments are treated as file
160 names. There is an overall maximum of 100 patterns. They are
161 applied to each line in the order in which they are defined
162 until one matches (or fails to match if -v is used). If -f is
163 used with -e, the command line patterns are matched first,
164 followed by the patterns from the file, independent of the
165 order in which these options are specified. Note that multi-
166 ple use of -e is not the same as a single pattern with alter-
167 natives. For example, X|Y finds the first character in a line
168 that is X or Y, whereas if the two patterns are given sepa-
169 rately, pcregrep finds X if it is present, even if it follows
170 Y in the line. It finds Y only if there is no X in the line.
171 This really matters only if you are using -o to show the
172 part(s) of the line that matched.
173
174 --exclude=pattern
175 When pcregrep is searching the files in a directory as a con-
176 sequence of the -r (recursive search) option, any regular
177 files whose names match the pattern are excluded. Subdirecto-
178 ries are not excluded by this option; they are searched
179 recursively, subject to the --exclude_dir and --include_dir
180 options. The pattern is a PCRE regular expression, and is
181 matched against the final component of the file name (not the
182 entire path). If a file name matches both --include and
183 --exclude, it is excluded. There is no short form for this
184 option.
185
186 --exclude_dir=pattern
187 When pcregrep is searching the contents of a directory as a
188 consequence of the -r (recursive search) option, any subdi-
189 rectories whose names match the pattern are excluded. (Note
190 that the --exclude option does not affect subdirectories.)
191 The pattern is a PCRE regular expression, and is matched
192 against the final component of the name (not the entire
193 path). If a subdirectory name matches both --include_dir and
194 --exclude_dir, it is excluded. There is no short form for
195 this option.
196
197 -F, --fixed-strings
198 Interpret each pattern as a list of fixed strings, separated
199 by newlines, instead of as a regular expression. The -w
200 (match as a word) and -x (match whole line) options can be
201 used with -F. They apply to each of the fixed strings. A line
202 is selected if any of the fixed strings are found in it (sub-
203 ject to -w or -x, if present).
204
205 -f filename, --file=filename
206 Read a number of patterns from the file, one per line, and
207 match them against each line of input. A data line is output
208 if any of the patterns match it. The filename can be given as
209 "-" to refer to the standard input. When -f is used, patterns
210 specified on the command line using -e may also be present;
211 they are tested before the file's patterns. However, no other
212 pattern is taken from the command line; all arguments are
213 treated as file names. There is an overall maximum of 100
214 patterns. Trailing white space is removed from each line, and
215 blank lines are ignored. An empty file contains no patterns
216 and therefore matches nothing. See also the comments about
217 multiple patterns versus a single pattern with alternatives
218 in the description of -e above.
219
220 --file-offsets
221 Instead of showing lines or parts of lines that match, show
222 each match as an offset from the start of the file and a
223 length, separated by a comma. In this mode, no context is
224 shown. That is, the -A, -B, and -C options are ignored. If
225 there is more than one match in a line, each of them is shown
226 separately. This option is mutually exclusive with --line-
227 offsets and --only-matching.
228
229 -H, --with-filename
230 Force the inclusion of the filename at the start of output
231 lines when searching a single file. By default, the filename
232 is not shown in this case. For matching lines, the filename
233 is followed by a colon and a space; for context lines, a
234 hyphen separator is used. If a line number is also being out-
235 put, it follows the file name without a space.
236
237 -h, --no-filename
238 Suppress the output filenames when searching multiple files.
239 By default, filenames are shown when multiple files are
240 searched. For matching lines, the filename is followed by a
241 colon and a space; for context lines, a hyphen separator is
242 used. If a line number is also being output, it follows the
243 file name without a space.
244
245 --help Output a help message, giving brief details of the command
246 options and file type support, and then exit.
247
248 -i, --ignore-case
249 Ignore upper/lower case distinctions during comparisons.
250
251 --include=pattern
252 When pcregrep is searching the files in a directory as a con-
253 sequence of the -r (recursive search) option, only those reg-
254 ular files whose names match the pattern are included. Subdi-
255 rectories are always included and searched recursively, sub-
256 ject to the --include_dir and --exclude_dir options. The pat-
257 tern is a PCRE regular expression, and is matched against the
258 final component of the file name (not the entire path). If a
259 file name matches both --include and --exclude, it is
260 excluded. There is no short form for this option.
261
262 --include_dir=pattern
263 When pcregrep is searching the contents of a directory as a
264 consequence of the -r (recursive search) option, only those
265 subdirectories whose names match the pattern are included.
266 (Note that the --include option does not affect subdirecto-
267 ries.) The pattern is a PCRE regular expression, and is
268 matched against the final component of the name (not the
269 entire path). If a subdirectory name matches both
270 --include_dir and --exclude_dir, it is excluded. There is no
271 short form for this option.
272
273 -L, --files-without-match
274 Instead of outputting lines from the files, just output the
275 names of the files that do not contain any lines that would
276 have been output. Each file name is output once, on a sepa-
277 rate line.
278
279 -l, --files-with-matches
280 Instead of outputting lines from the files, just output the
281 names of the files containing lines that would have been out-
282 put. Each file name is output once, on a separate line.
283 Searching stops as soon as a matching line is found in a
284 file.
285
286 --label=name
287 This option supplies a name to be used for the standard input
288 when file names are being output. If not supplied, "(standard
289 input)" is used. There is no short form for this option.
290
291 --line-offsets
292 Instead of showing lines or parts of lines that match, show
293 each match as a line number, the offset from the start of the
294 line, and a length. The line number is terminated by a colon
295 (as usual; see the -n option), and the offset and length are
296 separated by a comma. In this mode, no context is shown.
297 That is, the -A, -B, and -C options are ignored. If there is
298 more than one match in a line, each of them is shown sepa-
299 rately. This option is mutually exclusive with --file-offsets
300 and --only-matching.
301
302 --locale=locale-name
303 This option specifies a locale to be used for pattern match-
304 ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
305 ronment variables. If no locale is specified, the PCRE
306 library's default (usually the "C" locale) is used. There is
307 no short form for this option.
308
309 -M, --multiline
310 Allow patterns to match more than one line. When this option
311 is given, patterns may usefully contain literal newline char-
312 acters and internal occurrences of ^ and $ characters. The
313 output for any one match may consist of more than one line.
314 When this option is set, the PCRE library is called in "mul-
315 tiline" mode. There is a limit to the number of lines that
316 can be matched, imposed by the way that pcregrep buffers the
317 input file as it scans it. However, pcregrep ensures that at
318 least 8K characters or the rest of the document (whichever is
319 the shorter) are available for forward matching, and simi-
320 larly the previous 8K characters (or all the previous charac-
321 ters, if fewer than 8K) are guaranteed to be available for
322 lookbehind assertions.
323
324 -N newline-type, --newline=newline-type
325 The PCRE library supports five different conventions for
326 indicating the ends of lines. They are the single-character
327 sequences CR (carriage return) and LF (linefeed), the two-
328 character sequence CRLF, an "anycrlf" convention, which rec-
329 ognizes any of the preceding three types, and an "any" con-
330 vention, in which any Unicode line ending sequence is assumed
331 to end a line. The Unicode sequences are the three just men-
332 tioned, plus VT (vertical tab, U+000B), FF (formfeed,
333 U+000C), NEL (next line, U+0085), LS (line separator,
334 U+2028), and PS (paragraph separator, U+2029).
335
336 When the PCRE library is built, a default line-ending
337 sequence is specified. This is normally the standard
338 sequence for the operating system. Unless otherwise specified
339 by this option, pcregrep uses the library's default. The
340 possible values for this option are CR, LF, CRLF, ANYCRLF, or
341 ANY. This makes it possible to use pcregrep on files that
342 have come from other environments without having to modify
343 their line endings. If the data that is being scanned does
344 not agree with the convention set by this option, pcregrep
345 may behave in strange ways.
346
347 -n, --line-number
348 Precede each output line by its line number in the file, fol-
349 lowed by a colon and a space for matching lines or a hyphen
350 and a space for context lines. If the filename is also being
351 output, it precedes the line number. This option is forced if
352 --line-offsets is used.
353
354 -o, --only-matching
355 Show only the part of the line that matched a pattern. In
356 this mode, no context is shown. That is, the -A, -B, and -C
357 options are ignored. If there is more than one match in a
358 line, each of them is shown separately. If -o is combined
359 with -v (invert the sense of the match to find non-matching
360 lines), no output is generated, but the return code is set
361 appropriately. This option is mutually exclusive with --file-
362 offsets and --line-offsets.
363
364 -q, --quiet
365 Work quietly, that is, display nothing except error messages.
366 The exit status indicates whether or not any matches were
367 found.
368
369 -r, --recursive
370 If any given path is a directory, recursively scan the files
371 it contains, taking note of any --include and --exclude set-
372 tings. By default, a directory is read as a normal file; in
373 some operating systems this gives an immediate end-of-file.
374 This option is a shorthand for setting the -d option to
375 "recurse".
376
377 -s, --no-messages
378 Suppress error messages about non-existent or unreadable
379 files. Such files are quietly skipped. However, the return
380 code is still 2, even if matches were found in other files.
381
382 -u, --utf-8
383 Operate in UTF-8 mode. This option is available only if PCRE
384 has been compiled with UTF-8 support. Both patterns and sub-
385 ject lines must be valid strings of UTF-8 characters.
386
387 -V, --version
388 Write the version numbers of pcregrep and the PCRE library
389 that is being used to the standard error stream.
390
391 -v, --invert-match
392 Invert the sense of the match, so that lines which do not
393 match any of the patterns are the ones that are found.
394
395 -w, --word-regex, --word-regexp
396 Force the patterns to match only whole words. This is equiva-
397 lent to having \b at the start and end of the pattern.
398
399 -x, --line-regex, --line-regexp
400 Force the patterns to be anchored (each must start matching
401 at the beginning of a line) and in addition, require them to
402 match entire lines. This is equivalent to having ^ and $
403 characters at the start and end of each alternative branch in
404 every pattern.
405
406
407 ENVIRONMENT VARIABLES
408
409 The environment variables LC_ALL and LC_CTYPE are examined, in that
410 order, for a locale. The first one that is set is used. This can be
411 overridden by the --locale option. If no locale is set, the PCRE
412 library's default (usually the "C" locale) is used.
413
414
415 NEWLINES
416
417 The -N (--newline) option allows pcregrep to scan files with different
418 newline conventions from the default. However, the setting of this
419 option does not affect the way in which pcregrep writes information to
420 the standard error and output streams. It uses the string "\n" in C
421 printf() calls to indicate newlines, relying on the C I/O library to
422 convert this to an appropriate sequence if the output is sent to a
423 file.
424
425
426 OPTIONS COMPATIBILITY
427
428 The majority of short and long forms of pcregrep's options are the same
429 as in the GNU grep program. Any long option of the form --xxx-regexp
430 (GNU terminology) is also available as --xxx-regex (PCRE terminology).
431 However, the --locale, -M, --multiline, -u, and --utf-8 options are
432 specific to pcregrep.
433
434
435 OPTIONS WITH DATA
436
437 There are four different ways in which an option with data can be spec-
438 ified. If a short form option is used, the data may follow immedi-
439 ately, or in the next command line item. For example:
440
441 -f/some/file
442 -f /some/file
443
444 If a long form option is used, the data may appear in the same command
445 line item, separated by an equals character, or (with one exception) it
446 may appear in the next command line item. For example:
447
448 --file=/some/file
449 --file /some/file
450
451 Note, however, that if you want to supply a file name beginning with ~
452 as data in a shell command, and have the shell expand ~ to a home
453 directory, you must separate the file name from the option, because the
454 shell does not treat ~ specially unless it is at the start of an item.
455
456 The exception to the above is the --colour (or --color) option, for
457 which the data is optional. If this option does have data, it must be
458 given in the first form, using an equals character. Otherwise it will
459 be assumed that it has no data.
460
461
462 MATCHING ERRORS
463
464 It is possible to supply a regular expression that takes a very long
465 time to fail to match certain lines. Such patterns normally involve
466 nested indefinite repeats, for example: (a+)*\d when matched against a
467 line of a's with no final digit. The PCRE matching function has a
468 resource limit that causes it to abort in these circumstances. If this
469 happens, pcregrep outputs an error message and the line that caused the
470 problem to the standard error stream. If there are more than 20 such
471 errors, pcregrep gives up.
472
473
474 DIAGNOSTICS
475
476 Exit status is 0 if any matches were found, 1 if no matches were found,
477 and 2 for syntax errors and non-existent or inacessible files (even if
478 matches were found in other files) or too many matching errors. Using
479 the -s option to suppress error messages about inaccessble files does
480 not affect the return code.
481
482
483 SEE ALSO
484
485 pcrepattern(3), pcretest(1).
486
487
488 AUTHOR
489
490 Philip Hazel
491 University Computing Service
492 Cambridge CB2 3QH, England.
493
494
495 REVISION
496
497 Last updated: 08 March 2008
498 Copyright (c) 1997-2008 University of Cambridge.

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