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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 files whose
177 names match the pattern are excluded. The pattern is a PCRE
178 regular expression. If a file name matches both --include and
179 --exclude, it is excluded. There is no short form for this
180 option.
181
182 -F, --fixed-strings
183 Interpret each pattern as a list of fixed strings, separated
184 by newlines, instead of as a regular expression. The -w
185 (match as a word) and -x (match whole line) options can be
186 used with -F. They apply to each of the fixed strings. A line
187 is selected if any of the fixed strings are found in it (sub-
188 ject to -w or -x, if present).
189
190 -f filename, --file=filename
191 Read a number of patterns from the file, one per line, and
192 match them against each line of input. A data line is output
193 if any of the patterns match it. The filename can be given as
194 "-" to refer to the standard input. When -f is used, patterns
195 specified on the command line using -e may also be present;
196 they are tested before the file's patterns. However, no other
197 pattern is taken from the command line; all arguments are
198 treated as file names. There is an overall maximum of 100
199 patterns. Trailing white space is removed from each line, and
200 blank lines are ignored. An empty file contains no patterns
201 and therefore matches nothing. See also the comments about
202 multiple patterns versus a single pattern with alternatives
203 in the description of -e above.
204
205 --file-offsets
206 Instead of showing lines or parts of lines that match, show
207 each match as an offset from the start of the file and a
208 length, separated by a comma. In this mode, no context is
209 shown. That is, the -A, -B, and -C options are ignored. If
210 there is more than one match in a line, each of them is shown
211 separately. This option is mutually exclusive with --line-
212 offsets and --only-matching.
213
214 -H, --with-filename
215 Force the inclusion of the filename at the start of output
216 lines when searching a single file. By default, the filename
217 is not shown in this case. For matching lines, the filename
218 is followed by a colon and a space; for context lines, a
219 hyphen separator is used. If a line number is also being out-
220 put, it follows the file name without a space.
221
222 -h, --no-filename
223 Suppress the output filenames when searching multiple files.
224 By default, filenames are shown when multiple files are
225 searched. For matching lines, the filename is followed by a
226 colon and a space; for context lines, a hyphen separator is
227 used. If a line number is also being output, it follows the
228 file name without a space.
229
230 --help Output a help message, giving brief details of the command
231 options and file type support, and then exit.
232
233 -i, --ignore-case
234 Ignore upper/lower case distinctions during comparisons.
235
236 --include=pattern
237 When pcregrep is searching the files in a directory as a con-
238 sequence of the -r (recursive search) option, only those
239 files whose names match the pattern are included. The pattern
240 is a PCRE regular expression. If a file name matches both
241 --include and --exclude, it is excluded. There is no short
242 form for this option.
243
244 -L, --files-without-match
245 Instead of outputting lines from the files, just output the
246 names of the files that do not contain any lines that would
247 have been output. Each file name is output once, on a sepa-
248 rate line.
249
250 -l, --files-with-matches
251 Instead of outputting lines from the files, just output the
252 names of the files containing lines that would have been out-
253 put. Each file name is output once, on a separate line.
254 Searching stops as soon as a matching line is found in a
255 file.
256
257 --label=name
258 This option supplies a name to be used for the standard input
259 when file names are being output. If not supplied, "(standard
260 input)" is used. There is no short form for this option.
261
262 --line-offsets
263 Instead of showing lines or parts of lines that match, show
264 each match as a line number, the offset from the start of the
265 line, and a length. The line number is terminated by a colon
266 (as usual; see the -n option), and the offset and length are
267 separated by a comma. In this mode, no context is shown.
268 That is, the -A, -B, and -C options are ignored. If there is
269 more than one match in a line, each of them is shown sepa-
270 rately. This option is mutually exclusive with --file-offsets
271 and --only-matching.
272
273 --locale=locale-name
274 This option specifies a locale to be used for pattern match-
275 ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
276 ronment variables. If no locale is specified, the PCRE
277 library's default (usually the "C" locale) is used. There is
278 no short form for this option.
279
280 -M, --multiline
281 Allow patterns to match more than one line. When this option
282 is given, patterns may usefully contain literal newline char-
283 acters and internal occurrences of ^ and $ characters. The
284 output for any one match may consist of more than one line.
285 When this option is set, the PCRE library is called in "mul-
286 tiline" mode. There is a limit to the number of lines that
287 can be matched, imposed by the way that pcregrep buffers the
288 input file as it scans it. However, pcregrep ensures that at
289 least 8K characters or the rest of the document (whichever is
290 the shorter) are available for forward matching, and simi-
291 larly the previous 8K characters (or all the previous charac-
292 ters, if fewer than 8K) are guaranteed to be available for
293 lookbehind assertions.
294
295 -N newline-type, --newline=newline-type
296 The PCRE library supports five different conventions for
297 indicating the ends of lines. They are the single-character
298 sequences CR (carriage return) and LF (linefeed), the two-
299 character sequence CRLF, an "anycrlf" convention, which rec-
300 ognizes any of the preceding three types, and an "any" con-
301 vention, in which any Unicode line ending sequence is assumed
302 to end a line. The Unicode sequences are the three just men-
303 tioned, plus VT (vertical tab, U+000B), FF (formfeed,
304 U+000C), NEL (next line, U+0085), LS (line separator,
305 U+2028), and PS (paragraph separator, U+2029).
306
307 When the PCRE library is built, a default line-ending
308 sequence is specified. This is normally the standard
309 sequence for the operating system. Unless otherwise specified
310 by this option, pcregrep uses the library's default. The
311 possible values for this option are CR, LF, CRLF, ANYCRLF, or
312 ANY. This makes it possible to use pcregrep on files that
313 have come from other environments without having to modify
314 their line endings. If the data that is being scanned does
315 not agree with the convention set by this option, pcregrep
316 may behave in strange ways.
317
318 -n, --line-number
319 Precede each output line by its line number in the file, fol-
320 lowed by a colon and a space for matching lines or a hyphen
321 and a space for context lines. If the filename is also being
322 output, it precedes the line number. This option is forced if
323 --line-offsets is used.
324
325 -o, --only-matching
326 Show only the part of the line that matched a pattern. In
327 this mode, no context is shown. That is, the -A, -B, and -C
328 options are ignored. If there is more than one match in a
329 line, each of them is shown separately. If -o is combined
330 with -v (invert the sense of the match to find non-matching
331 lines), no output is generated, but the return code is set
332 appropriately. This option is mutually exclusive with --file-
333 offsets and --line-offsets.
334
335 -q, --quiet
336 Work quietly, that is, display nothing except error messages.
337 The exit status indicates whether or not any matches were
338 found.
339
340 -r, --recursive
341 If any given path is a directory, recursively scan the files
342 it contains, taking note of any --include and --exclude set-
343 tings. By default, a directory is read as a normal file; in
344 some operating systems this gives an immediate end-of-file.
345 This option is a shorthand for setting the -d option to
346 "recurse".
347
348 -s, --no-messages
349 Suppress error messages about non-existent or unreadable
350 files. Such files are quietly skipped. However, the return
351 code is still 2, even if matches were found in other files.
352
353 -u, --utf-8
354 Operate in UTF-8 mode. This option is available only if PCRE
355 has been compiled with UTF-8 support. Both patterns and sub-
356 ject lines must be valid strings of UTF-8 characters.
357
358 -V, --version
359 Write the version numbers of pcregrep and the PCRE library
360 that is being used to the standard error stream.
361
362 -v, --invert-match
363 Invert the sense of the match, so that lines which do not
364 match any of the patterns are the ones that are found.
365
366 -w, --word-regex, --word-regexp
367 Force the patterns to match only whole words. This is equiva-
368 lent to having \b at the start and end of the pattern.
369
370 -x, --line-regex, --line-regexp
371 Force the patterns to be anchored (each must start matching
372 at the beginning of a line) and in addition, require them to
373 match entire lines. This is equivalent to having ^ and $
374 characters at the start and end of each alternative branch in
375 every pattern.
376
377
378 ENVIRONMENT VARIABLES
379
380 The environment variables LC_ALL and LC_CTYPE are examined, in that
381 order, for a locale. The first one that is set is used. This can be
382 overridden by the --locale option. If no locale is set, the PCRE
383 library's default (usually the "C" locale) is used.
384
385
386 NEWLINES
387
388 The -N (--newline) option allows pcregrep to scan files with different
389 newline conventions from the default. However, the setting of this
390 option does not affect the way in which pcregrep writes information to
391 the standard error and output streams. It uses the string "\n" in C
392 printf() calls to indicate newlines, relying on the C I/O library to
393 convert this to an appropriate sequence if the output is sent to a
394 file.
395
396
397 OPTIONS COMPATIBILITY
398
399 The majority of short and long forms of pcregrep's options are the same
400 as in the GNU grep program. Any long option of the form --xxx-regexp
401 (GNU terminology) is also available as --xxx-regex (PCRE terminology).
402 However, the --locale, -M, --multiline, -u, and --utf-8 options are
403 specific to pcregrep.
404
405
406 OPTIONS WITH DATA
407
408 There are four different ways in which an option with data can be spec-
409 ified. If a short form option is used, the data may follow immedi-
410 ately, or in the next command line item. For example:
411
412 -f/some/file
413 -f /some/file
414
415 If a long form option is used, the data may appear in the same command
416 line item, separated by an equals character, or (with one exception) it
417 may appear in the next command line item. For example:
418
419 --file=/some/file
420 --file /some/file
421
422 Note, however, that if you want to supply a file name beginning with ~
423 as data in a shell command, and have the shell expand ~ to a home
424 directory, you must separate the file name from the option, because the
425 shell does not treat ~ specially unless it is at the start of an item.
426
427 The exception to the above is the --colour (or --color) option, for
428 which the data is optional. If this option does have data, it must be
429 given in the first form, using an equals character. Otherwise it will
430 be assumed that it has no data.
431
432
433 MATCHING ERRORS
434
435 It is possible to supply a regular expression that takes a very long
436 time to fail to match certain lines. Such patterns normally involve
437 nested indefinite repeats, for example: (a+)*\d when matched against a
438 line of a's with no final digit. The PCRE matching function has a
439 resource limit that causes it to abort in these circumstances. If this
440 happens, pcregrep outputs an error message and the line that caused the
441 problem to the standard error stream. If there are more than 20 such
442 errors, pcregrep gives up.
443
444
445 DIAGNOSTICS
446
447 Exit status is 0 if any matches were found, 1 if no matches were found,
448 and 2 for syntax errors and non-existent or inacessible files (even if
449 matches were found in other files) or too many matching errors. Using
450 the -s option to suppress error messages about inaccessble files does
451 not affect the return code.
452
453
454 SEE ALSO
455
456 pcrepattern(3), pcretest(1).
457
458
459 AUTHOR
460
461 Philip Hazel
462 University Computing Service
463 Cambridge CB2 3QH, England.
464
465
466 REVISION
467
468 Last updated: 17 December 2007
469 Copyright (c) 1997-2007 University of Cambridge.

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