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1 PCREGREP(1) General Commands Manual PCREGREP(1)
2
3
4
5 NAME
6 pcregrep - a grep with Perl-compatible regular expressions.
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 pcresyntax(3) for a quick-reference summary of pattern syn-
18 tax, or pcrepattern(3) for a full description of the syntax and seman-
19 tics of the regular expressions that PCRE supports.
20
21 Patterns, whether supplied on the command line or in a separate file,
22 are given without delimiters. For example:
23
24 pcregrep Thursday /etc/motd
25
26 If you attempt to use delimiters (for example, by surrounding a pattern
27 with slashes, as is common in Perl scripts), they are interpreted as
28 part of the pattern. Quotes can of course be used to delimit patterns
29 on the command line because they are interpreted by the shell, and
30 indeed quotes are required if a pattern contains white space or shell
31 metacharacters.
32
33 The first argument that follows any option settings is treated as the
34 single pattern to be matched when neither -e nor -f is present. Con-
35 versely, when one or both of these options are used to specify pat-
36 terns, all arguments are treated as path names. At least one of -e, -f,
37 or an argument pattern must be provided.
38
39 If no files are specified, pcregrep reads the standard input. The stan-
40 dard input can also be referenced by a name consisting of a single
41 hyphen. For example:
42
43 pcregrep some-pattern /file1 - /file3
44
45 By default, each line that matches a pattern is copied to the standard
46 output, and if there is more than one file, the file name is output at
47 the start of each line, followed by a colon. However, there are options
48 that can change how pcregrep behaves. In particular, the -M option
49 makes it possible to search for patterns that span line boundaries.
50 What defines a line boundary is controlled by the -N (--newline)
51 option.
52
53 The amount of memory used for buffering files that are being scanned is
54 controlled by a parameter that can be set by the --buffer-size option.
55 The default value for this parameter is specified when pcregrep is
56 built, with the default default being 20K. A block of memory three
57 times this size is used (to allow for buffering "before" and "after"
58 lines). An error occurs if a line overflows the buffer.
59
60 Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the
61 greater. BUFSIZ is defined in <stdio.h>. When there is more than one
62 pattern (specified by the use of -e and/or -f), each pattern is applied
63 to each line in the order in which they are defined, except that all
64 the -e patterns are tried before the -f patterns.
65
66 By default, as soon as one pattern matches a line, no further patterns
67 are considered. However, if --colour (or --color) is used to colour the
68 matching substrings, or if --only-matching, --file-offsets, or --line-
69 offsets is used to output only the part of the line that matched
70 (either shown literally, or as an offset), scanning resumes immediately
71 following the match, so that further matches on the same line can be
72 found. If there are multiple patterns, they are all tried on the
73 remainder of the line, but patterns that follow the one that matched
74 are not tried on the earlier part of the line.
75
76 This behaviour means that the order in which multiple patterns are
77 specified can affect the output when one of the above options is used.
78 This is no longer the same behaviour as GNU grep, which now manages to
79 display earlier matches for later patterns (as long as there is no
80 overlap).
81
82 Patterns that can match an empty string are accepted, but empty string
83 matches are never recognized. An example is the pattern
84 "(super)?(man)?", in which all components are optional. This pattern
85 finds all occurrences of both "super" and "man"; the output differs
86 from matching with "super|man" when only the matching substrings are
87 being shown.
88
89 If the LC_ALL or LC_CTYPE environment variable is set, pcregrep uses
90 the value to set a locale when calling the PCRE library. The --locale
91 option can be used to override this.
92
93
94 SUPPORT FOR COMPRESSED FILES
95
96 It is possible to compile pcregrep so that it uses libz or libbz2 to
97 read files whose names end in .gz or .bz2, respectively. You can find
98 out whether your binary has support for one or both of these file types
99 by running it with the --help option. If the appropriate support is not
100 present, files are treated as plain text. The standard input is always
101 so treated.
102
103
104 BINARY FILES
105
106 By default, a file that contains a binary zero byte within the first
107 1024 bytes is identified as a binary file, and is processed specially.
108 (GNU grep also identifies binary files in this manner.) See the
109 --binary-files option for a means of changing the way binary files are
110 handled.
111
112
113 OPTIONS
114
115 The order in which some of the options appear can affect the output.
116 For example, both the -h and -l options affect the printing of file
117 names. Whichever comes later in the command line will be the one that
118 takes effect. Similarly, except where noted below, if an option is
119 given twice, the later setting is used. Numerical values for options
120 may be followed by K or M, to signify multiplication by 1024 or
121 1024*1024 respectively.
122
123 -- This terminates the list of options. It is useful if the next
124 item on the command line starts with a hyphen but is not an
125 option. This allows for the processing of patterns and file-
126 names that start with hyphens.
127
128 -A number, --after-context=number
129 Output number lines of context after each matching line. If
130 filenames and/or line numbers are being output, a hyphen sep-
131 arator is used instead of a colon for the context lines. A
132 line containing "--" is output between each group of lines,
133 unless they are in fact contiguous in the input file. The
134 value of number is expected to be relatively small. However,
135 pcregrep guarantees to have up to 8K of following text avail-
136 able for context output.
137
138 -a, --text
139 Treat binary files as text. This is equivalent to --binary-
140 files=text.
141
142 -B number, --before-context=number
143 Output number lines of context before each matching line. If
144 filenames and/or line numbers are being output, a hyphen sep-
145 arator is used instead of a colon for the context lines. A
146 line containing "--" is output between each group of lines,
147 unless they are in fact contiguous in the input file. The
148 value of number is expected to be relatively small. However,
149 pcregrep guarantees to have up to 8K of preceding text avail-
150 able for context output.
151
152 --binary-files=word
153 Specify how binary files are to be processed. If the word is
154 "binary" (the default), pattern matching is performed on
155 binary files, but the only output is "Binary file <name>
156 matches" when a match succeeds. If the word is "text", which
157 is equivalent to the -a or --text option, binary files are
158 processed in the same way as any other file. In this case,
159 when a match succeeds, the output may be binary garbage,
160 which can have nasty effects if sent to a terminal. If the
161 word is "without-match", which is equivalent to the -I
162 option, binary files are not processed at all; they are
163 assumed not to be of interest.
164
165 --buffer-size=number
166 Set the parameter that controls how much memory is used for
167 buffering files that are being scanned.
168
169 -C number, --context=number
170 Output number lines of context both before and after each
171 matching line. This is equivalent to setting both -A and -B
172 to the same value.
173
174 -c, --count
175 Do not output individual lines from the files that are being
176 scanned; instead output the number of lines that would other-
177 wise have been shown. If no lines are selected, the number
178 zero is output. If several files are are being scanned, a
179 count is output for each of them. However, if the --files-
180 with-matches option is also used, only those files whose
181 counts are greater than zero are listed. When -c is used, the
182 -A, -B, and -C options are ignored.
183
184 --colour, --color
185 If this option is given without any data, it is equivalent to
186 "--colour=auto". If data is required, it must be given in
187 the same shell item, separated by an equals sign.
188
189 --colour=value, --color=value
190 This option specifies under what circumstances the parts of a
191 line that matched a pattern should be coloured in the output.
192 By default, the output is not coloured. The value (which is
193 optional, see above) may be "never", "always", or "auto". In
194 the latter case, colouring happens only if the standard out-
195 put is connected to a terminal. More resources are used when
196 colouring is enabled, because pcregrep has to search for all
197 possible matches in a line, not just one, in order to colour
198 them all.
199
200 The colour that is used can be specified by setting the envi-
201 ronment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value
202 of this variable should be a string of two numbers, separated
203 by a semicolon. They are copied directly into the control
204 string for setting colour on a terminal, so it is your
205 responsibility to ensure that they make sense. If neither of
206 the environment variables is set, the default is "1;31",
207 which gives red.
208
209 -D action, --devices=action
210 If an input path is not a regular file or a directory,
211 "action" specifies how it is to be processed. Valid values
212 are "read" (the default) or "skip" (silently skip the path).
213
214 -d action, --directories=action
215 If an input path is a directory, "action" specifies how it is
216 to be processed. Valid values are "read" (the default in
217 non-Windows environments, for compatibility with GNU grep),
218 "recurse" (equivalent to the -r option), or "skip" (silently
219 skip the path, the default in Windows environments). In the
220 "read" case, directories are read as if they were ordinary
221 files. In some operating systems the effect of reading a
222 directory like this is an immediate end-of-file; in others it
223 may provoke an error.
224
225 -e pattern, --regex=pattern, --regexp=pattern
226 Specify a pattern to be matched. This option can be used mul-
227 tiple times in order to specify several patterns. It can also
228 be used as a way of specifying a single pattern that starts
229 with a hyphen. When -e is used, no argument pattern is taken
230 from the command line; all arguments are treated as file
231 names. There is no limit to the number of patterns. They are
232 applied to each line in the order in which they are defined
233 until one matches.
234
235 If -f is used with -e, the command line patterns are matched
236 first, followed by the patterns from the file(s), independent
237 of the order in which these options are specified. Note that
238 multiple use of -e is not the same as a single pattern with
239 alternatives. For example, X|Y finds the first character in a
240 line that is X or Y, whereas if the two patterns are given
241 separately, with X first, pcregrep finds X if it is present,
242 even if it follows Y in the line. It finds Y only if there is
243 no X in the line. This matters only if you are using -o or
244 --colo(u)r to show the part(s) of the line that matched.
245
246 --exclude=pattern
247 Files (but not directories) whose names match the pattern are
248 skipped without being processed. This applies to all files,
249 whether listed on the command line, obtained from --file-
250 list, or by scanning a directory. The pattern is a PCRE regu-
251 lar expression, and is matched against the final component of
252 the file name, not the entire path. The -F, -w, and -x
253 options do not apply to this pattern. The option may be given
254 any number of times in order to specify multiple patterns. If
255 a file name matches both an --include and an --exclude pat-
256 tern, it is excluded. There is no short form for this option.
257
258 --exclude-from=filename
259 Treat each non-empty line of the file as the data for an
260 --exclude option. What constitutes a newline when reading the
261 file is the operating system's default. The --newline option
262 has no effect on this option. This option may be given more
263 than once in order to specify a number of files to read.
264
265 --exclude-dir=pattern
266 Directories whose names match the pattern are skipped without
267 being processed, whatever the setting of the --recursive
268 option. This applies to all directories, whether listed on
269 the command line, obtained from --file-list, or by scanning a
270 parent directory. The pattern is a PCRE regular expression,
271 and is matched against the final component of the directory
272 name, not the entire path. The -F, -w, and -x options do not
273 apply to this pattern. The option may be given any number of
274 times in order to specify more than one pattern. If a direc-
275 tory matches both --include-dir and --exclude-dir, it is
276 excluded. There is no short form for this option.
277
278 -F, --fixed-strings
279 Interpret each data-matching pattern as a list of fixed
280 strings, separated by newlines, instead of as a regular
281 expression. What constitutes a newline for this purpose is
282 controlled by the --newline option. The -w (match as a word)
283 and -x (match whole line) options can be used with -F. They
284 apply to each of the fixed strings. A line is selected if any
285 of the fixed strings are found in it (subject to -w or -x, if
286 present). This option applies only to the patterns that are
287 matched against the contents of files; it does not apply to
288 patterns specified by any of the --include or --exclude
289 options.
290
291 -f filename, --file=filename
292 Read patterns from the file, one per line, and match them
293 against each line of input. What constitutes a newline when
294 reading the file is the operating system's default. The
295 --newline option has no effect on this option. Trailing white
296 space is removed from each line, and blank lines are ignored.
297 An empty file contains no patterns and therefore matches
298 nothing. See also the comments about multiple patterns versus
299 a single pattern with alternatives in the description of -e
300 above.
301
302 If this option is given more than once, all the specified
303 files are read. A data line is output if any of the patterns
304 match it. A filename can be given as "-" to refer to the
305 standard input. When -f is used, patterns specified on the
306 command line using -e may also be present; they are tested
307 before the file's patterns. However, no other pattern is
308 taken from the command line; all arguments are treated as the
309 names of paths to be searched.
310
311 --file-list=filename
312 Read a list of files and/or directories that are to be
313 scanned from the given file, one per line. Trailing white
314 space is removed from each line, and blank lines are ignored.
315 These paths are processed before any that are listed on the
316 command line. The filename can be given as "-" to refer to
317 the standard input. If --file and --file-list are both spec-
318 ified as "-", patterns are read first. This is useful only
319 when the standard input is a terminal, from which further
320 lines (the list of files) can be read after an end-of-file
321 indication. If this option is given more than once, all the
322 specified files are read.
323
324 --file-offsets
325 Instead of showing lines or parts of lines that match, show
326 each match as an offset from the start of the file and a
327 length, separated by a comma. In this mode, no context is
328 shown. That is, the -A, -B, and -C options are ignored. If
329 there is more than one match in a line, each of them is shown
330 separately. This option is mutually exclusive with --line-
331 offsets and --only-matching.
332
333 -H, --with-filename
334 Force the inclusion of the filename at the start of output
335 lines when searching a single file. By default, the filename
336 is not shown in this case. For matching lines, the filename
337 is followed by a colon; for context lines, a hyphen separator
338 is used. If a line number is also being output, it follows
339 the file name.
340
341 -h, --no-filename
342 Suppress the output filenames when searching multiple files.
343 By default, filenames are shown when multiple files are
344 searched. For matching lines, the filename is followed by a
345 colon; for context lines, a hyphen separator is used. If a
346 line number is also being output, it follows the file name.
347
348 --help Output a help message, giving brief details of the command
349 options and file type support, and then exit. Anything else
350 on the command line is ignored.
351
352 -I Treat binary files as never matching. This is equivalent to
353 --binary-files=without-match.
354
355 -i, --ignore-case
356 Ignore upper/lower case distinctions during comparisons.
357
358 --include=pattern
359 If any --include patterns are specified, the only files that
360 are processed are those that match one of the patterns (and
361 do not match an --exclude pattern). This option does not
362 affect directories, but it applies to all files, whether
363 listed on the command line, obtained from --file-list, or by
364 scanning a directory. The pattern is a PCRE regular expres-
365 sion, and is matched against the final component of the file
366 name, not the entire path. The -F, -w, and -x options do not
367 apply to this pattern. The option may be given any number of
368 times. If a file name matches both an --include and an
369 --exclude pattern, it is excluded. There is no short form
370 for this option.
371
372 --include-from=filename
373 Treat each non-empty line of the file as the data for an
374 --include option. What constitutes a newline for this purpose
375 is the operating system's default. The --newline option has
376 no effect on this option. This option may be given any number
377 of times; all the files are read.
378
379 --include-dir=pattern
380 If any --include-dir patterns are specified, the only direc-
381 tories that are processed are those that match one of the
382 patterns (and do not match an --exclude-dir pattern). This
383 applies to all directories, whether listed on the command
384 line, obtained from --file-list, or by scanning a parent
385 directory. The pattern is a PCRE regular expression, and is
386 matched against the final component of the directory name,
387 not the entire path. The -F, -w, and -x options do not apply
388 to this pattern. The option may be given any number of times.
389 If a directory matches both --include-dir and --exclude-dir,
390 it is excluded. There is no short form for this option.
391
392 -L, --files-without-match
393 Instead of outputting lines from the files, just output the
394 names of the files that do not contain any lines that would
395 have been output. Each file name is output once, on a sepa-
396 rate line.
397
398 -l, --files-with-matches
399 Instead of outputting lines from the files, just output the
400 names of the files containing lines that would have been out-
401 put. Each file name is output once, on a separate line.
402 Searching normally stops as soon as a matching line is found
403 in a file. However, if the -c (count) option is also used,
404 matching continues in order to obtain the correct count, and
405 those files that have at least one match are listed along
406 with their counts. Using this option with -c is a way of sup-
407 pressing the listing of files with no matches.
408
409 --label=name
410 This option supplies a name to be used for the standard input
411 when file names are being output. If not supplied, "(standard
412 input)" is used. There is no short form for this option.
413
414 --line-buffered
415 When this option is given, input is read and processed line
416 by line, and the output is flushed after each write. By
417 default, input is read in large chunks, unless pcregrep can
418 determine that it is reading from a terminal (which is cur-
419 rently possible only in Unix-like environments). Output to
420 terminal is normally automatically flushed by the operating
421 system. This option can be useful when the input or output is
422 attached to a pipe and you do not want pcregrep to buffer up
423 large amounts of data. However, its use will affect perfor-
424 mance, and the -M (multiline) option ceases to work.
425
426 --line-offsets
427 Instead of showing lines or parts of lines that match, show
428 each match as a line number, the offset from the start of the
429 line, and a length. The line number is terminated by a colon
430 (as usual; see the -n option), and the offset and length are
431 separated by a comma. In this mode, no context is shown.
432 That is, the -A, -B, and -C options are ignored. If there is
433 more than one match in a line, each of them is shown sepa-
434 rately. This option is mutually exclusive with --file-offsets
435 and --only-matching.
436
437 --locale=locale-name
438 This option specifies a locale to be used for pattern match-
439 ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
440 ronment variables. If no locale is specified, the PCRE
441 library's default (usually the "C" locale) is used. There is
442 no short form for this option.
443
444 --match-limit=number
445 Processing some regular expression patterns can require a
446 very large amount of memory, leading in some cases to a pro-
447 gram crash if not enough is available. Other patterns may
448 take a very long time to search for all possible matching
449 strings. The pcre_exec() function that is called by pcregrep
450 to do the matching has two parameters that can limit the
451 resources that it uses.
452
453 The --match-limit option provides a means of limiting
454 resource usage when processing patterns that are not going to
455 match, but which have a very large number of possibilities in
456 their search trees. The classic example is a pattern that
457 uses nested unlimited repeats. Internally, PCRE uses a func-
458 tion called match() which it calls repeatedly (sometimes
459 recursively). The limit set by --match-limit is imposed on
460 the number of times this function is called during a match,
461 which has the effect of limiting the amount of backtracking
462 that can take place.
463
464 The --recursion-limit option is similar to --match-limit, but
465 instead of limiting the total number of times that match() is
466 called, it limits the depth of recursive calls, which in turn
467 limits the amount of memory that can be used. The recursion
468 depth is a smaller number than the total number of calls,
469 because not all calls to match() are recursive. This limit is
470 of use only if it is set smaller than --match-limit.
471
472 There are no short forms for these options. The default set-
473 tings are specified when the PCRE library is compiled, with
474 the default default being 10 million.
475
476 -M, --multiline
477 Allow patterns to match more than one line. When this option
478 is given, patterns may usefully contain literal newline char-
479 acters and internal occurrences of ^ and $ characters. The
480 output for a successful match may consist of more than one
481 line, the last of which is the one in which the match ended.
482 If the matched string ends with a newline sequence the output
483 ends at the end of that line.
484
485 When this option is set, the PCRE library is called in "mul-
486 tiline" mode. There is a limit to the number of lines that
487 can be matched, imposed by the way that pcregrep buffers the
488 input file as it scans it. However, pcregrep ensures that at
489 least 8K characters or the rest of the document (whichever is
490 the shorter) are available for forward matching, and simi-
491 larly the previous 8K characters (or all the previous charac-
492 ters, if fewer than 8K) are guaranteed to be available for
493 lookbehind assertions. This option does not work when input
494 is read line by line (see --line-buffered.)
495
496 -N newline-type, --newline=newline-type
497 The PCRE library supports five different conventions for
498 indicating the ends of lines. They are the single-character
499 sequences CR (carriage return) and LF (linefeed), the two-
500 character sequence CRLF, an "anycrlf" convention, which rec-
501 ognizes any of the preceding three types, and an "any" con-
502 vention, in which any Unicode line ending sequence is assumed
503 to end a line. The Unicode sequences are the three just men-
504 tioned, plus VT (vertical tab, U+000B), FF (form feed,
505 U+000C), NEL (next line, U+0085), LS (line separator,
506 U+2028), and PS (paragraph separator, U+2029).
507
508 When the PCRE library is built, a default line-ending
509 sequence is specified. This is normally the standard
510 sequence for the operating system. Unless otherwise specified
511 by this option, pcregrep uses the library's default. The
512 possible values for this option are CR, LF, CRLF, ANYCRLF, or
513 ANY. This makes it possible to use pcregrep to scan files
514 that have come from other environments without having to mod-
515 ify their line endings. If the data that is being scanned
516 does not agree with the convention set by this option, pcre-
517 grep may behave in strange ways. Note that this option does
518 not apply to files specified by the -f, --exclude-from, or
519 --include-from options, which are expected to use the operat-
520 ing system's standard newline sequence.
521
522 -n, --line-number
523 Precede each output line by its line number in the file, fol-
524 lowed by a colon for matching lines or a hyphen for context
525 lines. If the filename is also being output, it precedes the
526 line number. This option is forced if --line-offsets is used.
527
528 --no-jit If the PCRE library is built with support for just-in-time
529 compiling (which speeds up matching), pcregrep automatically
530 makes use of this, unless it was explicitly disabled at build
531 time. This option can be used to disable the use of JIT at
532 run time. It is provided for testing and working round prob-
533 lems. It should never be needed in normal use.
534
535 -o, --only-matching
536 Show only the part of the line that matched a pattern instead
537 of the whole line. In this mode, no context is shown. That
538 is, the -A, -B, and -C options are ignored. If there is more
539 than one match in a line, each of them is shown separately.
540 If -o is combined with -v (invert the sense of the match to
541 find non-matching lines), no output is generated, but the
542 return code is set appropriately. If the matched portion of
543 the line is empty, nothing is output unless the file name or
544 line number are being printed, in which case they are shown
545 on an otherwise empty line. This option is mutually exclusive
546 with --file-offsets and --line-offsets.
547
548 -onumber, --only-matching=number
549 Show only the part of the line that matched the capturing
550 parentheses of the given number. Up to 32 capturing parenthe-
551 ses are supported, and -o0 is equivalent to -o without a num-
552 ber. Because these options can be given without an argument
553 (see above), if an argument is present, it must be given in
554 the same shell item, for example, -o3 or --only-matching=2.
555 The comments given for the non-argument case above also apply
556 to this case. If the specified capturing parentheses do not
557 exist in the pattern, or were not set in the match, nothing
558 is output unless the file name or line number are being
559 printed.
560
561 If this option is given multiple times, multiple substrings
562 are output, in the order the options are given. For example,
563 -o3 -o1 -o3 causes the substrings matched by capturing paren-
564 theses 3 and 1 and then 3 again to be output. By default,
565 there is no separator (but see the next option).
566
567 --om-separator=text
568 Specify a separating string for multiple occurrences of -o.
569 The default is an empty string. Separating strings are never
570 coloured.
571
572 -q, --quiet
573 Work quietly, that is, display nothing except error messages.
574 The exit status indicates whether or not any matches were
575 found.
576
577 -r, --recursive
578 If any given path is a directory, recursively scan the files
579 it contains, taking note of any --include and --exclude set-
580 tings. By default, a directory is read as a normal file; in
581 some operating systems this gives an immediate end-of-file.
582 This option is a shorthand for setting the -d option to
583 "recurse".
584
585 --recursion-limit=number
586 See --match-limit above.
587
588 -s, --no-messages
589 Suppress error messages about non-existent or unreadable
590 files. Such files are quietly skipped. However, the return
591 code is still 2, even if matches were found in other files.
592
593 -u, --utf-8
594 Operate in UTF-8 mode. This option is available only if PCRE
595 has been compiled with UTF-8 support. All patterns (including
596 those for any --exclude and --include options) and all sub-
597 ject lines that are scanned must be valid strings of UTF-8
598 characters.
599
600 -V, --version
601 Write the version numbers of pcregrep and the PCRE library to
602 the standard output and then exit. Anything else on the com-
603 mand line is ignored.
604
605 -v, --invert-match
606 Invert the sense of the match, so that lines which do not
607 match any of the patterns are the ones that are found.
608
609 -w, --word-regex, --word-regexp
610 Force the patterns to match only whole words. This is equiva-
611 lent to having \b at the start and end of the pattern. This
612 option applies only to the patterns that are matched against
613 the contents of files; it does not apply to patterns speci-
614 fied by any of the --include or --exclude options.
615
616 -x, --line-regex, --line-regexp
617 Force the patterns to be anchored (each must start matching
618 at the beginning of a line) and in addition, require them to
619 match entire lines. This is equivalent to having ^ and $
620 characters at the start and end of each alternative branch in
621 every pattern. This option applies only to the patterns that
622 are matched against the contents of files; it does not apply
623 to patterns specified by any of the --include or --exclude
624 options.
625
626
627 ENVIRONMENT VARIABLES
628
629 The environment variables LC_ALL and LC_CTYPE are examined, in that
630 order, for a locale. The first one that is set is used. This can be
631 overridden by the --locale option. If no locale is set, the PCRE
632 library's default (usually the "C" locale) is used.
633
634
635 NEWLINES
636
637 The -N (--newline) option allows pcregrep to scan files with different
638 newline conventions from the default. Any parts of the input files that
639 are written to the standard output are copied identically, with what-
640 ever newline sequences they have in the input. However, the setting of
641 this option does not affect the interpretation of files specified by
642 the -f, --exclude-from, or --include-from options, which are assumed to
643 use the operating system's standard newline sequence, nor does it
644 affect the way in which pcregrep writes informational messages to the
645 standard error and output streams. For these it uses the string "\n" to
646 indicate newlines, relying on the C I/O library to convert this to an
647 appropriate sequence.
648
649
650 OPTIONS COMPATIBILITY
651
652 Many of the short and long forms of pcregrep's options are the same as
653 in the GNU grep program. Any long option of the form --xxx-regexp (GNU
654 terminology) is also available as --xxx-regex (PCRE terminology). How-
655 ever, the --file-list, --file-offsets, --include-dir, --line-offsets,
656 --locale, --match-limit, -M, --multiline, -N, --newline, --om-separa-
657 tor, --recursion-limit, -u, and --utf-8 options are specific to pcre-
658 grep, as is the use of the --only-matching option with a capturing
659 parentheses number.
660
661 Although most of the common options work the same way, a few are dif-
662 ferent in pcregrep. For example, the --include option's argument is a
663 glob for GNU grep, but a regular expression for pcregrep. If both the
664 -c and -l options are given, GNU grep lists only file names, without
665 counts, but pcregrep gives the counts.
666
667
668 OPTIONS WITH DATA
669
670 There are four different ways in which an option with data can be spec-
671 ified. If a short form option is used, the data may follow immedi-
672 ately, or (with one exception) in the next command line item. For exam-
673 ple:
674
675 -f/some/file
676 -f /some/file
677
678 The exception is the -o option, which may appear with or without data.
679 Because of this, if data is present, it must follow immediately in the
680 same item, for example -o3.
681
682 If a long form option is used, the data may appear in the same command
683 line item, separated by an equals character, or (with two exceptions)
684 it may appear in the next command line item. For example:
685
686 --file=/some/file
687 --file /some/file
688
689 Note, however, that if you want to supply a file name beginning with ~
690 as data in a shell command, and have the shell expand ~ to a home
691 directory, you must separate the file name from the option, because the
692 shell does not treat ~ specially unless it is at the start of an item.
693
694 The exceptions to the above are the --colour (or --color) and --only-
695 matching options, for which the data is optional. If one of these
696 options does have data, it must be given in the first form, using an
697 equals character. Otherwise pcregrep will assume that it has no data.
698
699
700 MATCHING ERRORS
701
702 It is possible to supply a regular expression that takes a very long
703 time to fail to match certain lines. Such patterns normally involve
704 nested indefinite repeats, for example: (a+)*\d when matched against a
705 line of a's with no final digit. The PCRE matching function has a
706 resource limit that causes it to abort in these circumstances. If this
707 happens, pcregrep outputs an error message and the line that caused the
708 problem to the standard error stream. If there are more than 20 such
709 errors, pcregrep gives up.
710
711 The --match-limit option of pcregrep can be used to set the overall
712 resource limit; there is a second option called --recursion-limit that
713 sets a limit on the amount of memory (usually stack) that is used (see
714 the discussion of these options above).
715
716
717 DIAGNOSTICS
718
719 Exit status is 0 if any matches were found, 1 if no matches were found,
720 and 2 for syntax errors, overlong lines, non-existent or inaccessible
721 files (even if matches were found in other files) or too many matching
722 errors. Using the -s option to suppress error messages about inaccessi-
723 ble files does not affect the return code.
724
725
726 SEE ALSO
727
728 pcrepattern(3), pcresyntax(3), pcretest(1).
729
730
731 AUTHOR
732
733 Philip Hazel
734 University Computing Service
735 Cambridge CB2 3QH, England.
736
737
738 REVISION
739
740 Last updated: 03 April 2014
741 Copyright (c) 1997-2014 University of Cambridge.

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