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1 PCREGREP(1) PCREGREP(1)
4 NAME
5 pcregrep - a grep with Perl-compatible regular expressions.
8 SYNOPSIS
9 pcregrep [options] [long options] [pattern] [path1 path2 ...]
12 DESCRIPTION
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.
20 Patterns, whether supplied on the command line or in a separate file,
21 are given without delimiters. For example:
23 pcregrep Thursday /etc/motd
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 quotes are required if a pattern contains white space or shell
30 metacharacters.
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.
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:
42 pcregrep some-pattern /file1 - /file3
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.
52 The amount of memory used for buffering files that are being scanned is
53 controlled by a parameter that can be set by the --buffer-size option.
54 The default value for this parameter is specified when pcregrep is
55 built, with the default default being 20K. A block of memory three
56 times this size is used (to allow for buffering "before" and "after"
57 lines). An error occurs if a line overflows the buffer.
59 Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the
60 greater. BUFSIZ is defined in <stdio.h>. When there is more than one
61 pattern (specified by the use of -e and/or -f), each pattern is applied
62 to each line in the order in which they are defined, except that all
63 the -e patterns are tried before the -f patterns.
65 By default, as soon as one pattern matches a line, no further patterns
66 are considered. However, if --colour (or --color) is used to colour the
67 matching substrings, or if --only-matching, --file-offsets, or --line-
68 offsets is used to output only the part of the line that matched
69 (either shown literally, or as an offset), scanning resumes immediately
70 following the match, so that further matches on the same line can be
71 found. If there are multiple patterns, they are all tried on the
72 remainder of the line, but patterns that follow the one that matched
73 are not tried on the earlier part of the line.
75 This behaviour means that the order in which multiple patterns are
76 specified can affect the output when one of the above options is used.
77 This is no longer the same behaviour as GNU grep, which now manages to
78 display earlier matches for later patterns (as long as there is no
79 overlap).
81 Patterns that can match an empty string are accepted, but empty string
82 matches are never recognized. An example is the pattern
83 "(super)?(man)?", in which all components are optional. This pattern
84 finds all occurrences of both "super" and "man"; the output differs
85 from matching with "super|man" when only the matching substrings are
86 being shown.
88 If the LC_ALL or LC_CTYPE environment variable is set, pcregrep uses
89 the value to set a locale when calling the PCRE library. The --locale
90 option can be used to override this.
93 SUPPORT FOR COMPRESSED FILES
95 It is possible to compile pcregrep so that it uses libz or libbz2 to
96 read files whose names end in .gz or .bz2, respectively. You can find
97 out whether your binary has support for one or both of these file types
98 by running it with the --help option. If the appropriate support is not
99 present, files are treated as plain text. The standard input is always
100 so treated.
103 BINARY FILES
105 By default, a file that contains a binary zero byte within the first
106 1024 bytes is identified as a binary file, and is processed specially.
107 (GNU grep also identifies binary files in this manner.) See the
108 --binary-files option for a means of changing the way binary files are
109 handled.
112 OPTIONS
114 The order in which some of the options appear can affect the output.
115 For example, both the -h and -l options affect the printing of file
116 names. Whichever comes later in the command line will be the one that
117 takes effect. Similarly, except where noted below, if an option is
118 given twice, the later setting is used. Numerical values for options
119 may be followed by K or M, to signify multiplication by 1024 or
120 1024*1024 respectively.
122 -- This terminates the list of options. It is useful if the next
123 item on the command line starts with a hyphen but is not an
124 option. This allows for the processing of patterns and file-
125 names that start with hyphens.
127 -A number, --after-context=number
128 Output number lines of context after each matching line. If
129 filenames and/or line numbers are being output, a hyphen sep-
130 arator is used instead of a colon for the context lines. A
131 line containing "--" is output between each group of lines,
132 unless they are in fact contiguous in the input file. The
133 value of number is expected to be relatively small. However,
134 pcregrep guarantees to have up to 8K of following text avail-
135 able for context output.
137 -a, --text
138 Treat binary files as text. This is equivalent to --binary-
139 files=text.
141 -B number, --before-context=number
142 Output number lines of context before each matching line. If
143 filenames and/or line numbers are being output, a hyphen sep-
144 arator is used instead of a colon for the context lines. A
145 line containing "--" is output between each group of lines,
146 unless they are in fact contiguous in the input file. The
147 value of number is expected to be relatively small. However,
148 pcregrep guarantees to have up to 8K of preceding text avail-
149 able for context output.
151 --binary-files=word
152 Specify how binary files are to be processed. If the word is
153 "binary" (the default), pattern matching is performed on
154 binary files, but the only output is "Binary file <name>
155 matches" when a match succeeds. If the word is "text", which
156 is equivalent to the -a or --text option, binary files are
157 processed in the same way as any other file. In this case,
158 when a match succeeds, the output may be binary garbage,
159 which can have nasty effects if sent to a terminal. If the
160 word is "without-match", which is equivalent to the -I
161 option, binary files are not processed at all; they are
162 assumed not to be of interest.
164 --buffer-size=number
165 Set the parameter that controls how much memory is used for
166 buffering files that are being scanned.
168 -C number, --context=number
169 Output number lines of context both before and after each
170 matching line. This is equivalent to setting both -A and -B
171 to the same value.
173 -c, --count
174 Do not output individual lines from the files that are being
175 scanned; instead output the number of lines that would other-
176 wise have been shown. If no lines are selected, the number
177 zero is output. If several files are are being scanned, a
178 count is output for each of them. However, if the --files-
179 with-matches option is also used, only those files whose
180 counts are greater than zero are listed. When -c is used, the
181 -A, -B, and -C options are ignored.
183 --colour, --color
184 If this option is given without any data, it is equivalent to
185 "--colour=auto". If data is required, it must be given in
186 the same shell item, separated by an equals sign.
188 --colour=value, --color=value
189 This option specifies under what circumstances the parts of a
190 line that matched a pattern should be coloured in the output.
191 By default, the output is not coloured. The value (which is
192 optional, see above) may be "never", "always", or "auto". In
193 the latter case, colouring happens only if the standard out-
194 put is connected to a terminal. More resources are used when
195 colouring is enabled, because pcregrep has to search for all
196 possible matches in a line, not just one, in order to colour
197 them all.
199 The colour that is used can be specified by setting the envi-
200 ronment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value
201 of this variable should be a string of two numbers, separated
202 by a semicolon. They are copied directly into the control
203 string for setting colour on a terminal, so it is your
204 responsibility to ensure that they make sense. If neither of
205 the environment variables is set, the default is "1;31",
206 which gives red.
208 -D action, --devices=action
209 If an input path is not a regular file or a directory,
210 "action" specifies how it is to be processed. Valid values
211 are "read" (the default) or "skip" (silently skip the path).
213 -d action, --directories=action
214 If an input path is a directory, "action" specifies how it is
215 to be processed. Valid values are "read" (the default in
216 non-Windows environments, for compatibility with GNU grep),
217 "recurse" (equivalent to the -r option), or "skip" (silently
218 skip the path, the default in Windows environments). In the
219 "read" case, directories are read as if they were ordinary
220 files. In some operating systems the effect of reading a
221 directory like this is an immediate end-of-file; in others it
222 may provoke an error.
224 -e pattern, --regex=pattern, --regexp=pattern
225 Specify a pattern to be matched. This option can be used mul-
226 tiple times in order to specify several patterns. It can also
227 be used as a way of specifying a single pattern that starts
228 with a hyphen. When -e is used, no argument pattern is taken
229 from the command line; all arguments are treated as file
230 names. There is no limit to the number of patterns. They are
231 applied to each line in the order in which they are defined
232 until one matches.
234 If -f is used with -e, the command line patterns are matched
235 first, followed by the patterns from the file(s), independent
236 of the order in which these options are specified. Note that
237 multiple use of -e is not the same as a single pattern with
238 alternatives. For example, X|Y finds the first character in a
239 line that is X or Y, whereas if the two patterns are given
240 separately, with X first, pcregrep finds X if it is present,
241 even if it follows Y in the line. It finds Y only if there is
242 no X in the line. This matters only if you are using -o or
243 --colo(u)r to show the part(s) of the line that matched.
245 --exclude=pattern
246 Files (but not directories) whose names match the pattern are
247 skipped without being processed. This applies to all files,
248 whether listed on the command line, obtained from --file-
249 list, or by scanning a directory. The pattern is a PCRE regu-
250 lar expression, and is matched against the final component of
251 the file name, not the entire path. The -F, -w, and -x
252 options do not apply to this pattern. The option may be given
253 any number of times in order to specify multiple patterns. If
254 a file name matches both an --include and an --exclude pat-
255 tern, it is excluded. There is no short form for this option.
257 --exclude-from=filename
258 Treat each non-empty line of the file as the data for an
259 --exclude option. What constitutes a newline when reading the
260 file is the operating system's default. The --newline option
261 has no effect on this option. This option may be given more
262 than once in order to specify a number of files to read.
264 --exclude-dir=pattern
265 Directories whose names match the pattern are skipped without
266 being processed, whatever the setting of the --recursive
267 option. This applies to all directories, whether listed on
268 the command line, obtained from --file-list, or by scanning a
269 parent directory. The pattern is a PCRE regular expression,
270 and is matched against the final component of the directory
271 name, not the entire path. The -F, -w, and -x options do not
272 apply to this pattern. The option may be given any number of
273 times in order to specify more than one pattern. If a direc-
274 tory matches both --include-dir and --exclude-dir, it is
275 excluded. There is no short form for this option.
277 -F, --fixed-strings
278 Interpret each data-matching pattern as a list of fixed
279 strings, separated by newlines, instead of as a regular
280 expression. What constitutes a newline for this purpose is
281 controlled by the --newline option. The -w (match as a word)
282 and -x (match whole line) options can be used with -F. They
283 apply to each of the fixed strings. A line is selected if any
284 of the fixed strings are found in it (subject to -w or -x, if
285 present). This option applies only to the patterns that are
286 matched against the contents of files; it does not apply to
287 patterns specified by any of the --include or --exclude
288 options.
290 -f filename, --file=filename
291 Read patterns from the file, one per line, and match them
292 against each line of input. What constitutes a newline when
293 reading the file is the operating system's default. The
294 --newline option has no effect on this option. Trailing white
295 space is removed from each line, and blank lines are ignored.
296 An empty file contains no patterns and therefore matches
297 nothing. See also the comments about multiple patterns versus
298 a single pattern with alternatives in the description of -e
299 above.
301 If this option is given more than once, all the specified
302 files are read. A data line is output if any of the patterns
303 match it. A filename can be given as "-" to refer to the
304 standard input. When -f is used, patterns specified on the
305 command line using -e may also be present; they are tested
306 before the file's patterns. However, no other pattern is
307 taken from the command line; all arguments are treated as the
308 names of paths to be searched.
310 --file-list=filename
311 Read a list of files and/or directories that are to be
312 scanned from the given file, one per line. Trailing white
313 space is removed from each line, and blank lines are ignored.
314 These paths are processed before any that are listed on the
315 command line. The filename can be given as "-" to refer to
316 the standard input. If --file and --file-list are both spec-
317 ified as "-", patterns are read first. This is useful only
318 when the standard input is a terminal, from which further
319 lines (the list of files) can be read after an end-of-file
320 indication. If this option is given more than once, all the
321 specified files are read.
323 --file-offsets
324 Instead of showing lines or parts of lines that match, show
325 each match as an offset from the start of the file and a
326 length, separated by a comma. In this mode, no context is
327 shown. That is, the -A, -B, and -C options are ignored. If
328 there is more than one match in a line, each of them is shown
329 separately. This option is mutually exclusive with --line-
330 offsets and --only-matching.
332 -H, --with-filename
333 Force the inclusion of the filename at the start of output
334 lines when searching a single file. By default, the filename
335 is not shown in this case. For matching lines, the filename
336 is followed by a colon; for context lines, a hyphen separator
337 is used. If a line number is also being output, it follows
338 the file name.
340 -h, --no-filename
341 Suppress the output filenames when searching multiple files.
342 By default, filenames are shown when multiple files are
343 searched. For matching lines, the filename is followed by a
344 colon; for context lines, a hyphen separator is used. If a
345 line number is also being output, it follows the file name.
347 --help Output a help message, giving brief details of the command
348 options and file type support, and then exit. Anything else
349 on the command line is ignored.
351 -I Treat binary files as never matching. This is equivalent to
352 --binary-files=without-match.
354 -i, --ignore-case
355 Ignore upper/lower case distinctions during comparisons.
357 --include=pattern
358 If any --include patterns are specified, the only files that
359 are processed are those that match one of the patterns (and
360 do not match an --exclude pattern). This option does not
361 affect directories, but it applies to all files, whether
362 listed on the command line, obtained from --file-list, or by
363 scanning a directory. The pattern is a PCRE regular expres-
364 sion, and is matched against the final component of the file
365 name, not the entire path. The -F, -w, and -x options do not
366 apply to this pattern. The option may be given any number of
367 times. If a file name matches both an --include and an
368 --exclude pattern, it is excluded. There is no short form
369 for this option.
371 --include-from=filename
372 Treat each non-empty line of the file as the data for an
373 --include option. What constitutes a newline for this purpose
374 is the operating system's default. The --newline option has
375 no effect on this option. This option may be given any number
376 of times; all the files are read.
378 --include-dir=pattern
379 If any --include-dir patterns are specified, the only direc-
380 tories that are processed are those that match one of the
381 patterns (and do not match an --exclude-dir pattern). This
382 applies to all directories, whether listed on the command
383 line, obtained from --file-list, or by scanning a parent
384 directory. The pattern is a PCRE regular expression, and is
385 matched against the final component of the directory name,
386 not the entire path. The -F, -w, and -x options do not apply
387 to this pattern. The option may be given any number of times.
388 If a directory matches both --include-dir and --exclude-dir,
389 it is excluded. There is no short form for this option.
391 -L, --files-without-match
392 Instead of outputting lines from the files, just output the
393 names of the files that do not contain any lines that would
394 have been output. Each file name is output once, on a sepa-
395 rate line.
397 -l, --files-with-matches
398 Instead of outputting lines from the files, just output the
399 names of the files containing lines that would have been out-
400 put. Each file name is output once, on a separate line.
401 Searching normally stops as soon as a matching line is found
402 in a file. However, if the -c (count) option is also used,
403 matching continues in order to obtain the correct count, and
404 those files that have at least one match are listed along
405 with their counts. Using this option with -c is a way of sup-
406 pressing the listing of files with no matches.
408 --label=name
409 This option supplies a name to be used for the standard input
410 when file names are being output. If not supplied, "(standard
411 input)" is used. There is no short form for this option.
413 --line-buffered
414 When this option is given, input is read and processed line
415 by line, and the output is flushed after each write. By
416 default, input is read in large chunks, unless pcregrep can
417 determine that it is reading from a terminal (which is cur-
418 rently possible only in Unix-like environments). Output to
419 terminal is normally automatically flushed by the operating
420 system. This option can be useful when the input or output is
421 attached to a pipe and you do not want pcregrep to buffer up
422 large amounts of data. However, its use will affect perfor-
423 mance, and the -M (multiline) option ceases to work.
425 --line-offsets
426 Instead of showing lines or parts of lines that match, show
427 each match as a line number, the offset from the start of the
428 line, and a length. The line number is terminated by a colon
429 (as usual; see the -n option), and the offset and length are
430 separated by a comma. In this mode, no context is shown.
431 That is, the -A, -B, and -C options are ignored. If there is
432 more than one match in a line, each of them is shown sepa-
433 rately. This option is mutually exclusive with --file-offsets
434 and --only-matching.
436 --locale=locale-name
437 This option specifies a locale to be used for pattern match-
438 ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
439 ronment variables. If no locale is specified, the PCRE
440 library's default (usually the "C" locale) is used. There is
441 no short form for this option.
443 --match-limit=number
444 Processing some regular expression patterns can require a
445 very large amount of memory, leading in some cases to a pro-
446 gram crash if not enough is available. Other patterns may
447 take a very long time to search for all possible matching
448 strings. The pcre_exec() function that is called by pcregrep
449 to do the matching has two parameters that can limit the
450 resources that it uses.
452 The --match-limit option provides a means of limiting
453 resource usage when processing patterns that are not going to
454 match, but which have a very large number of possibilities in
455 their search trees. The classic example is a pattern that
456 uses nested unlimited repeats. Internally, PCRE uses a func-
457 tion called match() which it calls repeatedly (sometimes
458 recursively). The limit set by --match-limit is imposed on
459 the number of times this function is called during a match,
460 which has the effect of limiting the amount of backtracking
461 that can take place.
463 The --recursion-limit option is similar to --match-limit, but
464 instead of limiting the total number of times that match() is
465 called, it limits the depth of recursive calls, which in turn
466 limits the amount of memory that can be used. The recursion
467 depth is a smaller number than the total number of calls,
468 because not all calls to match() are recursive. This limit is
469 of use only if it is set smaller than --match-limit.
471 There are no short forms for these options. The default set-
472 tings are specified when the PCRE library is compiled, with
473 the default default being 10 million.
475 -M, --multiline
476 Allow patterns to match more than one line. When this option
477 is given, patterns may usefully contain literal newline char-
478 acters and internal occurrences of ^ and $ characters. The
479 output for a successful match may consist of more than one
480 line, the last of which is the one in which the match ended.
481 If the matched string ends with a newline sequence the output
482 ends at the end of that line.
484 When this option is set, the PCRE library is called in "mul-
485 tiline" mode. There is a limit to the number of lines that
486 can be matched, imposed by the way that pcregrep buffers the
487 input file as it scans it. However, pcregrep ensures that at
488 least 8K characters or the rest of the document (whichever is
489 the shorter) are available for forward matching, and simi-
490 larly the previous 8K characters (or all the previous charac-
491 ters, if fewer than 8K) are guaranteed to be available for
492 lookbehind assertions. This option does not work when input
493 is read line by line (see --line-buffered.)
495 -N newline-type, --newline=newline-type
496 The PCRE library supports five different conventions for
497 indicating the ends of lines. They are the single-character
498 sequences CR (carriage return) and LF (linefeed), the two-
499 character sequence CRLF, an "anycrlf" convention, which rec-
500 ognizes any of the preceding three types, and an "any" con-
501 vention, in which any Unicode line ending sequence is assumed
502 to end a line. The Unicode sequences are the three just men-
503 tioned, plus VT (vertical tab, U+000B), FF (form feed,
504 U+000C), NEL (next line, U+0085), LS (line separator,
505 U+2028), and PS (paragraph separator, U+2029).
507 When the PCRE library is built, a default line-ending
508 sequence is specified. This is normally the standard
509 sequence for the operating system. Unless otherwise specified
510 by this option, pcregrep uses the library's default. The
511 possible values for this option are CR, LF, CRLF, ANYCRLF, or
512 ANY. This makes it possible to use pcregrep to scan files
513 that have come from other environments without having to mod-
514 ify their line endings. If the data that is being scanned
515 does not agree with the convention set by this option, pcre-
516 grep may behave in strange ways. Note that this option does
517 not apply to files specified by the -f, --exclude-from, or
518 --include-from options, which are expected to use the operat-
519 ing system's standard newline sequence.
521 -n, --line-number
522 Precede each output line by its line number in the file, fol-
523 lowed by a colon for matching lines or a hyphen for context
524 lines. If the filename is also being output, it precedes the
525 line number. This option is forced if --line-offsets is used.
527 --no-jit If the PCRE library is built with support for just-in-time
528 compiling (which speeds up matching), pcregrep automatically
529 makes use of this, unless it was explicitly disabled at build
530 time. This option can be used to disable the use of JIT at
531 run time. It is provided for testing and working round prob-
532 lems. It should never be needed in normal use.
534 -o, --only-matching
535 Show only the part of the line that matched a pattern instead
536 of the whole line. In this mode, no context is shown. That
537 is, the -A, -B, and -C options are ignored. If there is more
538 than one match in a line, each of them is shown separately.
539 If -o is combined with -v (invert the sense of the match to
540 find non-matching lines), no output is generated, but the
541 return code is set appropriately. If the matched portion of
542 the line is empty, nothing is output unless the file name or
543 line number are being printed, in which case they are shown
544 on an otherwise empty line. This option is mutually exclusive
545 with --file-offsets and --line-offsets.
547 -onumber, --only-matching=number
548 Show only the part of the line that matched the capturing
549 parentheses of the given number. Up to 32 capturing parenthe-
550 ses are supported, and -o0 is equivalent to -o without a num-
551 ber. Because these options can be given without an argument
552 (see above), if an argument is present, it must be given in
553 the same shell item, for example, -o3 or --only-matching=2.
554 The comments given for the non-argument case above also apply
555 to this case. If the specified capturing parentheses do not
556 exist in the pattern, or were not set in the match, nothing
557 is output unless the file name or line number are being
558 printed.
560 If this option is given multiple times, multiple substrings
561 are output, in the order the options are given. For example,
562 -o3 -o1 -o3 causes the substrings matched by capturing paren-
563 theses 3 and 1 and then 3 again to be output. By default,
564 there is no separator (but see the next option).
566 --om-separator=text
567 Specify a separating string for multiple occurrences of -o.
568 The default is an empty string. Separating strings are never
569 coloured.
571 -q, --quiet
572 Work quietly, that is, display nothing except error messages.
573 The exit status indicates whether or not any matches were
574 found.
576 -r, --recursive
577 If any given path is a directory, recursively scan the files
578 it contains, taking note of any --include and --exclude set-
579 tings. By default, a directory is read as a normal file; in
580 some operating systems this gives an immediate end-of-file.
581 This option is a shorthand for setting the -d option to
582 "recurse".
584 --recursion-limit=number
585 See --match-limit above.
587 -s, --no-messages
588 Suppress error messages about non-existent or unreadable
589 files. Such files are quietly skipped. However, the return
590 code is still 2, even if matches were found in other files.
592 -u, --utf-8
593 Operate in UTF-8 mode. This option is available only if PCRE
594 has been compiled with UTF-8 support. All patterns (including
595 those for any --exclude and --include options) and all sub-
596 ject lines that are scanned must be valid strings of UTF-8
597 characters.
599 -V, --version
600 Write the version numbers of pcregrep and the PCRE library to
601 the standard output and then exit. Anything else on the com-
602 mand line is ignored.
604 -v, --invert-match
605 Invert the sense of the match, so that lines which do not
606 match any of the patterns are the ones that are found.
608 -w, --word-regex, --word-regexp
609 Force the patterns to match only whole words. This is equiva-
610 lent to having \b at the start and end of the pattern. This
611 option applies only to the patterns that are matched against
612 the contents of files; it does not apply to patterns speci-
613 fied by any of the --include or --exclude options.
615 -x, --line-regex, --line-regexp
616 Force the patterns to be anchored (each must start matching
617 at the beginning of a line) and in addition, require them to
618 match entire lines. This is equivalent to having ^ and $
619 characters at the start and end of each alternative branch in
620 every pattern. This option applies only to the patterns that
621 are matched against the contents of files; it does not apply
622 to patterns specified by any of the --include or --exclude
623 options.
626 ENVIRONMENT VARIABLES
628 The environment variables LC_ALL and LC_CTYPE are examined, in that
629 order, for a locale. The first one that is set is used. This can be
630 overridden by the --locale option. If no locale is set, the PCRE
631 library's default (usually the "C" locale) is used.
634 NEWLINES
636 The -N (--newline) option allows pcregrep to scan files with different
637 newline conventions from the default. Any parts of the input files that
638 are written to the standard output are copied identically, with what-
639 ever newline sequences they have in the input. However, the setting of
640 this option does not affect the interpretation of files specified by
641 the -f, --exclude-from, or --include-from options, which are assumed to
642 use the operating system's standard newline sequence, nor does it
643 affect the way in which pcregrep writes informational messages to the
644 standard error and output streams. For these it uses the string "\n" to
645 indicate newlines, relying on the C I/O library to convert this to an
646 appropriate sequence.
649 OPTIONS COMPATIBILITY
651 Many of the short and long forms of pcregrep's options are the same as
652 in the GNU grep program. Any long option of the form --xxx-regexp (GNU
653 terminology) is also available as --xxx-regex (PCRE terminology). How-
654 ever, the --file-list, --file-offsets, --include-dir, --line-offsets,
655 --locale, --match-limit, -M, --multiline, -N, --newline, --om-separa-
656 tor, --recursion-limit, -u, and --utf-8 options are specific to pcre-
657 grep, as is the use of the --only-matching option with a capturing
658 parentheses number.
660 Although most of the common options work the same way, a few are dif-
661 ferent in pcregrep. For example, the --include option's argument is a
662 glob for GNU grep, but a regular expression for pcregrep. If both the
663 -c and -l options are given, GNU grep lists only file names, without
664 counts, but pcregrep gives the counts.
667 OPTIONS WITH DATA
669 There are four different ways in which an option with data can be spec-
670 ified. If a short form option is used, the data may follow immedi-
671 ately, or (with one exception) in the next command line item. For exam-
672 ple:
674 -f/some/file
675 -f /some/file
677 The exception is the -o option, which may appear with or without data.
678 Because of this, if data is present, it must follow immediately in the
679 same item, for example -o3.
681 If a long form option is used, the data may appear in the same command
682 line item, separated by an equals character, or (with two exceptions)
683 it may appear in the next command line item. For example:
685 --file=/some/file
686 --file /some/file
688 Note, however, that if you want to supply a file name beginning with ~
689 as data in a shell command, and have the shell expand ~ to a home
690 directory, you must separate the file name from the option, because the
691 shell does not treat ~ specially unless it is at the start of an item.
693 The exceptions to the above are the --colour (or --color) and --only-
694 matching options, for which the data is optional. If one of these
695 options does have data, it must be given in the first form, using an
696 equals character. Otherwise pcregrep will assume that it has no data.
699 MATCHING ERRORS
701 It is possible to supply a regular expression that takes a very long
702 time to fail to match certain lines. Such patterns normally involve
703 nested indefinite repeats, for example: (a+)*\d when matched against a
704 line of a's with no final digit. The PCRE matching function has a
705 resource limit that causes it to abort in these circumstances. If this
706 happens, pcregrep outputs an error message and the line that caused the
707 problem to the standard error stream. If there are more than 20 such
708 errors, pcregrep gives up.
710 The --match-limit option of pcregrep can be used to set the overall
711 resource limit; there is a second option called --recursion-limit that
712 sets a limit on the amount of memory (usually stack) that is used (see
713 the discussion of these options above).
716 DIAGNOSTICS
718 Exit status is 0 if any matches were found, 1 if no matches were found,
719 and 2 for syntax errors, overlong lines, non-existent or inaccessible
720 files (even if matches were found in other files) or too many matching
721 errors. Using the -s option to suppress error messages about inaccessi-
722 ble files does not affect the return code.
725 SEE ALSO
727 pcrepattern(3), pcresyntax(3), pcretest(1).
730 AUTHOR
732 Philip Hazel
733 University Computing Service
734 Cambridge CB2 3QH, England.
737 REVISION
739 Last updated: 13 September 2012
740 Copyright (c) 1997-2012 University of Cambridge.