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1 .TH PCREGREP 1
2 .SH NAME
3 pcregrep - a grep with Perl-compatible regular expressions.
4 .SH SYNOPSIS
5 .B pcregrep [options] [long options] [pattern] [path1 path2 ...]
6 .
7 .SH DESCRIPTION
8 .rs
9 .sp
10 \fBpcregrep\fP searches files for character patterns, in the same way as other
11 grep commands do, but it uses the PCRE regular expression library to support
12 patterns that are compatible with the regular expressions of Perl 5. See
13 .\" HREF
14 \fBpcrepattern\fP(3)
15 .\"
16 for a full description of syntax and semantics of the regular expressions
17 that PCRE supports.
18 .P
19 Patterns, whether supplied on the command line or in a separate file, are given
20 without delimiters. For example:
21 .sp
22 pcregrep Thursday /etc/motd
23 .sp
24 If you attempt to use delimiters (for example, by surrounding a pattern with
25 slashes, as is common in Perl scripts), they are interpreted as part of the
26 pattern. Quotes can of course be used to delimit patterns on the command line
27 because they are interpreted by the shell, and indeed they are required if a
28 pattern contains white space or shell metacharacters.
29 .P
30 The first argument that follows any option settings is treated as the single
31 pattern to be matched when neither \fB-e\fP nor \fB-f\fP is present.
32 Conversely, when one or both of these options are used to specify patterns, all
33 arguments are treated as path names. At least one of \fB-e\fP, \fB-f\fP, or an
34 argument pattern must be provided.
35 .P
36 If no files are specified, \fBpcregrep\fP reads the standard input. The
37 standard input can also be referenced by a name consisting of a single hyphen.
38 For example:
39 .sp
40 pcregrep some-pattern /file1 - /file3
41 .sp
42 By default, each line that matches a pattern is copied to the standard
43 output, and if there is more than one file, the file name is output at the
44 start of each line, followed by a colon. However, there are options that can
45 change how \fBpcregrep\fP behaves. In particular, the \fB-M\fP option makes it
46 possible to search for patterns that span line boundaries. What defines a line
47 boundary is controlled by the \fB-N\fP (\fB--newline\fP) option.
48 .P
49 Patterns are limited to 8K or BUFSIZ characters, whichever is the greater.
50 BUFSIZ is defined in \fB<stdio.h>\fP. When there is more than one pattern
51 (specified by the use of \fB-e\fP and/or \fB-f\fP), each pattern is applied to
52 each line in the order in which they are defined, except that all the \fB-e\fP
53 patterns are tried before the \fB-f\fP patterns. As soon as one pattern matches
54 (or fails to match when \fB-v\fP is used), no further patterns are considered.
55 .P
56 When \fB--only-matching\fP, \fB--file-offsets\fP, or \fB--line-offsets\fP
57 is used, the output is the part of the line that matched (either shown
58 literally, or as an offset). In this case, scanning resumes immediately
59 following the match, so that further matches on the same line can be found.
60 If there are multiple patterns, they are all tried on the remainder of the
61 line. However, patterns that follow the one that matched are not tried on the
62 earlier part of the line.
63 .P
64 If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set,
65 \fBpcregrep\fP uses the value to set a locale when calling the PCRE library.
66 The \fB--locale\fP option can be used to override this.
67 .
68 .SH "SUPPORT FOR COMPRESSED FILES"
69 .rs
70 .sp
71 It is possible to compile \fBpcregrep\fP so that it uses \fBlibz\fP or
72 \fBlibbz2\fP to read files whose names end in \fB.gz\fP or \fB.bz2\fP,
73 respectively. You can find out whether your binary has support for one or both
74 of these file types by running it with the \fB--help\fP option. If the
75 appropriate support is not present, files are treated as plain text. The
76 standard input is always so treated.
77 .
78 .SH OPTIONS
79 .rs
80 .TP 10
81 \fB--\fP
82 This terminate the list of options. It is useful if the next item on the
83 command line starts with a hyphen but is not an option. This allows for the
84 processing of patterns and filenames that start with hyphens.
85 .TP
86 \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
87 Output \fInumber\fP lines of context after each matching line. If filenames
88 and/or line numbers are being output, a hyphen separator is used instead of a
89 colon for the context lines. A line containing "--" is output between each
90 group of lines, unless they are in fact contiguous in the input file. The value
91 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
92 guarantees to have up to 8K of following text available for context output.
93 .TP
94 \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
95 Output \fInumber\fP lines of context before each matching line. If filenames
96 and/or line numbers are being output, a hyphen separator is used instead of a
97 colon for the context lines. A line containing "--" is output between each
98 group of lines, unless they are in fact contiguous in the input file. The value
99 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
100 guarantees to have up to 8K of preceding text available for context output.
101 .TP
102 \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
103 Output \fInumber\fP lines of context both before and after each matching line.
104 This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
105 .TP
106 \fB-c\fP, \fB--count\fP
107 Do not output individual lines; instead just output a count of the number of
108 lines that would otherwise have been output. If several files are given, a
109 count is output for each of them. In this mode, the \fB-A\fP, \fB-B\fP, and
110 \fB-C\fP options are ignored.
111 .TP
112 \fB--colour\fP, \fB--color\fP
113 If this option is given without any data, it is equivalent to "--colour=auto".
114 If data is required, it must be given in the same shell item, separated by an
115 equals sign.
116 .TP
117 \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
118 This option specifies under what circumstances the parts of a line that matched
119 a pattern should be coloured in the output. By default, the output is not
120 coloured. The value (which is optional, see above) may be "never", "always", or
121 "auto". In the latter case, colouring happens only if the standard output is
122 connected to a terminal. The colour that is used can be specified by setting
123 the environment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value of this
124 variable should be a string of two numbers, separated by a semicolon. They are
125 copied directly into the control string for setting colour on a terminal, so it
126 is your responsibility to ensure that they make sense. If neither of the
127 environment variables is set, the default is "1;31", which gives red.
128 .TP
129 \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
130 If an input path is not a regular file or a directory, "action" specifies how
131 it is to be processed. Valid values are "read" (the default) or "skip"
132 (silently skip the path).
133 .TP
134 \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
135 If an input path is a directory, "action" specifies how it is to be processed.
136 Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP
137 option), or "skip" (silently skip the path). In the default case, directories
138 are read as if they were ordinary files. In some operating systems the effect
139 of reading a directory like this is an immediate end-of-file.
140 .TP
141 \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP, \fB--regexp=\fP\fIpattern\fP
142 Specify a pattern to be matched. This option can be used multiple times in
143 order to specify several patterns. It can also be used as a way of specifying a
144 single pattern that starts with a hyphen. When \fB-e\fP is used, no argument
145 pattern is taken from the command line; all arguments are treated as file
146 names. There is an overall maximum of 100 patterns. They are applied to each
147 line in the order in which they are defined until one matches (or fails to
148 match if \fB-v\fP is used). If \fB-f\fP is used with \fB-e\fP, the command line
149 patterns are matched first, followed by the patterns from the file, independent
150 of the order in which these options are specified. Note that multiple use of
151 \fB-e\fP is not the same as a single pattern with alternatives. For example,
152 X|Y finds the first character in a line that is X or Y, whereas if the two
153 patterns are given separately, \fBpcregrep\fP finds X if it is present, even if
154 it follows Y in the line. It finds Y only if there is no X in the line. This
155 really matters only if you are using \fB-o\fP to show the part(s) of the line
156 that matched.
157 .TP
158 \fB--exclude\fP=\fIpattern\fP
159 When \fBpcregrep\fP is searching the files in a directory as a consequence of
160 the \fB-r\fP (recursive search) option, any regular files whose names match the
161 pattern are excluded. Subdirectories are not excluded by this option; they are
162 searched recursively, subject to the \fB--exclude_dir\fP and
163 \fB--include_dir\fP options. The pattern is a PCRE regular expression, and is
164 matched against the final component of the file name (not the entire path). If
165 a file name matches both \fB--include\fP and \fB--exclude\fP, it is excluded.
166 There is no short form for this option.
167 .TP
168 \fB--exclude_dir\fP=\fIpattern\fP
169 When \fBpcregrep\fP is searching the contents of a directory as a consequence
170 of the \fB-r\fP (recursive search) option, any subdirectories whose names match
171 the pattern are excluded. (Note that the \fP--exclude\fP option does not affect
172 subdirectories.) The pattern is a PCRE regular expression, and is matched
173 against the final component of the name (not the entire path). If a
174 subdirectory name matches both \fB--include_dir\fP and \fB--exclude_dir\fP, it
175 is excluded. There is no short form for this option.
176 .TP
177 \fB-F\fP, \fB--fixed-strings\fP
178 Interpret each pattern as a list of fixed strings, separated by newlines,
179 instead of as a regular expression. The \fB-w\fP (match as a word) and \fB-x\fP
180 (match whole line) options can be used with \fB-F\fP. They apply to each of the
181 fixed strings. A line is selected if any of the fixed strings are found in it
182 (subject to \fB-w\fP or \fB-x\fP, if present).
183 .TP
184 \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
185 Read a number of patterns from the file, one per line, and match them against
186 each line of input. A data line is output if any of the patterns match it. The
187 filename can be given as "-" to refer to the standard input. When \fB-f\fP is
188 used, patterns specified on the command line using \fB-e\fP may also be
189 present; they are tested before the file's patterns. However, no other pattern
190 is taken from the command line; all arguments are treated as file names. There
191 is an overall maximum of 100 patterns. Trailing white space is removed from
192 each line, and blank lines are ignored. An empty file contains no patterns and
193 therefore matches nothing. See also the comments about multiple patterns versus
194 a single pattern with alternatives in the description of \fB-e\fP above.
195 .TP
196 \fB--file-offsets\fP
197 Instead of showing lines or parts of lines that match, show each match as an
198 offset from the start of the file and a length, separated by a comma. In this
199 mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP
200 options are ignored. If there is more than one match in a line, each of them is
201 shown separately. This option is mutually exclusive with \fB--line-offsets\fP
202 and \fB--only-matching\fP.
203 .TP
204 \fB-H\fP, \fB--with-filename\fP
205 Force the inclusion of the filename at the start of output lines when searching
206 a single file. By default, the filename is not shown in this case. For matching
207 lines, the filename is followed by a colon; for context lines, a hyphen
208 separator is used. If a line number is also being output, it follows the file
209 name.
210 .TP
211 \fB-h\fP, \fB--no-filename\fP
212 Suppress the output filenames when searching multiple files. By default,
213 filenames are shown when multiple files are searched. For matching lines, the
214 filename is followed by a colon; for context lines, a hyphen separator is used.
215 If a line number is also being output, it follows the file name.
216 .TP
217 \fB--help\fP
218 Output a help message, giving brief details of the command options and file
219 type support, and then exit.
220 .TP
221 \fB-i\fP, \fB--ignore-case\fP
222 Ignore upper/lower case distinctions during comparisons.
223 .TP
224 \fB--include\fP=\fIpattern\fP
225 When \fBpcregrep\fP is searching the files in a directory as a consequence of
226 the \fB-r\fP (recursive search) option, only those regular files whose names
227 match the pattern are included. Subdirectories are always included and searched
228 recursively, subject to the \fP--include_dir\fP and \fB--exclude_dir\fP
229 options. The pattern is a PCRE regular expression, and is matched against the
230 final component of the file name (not the entire path). If a file name matches
231 both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no short
232 form for this option.
233 .TP
234 \fB--include_dir\fP=\fIpattern\fP
235 When \fBpcregrep\fP is searching the contents of a directory as a consequence
236 of the \fB-r\fP (recursive search) option, only those subdirectories whose
237 names match the pattern are included. (Note that the \fB--include\fP option
238 does not affect subdirectories.) The pattern is a PCRE regular expression, and
239 is matched against the final component of the name (not the entire path). If a
240 subdirectory name matches both \fB--include_dir\fP and \fB--exclude_dir\fP, it
241 is excluded. There is no short form for this option.
242 .TP
243 \fB-L\fP, \fB--files-without-match\fP
244 Instead of outputting lines from the files, just output the names of the files
245 that do not contain any lines that would have been output. Each file name is
246 output once, on a separate line.
247 .TP
248 \fB-l\fP, \fB--files-with-matches\fP
249 Instead of outputting lines from the files, just output the names of the files
250 containing lines that would have been output. Each file name is output
251 once, on a separate line. Searching stops as soon as a matching line is found
252 in a file.
253 .TP
254 \fB--label\fP=\fIname\fP
255 This option supplies a name to be used for the standard input when file names
256 are being output. If not supplied, "(standard input)" is used. There is no
257 short form for this option.
258 .TP
259 \fB--line-offsets\fP
260 Instead of showing lines or parts of lines that match, show each match as a
261 line number, the offset from the start of the line, and a length. The line
262 number is terminated by a colon (as usual; see the \fB-n\fP option), and the
263 offset and length are separated by a comma. In this mode, no context is shown.
264 That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are ignored. If there is
265 more than one match in a line, each of them is shown separately. This option is
266 mutually exclusive with \fB--file-offsets\fP and \fB--only-matching\fP.
267 .TP
268 \fB--locale\fP=\fIlocale-name\fP
269 This option specifies a locale to be used for pattern matching. It overrides
270 the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
271 locale is specified, the PCRE library's default (usually the "C" locale) is
272 used. There is no short form for this option.
273 .TP
274 \fB-M\fP, \fB--multiline\fP
275 Allow patterns to match more than one line. When this option is given, patterns
276 may usefully contain literal newline characters and internal occurrences of ^
277 and $ characters. The output for any one match may consist of more than one
278 line. When this option is set, the PCRE library is called in "multiline" mode.
279 There is a limit to the number of lines that can be matched, imposed by the way
280 that \fBpcregrep\fP buffers the input file as it scans it. However,
281 \fBpcregrep\fP ensures that at least 8K characters or the rest of the document
282 (whichever is the shorter) are available for forward matching, and similarly
283 the previous 8K characters (or all the previous characters, if fewer than 8K)
284 are guaranteed to be available for lookbehind assertions.
285 .TP
286 \fB-N\fP \fInewline-type\fP, \fB--newline=\fP\fInewline-type\fP
287 The PCRE library supports five different conventions for indicating
288 the ends of lines. They are the single-character sequences CR (carriage return)
289 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
290 which recognizes any of the preceding three types, and an "any" convention, in
291 which any Unicode line ending sequence is assumed to end a line. The Unicode
292 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
293 (formfeed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
294 PS (paragraph separator, U+2029).
295 .sp
296 When the PCRE library is built, a default line-ending sequence is specified.
297 This is normally the standard sequence for the operating system. Unless
298 otherwise specified by this option, \fBpcregrep\fP uses the library's default.
299 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
300 makes it possible to use \fBpcregrep\fP on files that have come from other
301 environments without having to modify their line endings. If the data that is
302 being scanned does not agree with the convention set by this option,
303 \fBpcregrep\fP may behave in strange ways.
304 .TP
305 \fB-n\fP, \fB--line-number\fP
306 Precede each output line by its line number in the file, followed by a colon
307 for matching lines or a hyphen for context lines. If the filename is also being
308 output, it precedes the line number. This option is forced if
309 \fB--line-offsets\fP is used.
310 .TP
311 \fB-o\fP, \fB--only-matching\fP
312 Show only the part of the line that matched a pattern. In this mode, no
313 context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are
314 ignored. If there is more than one match in a line, each of them is shown
315 separately. If \fB-o\fP is combined with \fB-v\fP (invert the sense of the
316 match to find non-matching lines), no output is generated, but the return code
317 is set appropriately. This option is mutually exclusive with
318 \fB--file-offsets\fP and \fB--line-offsets\fP.
319 .TP
320 \fB-q\fP, \fB--quiet\fP
321 Work quietly, that is, display nothing except error messages. The exit
322 status indicates whether or not any matches were found.
323 .TP
324 \fB-r\fP, \fB--recursive\fP
325 If any given path is a directory, recursively scan the files it contains,
326 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
327 directory is read as a normal file; in some operating systems this gives an
328 immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
329 option to "recurse".
330 .TP
331 \fB-s\fP, \fB--no-messages\fP
332 Suppress error messages about non-existent or unreadable files. Such files are
333 quietly skipped. However, the return code is still 2, even if matches were
334 found in other files.
335 .TP
336 \fB-u\fP, \fB--utf-8\fP
337 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
338 with UTF-8 support. Both patterns and subject lines must be valid strings of
339 UTF-8 characters.
340 .TP
341 \fB-V\fP, \fB--version\fP
342 Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
343 used to the standard error stream.
344 .TP
345 \fB-v\fP, \fB--invert-match\fP
346 Invert the sense of the match, so that lines which do \fInot\fP match any of
347 the patterns are the ones that are found.
348 .TP
349 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
350 Force the patterns to match only whole words. This is equivalent to having \eb
351 at the start and end of the pattern.
352 .TP
353 \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
354 Force the patterns to be anchored (each must start matching at the beginning of
355 a line) and in addition, require them to match entire lines. This is
356 equivalent to having ^ and $ characters at the start and end of each
357 alternative branch in every pattern.
358 .
359 .
360 .SH "ENVIRONMENT VARIABLES"
361 .rs
362 .sp
363 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
364 order, for a locale. The first one that is set is used. This can be overridden
365 by the \fB--locale\fP option. If no locale is set, the PCRE library's default
366 (usually the "C" locale) is used.
367 .
368 .
369 .SH "NEWLINES"
370 .rs
371 .sp
372 The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
373 different newline conventions from the default. However, the setting of this
374 option does not affect the way in which \fBpcregrep\fP writes information to
375 the standard error and output streams. It uses the string "\en" in C
376 \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to
377 convert this to an appropriate sequence if the output is sent to a file.
378 .
379 .
380 .SH "OPTIONS COMPATIBILITY"
381 .rs
382 .sp
383 The majority of short and long forms of \fBpcregrep\fP's options are the same
384 as in the GNU \fBgrep\fP program. Any long option of the form
385 \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
386 (PCRE terminology). However, the \fB--locale\fP, \fB-M\fP, \fB--multiline\fP,
387 \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP.
388 .
389 .
390 .SH "OPTIONS WITH DATA"
391 .rs
392 .sp
393 There are four different ways in which an option with data can be specified.
394 If a short form option is used, the data may follow immediately, or in the next
395 command line item. For example:
396 .sp
397 -f/some/file
398 -f /some/file
399 .sp
400 If a long form option is used, the data may appear in the same command line
401 item, separated by an equals character, or (with one exception) it may appear
402 in the next command line item. For example:
403 .sp
404 --file=/some/file
405 --file /some/file
406 .sp
407 Note, however, that if you want to supply a file name beginning with ~ as data
408 in a shell command, and have the shell expand ~ to a home directory, you must
409 separate the file name from the option, because the shell does not treat ~
410 specially unless it is at the start of an item.
411 .P
412 The exception to the above is the \fB--colour\fP (or \fB--color\fP) option,
413 for which the data is optional. If this option does have data, it must be given
414 in the first form, using an equals character. Otherwise it will be assumed that
415 it has no data.
416 .
417 .
418 .SH "MATCHING ERRORS"
419 .rs
420 .sp
421 It is possible to supply a regular expression that takes a very long time to
422 fail to match certain lines. Such patterns normally involve nested indefinite
423 repeats, for example: (a+)*\ed when matched against a line of a's with no final
424 digit. The PCRE matching function has a resource limit that causes it to abort
425 in these circumstances. If this happens, \fBpcregrep\fP outputs an error
426 message and the line that caused the problem to the standard error stream. If
427 there are more than 20 such errors, \fBpcregrep\fP gives up.
428 .
429 .
430 .SH DIAGNOSTICS
431 .rs
432 .sp
433 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
434 for syntax errors and non-existent or inacessible files (even if matches were
435 found in other files) or too many matching errors. Using the \fB-s\fP option to
436 suppress error messages about inaccessble files does not affect the return
437 code.
438 .
439 .
440 .SH "SEE ALSO"
441 .rs
442 .sp
443 \fBpcrepattern\fP(3), \fBpcretest\fP(1).
444 .
445 .
446 .SH AUTHOR
447 .rs
448 .sp
449 .nf
450 Philip Hazel
451 University Computing Service
452 Cambridge CB2 3QH, England.
453 .fi
454 .
455 .
456 .SH REVISION
457 .rs
458 .sp
459 .nf
460 Last updated: 01 March 2009
461 Copyright (c) 1997-2009 University of Cambridge.
462 .fi

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