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Final tidies for 8.35 release.
1 .TH PCREGREP 1 "03 April 2014" "PCRE 8.35"
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 \fBpcresyntax\fP(3)
15 .\"
16 for a quick-reference summary of pattern syntax, or
17 .\" HREF
18 \fBpcrepattern\fP(3)
19 .\"
20 for a full description of the syntax and semantics of the regular expressions
21 that PCRE supports.
22 .P
23 Patterns, whether supplied on the command line or in a separate file, are given
24 without delimiters. For example:
25 .sp
26 pcregrep Thursday /etc/motd
27 .sp
28 If you attempt to use delimiters (for example, by surrounding a pattern with
29 slashes, as is common in Perl scripts), they are interpreted as part of the
30 pattern. Quotes can of course be used to delimit patterns on the command line
31 because they are interpreted by the shell, and indeed quotes are required if a
32 pattern contains white space or shell metacharacters.
33 .P
34 The first argument that follows any option settings is treated as the single
35 pattern to be matched when neither \fB-e\fP nor \fB-f\fP is present.
36 Conversely, when one or both of these options are used to specify patterns, all
37 arguments are treated as path names. At least one of \fB-e\fP, \fB-f\fP, or an
38 argument pattern must be provided.
39 .P
40 If no files are specified, \fBpcregrep\fP reads the standard input. The
41 standard input can also be referenced by a name consisting of a single hyphen.
42 For example:
43 .sp
44 pcregrep some-pattern /file1 - /file3
45 .sp
46 By default, each line that matches a pattern is copied to the standard
47 output, and if there is more than one file, the file name is output at the
48 start of each line, followed by a colon. However, there are options that can
49 change how \fBpcregrep\fP behaves. In particular, the \fB-M\fP option makes it
50 possible to search for patterns that span line boundaries. What defines a line
51 boundary is controlled by the \fB-N\fP (\fB--newline\fP) option.
52 .P
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 \fB--buffer-size\fP option.
55 The default value for this parameter is specified when \fBpcregrep\fP is built,
56 with the default default being 20K. A block of memory three times this size is
57 used (to allow for buffering "before" and "after" lines). An error occurs if a
58 line overflows the buffer.
59 .P
60 Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the greater.
61 BUFSIZ is defined in \fB<stdio.h>\fP. When there is more than one pattern
62 (specified by the use of \fB-e\fP and/or \fB-f\fP), each pattern is applied to
63 each line in the order in which they are defined, except that all the \fB-e\fP
64 patterns are tried before the \fB-f\fP patterns.
65 .P
66 By default, as soon as one pattern matches a line, no further patterns are
67 considered. However, if \fB--colour\fP (or \fB--color\fP) is used to colour the
68 matching substrings, or if \fB--only-matching\fP, \fB--file-offsets\fP, or
69 \fB--line-offsets\fP 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 found. If
72 there are multiple patterns, they are all tried on the remainder of the line,
73 but patterns that follow the one that matched are not tried on the earlier part
74 of the line.
75 .P
76 This behaviour means that the order in which multiple patterns are specified
77 can affect the output when one of the above options is used. This is no longer
78 the same behaviour as GNU grep, which now manages to display earlier matches
79 for later patterns (as long as there is no overlap).
80 .P
81 Patterns that can match an empty string are accepted, but empty string
82 matches are never recognized. An example is the pattern "(super)?(man)?", in
83 which all components are optional. This pattern finds all occurrences of both
84 "super" and "man"; the output differs from matching with "super|man" when only
85 the matching substrings are being shown.
86 .P
87 If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set,
88 \fBpcregrep\fP uses the value to set a locale when calling the PCRE library.
89 The \fB--locale\fP option can be used to override this.
90 .
91 .
92 .SH "SUPPORT FOR COMPRESSED FILES"
93 .rs
94 .sp
95 It is possible to compile \fBpcregrep\fP so that it uses \fBlibz\fP or
96 \fBlibbz2\fP to read files whose names end in \fB.gz\fP or \fB.bz2\fP,
97 respectively. You can find out whether your binary has support for one or both
98 of these file types by running it with the \fB--help\fP option. If the
99 appropriate support is not present, files are treated as plain text. The
100 standard input is always so treated.
101 .
102 .
103 .SH "BINARY FILES"
104 .rs
105 .sp
106 By default, a file that contains a binary zero byte within the first 1024 bytes
107 is identified as a binary file, and is processed specially. (GNU grep also
108 identifies binary files in this manner.) See the \fB--binary-files\fP option
109 for a means of changing the way binary files are handled.
110 .
111 .
112 .SH OPTIONS
113 .rs
114 .sp
115 The order in which some of the options appear can affect the output. For
116 example, both the \fB-h\fP and \fB-l\fP options affect the printing of file
117 names. Whichever comes later in the command line will be the one that takes
118 effect. Similarly, except where noted below, if an option is given twice, the
119 later setting is used. Numerical values for options may be followed by K or M,
120 to signify multiplication by 1024 or 1024*1024 respectively.
121 .TP 10
122 \fB--\fP
123 This terminates the list of options. It is useful if the next item on the
124 command line starts with a hyphen but is not an option. This allows for the
125 processing of patterns and filenames that start with hyphens.
126 .TP
127 \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
128 Output \fInumber\fP lines of context after each matching line. If filenames
129 and/or line numbers are being output, a hyphen separator is used instead of a
130 colon for the context lines. A line containing "--" is output between each
131 group of lines, unless they are in fact contiguous in the input file. The value
132 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
133 guarantees to have up to 8K of following text available for context output.
134 .TP
135 \fB-a\fP, \fB--text\fP
136 Treat binary files as text. This is equivalent to
137 \fB--binary-files\fP=\fItext\fP.
138 .TP
139 \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
140 Output \fInumber\fP lines of context before each matching line. If filenames
141 and/or line numbers are being output, a hyphen separator is used instead of a
142 colon for the context lines. A line containing "--" is output between each
143 group of lines, unless they are in fact contiguous in the input file. The value
144 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
145 guarantees to have up to 8K of preceding text available for context output.
146 .TP
147 \fB--binary-files=\fP\fIword\fP
148 Specify how binary files are to be processed. If the word is "binary" (the
149 default), pattern matching is performed on binary files, but the only output is
150 "Binary file <name> matches" when a match succeeds. If the word is "text",
151 which is equivalent to the \fB-a\fP or \fB--text\fP option, binary files are
152 processed in the same way as any other file. In this case, when a match
153 succeeds, the output may be binary garbage, which can have nasty effects if
154 sent to a terminal. If the word is "without-match", which is equivalent to the
155 \fB-I\fP option, binary files are not processed at all; they are assumed not to
156 be of interest.
157 .TP
158 \fB--buffer-size=\fP\fInumber\fP
159 Set the parameter that controls how much memory is used for buffering files
160 that are being scanned.
161 .TP
162 \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
163 Output \fInumber\fP lines of context both before and after each matching line.
164 This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
165 .TP
166 \fB-c\fP, \fB--count\fP
167 Do not output individual lines from the files that are being scanned; instead
168 output the number of lines that would otherwise have been shown. If no lines
169 are selected, the number zero is output. If several files are are being
170 scanned, a count is output for each of them. However, if the
171 \fB--files-with-matches\fP option is also used, only those files whose counts
172 are greater than zero are listed. When \fB-c\fP is used, the \fB-A\fP,
173 \fB-B\fP, and \fB-C\fP options are ignored.
174 .TP
175 \fB--colour\fP, \fB--color\fP
176 If this option is given without any data, it is equivalent to "--colour=auto".
177 If data is required, it must be given in the same shell item, separated by an
178 equals sign.
179 .TP
180 \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
181 This option specifies under what circumstances the parts of a line that matched
182 a pattern should be coloured in the output. By default, the output is not
183 coloured. The value (which is optional, see above) may be "never", "always", or
184 "auto". In the latter case, colouring happens only if the standard output is
185 connected to a terminal. More resources are used when colouring is enabled,
186 because \fBpcregrep\fP has to search for all possible matches in a line, not
187 just one, in order to colour them all.
188 .sp
189 The colour that is used can be specified by setting the environment variable
190 PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
191 string of two numbers, separated by a semicolon. They are copied directly into
192 the control string for setting colour on a terminal, so it is your
193 responsibility to ensure that they make sense. If neither of the environment
194 variables is set, the default is "1;31", which gives red.
195 .TP
196 \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
197 If an input path is not a regular file or a directory, "action" specifies how
198 it is to be processed. Valid values are "read" (the default) or "skip"
199 (silently skip the path).
200 .TP
201 \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
202 If an input path is a directory, "action" specifies how it is to be processed.
203 Valid values are "read" (the default in non-Windows environments, for
204 compatibility with GNU grep), "recurse" (equivalent to the \fB-r\fP option), or
205 "skip" (silently skip the path, the default in Windows environments). In the
206 "read" case, directories are read as if they were ordinary files. In some
207 operating systems the effect of reading a directory like this is an immediate
208 end-of-file; in others it may provoke an error.
209 .TP
210 \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP, \fB--regexp=\fP\fIpattern\fP
211 Specify a pattern to be matched. This option can be used multiple times in
212 order to specify several patterns. It can also be used as a way of specifying a
213 single pattern that starts with a hyphen. When \fB-e\fP is used, no argument
214 pattern is taken from the command line; all arguments are treated as file
215 names. There is no limit to the number of patterns. They are applied to each
216 line in the order in which they are defined until one matches.
217 .sp
218 If \fB-f\fP is used with \fB-e\fP, the command line patterns are matched first,
219 followed by the patterns from the file(s), independent of the order in which
220 these options are specified. Note that multiple use of \fB-e\fP is not the same
221 as a single pattern with alternatives. For example, X|Y finds the first
222 character in a line that is X or Y, whereas if the two patterns are given
223 separately, with X first, \fBpcregrep\fP finds X if it is present, even if it
224 follows Y in the line. It finds Y only if there is no X in the line. This
225 matters only if you are using \fB-o\fP or \fB--colo(u)r\fP to show the part(s)
226 of the line that matched.
227 .TP
228 \fB--exclude\fP=\fIpattern\fP
229 Files (but not directories) whose names match the pattern are skipped without
230 being processed. This applies to all files, whether listed on the command line,
231 obtained from \fB--file-list\fP, or by scanning a directory. The pattern is a
232 PCRE regular expression, and is matched against the final component of the file
233 name, not the entire path. The \fB-F\fP, \fB-w\fP, and \fB-x\fP options do not
234 apply to this pattern. The option may be given any number of times in order to
235 specify multiple patterns. If a file name matches both an \fB--include\fP
236 and an \fB--exclude\fP pattern, it is excluded. There is no short form for this
237 option.
238 .TP
239 \fB--exclude-from=\fP\fIfilename\fP
240 Treat each non-empty line of the file as the data for an \fB--exclude\fP
241 option. What constitutes a newline when reading the file is the operating
242 system's default. The \fB--newline\fP option has no effect on this option. This
243 option may be given more than once in order to specify a number of files to
244 read.
245 .TP
246 \fB--exclude-dir\fP=\fIpattern\fP
247 Directories whose names match the pattern are skipped without being processed,
248 whatever the setting of the \fB--recursive\fP option. This applies to all
249 directories, whether listed on the command line, obtained from
250 \fB--file-list\fP, or by scanning a parent directory. The pattern is a PCRE
251 regular expression, and is matched against the final component of the directory
252 name, not the entire path. The \fB-F\fP, \fB-w\fP, and \fB-x\fP options do not
253 apply to this pattern. The option may be given any number of times in order to
254 specify more than one pattern. If a directory matches both \fB--include-dir\fP
255 and \fB--exclude-dir\fP, it is excluded. There is no short form for this
256 option.
257 .TP
258 \fB-F\fP, \fB--fixed-strings\fP
259 Interpret each data-matching pattern as a list of fixed strings, separated by
260 newlines, instead of as a regular expression. What constitutes a newline for
261 this purpose is controlled by the \fB--newline\fP option. The \fB-w\fP (match
262 as a word) and \fB-x\fP (match whole line) options can be used with \fB-F\fP.
263 They apply to each of the fixed strings. A line is selected if any of the fixed
264 strings are found in it (subject to \fB-w\fP or \fB-x\fP, if present). This
265 option applies only to the patterns that are matched against the contents of
266 files; it does not apply to patterns specified by any of the \fB--include\fP or
267 \fB--exclude\fP options.
268 .TP
269 \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
270 Read patterns from the file, one per line, and match them against
271 each line of input. What constitutes a newline when reading the file is the
272 operating system's default. The \fB--newline\fP option has no effect on this
273 option. Trailing white space is removed from each line, and blank lines are
274 ignored. An empty file contains no patterns and therefore matches nothing. See
275 also the comments about multiple patterns versus a single pattern with
276 alternatives in the description of \fB-e\fP above.
277 .sp
278 If this option is given more than once, all the specified files are
279 read. A data line is output if any of the patterns match it. A filename can
280 be given as "-" to refer to the standard input. When \fB-f\fP is used, patterns
281 specified on the command line using \fB-e\fP may also be present; they are
282 tested before the file's patterns. However, no other pattern is taken from the
283 command line; all arguments are treated as the names of paths to be searched.
284 .TP
285 \fB--file-list\fP=\fIfilename\fP
286 Read a list of files and/or directories that are to be scanned from the given
287 file, one per line. Trailing white space is removed from each line, and blank
288 lines are ignored. These paths are processed before any that are listed on the
289 command line. The filename can be given as "-" to refer to the standard input.
290 If \fB--file\fP and \fB--file-list\fP are both specified as "-", patterns are
291 read first. This is useful only when the standard input is a terminal, from
292 which further lines (the list of files) can be read after an end-of-file
293 indication. If this option is given more than once, all the specified files are
294 read.
295 .TP
296 \fB--file-offsets\fP
297 Instead of showing lines or parts of lines that match, show each match as an
298 offset from the start of the file and a length, separated by a comma. In this
299 mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP
300 options are ignored. If there is more than one match in a line, each of them is
301 shown separately. This option is mutually exclusive with \fB--line-offsets\fP
302 and \fB--only-matching\fP.
303 .TP
304 \fB-H\fP, \fB--with-filename\fP
305 Force the inclusion of the filename at the start of output lines when searching
306 a single file. By default, the filename is not shown in this case. For matching
307 lines, the filename is followed by a colon; for context lines, a hyphen
308 separator is used. If a line number is also being output, it follows the file
309 name.
310 .TP
311 \fB-h\fP, \fB--no-filename\fP
312 Suppress the output filenames when searching multiple files. By default,
313 filenames are shown when multiple files are searched. For matching lines, the
314 filename is followed by a colon; for context lines, a hyphen separator is used.
315 If a line number is also being output, it follows the file name.
316 .TP
317 \fB--help\fP
318 Output a help message, giving brief details of the command options and file
319 type support, and then exit. Anything else on the command line is
320 ignored.
321 .TP
322 \fB-I\fP
323 Treat binary files as never matching. This is equivalent to
324 \fB--binary-files\fP=\fIwithout-match\fP.
325 .TP
326 \fB-i\fP, \fB--ignore-case\fP
327 Ignore upper/lower case distinctions during comparisons.
328 .TP
329 \fB--include\fP=\fIpattern\fP
330 If any \fB--include\fP patterns are specified, the only files that are
331 processed are those that match one of the patterns (and do not match an
332 \fB--exclude\fP pattern). This option does not affect directories, but it
333 applies to all files, whether listed on the command line, obtained from
334 \fB--file-list\fP, or by scanning a directory. The pattern is a PCRE regular
335 expression, and is matched against the final component of the file name, not
336 the entire path. The \fB-F\fP, \fB-w\fP, and \fB-x\fP options do not apply to
337 this pattern. The option may be given any number of times. If a file name
338 matches both an \fB--include\fP and an \fB--exclude\fP pattern, it is excluded.
339 There is no short form for this option.
340 .TP
341 \fB--include-from=\fP\fIfilename\fP
342 Treat each non-empty line of the file as the data for an \fB--include\fP
343 option. What constitutes a newline for this purpose is the operating system's
344 default. The \fB--newline\fP option has no effect on this option. This option
345 may be given any number of times; all the files are read.
346 .TP
347 \fB--include-dir\fP=\fIpattern\fP
348 If any \fB--include-dir\fP patterns are specified, the only directories that
349 are processed are those that match one of the patterns (and do not match an
350 \fB--exclude-dir\fP pattern). This applies to all directories, whether listed
351 on the command line, obtained from \fB--file-list\fP, or by scanning a parent
352 directory. The pattern is a PCRE regular expression, and is matched against the
353 final component of the directory name, not the entire path. The \fB-F\fP,
354 \fB-w\fP, and \fB-x\fP options do not apply to this pattern. The option may be
355 given any number of times. If a directory matches both \fB--include-dir\fP and
356 \fB--exclude-dir\fP, it is excluded. There is no short form for this option.
357 .TP
358 \fB-L\fP, \fB--files-without-match\fP
359 Instead of outputting lines from the files, just output the names of the files
360 that do not contain any lines that would have been output. Each file name is
361 output once, on a separate line.
362 .TP
363 \fB-l\fP, \fB--files-with-matches\fP
364 Instead of outputting lines from the files, just output the names of the files
365 containing lines that would have been output. Each file name is output
366 once, on a separate line. Searching normally stops as soon as a matching line
367 is found in a file. However, if the \fB-c\fP (count) option is also used,
368 matching continues in order to obtain the correct count, and those files that
369 have at least one match are listed along with their counts. Using this option
370 with \fB-c\fP is a way of suppressing the listing of files with no matches.
371 .TP
372 \fB--label\fP=\fIname\fP
373 This option supplies a name to be used for the standard input when file names
374 are being output. If not supplied, "(standard input)" is used. There is no
375 short form for this option.
376 .TP
377 \fB--line-buffered\fP
378 When this option is given, input is read and processed line by line, and the
379 output is flushed after each write. By default, input is read in large chunks,
380 unless \fBpcregrep\fP can determine that it is reading from a terminal (which
381 is currently possible only in Unix-like environments). Output to terminal is
382 normally automatically flushed by the operating system. This option can be
383 useful when the input or output is attached to a pipe and you do not want
384 \fBpcregrep\fP to buffer up large amounts of data. However, its use will affect
385 performance, and the \fB-M\fP (multiline) option ceases to work.
386 .TP
387 \fB--line-offsets\fP
388 Instead of showing lines or parts of lines that match, show each match as a
389 line number, the offset from the start of the line, and a length. The line
390 number is terminated by a colon (as usual; see the \fB-n\fP option), and the
391 offset and length are separated by a comma. In this mode, no context is shown.
392 That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are ignored. If there is
393 more than one match in a line, each of them is shown separately. This option is
394 mutually exclusive with \fB--file-offsets\fP and \fB--only-matching\fP.
395 .TP
396 \fB--locale\fP=\fIlocale-name\fP
397 This option specifies a locale to be used for pattern matching. It overrides
398 the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
399 locale is specified, the PCRE library's default (usually the "C" locale) is
400 used. There is no short form for this option.
401 .TP
402 \fB--match-limit\fP=\fInumber\fP
403 Processing some regular expression patterns can require a very large amount of
404 memory, leading in some cases to a program crash if not enough is available.
405 Other patterns may take a very long time to search for all possible matching
406 strings. The \fBpcre_exec()\fP function that is called by \fBpcregrep\fP to do
407 the matching has two parameters that can limit the resources that it uses.
408 .sp
409 The \fB--match-limit\fP option provides a means of limiting resource usage
410 when processing patterns that are not going to match, but which have a very
411 large number of possibilities in their search trees. The classic example is a
412 pattern that uses nested unlimited repeats. Internally, PCRE uses a function
413 called \fBmatch()\fP which it calls repeatedly (sometimes recursively). The
414 limit set by \fB--match-limit\fP is imposed on the number of times this
415 function is called during a match, which has the effect of limiting the amount
416 of backtracking that can take place.
417 .sp
418 The \fB--recursion-limit\fP option is similar to \fB--match-limit\fP, but
419 instead of limiting the total number of times that \fBmatch()\fP is called, it
420 limits the depth of recursive calls, which in turn limits the amount of memory
421 that can be used. The recursion depth is a smaller number than the total number
422 of calls, because not all calls to \fBmatch()\fP are recursive. This limit is
423 of use only if it is set smaller than \fB--match-limit\fP.
424 .sp
425 There are no short forms for these options. The default settings are specified
426 when the PCRE library is compiled, with the default default being 10 million.
427 .TP
428 \fB-M\fP, \fB--multiline\fP
429 Allow patterns to match more than one line. When this option is given, patterns
430 may usefully contain literal newline characters and internal occurrences of ^
431 and $ characters. The output for a successful match may consist of more than
432 one line, the last of which is the one in which the match ended. If the matched
433 string ends with a newline sequence the output ends at the end of that line.
434 .sp
435 When this option is set, the PCRE library is called in "multiline" mode.
436 There is a limit to the number of lines that can be matched, imposed by the way
437 that \fBpcregrep\fP buffers the input file as it scans it. However,
438 \fBpcregrep\fP ensures that at least 8K characters or the rest of the document
439 (whichever is the shorter) are available for forward matching, and similarly
440 the previous 8K characters (or all the previous characters, if fewer than 8K)
441 are guaranteed to be available for lookbehind assertions. This option does not
442 work when input is read line by line (see \fP--line-buffered\fP.)
443 .TP
444 \fB-N\fP \fInewline-type\fP, \fB--newline\fP=\fInewline-type\fP
445 The PCRE library supports five different conventions for indicating
446 the ends of lines. They are the single-character sequences CR (carriage return)
447 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
448 which recognizes any of the preceding three types, and an "any" convention, in
449 which any Unicode line ending sequence is assumed to end a line. The Unicode
450 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
451 (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
452 PS (paragraph separator, U+2029).
453 .sp
454 When the PCRE library is built, a default line-ending sequence is specified.
455 This is normally the standard sequence for the operating system. Unless
456 otherwise specified by this option, \fBpcregrep\fP uses the library's default.
457 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
458 makes it possible to use \fBpcregrep\fP to scan files that have come from other
459 environments without having to modify their line endings. If the data that is
460 being scanned does not agree with the convention set by this option,
461 \fBpcregrep\fP may behave in strange ways. Note that this option does not
462 apply to files specified by the \fB-f\fP, \fB--exclude-from\fP, or
463 \fB--include-from\fP options, which are expected to use the operating system's
464 standard newline sequence.
465 .TP
466 \fB-n\fP, \fB--line-number\fP
467 Precede each output line by its line number in the file, followed by a colon
468 for matching lines or a hyphen for context lines. If the filename is also being
469 output, it precedes the line number. This option is forced if
470 \fB--line-offsets\fP is used.
471 .TP
472 \fB--no-jit\fP
473 If the PCRE library is built with support for just-in-time compiling (which
474 speeds up matching), \fBpcregrep\fP automatically makes use of this, unless it
475 was explicitly disabled at build time. This option can be used to disable the
476 use of JIT at run time. It is provided for testing and working round problems.
477 It should never be needed in normal use.
478 .TP
479 \fB-o\fP, \fB--only-matching\fP
480 Show only the part of the line that matched a pattern instead of the whole
481 line. In this mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and
482 \fB-C\fP options are ignored. If there is more than one match in a line, each
483 of them is shown separately. If \fB-o\fP is combined with \fB-v\fP (invert the
484 sense of the match to find non-matching lines), no output is generated, but the
485 return code is set appropriately. If the matched portion of the line is empty,
486 nothing is output unless the file name or line number are being printed, in
487 which case they are shown on an otherwise empty line. This option is mutually
488 exclusive with \fB--file-offsets\fP and \fB--line-offsets\fP.
489 .TP
490 \fB-o\fP\fInumber\fP, \fB--only-matching\fP=\fInumber\fP
491 Show only the part of the line that matched the capturing parentheses of the
492 given number. Up to 32 capturing parentheses are supported, and -o0 is
493 equivalent to \fB-o\fP without a number. Because these options can be given
494 without an argument (see above), if an argument is present, it must be given in
495 the same shell item, for example, -o3 or --only-matching=2. The comments given
496 for the non-argument case above also apply to this case. If the specified
497 capturing parentheses do not exist in the pattern, or were not set in the
498 match, nothing is output unless the file name or line number are being printed.
499 .sp
500 If this option is given multiple times, multiple substrings are output, in the
501 order the options are given. For example, -o3 -o1 -o3 causes the substrings
502 matched by capturing parentheses 3 and 1 and then 3 again to be output. By
503 default, there is no separator (but see the next option).
504 .TP
505 \fB--om-separator\fP=\fItext\fP
506 Specify a separating string for multiple occurrences of \fB-o\fP. The default
507 is an empty string. Separating strings are never coloured.
508 .TP
509 \fB-q\fP, \fB--quiet\fP
510 Work quietly, that is, display nothing except error messages. The exit
511 status indicates whether or not any matches were found.
512 .TP
513 \fB-r\fP, \fB--recursive\fP
514 If any given path is a directory, recursively scan the files it contains,
515 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
516 directory is read as a normal file; in some operating systems this gives an
517 immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
518 option to "recurse".
519 .TP
520 \fB--recursion-limit\fP=\fInumber\fP
521 See \fB--match-limit\fP above.
522 .TP
523 \fB-s\fP, \fB--no-messages\fP
524 Suppress error messages about non-existent or unreadable files. Such files are
525 quietly skipped. However, the return code is still 2, even if matches were
526 found in other files.
527 .TP
528 \fB-u\fP, \fB--utf-8\fP
529 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
530 with UTF-8 support. All patterns (including those for any \fB--exclude\fP and
531 \fB--include\fP options) and all subject lines that are scanned must be valid
532 strings of UTF-8 characters.
533 .TP
534 \fB-V\fP, \fB--version\fP
535 Write the version numbers of \fBpcregrep\fP and the PCRE library to the
536 standard output and then exit. Anything else on the command line is
537 ignored.
538 .TP
539 \fB-v\fP, \fB--invert-match\fP
540 Invert the sense of the match, so that lines which do \fInot\fP match any of
541 the patterns are the ones that are found.
542 .TP
543 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
544 Force the patterns to match only whole words. This is equivalent to having \eb
545 at the start and end of the pattern. This option applies only to the patterns
546 that are matched against the contents of files; it does not apply to patterns
547 specified by any of the \fB--include\fP or \fB--exclude\fP options.
548 .TP
549 \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
550 Force the patterns to be anchored (each must start matching at the beginning of
551 a line) and in addition, require them to match entire lines. This is equivalent
552 to having ^ and $ characters at the start and end of each alternative branch in
553 every pattern. This option applies only to the patterns that are matched
554 against the contents of files; it does not apply to patterns specified by any
555 of the \fB--include\fP or \fB--exclude\fP options.
556 .
557 .
558 .SH "ENVIRONMENT VARIABLES"
559 .rs
560 .sp
561 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
562 order, for a locale. The first one that is set is used. This can be overridden
563 by the \fB--locale\fP option. If no locale is set, the PCRE library's default
564 (usually the "C" locale) is used.
565 .
566 .
567 .SH "NEWLINES"
568 .rs
569 .sp
570 The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
571 different newline conventions from the default. Any parts of the input files
572 that are written to the standard output are copied identically, with whatever
573 newline sequences they have in the input. However, the setting of this option
574 does not affect the interpretation of files specified by the \fB-f\fP,
575 \fB--exclude-from\fP, or \fB--include-from\fP options, which are assumed to use
576 the operating system's standard newline sequence, nor does it affect the way in
577 which \fBpcregrep\fP writes informational messages to the standard error and
578 output streams. For these it uses the string "\en" to indicate newlines,
579 relying on the C I/O library to convert this to an appropriate sequence.
580 .
581 .
582 .SH "OPTIONS COMPATIBILITY"
583 .rs
584 .sp
585 Many of the short and long forms of \fBpcregrep\fP's options are the same
586 as in the GNU \fBgrep\fP program. Any long option of the form
587 \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
588 (PCRE terminology). However, the \fB--file-list\fP, \fB--file-offsets\fP,
589 \fB--include-dir\fP, \fB--line-offsets\fP, \fB--locale\fP, \fB--match-limit\fP,
590 \fB-M\fP, \fB--multiline\fP, \fB-N\fP, \fB--newline\fP, \fB--om-separator\fP,
591 \fB--recursion-limit\fP, \fB-u\fP, and \fB--utf-8\fP options are specific to
592 \fBpcregrep\fP, as is the use of the \fB--only-matching\fP option with a
593 capturing parentheses number.
594 .P
595 Although most of the common options work the same way, a few are different in
596 \fBpcregrep\fP. For example, the \fB--include\fP option's argument is a glob
597 for GNU \fBgrep\fP, but a regular expression for \fBpcregrep\fP. If both the
598 \fB-c\fP and \fB-l\fP options are given, GNU grep lists only file names,
599 without counts, but \fBpcregrep\fP gives the counts.
600 .
601 .
602 .SH "OPTIONS WITH DATA"
603 .rs
604 .sp
605 There are four different ways in which an option with data can be specified.
606 If a short form option is used, the data may follow immediately, or (with one
607 exception) in the next command line item. For example:
608 .sp
609 -f/some/file
610 -f /some/file
611 .sp
612 The exception is the \fB-o\fP option, which may appear with or without data.
613 Because of this, if data is present, it must follow immediately in the same
614 item, for example -o3.
615 .P
616 If a long form option is used, the data may appear in the same command line
617 item, separated by an equals character, or (with two exceptions) it may appear
618 in the next command line item. For example:
619 .sp
620 --file=/some/file
621 --file /some/file
622 .sp
623 Note, however, that if you want to supply a file name beginning with ~ as data
624 in a shell command, and have the shell expand ~ to a home directory, you must
625 separate the file name from the option, because the shell does not treat ~
626 specially unless it is at the start of an item.
627 .P
628 The exceptions to the above are the \fB--colour\fP (or \fB--color\fP) and
629 \fB--only-matching\fP options, for which the data is optional. If one of these
630 options does have data, it must be given in the first form, using an equals
631 character. Otherwise \fBpcregrep\fP will assume that it has no data.
632 .
633 .
634 .SH "MATCHING ERRORS"
635 .rs
636 .sp
637 It is possible to supply a regular expression that takes a very long time to
638 fail to match certain lines. Such patterns normally involve nested indefinite
639 repeats, for example: (a+)*\ed when matched against a line of a's with no final
640 digit. The PCRE matching function has a resource limit that causes it to abort
641 in these circumstances. If this happens, \fBpcregrep\fP outputs an error
642 message and the line that caused the problem to the standard error stream. If
643 there are more than 20 such errors, \fBpcregrep\fP gives up.
644 .P
645 The \fB--match-limit\fP option of \fBpcregrep\fP can be used to set the overall
646 resource limit; there is a second option called \fB--recursion-limit\fP that
647 sets a limit on the amount of memory (usually stack) that is used (see the
648 discussion of these options above).
649 .
650 .
651 .SH DIAGNOSTICS
652 .rs
653 .sp
654 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
655 for syntax errors, overlong lines, non-existent or inaccessible files (even if
656 matches were found in other files) or too many matching errors. Using the
657 \fB-s\fP option to suppress error messages about inaccessible files does not
658 affect the return code.
659 .
660 .
661 .SH "SEE ALSO"
662 .rs
663 .sp
664 \fBpcrepattern\fP(3), \fBpcresyntax\fP(3), \fBpcretest\fP(1).
665 .
666 .
667 .SH AUTHOR
668 .rs
669 .sp
670 .nf
671 Philip Hazel
672 University Computing Service
673 Cambridge CB2 3QH, England.
674 .fi
675 .
676 .
677 .SH REVISION
678 .rs
679 .sp
680 .nf
681 Last updated: 03 April 2014
682 Copyright (c) 1997-2014 University of Cambridge.
683 .fi

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