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Load pcre-6.7 into code/trunk.
3 pcregrep - a grep with Perl-compatible regular expressions.
5 .B pcregrep [options] [long options] [pattern] [path1 path2 ...]
6 .
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
15 .\"
16 for a full description of syntax and semantics of the regular expressions that
17 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 on the command line because they are
27 interpreted by the shell, and indeed they are required if a pattern contains
28 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 the 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. However, there are options that can change how
45 \fBpcregrep\fP behaves. In particular, the \fB-M\fP option makes it possible to
46 search for patterns that span line boundaries. What defines a line boundary is
47 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.
51 .P
52 If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set,
53 \fBpcregrep\fP uses the value to set a locale when calling the PCRE library.
54 The \fB--locale\fP option can be used to override this.
55 .
57 .rs
58 .TP 10
59 \fB--\fP
60 This terminate the list of options. It is useful if the next item on the
61 command line starts with a hyphen but is not an option. This allows for the
62 processing of patterns and filenames that start with hyphens.
63 .TP
64 \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
65 Output \fInumber\fP lines of context after each matching line. If filenames
66 and/or line numbers are being output, a hyphen separator is used instead of a
67 colon for the context lines. A line containing "--" is output between each
68 group of lines, unless they are in fact contiguous in the input file. The value
69 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
70 guarantees to have up to 8K of following text available for context output.
71 .TP
72 \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
73 Output \fInumber\fP lines of context before each matching line. If filenames
74 and/or line numbers are being output, a hyphen separator is used instead of a
75 colon for the context lines. A line containing "--" is output between each
76 group of lines, unless they are in fact contiguous in the input file. The value
77 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
78 guarantees to have up to 8K of preceding text available for context output.
79 .TP
80 \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
81 Output \fInumber\fP lines of context both before and after each matching line.
82 This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
83 .TP
84 \fB-c\fP, \fB--count\fP
85 Do not output individual lines; instead just output a count of the number of
86 lines that would otherwise have been output. If several files are given, a
87 count is output for each of them. In this mode, the \fB-A\fP, \fB-B\fP, and
88 \fB-C\fP options are ignored.
89 .TP
90 \fB--colour\fP, \fB--color\fP
91 If this option is given without any data, it is equivalent to "--colour=auto".
92 If data is required, it must be given in the same shell item, separated by an
93 equals sign.
94 .TP
95 \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
96 This option specifies under what circumstances the part of a line that matched
97 a pattern should be coloured in the output. The value may be "never" (the
98 default), "always", or "auto". In the latter case, colouring happens only if
99 the standard output is connected to a terminal. The colour can be specified by
100 setting the environment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value
101 of this variable should be a string of two numbers, separated by a semicolon.
102 They are copied directly into the control string for setting colour on a
103 terminal, so it is your responsibility to ensure that they make sense. If
104 neither of the environment variables is set, the default is "1;31", which gives
105 red.
106 .TP
107 \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
108 If an input path is not a regular file or a directory, "action" specifies how
109 it is to be processed. Valid values are "read" (the default) or "skip"
110 (silently skip the path).
111 .TP
112 \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
113 If an input path is a directory, "action" specifies how it is to be processed.
114 Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP
115 option), or "skip" (silently skip the path). In the default case, directories
116 are read as if they were ordinary files. In some operating systems the effect
117 of reading a directory like this is an immediate end-of-file.
118 .TP
119 \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP,
120 \fB--regexp=\fP\fIpattern\fP Specify a pattern to be matched. This option can
121 be used multiple times in order to specify several patterns. It can also be
122 used as a way of specifying a single pattern that starts with a hyphen. When
123 \fB-e\fP is used, no argument pattern is taken from the command line; all
124 arguments are treated as file names. There is an overall maximum of 100
125 patterns. They are applied to each line in the order in which they are defined
126 until one matches (or fails to match if \fB-v\fP is used). If \fB-f\fP is used
127 with \fB-e\fP, the command line patterns are matched first, followed by the
128 patterns from the file, independent of the order in which these options are
129 specified. Note that multiple use of \fB-e\fP is not the same as a single
130 pattern with alternatives. For example, X|Y finds the first character in a line
131 that is X or Y, whereas if the two patterns are given separately,
132 \fBpcregrep\fP finds X if it is present, even if it follows Y in the line. It
133 finds Y only if there is no X in the line. This really matters only if you are
134 using \fB-o\fP to show the portion of the line that matched.
135 .TP
136 \fB--exclude\fP=\fIpattern\fP
137 When \fBpcregrep\fP is searching the files in a directory as a consequence of
138 the \fB-r\fP (recursive search) option, any files whose names match the pattern
139 are excluded. The pattern is a PCRE regular expression. If a file name matches
140 both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no short
141 form for this option.
142 .TP
143 \fB-F\fP, \fB--fixed-strings\fP
144 Interpret each pattern as a list of fixed strings, separated by newlines,
145 instead of as a regular expression. The \fB-w\fP (match as a word) and \fB-x\fP
146 (match whole line) options can be used with \fB-F\fP. They apply to each of the
147 fixed strings. A line is selected if any of the fixed strings are found in it
148 (subject to \fB-w\fP or \fB-x\fP, if present).
149 .TP
150 \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
151 Read a number of patterns from the file, one per line, and match them against
152 each line of input. A data line is output if any of the patterns match it. The
153 filename can be given as "-" to refer to the standard input. When \fB-f\fP is
154 used, patterns specified on the command line using \fB-e\fP may also be
155 present; they are tested before the file's patterns. However, no other pattern
156 is taken from the command line; all arguments are treated as file names. There
157 is an overall maximum of 100 patterns. Trailing white space is removed from
158 each line, and blank lines are ignored. An empty file contains no patterns and
159 therefore matches nothing.
160 .TP
161 \fB-H\fP, \fB--with-filename\fP
162 Force the inclusion of the filename at the start of output lines when searching
163 a single file. By default, the filename is not shown in this case. For matching
164 lines, the filename is followed by a colon and a space; for context lines, a
165 hyphen separator is used. If a line number is also being output, it follows the
166 file name without a space.
167 .TP
168 \fB-h\fP, \fB--no-filename\fP
169 Suppress the output filenames when searching multiple files. By default,
170 filenames are shown when multiple files are searched. For matching lines, the
171 filename is followed by a colon and a space; for context lines, a hyphen
172 separator is used. If a line number is also being output, it follows the file
173 name without a space.
174 .TP
175 \fB--help\fP
176 Output a brief help message and exit.
177 .TP
178 \fB-i\fP, \fB--ignore-case\fP
179 Ignore upper/lower case distinctions during comparisons.
180 .TP
181 \fB--include\fP=\fIpattern\fP
182 When \fBpcregrep\fP is searching the files in a directory as a consequence of
183 the \fB-r\fP (recursive search) option, only those files whose names match the
184 pattern are included. The pattern is a PCRE regular expression. If a file name
185 matches both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no
186 short form for this option.
187 .TP
188 \fB-L\fP, \fB--files-without-match\fP
189 Instead of outputting lines from the files, just output the names of the files
190 that do not contain any lines that would have been output. Each file name is
191 output once, on a separate line.
192 .TP
193 \fB-l\fP, \fB--files-with-matches\fP
194 Instead of outputting lines from the files, just output the names of the files
195 containing lines that would have been output. Each file name is output
196 once, on a separate line. Searching stops as soon as a matching line is found
197 in a file.
198 .TP
199 \fB--label\fP=\fIname\fP
200 This option supplies a name to be used for the standard input when file names
201 are being output. If not supplied, "(standard input)" is used. There is no
202 short form for this option.
203 .TP
204 \fB--locale\fP=\fIlocale-name\fP
205 This option specifies a locale to be used for pattern matching. It overrides
206 the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
207 locale is specified, the PCRE library's default (usually the "C" locale) is
208 used. There is no short form for this option.
209 .TP
210 \fB-M\fP, \fB--multiline\fP
211 Allow patterns to match more than one line. When this option is given, patterns
212 may usefully contain literal newline characters and internal occurrences of ^
213 and $ characters. The output for any one match may consist of more than one
214 line. When this option is set, the PCRE library is called in "multiline" mode.
215 There is a limit to the number of lines that can be matched, imposed by the way
216 that \fBpcregrep\fP buffers the input file as it scans it. However,
217 \fBpcregrep\fP ensures that at least 8K characters or the rest of the document
218 (whichever is the shorter) are available for forward matching, and similarly
219 the previous 8K characters (or all the previous characters, if fewer than 8K)
220 are guaranteed to be available for lookbehind assertions.
221 .TP
222 \fB-N\fP \fInewline-type\fP, \fB--newline=\fP\fInewline-type\fP
223 The PCRE library supports three different character sequences for indicating
224 the ends of lines. They are the single-character sequences CR (carriage return)
225 and LF (linefeed), and the two-character sequence CR, LF. When the library is
226 built, a default line-ending sequence is specified. This is normally the
227 standard sequence for the operating system. Unless otherwise specified by this
228 option, \fBpcregrep\fP uses the default. The possible values for this option
229 are CR, LF, or CRLF. This makes it possible to use \fBpcregrep\fP on files that
230 have come from other environments without having to modify their line endings.
231 If the data that is being scanned does not agree with the convention set by
232 this option, \fBpcregrep\fP may behave in strange ways.
233 .TP
234 \fB-n\fP, \fB--line-number\fP
235 Precede each output line by its line number in the file, followed by a colon
236 and a space for matching lines or a hyphen and a space for context lines. If
237 the filename is also being output, it precedes the line number.
238 .TP
239 \fB-o\fP, \fB--only-matching\fP
240 Show only the part of the line that matched a pattern. In this mode, no
241 context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are
242 ignored.
243 .TP
244 \fB-q\fP, \fB--quiet\fP
245 Work quietly, that is, display nothing except error messages. The exit
246 status indicates whether or not any matches were found.
247 .TP
248 \fB-r\fP, \fB--recursive\fP
249 If any given path is a directory, recursively scan the files it contains,
250 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
251 directory is read as a normal file; in some operating systems this gives an
252 immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
253 option to "recurse".
254 .TP
255 \fB-s\fP, \fB--no-messages\fP
256 Suppress error messages about non-existent or unreadable files. Such files are
257 quietly skipped. However, the return code is still 2, even if matches were
258 found in other files.
259 .TP
260 \fB-u\fP, \fB--utf-8\fP
261 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
262 with UTF-8 support. Both patterns and subject lines must be valid strings of
263 UTF-8 characters.
264 .TP
265 \fB-V\fP, \fB--version\fP
266 Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
267 used to the standard error stream.
268 .TP
269 \fB-v\fP, \fB--invert-match\fP
270 Invert the sense of the match, so that lines which do \fInot\fP match any of
271 the patterns are the ones that are found.
272 .TP
273 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
274 Force the patterns to match only whole words. This is equivalent to having \eb
275 at the start and end of the pattern.
276 .TP
277 \fB-x\fP, \fB--line-regex\fP, \fP--line-regexp\fP
278 Force the patterns to be anchored (each must start matching at the beginning of
279 a line) and in addition, require them to match entire lines. This is
280 equivalent to having ^ and $ characters at the start and end of each
281 alternative branch in every pattern.
282 .
283 .
285 .rs
286 .sp
287 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
288 order, for a locale. The first one that is set is used. This can be overridden
289 by the \fB--locale\fP option. If no locale is set, the PCRE library's default
290 (usually the "C" locale) is used.
291 .
292 .
294 .rs
295 .sp
296 The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
297 different newline conventions from the default. However, the setting of this
298 option does not affect the way in which \fBpcregrep\fP writes information to
299 the standard error and output streams. It uses the string "\en" in C
300 \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to
301 convert this to an appropriate sequence if the output is sent to a file.
302 .
303 .
305 .rs
306 .sp
307 The majority of short and long forms of \fBpcregrep\fP's options are the same
308 as in the GNU \fBgrep\fP program. Any long option of the form
309 \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
310 (PCRE terminology). However, the \fB--locale\fP, \fB-M\fP, \fB--multiline\fP,
311 \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP.
312 .
313 .
315 .rs
316 .sp
317 There are four different ways in which an option with data can be specified.
318 If a short form option is used, the data may follow immediately, or in the next
319 command line item. For example:
320 .sp
321 -f/some/file
322 -f /some/file
323 .sp
324 If a long form option is used, the data may appear in the same command line
325 item, separated by an equals character, or (with one exception) it may appear
326 in the next command line item. For example:
327 .sp
328 --file=/some/file
329 --file /some/file
330 .sp
331 Note, however, that if you want to supply a file name beginning with ~ as data
332 in a shell command, and have the shell expand ~ to a home directory, you must
333 separate the file name from the option, because the shell does not treat ~
334 specially unless it is at the start of an item.
335 .P
336 The exception to the above is the \fB--colour\fP (or \fB--color\fP) option,
337 for which the data is optional. If this option does have data, it must be given
338 in the first form, using an equals character. Otherwise it will be assumed that
339 it has no data.
340 .
341 .
343 .rs
344 .sp
345 It is possible to supply a regular expression that takes a very long time to
346 fail to match certain lines. Such patterns normally involve nested indefinite
347 repeats, for example: (a+)*\ed when matched against a line of a's with no final
348 digit. The PCRE matching function has a resource limit that causes it to abort
349 in these circumstances. If this happens, \fBpcregrep\fP outputs an error
350 message and the line that caused the problem to the standard error stream. If
351 there are more than 20 such errors, \fBpcregrep\fP gives up.
352 .
353 .
355 .rs
356 .sp
357 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
358 for syntax errors and non-existent or inacessible files (even if matches were
359 found in other files) or too many matching errors. Using the \fB-s\fP option to
360 suppress error messages about inaccessble files does not affect the return
361 code.
362 .
363 .
365 .rs
366 .sp
367 Philip Hazel
368 .br
369 University Computing Service
370 .br
371 Cambridge CB2 3QG, England.
372 .P
373 .in 0
374 Last updated: 06 June 2006
375 .br
376 Copyright (c) 1997-2006 University of Cambridge.

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