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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
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.
47 .P
48 Patterns are limited to 8K or BUFSIZ characters, whichever is the greater.
49 BUFSIZ is defined in \fB<stdio.h>\fP.
50 .P
51 If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set,
52 \fBpcregrep\fP uses the value to set a locale when calling the PCRE library.
53 The \fB--locale\fP option can be used to override this.
54 .
55 .SH OPTIONS
56 .rs
57 .TP 10
58 \fB--\fP
59 This terminate the list of options. It is useful if the next item on the
60 command line starts with a hyphen but is not an option. This allows for the
61 processing of patterns and filenames that start with hyphens.
62 .TP
63 \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
64 Output \fInumber\fP lines of context after each matching line. If filenames
65 and/or line numbers are being output, a hyphen separator is used instead of a
66 colon for the context lines. A line containing "--" is output between each
67 group of lines, unless they are in fact contiguous in the input file. The value
68 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
69 guarantees to have up to 8K of following text available for context output.
70 .TP
71 \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
72 Output \fInumber\fP lines of context before each matching line. If filenames
73 and/or line numbers are being output, a hyphen separator is used instead of a
74 colon for the context lines. A line containing "--" is output between each
75 group of lines, unless they are in fact contiguous in the input file. The value
76 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
77 guarantees to have up to 8K of preceding text available for context output.
78 .TP
79 \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
80 Output \fInumber\fP lines of context both before and after each matching line.
81 This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
82 .TP
83 \fB-c\fP, \fB--count\fP
84 Do not output individual lines; instead just output a count of the number of
85 lines that would otherwise have been output. If several files are given, a
86 count is output for each of them. In this mode, the \fB-A\fP, \fB-B\fP, and
87 \fB-C\fP options are ignored.
88 .TP
89 \fB--colour\fP, \fB--color\fP
90 If this option is given without any data, it is equivalent to "--colour=auto".
91 If data is required, it must be given in the same shell item, separated by an
92 equals sign.
93 .TP
94 \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
95 This option specifies under what circumstances the part of a line that matched
96 a pattern should be coloured in the output. The value may be "never" (the
97 default), "always", or "auto". In the latter case, colouring happens only if
98 the standard output is connected to a terminal. The colour can be specified by
99 setting the environment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value
100 of this variable should be a string of two numbers, separated by a semicolon.
101 They are copied directly into the control string for setting colour on a
102 terminal, so it is your responsibility to ensure that they make sense. If
103 neither of the environment variables is set, the default is "1;31", which gives
104 red.
105 .TP
106 \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
107 If an input path is not a regular file or a directory, "action" specifies how
108 it is to be processed. Valid values are "read" (the default) or "skip"
109 (silently skip the path).
110 .TP
111 \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
112 If an input path is a directory, "action" specifies how it is to be processed.
113 Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP
114 option), or "skip" (silently skip the path). In the default case, directories
115 are read as if they were ordinary files. In some operating systems the effect
116 of reading a directory like this is an immediate end-of-file.
117 .TP
118 \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP,
119 \fB--regexp=\fP\fIpattern\fP Specify a pattern to be matched. This option can
120 be used multiple times in order to specify several patterns. It can also be
121 used as a way of specifying a single pattern that starts with a hyphen. When
122 \fB-e\fP is used, no argument pattern is taken from the command line; all
123 arguments are treated as file names. There is an overall maximum of 100
124 patterns. They are applied to each line in the order in which they are defined
125 until one matches (or fails to match if \fB-v\fP is used). If \fB-f\fP is used
126 with \fB-e\fP, the command line patterns are matched first, followed by the
127 patterns from the file, independent of the order in which these options are
128 specified. Note that multiple use of \fB-e\fP is not the same as a single
129 pattern with alternatives. For example, X|Y finds the first character in a line
130 that is X or Y, whereas if the two patterns are given separately,
131 \fBpcregrep\fP finds X if it is present, even if it follows Y in the line. It
132 finds Y only if there is no X in the line. This really matters only if you are
133 using \fB-o\fP to show the portion of the line that matched.
134 .TP
135 \fB--exclude\fP=\fIpattern\fP
136 When \fBpcregrep\fP is searching the files in a directory as a consequence of
137 the \fB-r\fP (recursive search) option, any files whose names match the pattern
138 are excluded. The pattern is a PCRE regular expression. If a file name matches
139 both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no short
140 form for this option.
141 .TP
142 \fB-F\fP, \fB--fixed-strings\fP
143 Interpret each pattern as a list of fixed strings, separated by newlines,
144 instead of as a regular expression. The \fB-w\fP (match as a word) and \fB-x\fP
145 (match whole line) options can be used with \fB-F\fP. They apply to each of the
146 fixed strings. A line is selected if any of the fixed strings are found in it
147 (subject to \fB-w\fP or \fB-x\fP, if present).
148 .TP
149 \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
150 Read a number of patterns from the file, one per line, and match them against
151 each line of input. A data line is output if any of the patterns match it. The
152 filename can be given as "-" to refer to the standard input. When \fB-f\fP is
153 used, patterns specified on the command line using \fB-e\fP may also be
154 present; they are tested before the file's patterns. However, no other pattern
155 is taken from the command line; all arguments are treated as file names. There
156 is an overall maximum of 100 patterns. Trailing white space is removed from
157 each line, and blank lines are ignored. An empty file contains no patterns and
158 therefore matches nothing.
159 .TP
160 \fB-H\fP, \fB--with-filename\fP
161 Force the inclusion of the filename at the start of output lines when searching
162 a single file. By default, the filename is not shown in this case. For matching
163 lines, the filename is followed by a colon and a space; for context lines, a
164 hyphen separator is used. If a line number is also being output, it follows the
165 file name without a space.
166 .TP
167 \fB-h\fP, \fB--no-filename\fP
168 Suppress the output filenames when searching multiple files. By default,
169 filenames are shown when multiple files are searched. For matching lines, the
170 filename is followed by a colon and a space; for context lines, a hyphen
171 separator is used. If a line number is also being output, it follows the file
172 name without a space.
173 .TP
174 \fB--help\fP
175 Output a brief help message and exit.
176 .TP
177 \fB-i\fP, \fB--ignore-case\fP
178 Ignore upper/lower case distinctions during comparisons.
179 .TP
180 \fB--include\fP=\fIpattern\fP
181 When \fBpcregrep\fP is searching the files in a directory as a consequence of
182 the \fB-r\fP (recursive search) option, only those files whose names match the
183 pattern are included. The pattern is a PCRE regular expression. If a file name
184 matches both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no
185 short form for this option.
186 .TP
187 \fB-L\fP, \fB--files-without-match\fP
188 Instead of outputting lines from the files, just output the names of the files
189 that do not contain any lines that would have been output. Each file name is
190 output once, on a separate line.
191 .TP
192 \fB-l\fP, \fB--files-with-matches\fP
193 Instead of outputting lines from the files, just output the names of the files
194 containing lines that would have been output. Each file name is output
195 once, on a separate line. Searching stops as soon as a matching line is found
196 in a file.
197 .TP
198 \fB--label\fP=\fIname\fP
199 This option supplies a name to be used for the standard input when file names
200 are being output. If not supplied, "(standard input)" is used. There is no
201 short form for this option.
202 .TP
203 \fB--locale\fP=\fIlocale-name\fP
204 This option specifies a locale to be used for pattern matching. It overrides
205 the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
206 locale is specified, the PCRE library's default (usually the "C" locale) is
207 used. There is no short form for this option.
208 .TP
209 \fB-M\fP, \fB--multiline\fP
210 Allow patterns to match more than one line. When this option is given, patterns
211 may usefully contain literal newline characters and internal occurrences of ^
212 and $ characters. The output for any one match may consist of more than one
213 line. When this option is set, the PCRE library is called in "multiline" mode.
214 There is a limit to the number of lines that can be matched, imposed by the way
215 that \fBpcregrep\fP buffers the input file as it scans it. However,
216 \fBpcregrep\fP ensures that at least 8K characters or the rest of the document
217 (whichever is the shorter) are available for forward matching, and similarly
218 the previous 8K characters (or all the previous characters, if fewer than 8K)
219 are guaranteed to be available for lookbehind assertions.
220 .TP
221 \fB-n\fP, \fB--line-number\fP
222 Precede each output line by its line number in the file, followed by a colon
223 and a space for matching lines or a hyphen and a space for context lines. If
224 the filename is also being output, it precedes the line number.
225 .TP
226 \fB-o\fP, \fB--only-matching\fP
227 Show only the part of the line that matched a pattern. In this mode, no
228 context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are
229 ignored.
230 .TP
231 \fB-q\fP, \fB--quiet\fP
232 Work quietly, that is, display nothing except error messages. The exit
233 status indicates whether or not any matches were found.
234 .TP
235 \fB-r\fP, \fB--recursive\fP
236 If any given path is a directory, recursively scan the files it contains,
237 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
238 directory is read as a normal file; in some operating systems this gives an
239 immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
240 option to "recurse".
241 .TP
242 \fB-s\fP, \fB--no-messages\fP
243 Suppress error messages about non-existent or unreadable files. Such files are
244 quietly skipped. However, the return code is still 2, even if matches were
245 found in other files.
246 .TP
247 \fB-u\fP, \fB--utf-8\fP
248 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
249 with UTF-8 support. Both patterns and subject lines must be valid strings of
250 UTF-8 characters.
251 .TP
252 \fB-V\fP, \fB--version\fP
253 Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
254 used to the standard error stream.
255 .TP
256 \fB-v\fP, \fB--invert-match\fP
257 Invert the sense of the match, so that lines which do \fInot\fP match any of
258 the patterns are the ones that are found.
259 .TP
260 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
261 Force the patterns to match only whole words. This is equivalent to having \eb
262 at the start and end of the pattern.
263 .TP
264 \fB-x\fP, \fB--line-regex\fP, \fP--line-regexp\fP
265 Force the patterns to be anchored (each must start matching at the beginning of
266 a line) and in addition, require them to match entire lines. This is
267 equivalent to having ^ and $ characters at the start and end of each
268 alternative branch in every pattern.
269 .
270 .
271 .SH "ENVIRONMENT VARIABLES"
272 .rs
273 .sp
274 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
275 order, for a locale. The first one that is set is used. This can be overridden
276 by the \fB--locale\fP option. If no locale is set, the PCRE library's default
277 (usually the "C" locale) is used.
278 .
279 .
280 .SH "OPTIONS COMPATIBILITY"
281 .rs
282 .sp
283 The majority of short and long forms of \fBpcregrep\fP's options are the same
284 as in the GNU \fBgrep\fP program. Any long option of the form
285 \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
286 (PCRE terminology). However, the \fB--locale\fP, \fB-M\fP, \fB--multiline\fP,
287 \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP.
288 .
289 .
290 .SH "OPTIONS WITH DATA"
291 .rs
292 .sp
293 There are four different ways in which an option with data can be specified.
294 If a short form option is used, the data may follow immediately, or in the next
295 command line item. For example:
296 .sp
297 -f/some/file
298 -f /some/file
299 .sp
300 If a long form option is used, the data may appear in the same command line
301 item, separated by an equals character, or (with one exception) it may appear
302 in the next command line item. For example:
303 .sp
304 --file=/some/file
305 --file /some/file
306 .sp
307 Note, however, that if you want to supply a file name beginning with ~ as data
308 in a shell command, and have the shell expand ~ to a home directory, you must
309 separate the file name from the option, because the shell does not treat ~
310 specially unless it is at the start of an item.
311 .P
312 The exception to the above is the \fB--colour\fP (or \fB--color\fP) option,
313 for which the data is optional. If this option does have data, it must be given
314 in the first form, using an equals character. Otherwise it will be assumed that
315 it has no data.
316 .
317 .
318 .SH MATCHING ERRORS
319 .rs
320 .sp
321 It is possible to supply a regular expression that takes a very long time to
322 fail to match certain lines. Such patterns normally involve nested indefinite
323 repeats, for example: (a+)*\ed when matched against a line of a's with no final
324 digit. The PCRE matching function has a resource limit that causes it to abort
325 in these circumstances. If this happens, \fBpcregrep\fP outputs an error
326 message and the line that caused the problem to the standard error stream. If
327 there are more than 20 such errors, \fBpcregrep\fP gives up.
328 .
329 .
330 .SH DIAGNOSTICS
331 .rs
332 .sp
333 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
334 for syntax errors and non-existent or inacessible files (even if matches were
335 found in other files) or too many matching errors. Using the \fB-s\fP option to
336 suppress error messages about inaccessble files does not affect the return
337 code.
338 .
339 .
340 .SH AUTHOR
341 .rs
342 .sp
343 Philip Hazel
344 .br
345 University Computing Service
346 .br
347 Cambridge CB2 3QG, England.
348 .P
349 .in 0
350 Last updated: 23 January 2006
351 .br
352 Copyright (c) 1997-2006 University of Cambridge.

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