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Tue Dec 4 20:01:43 2007 UTC (7 years, 5 months ago) by ph10
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Fix -o bugs in pcregrep.
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(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 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, 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.
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, \fB--regexp=\fP\fIpattern\fP
120 Specify a pattern to be matched. This option can be used multiple times in
121 order to specify several patterns. It can also be used as a way of specifying a
122 single pattern that starts with a hyphen. When \fB-e\fP is used, no argument
123 pattern is taken from the command line; all arguments are treated as file
124 names. There is an overall maximum of 100 patterns. They are applied to each
125 line in the order in which they are defined until one matches (or fails to
126 match if \fB-v\fP is used). If \fB-f\fP is used with \fB-e\fP, the command line
127 patterns are matched first, followed by the patterns from the file, independent
128 of the order in which these options are specified. Note that multiple use of
129 \fB-e\fP is not the same as a single pattern with alternatives. For example,
130 X|Y finds the first character in a line that is X or Y, whereas if the two
131 patterns are given separately, \fBpcregrep\fP finds X if it is present, even if
132 it follows Y in the line. It finds Y only if there is no X in the line. This
133 really matters only if you are using \fB-o\fP to show the part(s) of the line
134 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 five different conventions for indicating
224 the ends of lines. They are the single-character sequences CR (carriage return)
225 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
226 which recognizes any of the preceding three types, and an "any" convention, in
227 which any Unicode line ending sequence is assumed to end a line. The Unicode
228 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
229 (formfeed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
230 PS (paragraph separator, U+2029).
231 .sp
232 When the PCRE library is built, a default line-ending sequence is specified.
233 This is normally the standard sequence for the operating system. Unless
234 otherwise specified by this option, \fBpcregrep\fP uses the library's default.
235 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
236 makes it possible to use \fBpcregrep\fP on files that have come from other
237 environments without having to modify their line endings. If the data that is
238 being scanned does not agree with the convention set by this option,
239 \fBpcregrep\fP may behave in strange ways.
240 .TP
241 \fB-n\fP, \fB--line-number\fP
242 Precede each output line by its line number in the file, followed by a colon
243 and a space for matching lines or a hyphen and a space for context lines. If
244 the filename is also being output, it precedes the line number.
245 .TP
246 \fB-o\fP, \fB--only-matching\fP
247 Show only the part of the line that matched a pattern. In this mode, no
248 context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are
249 ignored. If there is more than one match in a line, each of them is shown
250 separately. If \fB-o\fP is combined with \fB-v\fP (invert the sense of the
251 match to find non-matching lines), no output is generated, but the return code
252 is set appropriately.
253 .TP
254 \fB-q\fP, \fB--quiet\fP
255 Work quietly, that is, display nothing except error messages. The exit
256 status indicates whether or not any matches were found.
257 .TP
258 \fB-r\fP, \fB--recursive\fP
259 If any given path is a directory, recursively scan the files it contains,
260 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
261 directory is read as a normal file; in some operating systems this gives an
262 immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
263 option to "recurse".
264 .TP
265 \fB-s\fP, \fB--no-messages\fP
266 Suppress error messages about non-existent or unreadable files. Such files are
267 quietly skipped. However, the return code is still 2, even if matches were
268 found in other files.
269 .TP
270 \fB-u\fP, \fB--utf-8\fP
271 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
272 with UTF-8 support. Both patterns and subject lines must be valid strings of
273 UTF-8 characters.
274 .TP
275 \fB-V\fP, \fB--version\fP
276 Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
277 used to the standard error stream.
278 .TP
279 \fB-v\fP, \fB--invert-match\fP
280 Invert the sense of the match, so that lines which do \fInot\fP match any of
281 the patterns are the ones that are found.
282 .TP
283 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
284 Force the patterns to match only whole words. This is equivalent to having \eb
285 at the start and end of the pattern.
286 .TP
287 \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
288 Force the patterns to be anchored (each must start matching at the beginning of
289 a line) and in addition, require them to match entire lines. This is
290 equivalent to having ^ and $ characters at the start and end of each
291 alternative branch in every pattern.
292 .
293 .
295 .rs
296 .sp
297 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
298 order, for a locale. The first one that is set is used. This can be overridden
299 by the \fB--locale\fP option. If no locale is set, the PCRE library's default
300 (usually the "C" locale) is used.
301 .
302 .
304 .rs
305 .sp
306 The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
307 different newline conventions from the default. However, the setting of this
308 option does not affect the way in which \fBpcregrep\fP writes information to
309 the standard error and output streams. It uses the string "\en" in C
310 \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to
311 convert this to an appropriate sequence if the output is sent to a file.
312 .
313 .
315 .rs
316 .sp
317 The majority of short and long forms of \fBpcregrep\fP's options are the same
318 as in the GNU \fBgrep\fP program. Any long option of the form
319 \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
320 (PCRE terminology). However, the \fB--locale\fP, \fB-M\fP, \fB--multiline\fP,
321 \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP.
322 .
323 .
325 .rs
326 .sp
327 There are four different ways in which an option with data can be specified.
328 If a short form option is used, the data may follow immediately, or in the next
329 command line item. For example:
330 .sp
331 -f/some/file
332 -f /some/file
333 .sp
334 If a long form option is used, the data may appear in the same command line
335 item, separated by an equals character, or (with one exception) it may appear
336 in the next command line item. For example:
337 .sp
338 --file=/some/file
339 --file /some/file
340 .sp
341 Note, however, that if you want to supply a file name beginning with ~ as data
342 in a shell command, and have the shell expand ~ to a home directory, you must
343 separate the file name from the option, because the shell does not treat ~
344 specially unless it is at the start of an item.
345 .P
346 The exception to the above is the \fB--colour\fP (or \fB--color\fP) option,
347 for which the data is optional. If this option does have data, it must be given
348 in the first form, using an equals character. Otherwise it will be assumed that
349 it has no data.
350 .
351 .
353 .rs
354 .sp
355 It is possible to supply a regular expression that takes a very long time to
356 fail to match certain lines. Such patterns normally involve nested indefinite
357 repeats, for example: (a+)*\ed when matched against a line of a's with no final
358 digit. The PCRE matching function has a resource limit that causes it to abort
359 in these circumstances. If this happens, \fBpcregrep\fP outputs an error
360 message and the line that caused the problem to the standard error stream. If
361 there are more than 20 such errors, \fBpcregrep\fP gives up.
362 .
363 .
365 .rs
366 .sp
367 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
368 for syntax errors and non-existent or inacessible files (even if matches were
369 found in other files) or too many matching errors. Using the \fB-s\fP option to
370 suppress error messages about inaccessble files does not affect the return
371 code.
372 .
373 .
374 .SH "SEE ALSO"
375 .rs
376 .sp
377 \fBpcrepattern\fP(3), \fBpcretest\fP(1).
378 .
379 .
381 .rs
382 .sp
383 .nf
384 Philip Hazel
385 University Computing Service
386 Cambridge CB2 3QH, England.
387 .fi
388 .
389 .
391 .rs
392 .sp
393 .nf
394 Last updated: 04 December 2007
395 Copyright (c) 1997-2007 University of Cambridge.
396 .fi


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