/[pcre]/code/trunk/doc/pcregrep.1
ViewVC logotype

Contents of /code/trunk/doc/pcregrep.1

Parent Directory Parent Directory | Revision Log Revision Log


Revision 654 - (show annotations)
Tue Aug 2 11:00:40 2011 UTC (8 years, 1 month ago) by ph10
File size: 29417 byte(s)
Error occurred while calculating annotation data.
Documentation and general text tidies in preparation for test release.
1 .TH PCREGREP 1
2 .SH NAME
3 pcregrep - a grep with Perl-compatible regular expressions.
4 .SH SYNOPSIS
5 .B pcregrep [options] [long options] [pattern] [path1 path2 ...]
6 .
7 .SH DESCRIPTION
8 .rs
9 .sp
10 \fBpcregrep\fP searches files for character patterns, in the same way as other
11 grep commands do, but it uses the PCRE regular expression library to support
12 patterns that are compatible with the regular expressions of Perl 5. See
13 .\" HREF
14 \fBpcrepattern\fP(3)
15 .\"
16 for a full description of syntax and semantics of the regular expressions
17 that PCRE supports.
18 .P
19 Patterns, whether supplied on the command line or in a separate file, are given
20 without delimiters. For example:
21 .sp
22 pcregrep Thursday /etc/motd
23 .sp
24 If you attempt to use delimiters (for example, by surrounding a pattern with
25 slashes, as is common in Perl scripts), they are interpreted as part of the
26 pattern. Quotes can of course be used to delimit patterns on the command line
27 because they are interpreted by the shell, and indeed they are required if a
28 pattern contains white space or shell metacharacters.
29 .P
30 The first argument that follows any option settings is treated as the single
31 pattern to be matched when neither \fB-e\fP nor \fB-f\fP is present.
32 Conversely, when one or both of these options are used to specify patterns, all
33 arguments are treated as path names. At least one of \fB-e\fP, \fB-f\fP, or an
34 argument pattern must be provided.
35 .P
36 If no files are specified, \fBpcregrep\fP reads the standard input. The
37 standard input can also be referenced by a name consisting of a single hyphen.
38 For example:
39 .sp
40 pcregrep some-pattern /file1 - /file3
41 .sp
42 By default, each line that matches a pattern is copied to the standard
43 output, and if there is more than one file, the file name is output at the
44 start of each line, followed by a colon. However, there are options that can
45 change how \fBpcregrep\fP behaves. In particular, the \fB-M\fP option makes it
46 possible to search for patterns that span line boundaries. What defines a line
47 boundary is controlled by the \fB-N\fP (\fB--newline\fP) option.
48 .P
49 The amount of memory used for buffering files that are being scanned is
50 controlled by a parameter that can be set by the \fB--buffer-size\fP option.
51 The default value for this parameter is specified when \fBpcregrep\fP is built,
52 with the default default being 20K. A block of memory three times this size is
53 used (to allow for buffering "before" and "after" lines). An error occurs if a
54 line overflows the buffer.
55 .P
56 Patterns are limited to 8K or BUFSIZ bytes, whichever is the greater. BUFSIZ is
57 defined in \fB<stdio.h>\fP. When there is more than one pattern (specified by
58 the use of \fB-e\fP and/or \fB-f\fP), each pattern is applied to each line in
59 the order in which they are defined, except that all the \fB-e\fP patterns are
60 tried before the \fB-f\fP patterns.
61 .P
62 By default, as soon as one pattern matches (or fails to match when \fB-v\fP is
63 used), no further patterns are considered. However, if \fB--colour\fP (or
64 \fB--color\fP) is used to colour the matching substrings, or if
65 \fB--only-matching\fP, \fB--file-offsets\fP, or \fB--line-offsets\fP is used to
66 output only the part of the line that matched (either shown literally, or as an
67 offset), scanning resumes immediately following the match, so that further
68 matches on the same line can be found. If there are multiple patterns, they are
69 all tried on the remainder of the line, but patterns that follow the one that
70 matched are not tried on the earlier part of the line.
71 .P
72 This is the same behaviour as GNU grep, but it does mean that the order in
73 which multiple patterns are specified can affect the output when one of the
74 above options is used.
75 .P
76 Patterns that can match an empty string are accepted, but empty string
77 matches are never recognized. An example is the pattern "(super)?(man)?", in
78 which all components are optional. This pattern finds all occurrences of both
79 "super" and "man"; the output differs from matching with "super|man" when only
80 the matching substrings are being shown.
81 .P
82 If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set,
83 \fBpcregrep\fP uses the value to set a locale when calling the PCRE library.
84 The \fB--locale\fP option can be used to override this.
85 .
86 .SH "SUPPORT FOR COMPRESSED FILES"
87 .rs
88 .sp
89 It is possible to compile \fBpcregrep\fP so that it uses \fBlibz\fP or
90 \fBlibbz2\fP to read files whose names end in \fB.gz\fP or \fB.bz2\fP,
91 respectively. You can find out whether your binary has support for one or both
92 of these file types by running it with the \fB--help\fP option. If the
93 appropriate support is not present, files are treated as plain text. The
94 standard input is always so treated.
95 .
96 .
97 .SH OPTIONS
98 .rs
99 .sp
100 The order in which some of the options appear can affect the output. For
101 example, both the \fB-h\fP and \fB-l\fP options affect the printing of file
102 names. Whichever comes later in the command line will be the one that takes
103 effect. Numerical values for options may be followed by K or M, to signify
104 multiplication by 1024 or 1024*1024 respectively.
105 .TP 10
106 \fB--\fP
107 This terminates the list of options. It is useful if the next item on the
108 command line starts with a hyphen but is not an option. This allows for the
109 processing of patterns and filenames that start with hyphens.
110 .TP
111 \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
112 Output \fInumber\fP lines of context after each matching line. If filenames
113 and/or line numbers are being output, a hyphen separator is used instead of a
114 colon for the context lines. A line containing "--" is output between each
115 group of lines, unless they are in fact contiguous in the input file. The value
116 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
117 guarantees to have up to 8K of following text available for context output.
118 .TP
119 \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
120 Output \fInumber\fP lines of context before each matching line. If filenames
121 and/or line numbers are being output, a hyphen separator is used instead of a
122 colon for the context lines. A line containing "--" is output between each
123 group of lines, unless they are in fact contiguous in the input file. The value
124 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
125 guarantees to have up to 8K of preceding text available for context output.
126 .TP
127 \fB--buffer-size=\fP\fInumber\fP
128 Set the parameter that controls how much memory is used for buffering files
129 that are being scanned.
130 .TP
131 \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
132 Output \fInumber\fP lines of context both before and after each matching line.
133 This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
134 .TP
135 \fB-c\fP, \fB--count\fP
136 Do not output individual lines from the files that are being scanned; instead
137 output the number of lines that would otherwise have been shown. If no lines
138 are selected, the number zero is output. If several files are are being
139 scanned, a count is output for each of them. However, if the
140 \fB--files-with-matches\fP option is also used, only those files whose counts
141 are greater than zero are listed. When \fB-c\fP is used, the \fB-A\fP,
142 \fB-B\fP, and \fB-C\fP options are ignored.
143 .TP
144 \fB--colour\fP, \fB--color\fP
145 If this option is given without any data, it is equivalent to "--colour=auto".
146 If data is required, it must be given in the same shell item, separated by an
147 equals sign.
148 .TP
149 \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
150 This option specifies under what circumstances the parts of a line that matched
151 a pattern should be coloured in the output. By default, the output is not
152 coloured. The value (which is optional, see above) may be "never", "always", or
153 "auto". In the latter case, colouring happens only if the standard output is
154 connected to a terminal. More resources are used when colouring is enabled,
155 because \fBpcregrep\fP has to search for all possible matches in a line, not
156 just one, in order to colour them all.
157 .sp
158 The colour that is used can be specified by setting the environment variable
159 PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
160 string of two numbers, separated by a semicolon. They are copied directly into
161 the control string for setting colour on a terminal, so it is your
162 responsibility to ensure that they make sense. If neither of the environment
163 variables is set, the default is "1;31", which gives red.
164 .TP
165 \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
166 If an input path is not a regular file or a directory, "action" specifies how
167 it is to be processed. Valid values are "read" (the default) or "skip"
168 (silently skip the path).
169 .TP
170 \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
171 If an input path is a directory, "action" specifies how it is to be processed.
172 Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP
173 option), or "skip" (silently skip the path). In the default case, directories
174 are read as if they were ordinary files. In some operating systems the effect
175 of reading a directory like this is an immediate end-of-file.
176 .TP
177 \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP, \fB--regexp=\fP\fIpattern\fP
178 Specify a pattern to be matched. This option can be used multiple times in
179 order to specify several patterns. It can also be used as a way of specifying a
180 single pattern that starts with a hyphen. When \fB-e\fP is used, no argument
181 pattern is taken from the command line; all arguments are treated as file
182 names. There is an overall maximum of 100 patterns. They are applied to each
183 line in the order in which they are defined until one matches (or fails to
184 match if \fB-v\fP is used). If \fB-f\fP is used with \fB-e\fP, the command line
185 patterns are matched first, followed by the patterns from the file, independent
186 of the order in which these options are specified. Note that multiple use of
187 \fB-e\fP is not the same as a single pattern with alternatives. For example,
188 X|Y finds the first character in a line that is X or Y, whereas if the two
189 patterns are given separately, \fBpcregrep\fP finds X if it is present, even if
190 it follows Y in the line. It finds Y only if there is no X in the line. This
191 really matters only if you are using \fB-o\fP to show the part(s) of the line
192 that matched.
193 .TP
194 \fB--exclude\fP=\fIpattern\fP
195 When \fBpcregrep\fP is searching the files in a directory as a consequence of
196 the \fB-r\fP (recursive search) option, any regular files whose names match the
197 pattern are excluded. Subdirectories are not excluded by this option; they are
198 searched recursively, subject to the \fB--exclude-dir\fP and
199 \fB--include_dir\fP options. The pattern is a PCRE regular expression, and is
200 matched against the final component of the file name (not the entire path). If
201 a file name matches both \fB--include\fP and \fB--exclude\fP, it is excluded.
202 There is no short form for this option.
203 .TP
204 \fB--exclude-dir\fP=\fIpattern\fP
205 When \fBpcregrep\fP is searching the contents of a directory as a consequence
206 of the \fB-r\fP (recursive search) option, any subdirectories whose names match
207 the pattern are excluded. (Note that the \fP--exclude\fP option does not affect
208 subdirectories.) The pattern is a PCRE regular expression, and is matched
209 against the final component of the name (not the entire path). If a
210 subdirectory name matches both \fB--include-dir\fP and \fB--exclude-dir\fP, it
211 is excluded. There is no short form for this option.
212 .TP
213 \fB-F\fP, \fB--fixed-strings\fP
214 Interpret each pattern as a list of fixed strings, separated by newlines,
215 instead of as a regular expression. The \fB-w\fP (match as a word) and \fB-x\fP
216 (match whole line) options can be used with \fB-F\fP. They apply to each of the
217 fixed strings. A line is selected if any of the fixed strings are found in it
218 (subject to \fB-w\fP or \fB-x\fP, if present).
219 .TP
220 \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
221 Read a number of patterns from the file, one per line, and match them against
222 each line of input. A data line is output if any of the patterns match it. The
223 filename can be given as "-" to refer to the standard input. When \fB-f\fP is
224 used, patterns specified on the command line using \fB-e\fP may also be
225 present; they are tested before the file's patterns. However, no other pattern
226 is taken from the command line; all arguments are treated as file names. There
227 is an overall maximum of 100 patterns. Trailing white space is removed from
228 each line, and blank lines are ignored. An empty file contains no patterns and
229 therefore matches nothing. See also the comments about multiple patterns versus
230 a single pattern with alternatives in the description of \fB-e\fP above.
231 .TP
232 \fB--file-offsets\fP
233 Instead of showing lines or parts of lines that match, show each match as an
234 offset from the start of the file and a length, separated by a comma. In this
235 mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP
236 options are ignored. If there is more than one match in a line, each of them is
237 shown separately. This option is mutually exclusive with \fB--line-offsets\fP
238 and \fB--only-matching\fP.
239 .TP
240 \fB-H\fP, \fB--with-filename\fP
241 Force the inclusion of the filename at the start of output lines when searching
242 a single file. By default, the filename is not shown in this case. For matching
243 lines, the filename is followed by a colon; for context lines, a hyphen
244 separator is used. If a line number is also being output, it follows the file
245 name.
246 .TP
247 \fB-h\fP, \fB--no-filename\fP
248 Suppress the output filenames when searching multiple files. By default,
249 filenames are shown when multiple files are searched. For matching lines, the
250 filename is followed by a colon; for context lines, a hyphen separator is used.
251 If a line number is also being output, it follows the file name.
252 .TP
253 \fB--help\fP
254 Output a help message, giving brief details of the command options and file
255 type support, and then exit.
256 .TP
257 \fB-i\fP, \fB--ignore-case\fP
258 Ignore upper/lower case distinctions during comparisons.
259 .TP
260 \fB--include\fP=\fIpattern\fP
261 When \fBpcregrep\fP is searching the files in a directory as a consequence of
262 the \fB-r\fP (recursive search) option, only those regular files whose names
263 match the pattern are included. Subdirectories are always included and searched
264 recursively, subject to the \fP--include-dir\fP and \fB--exclude-dir\fP
265 options. The pattern is a PCRE regular expression, and is matched against the
266 final component of the file name (not the entire path). If a file name matches
267 both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no short
268 form for this option.
269 .TP
270 \fB--include-dir\fP=\fIpattern\fP
271 When \fBpcregrep\fP is searching the contents of a directory as a consequence
272 of the \fB-r\fP (recursive search) option, only those subdirectories whose
273 names match the pattern are included. (Note that the \fB--include\fP option
274 does not affect subdirectories.) The pattern is a PCRE regular expression, and
275 is matched against the final component of the name (not the entire path). If a
276 subdirectory name matches both \fB--include-dir\fP and \fB--exclude-dir\fP, it
277 is excluded. There is no short form for this option.
278 .TP
279 \fB-L\fP, \fB--files-without-match\fP
280 Instead of outputting lines from the files, just output the names of the files
281 that do not contain any lines that would have been output. Each file name is
282 output once, on a separate line.
283 .TP
284 \fB-l\fP, \fB--files-with-matches\fP
285 Instead of outputting lines from the files, just output the names of the files
286 containing lines that would have been output. Each file name is output
287 once, on a separate line. Searching normally stops as soon as a matching line
288 is found in a file. However, if the \fB-c\fP (count) option is also used,
289 matching continues in order to obtain the correct count, and those files that
290 have at least one match are listed along with their counts. Using this option
291 with \fB-c\fP is a way of suppressing the listing of files with no matches.
292 .TP
293 \fB--label\fP=\fIname\fP
294 This option supplies a name to be used for the standard input when file names
295 are being output. If not supplied, "(standard input)" is used. There is no
296 short form for this option.
297 .TP
298 \fB--line-buffered\fP
299 When this option is given, input is read and processed line by line, and the
300 output is flushed after each write. By default, input is read in large chunks,
301 unless \fBpcregrep\fP can determine that it is reading from a terminal (which
302 is currently possible only in Unix environments). Output to terminal is
303 normally automatically flushed by the operating system. This option can be
304 useful when the input or output is attached to a pipe and you do not want
305 \fBpcregrep\fP to buffer up large amounts of data. However, its use will affect
306 performance, and the \fB-M\fP (multiline) option ceases to work.
307 .TP
308 \fB--line-offsets\fP
309 Instead of showing lines or parts of lines that match, show each match as a
310 line number, the offset from the start of the line, and a length. The line
311 number is terminated by a colon (as usual; see the \fB-n\fP option), and the
312 offset and length are separated by a comma. In this mode, no context is shown.
313 That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are ignored. If there is
314 more than one match in a line, each of them is shown separately. This option is
315 mutually exclusive with \fB--file-offsets\fP and \fB--only-matching\fP.
316 .TP
317 \fB--locale\fP=\fIlocale-name\fP
318 This option specifies a locale to be used for pattern matching. It overrides
319 the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
320 locale is specified, the PCRE library's default (usually the "C" locale) is
321 used. There is no short form for this option.
322 .TP
323 \fB--match-limit\fP=\fInumber\fP
324 Processing some regular expression patterns can require a very large amount of
325 memory, leading in some cases to a program crash if not enough is available.
326 Other patterns may take a very long time to search for all possible matching
327 strings. The \fBpcre_exec()\fP function that is called by \fBpcregrep\fP to do
328 the matching has two parameters that can limit the resources that it uses.
329 .sp
330 The \fB--match-limit\fP option provides a means of limiting resource usage
331 when processing patterns that are not going to match, but which have a very
332 large number of possibilities in their search trees. The classic example is a
333 pattern that uses nested unlimited repeats. Internally, PCRE uses a function
334 called \fBmatch()\fP which it calls repeatedly (sometimes recursively). The
335 limit set by \fB--match-limit\fP is imposed on the number of times this
336 function is called during a match, which has the effect of limiting the amount
337 of backtracking that can take place.
338 .sp
339 The \fB--recursion-limit\fP option is similar to \fB--match-limit\fP, but
340 instead of limiting the total number of times that \fBmatch()\fP is called, it
341 limits the depth of recursive calls, which in turn limits the amount of memory
342 that can be used. The recursion depth is a smaller number than the total number
343 of calls, because not all calls to \fBmatch()\fP are recursive. This limit is
344 of use only if it is set smaller than \fB--match-limit\fP.
345 .sp
346 There are no short forms for these options. The default settings are specified
347 when the PCRE library is compiled, with the default default being 10 million.
348 .TP
349 \fB-M\fP, \fB--multiline\fP
350 Allow patterns to match more than one line. When this option is given, patterns
351 may usefully contain literal newline characters and internal occurrences of ^
352 and $ characters. The output for a successful match may consist of more than
353 one line, the last of which is the one in which the match ended. If the matched
354 string ends with a newline sequence the output ends at the end of that line.
355 .sp
356 When this option is set, the PCRE library is called in "multiline" mode.
357 There is a limit to the number of lines that can be matched, imposed by the way
358 that \fBpcregrep\fP buffers the input file as it scans it. However,
359 \fBpcregrep\fP ensures that at least 8K characters or the rest of the document
360 (whichever is the shorter) are available for forward matching, and similarly
361 the previous 8K characters (or all the previous characters, if fewer than 8K)
362 are guaranteed to be available for lookbehind assertions. This option does not
363 work when input is read line by line (see \fP--line-buffered\fP.)
364 .TP
365 \fB-N\fP \fInewline-type\fP, \fB--newline\fP=\fInewline-type\fP
366 The PCRE library supports five different conventions for indicating
367 the ends of lines. They are the single-character sequences CR (carriage return)
368 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
369 which recognizes any of the preceding three types, and an "any" convention, in
370 which any Unicode line ending sequence is assumed to end a line. The Unicode
371 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
372 (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
373 PS (paragraph separator, U+2029).
374 .sp
375 When the PCRE library is built, a default line-ending sequence is specified.
376 This is normally the standard sequence for the operating system. Unless
377 otherwise specified by this option, \fBpcregrep\fP uses the library's default.
378 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
379 makes it possible to use \fBpcregrep\fP on files that have come from other
380 environments without having to modify their line endings. If the data that is
381 being scanned does not agree with the convention set by this option,
382 \fBpcregrep\fP may behave in strange ways.
383 .TP
384 \fB-n\fP, \fB--line-number\fP
385 Precede each output line by its line number in the file, followed by a colon
386 for matching lines or a hyphen for context lines. If the filename is also being
387 output, it precedes the line number. This option is forced if
388 \fB--line-offsets\fP is used.
389 .TP
390 \fB-o\fP, \fB--only-matching\fP
391 Show only the part of the line that matched a pattern instead of the whole
392 line. In this mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and
393 \fB-C\fP options are ignored. If there is more than one match in a line, each
394 of them is shown separately. If \fB-o\fP is combined with \fB-v\fP (invert the
395 sense of the match to find non-matching lines), no output is generated, but the
396 return code is set appropriately. If the matched portion of the line is empty,
397 nothing is output unless the file name or line number are being printed, in
398 which case they are shown on an otherwise empty line. This option is mutually
399 exclusive with \fB--file-offsets\fP and \fB--line-offsets\fP.
400 .TP
401 \fB-o\fP\fInumber\fP, \fB--only-matching\fP=\fInumber\fP
402 Show only the part of the line that matched the capturing parentheses of the
403 given number. Up to 32 capturing parentheses are supported. Because these
404 options can be given without an argument (see above), if an argument is
405 present, it must be given in the same shell item, for example, -o3 or
406 --only-matching=2. The comments given for the non-argument case above also
407 apply to this case. If the specified capturing parentheses do not exist in the
408 pattern, or were not set in the match, nothing is output unless the file name
409 or line number are being printed.
410 .TP
411 \fB-q\fP, \fB--quiet\fP
412 Work quietly, that is, display nothing except error messages. The exit
413 status indicates whether or not any matches were found.
414 .TP
415 \fB-r\fP, \fB--recursive\fP
416 If any given path is a directory, recursively scan the files it contains,
417 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
418 directory is read as a normal file; in some operating systems this gives an
419 immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
420 option to "recurse".
421 .TP
422 \fB--recursion-limit\fP=\fInumber\fP
423 See \fB--match-limit\fP above.
424 .TP
425 \fB-s\fP, \fB--no-messages\fP
426 Suppress error messages about non-existent or unreadable files. Such files are
427 quietly skipped. However, the return code is still 2, even if matches were
428 found in other files.
429 .TP
430 \fB-u\fP, \fB--utf-8\fP
431 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
432 with UTF-8 support. Both patterns and subject lines must be valid strings of
433 UTF-8 characters.
434 .TP
435 \fB-V\fP, \fB--version\fP
436 Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
437 used to the standard error stream.
438 .TP
439 \fB-v\fP, \fB--invert-match\fP
440 Invert the sense of the match, so that lines which do \fInot\fP match any of
441 the patterns are the ones that are found.
442 .TP
443 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
444 Force the patterns to match only whole words. This is equivalent to having \eb
445 at the start and end of the pattern.
446 .TP
447 \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
448 Force the patterns to be anchored (each must start matching at the beginning of
449 a line) and in addition, require them to match entire lines. This is
450 equivalent to having ^ and $ characters at the start and end of each
451 alternative branch in every pattern.
452 .
453 .
454 .SH "ENVIRONMENT VARIABLES"
455 .rs
456 .sp
457 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
458 order, for a locale. The first one that is set is used. This can be overridden
459 by the \fB--locale\fP option. If no locale is set, the PCRE library's default
460 (usually the "C" locale) is used.
461 .
462 .
463 .SH "NEWLINES"
464 .rs
465 .sp
466 The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
467 different newline conventions from the default. However, the setting of this
468 option does not affect the way in which \fBpcregrep\fP writes information to
469 the standard error and output streams. It uses the string "\en" in C
470 \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to
471 convert this to an appropriate sequence if the output is sent to a file.
472 .
473 .
474 .SH "OPTIONS COMPATIBILITY"
475 .rs
476 .sp
477 Many of the short and long forms of \fBpcregrep\fP's options are the same
478 as in the GNU \fBgrep\fP program (version 2.5.4). Any long option of the form
479 \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
480 (PCRE terminology). However, the \fB--file-offsets\fP, \fB--include-dir\fP,
481 \fB--line-offsets\fP, \fB--locale\fP, \fB--match-limit\fP, \fB-M\fP,
482 \fB--multiline\fP, \fB-N\fP, \fB--newline\fP, \fB--recursion-limit\fP,
483 \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP, as is the
484 use of the \fB--only-matching\fP option with a capturing parentheses number.
485 .P
486 Although most of the common options work the same way, a few are different in
487 \fBpcregrep\fP. For example, the \fB--include\fP option's argument is a glob
488 for GNU \fBgrep\fP, but a regular expression for \fBpcregrep\fP. If both the
489 \fB-c\fP and \fB-l\fP options are given, GNU grep lists only file names,
490 without counts, but \fBpcregrep\fP gives the counts.
491 .
492 .
493 .SH "OPTIONS WITH DATA"
494 .rs
495 .sp
496 There are four different ways in which an option with data can be specified.
497 If a short form option is used, the data may follow immediately, or (with one
498 exception) in the next command line item. For example:
499 .sp
500 -f/some/file
501 -f /some/file
502 .sp
503 The exception is the \fB-o\fP option, which may appear with or without data.
504 Because of this, if data is present, it must follow immediately in the same
505 item, for example -o3.
506 .P
507 If a long form option is used, the data may appear in the same command line
508 item, separated by an equals character, or (with two exceptions) it may appear
509 in the next command line item. For example:
510 .sp
511 --file=/some/file
512 --file /some/file
513 .sp
514 Note, however, that if you want to supply a file name beginning with ~ as data
515 in a shell command, and have the shell expand ~ to a home directory, you must
516 separate the file name from the option, because the shell does not treat ~
517 specially unless it is at the start of an item.
518 .P
519 The exceptions to the above are the \fB--colour\fP (or \fB--color\fP) and
520 \fB--only-matching\fP options, for which the data is optional. If one of these
521 options does have data, it must be given in the first form, using an equals
522 character. Otherwise \fBpcregrep\fP will assume that it has no data.
523 .
524 .
525 .SH "MATCHING ERRORS"
526 .rs
527 .sp
528 It is possible to supply a regular expression that takes a very long time to
529 fail to match certain lines. Such patterns normally involve nested indefinite
530 repeats, for example: (a+)*\ed when matched against a line of a's with no final
531 digit. The PCRE matching function has a resource limit that causes it to abort
532 in these circumstances. If this happens, \fBpcregrep\fP outputs an error
533 message and the line that caused the problem to the standard error stream. If
534 there are more than 20 such errors, \fBpcregrep\fP gives up.
535 .P
536 The \fB--match-limit\fP option of \fBpcregrep\fP can be used to set the overall
537 resource limit; there is a second option called \fB--recursion-limit\fP that
538 sets a limit on the amount of memory (usually stack) that is used (see the
539 discussion of these options above).
540 .
541 .
542 .SH DIAGNOSTICS
543 .rs
544 .sp
545 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
546 for syntax errors, overlong lines, non-existent or inaccessible files (even if
547 matches were found in other files) or too many matching errors. Using the
548 \fB-s\fP option to suppress error messages about inaccessible files does not
549 affect the return code.
550 .
551 .
552 .SH "SEE ALSO"
553 .rs
554 .sp
555 \fBpcrepattern\fP(3), \fBpcretest\fP(1).
556 .
557 .
558 .SH AUTHOR
559 .rs
560 .sp
561 .nf
562 Philip Hazel
563 University Computing Service
564 Cambridge CB2 3QH, England.
565 .fi
566 .
567 .
568 .SH REVISION
569 .rs
570 .sp
571 .nf
572 Last updated: 30 July 2011
573 Copyright (c) 1997-2011 University of Cambridge.
574 .fi

Properties

Name Value
svn:eol-style native
svn:keywords "Author Date Id Revision Url"

  ViewVC Help
Powered by ViewVC 1.1.5