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Revision 691 - (show annotations)
Sun Sep 11 14:31:21 2011 UTC (8 years, 5 months ago) by ph10
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Final source and document tidies for 8.20-RC1.
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 .
87 .SH "SUPPORT FOR COMPRESSED FILES"
88 .rs
89 .sp
90 It is possible to compile \fBpcregrep\fP so that it uses \fBlibz\fP or
91 \fBlibbz2\fP to read files whose names end in \fB.gz\fP or \fB.bz2\fP,
92 respectively. You can find out whether your binary has support for one or both
93 of these file types by running it with the \fB--help\fP option. If the
94 appropriate support is not present, files are treated as plain text. The
95 standard input is always so treated.
96 .
97 .
98 .SH OPTIONS
99 .rs
100 .sp
101 The order in which some of the options appear can affect the output. For
102 example, both the \fB-h\fP and \fB-l\fP options affect the printing of file
103 names. Whichever comes later in the command line will be the one that takes
104 effect. Numerical values for options may be followed by K or M, to signify
105 multiplication by 1024 or 1024*1024 respectively.
106 .TP 10
107 \fB--\fP
108 This terminates the list of options. It is useful if the next item on the
109 command line starts with a hyphen but is not an option. This allows for the
110 processing of patterns and filenames that start with hyphens.
111 .TP
112 \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
113 Output \fInumber\fP lines of context after each matching line. If filenames
114 and/or line numbers are being output, a hyphen separator is used instead of a
115 colon for the context lines. A line containing "--" is output between each
116 group of lines, unless they are in fact contiguous in the input file. The value
117 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
118 guarantees to have up to 8K of following text available for context output.
119 .TP
120 \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
121 Output \fInumber\fP lines of context before each matching line. If filenames
122 and/or line numbers are being output, a hyphen separator is used instead of a
123 colon for the context lines. A line containing "--" is output between each
124 group of lines, unless they are in fact contiguous in the input file. The value
125 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
126 guarantees to have up to 8K of preceding text available for context output.
127 .TP
128 \fB--buffer-size=\fP\fInumber\fP
129 Set the parameter that controls how much memory is used for buffering files
130 that are being scanned.
131 .TP
132 \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
133 Output \fInumber\fP lines of context both before and after each matching line.
134 This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
135 .TP
136 \fB-c\fP, \fB--count\fP
137 Do not output individual lines from the files that are being scanned; instead
138 output the number of lines that would otherwise have been shown. If no lines
139 are selected, the number zero is output. If several files are are being
140 scanned, a count is output for each of them. However, if the
141 \fB--files-with-matches\fP option is also used, only those files whose counts
142 are greater than zero are listed. When \fB-c\fP is used, the \fB-A\fP,
143 \fB-B\fP, and \fB-C\fP options are ignored.
144 .TP
145 \fB--colour\fP, \fB--color\fP
146 If this option is given without any data, it is equivalent to "--colour=auto".
147 If data is required, it must be given in the same shell item, separated by an
148 equals sign.
149 .TP
150 \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
151 This option specifies under what circumstances the parts of a line that matched
152 a pattern should be coloured in the output. By default, the output is not
153 coloured. The value (which is optional, see above) may be "never", "always", or
154 "auto". In the latter case, colouring happens only if the standard output is
155 connected to a terminal. More resources are used when colouring is enabled,
156 because \fBpcregrep\fP has to search for all possible matches in a line, not
157 just one, in order to colour them all.
158 .sp
159 The colour that is used can be specified by setting the environment variable
160 PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
161 string of two numbers, separated by a semicolon. They are copied directly into
162 the control string for setting colour on a terminal, so it is your
163 responsibility to ensure that they make sense. If neither of the environment
164 variables is set, the default is "1;31", which gives red.
165 .TP
166 \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
167 If an input path is not a regular file or a directory, "action" specifies how
168 it is to be processed. Valid values are "read" (the default) or "skip"
169 (silently skip the path).
170 .TP
171 \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
172 If an input path is a directory, "action" specifies how it is to be processed.
173 Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP
174 option), or "skip" (silently skip the path). In the default case, directories
175 are read as if they were ordinary files. In some operating systems the effect
176 of reading a directory like this is an immediate end-of-file.
177 .TP
178 \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP, \fB--regexp=\fP\fIpattern\fP
179 Specify a pattern to be matched. This option can be used multiple times in
180 order to specify several patterns. It can also be used as a way of specifying a
181 single pattern that starts with a hyphen. When \fB-e\fP is used, no argument
182 pattern is taken from the command line; all arguments are treated as file
183 names. There is an overall maximum of 100 patterns. They are applied to each
184 line in the order in which they are defined until one matches (or fails to
185 match if \fB-v\fP is used). If \fB-f\fP is used with \fB-e\fP, the command line
186 patterns are matched first, followed by the patterns from the file, independent
187 of the order in which these options are specified. Note that multiple use of
188 \fB-e\fP is not the same as a single pattern with alternatives. For example,
189 X|Y finds the first character in a line that is X or Y, whereas if the two
190 patterns are given separately, \fBpcregrep\fP finds X if it is present, even if
191 it follows Y in the line. It finds Y only if there is no X in the line. This
192 really matters only if you are using \fB-o\fP to show the part(s) of the line
193 that matched.
194 .TP
195 \fB--exclude\fP=\fIpattern\fP
196 When \fBpcregrep\fP is searching the files in a directory as a consequence of
197 the \fB-r\fP (recursive search) option, any regular files whose names match the
198 pattern are excluded. Subdirectories are not excluded by this option; they are
199 searched recursively, subject to the \fB--exclude-dir\fP and
200 \fB--include_dir\fP options. The pattern is a PCRE regular expression, and is
201 matched against the final component of the file name (not the entire path). If
202 a file name matches both \fB--include\fP and \fB--exclude\fP, it is excluded.
203 There is no short form for this option.
204 .TP
205 \fB--exclude-dir\fP=\fIpattern\fP
206 When \fBpcregrep\fP is searching the contents of a directory as a consequence
207 of the \fB-r\fP (recursive search) option, any subdirectories whose names match
208 the pattern are excluded. (Note that the \fP--exclude\fP option does not affect
209 subdirectories.) The pattern is a PCRE regular expression, and is matched
210 against the final component of the name (not the entire path). If a
211 subdirectory name matches both \fB--include-dir\fP and \fB--exclude-dir\fP, it
212 is excluded. There is no short form for this option.
213 .TP
214 \fB-F\fP, \fB--fixed-strings\fP
215 Interpret each pattern as a list of fixed strings, separated by newlines,
216 instead of as a regular expression. The \fB-w\fP (match as a word) and \fB-x\fP
217 (match whole line) options can be used with \fB-F\fP. They apply to each of the
218 fixed strings. A line is selected if any of the fixed strings are found in it
219 (subject to \fB-w\fP or \fB-x\fP, if present).
220 .TP
221 \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
222 Read a number of patterns from the file, one per line, and match them against
223 each line of input. A data line is output if any of the patterns match it. The
224 filename can be given as "-" to refer to the standard input. When \fB-f\fP is
225 used, patterns specified on the command line using \fB-e\fP may also be
226 present; they are tested before the file's patterns. However, no other pattern
227 is taken from the command line; all arguments are treated as file names. There
228 is an overall maximum of 100 patterns. Trailing white space is removed from
229 each line, and blank lines are ignored. An empty file contains no patterns and
230 therefore matches nothing. See also the comments about multiple patterns versus
231 a single pattern with alternatives in the description of \fB-e\fP above.
232 .TP
233 \fB--file-offsets\fP
234 Instead of showing lines or parts of lines that match, show each match as an
235 offset from the start of the file and a length, separated by a comma. In this
236 mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP
237 options are ignored. If there is more than one match in a line, each of them is
238 shown separately. This option is mutually exclusive with \fB--line-offsets\fP
239 and \fB--only-matching\fP.
240 .TP
241 \fB-H\fP, \fB--with-filename\fP
242 Force the inclusion of the filename at the start of output lines when searching
243 a single file. By default, the filename is not shown in this case. For matching
244 lines, the filename is followed by a colon; for context lines, a hyphen
245 separator is used. If a line number is also being output, it follows the file
246 name.
247 .TP
248 \fB-h\fP, \fB--no-filename\fP
249 Suppress the output filenames when searching multiple files. By default,
250 filenames are shown when multiple files are searched. For matching lines, the
251 filename is followed by a colon; for context lines, a hyphen separator is used.
252 If a line number is also being output, it follows the file name.
253 .TP
254 \fB--help\fP
255 Output a help message, giving brief details of the command options and file
256 type support, and then exit.
257 .TP
258 \fB-i\fP, \fB--ignore-case\fP
259 Ignore upper/lower case distinctions during comparisons.
260 .TP
261 \fB--include\fP=\fIpattern\fP
262 When \fBpcregrep\fP is searching the files in a directory as a consequence of
263 the \fB-r\fP (recursive search) option, only those regular files whose names
264 match the pattern are included. Subdirectories are always included and searched
265 recursively, subject to the \fP--include-dir\fP and \fB--exclude-dir\fP
266 options. The pattern is a PCRE regular expression, and is matched against the
267 final component of the file name (not the entire path). If a file name matches
268 both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no short
269 form for this option.
270 .TP
271 \fB--include-dir\fP=\fIpattern\fP
272 When \fBpcregrep\fP is searching the contents of a directory as a consequence
273 of the \fB-r\fP (recursive search) option, only those subdirectories whose
274 names match the pattern are included. (Note that the \fB--include\fP option
275 does not affect subdirectories.) The pattern is a PCRE regular expression, and
276 is matched against the final component of the name (not the entire path). If a
277 subdirectory name matches both \fB--include-dir\fP and \fB--exclude-dir\fP, it
278 is excluded. There is no short form for this option.
279 .TP
280 \fB-L\fP, \fB--files-without-match\fP
281 Instead of outputting lines from the files, just output the names of the files
282 that do not contain any lines that would have been output. Each file name is
283 output once, on a separate line.
284 .TP
285 \fB-l\fP, \fB--files-with-matches\fP
286 Instead of outputting lines from the files, just output the names of the files
287 containing lines that would have been output. Each file name is output
288 once, on a separate line. Searching normally stops as soon as a matching line
289 is found in a file. However, if the \fB-c\fP (count) option is also used,
290 matching continues in order to obtain the correct count, and those files that
291 have at least one match are listed along with their counts. Using this option
292 with \fB-c\fP is a way of suppressing the listing of files with no matches.
293 .TP
294 \fB--label\fP=\fIname\fP
295 This option supplies a name to be used for the standard input when file names
296 are being output. If not supplied, "(standard input)" is used. There is no
297 short form for this option.
298 .TP
299 \fB--line-buffered\fP
300 When this option is given, input is read and processed line by line, and the
301 output is flushed after each write. By default, input is read in large chunks,
302 unless \fBpcregrep\fP can determine that it is reading from a terminal (which
303 is currently possible only in Unix environments). Output to terminal is
304 normally automatically flushed by the operating system. This option can be
305 useful when the input or output is attached to a pipe and you do not want
306 \fBpcregrep\fP to buffer up large amounts of data. However, its use will affect
307 performance, and the \fB-M\fP (multiline) option ceases to work.
308 .TP
309 \fB--line-offsets\fP
310 Instead of showing lines or parts of lines that match, show each match as a
311 line number, the offset from the start of the line, and a length. The line
312 number is terminated by a colon (as usual; see the \fB-n\fP option), and the
313 offset and length are separated by a comma. In this mode, no context is shown.
314 That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are ignored. If there is
315 more than one match in a line, each of them is shown separately. This option is
316 mutually exclusive with \fB--file-offsets\fP and \fB--only-matching\fP.
317 .TP
318 \fB--locale\fP=\fIlocale-name\fP
319 This option specifies a locale to be used for pattern matching. It overrides
320 the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
321 locale is specified, the PCRE library's default (usually the "C" locale) is
322 used. There is no short form for this option.
323 .TP
324 \fB--match-limit\fP=\fInumber\fP
325 Processing some regular expression patterns can require a very large amount of
326 memory, leading in some cases to a program crash if not enough is available.
327 Other patterns may take a very long time to search for all possible matching
328 strings. The \fBpcre_exec()\fP function that is called by \fBpcregrep\fP to do
329 the matching has two parameters that can limit the resources that it uses.
330 .sp
331 The \fB--match-limit\fP option provides a means of limiting resource usage
332 when processing patterns that are not going to match, but which have a very
333 large number of possibilities in their search trees. The classic example is a
334 pattern that uses nested unlimited repeats. Internally, PCRE uses a function
335 called \fBmatch()\fP which it calls repeatedly (sometimes recursively). The
336 limit set by \fB--match-limit\fP is imposed on the number of times this
337 function is called during a match, which has the effect of limiting the amount
338 of backtracking that can take place.
339 .sp
340 The \fB--recursion-limit\fP option is similar to \fB--match-limit\fP, but
341 instead of limiting the total number of times that \fBmatch()\fP is called, it
342 limits the depth of recursive calls, which in turn limits the amount of memory
343 that can be used. The recursion depth is a smaller number than the total number
344 of calls, because not all calls to \fBmatch()\fP are recursive. This limit is
345 of use only if it is set smaller than \fB--match-limit\fP.
346 .sp
347 There are no short forms for these options. The default settings are specified
348 when the PCRE library is compiled, with the default default being 10 million.
349 .TP
350 \fB-M\fP, \fB--multiline\fP
351 Allow patterns to match more than one line. When this option is given, patterns
352 may usefully contain literal newline characters and internal occurrences of ^
353 and $ characters. The output for a successful match may consist of more than
354 one line, the last of which is the one in which the match ended. If the matched
355 string ends with a newline sequence the output ends at the end of that line.
356 .sp
357 When this option is set, the PCRE library is called in "multiline" mode.
358 There is a limit to the number of lines that can be matched, imposed by the way
359 that \fBpcregrep\fP buffers the input file as it scans it. However,
360 \fBpcregrep\fP ensures that at least 8K characters or the rest of the document
361 (whichever is the shorter) are available for forward matching, and similarly
362 the previous 8K characters (or all the previous characters, if fewer than 8K)
363 are guaranteed to be available for lookbehind assertions. This option does not
364 work when input is read line by line (see \fP--line-buffered\fP.)
365 .TP
366 \fB-N\fP \fInewline-type\fP, \fB--newline\fP=\fInewline-type\fP
367 The PCRE library supports five different conventions for indicating
368 the ends of lines. They are the single-character sequences CR (carriage return)
369 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
370 which recognizes any of the preceding three types, and an "any" convention, in
371 which any Unicode line ending sequence is assumed to end a line. The Unicode
372 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
373 (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
374 PS (paragraph separator, U+2029).
375 .sp
376 When the PCRE library is built, a default line-ending sequence is specified.
377 This is normally the standard sequence for the operating system. Unless
378 otherwise specified by this option, \fBpcregrep\fP uses the library's default.
379 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
380 makes it possible to use \fBpcregrep\fP on files that have come from other
381 environments without having to modify their line endings. If the data that is
382 being scanned does not agree with the convention set by this option,
383 \fBpcregrep\fP may behave in strange ways.
384 .TP
385 \fB-n\fP, \fB--line-number\fP
386 Precede each output line by its line number in the file, followed by a colon
387 for matching lines or a hyphen for context lines. If the filename is also being
388 output, it precedes the line number. This option is forced if
389 \fB--line-offsets\fP is used.
390 .TP
391 \fB--no-jit\fP
392 If the PCRE library is built with support for just-in-time compiling (which
393 speeds up matching), \fBpcregrep\fP automatically makes use of this, unless it
394 was explicitly disabled at build time. This option can be used to disable the
395 use of JIT at run time. It is provided for testing and working round problems.
396 It should never be needed in normal use.
397 .TP
398 \fB-o\fP, \fB--only-matching\fP
399 Show only the part of the line that matched a pattern instead of the whole
400 line. In this mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and
401 \fB-C\fP options are ignored. If there is more than one match in a line, each
402 of them is shown separately. If \fB-o\fP is combined with \fB-v\fP (invert the
403 sense of the match to find non-matching lines), no output is generated, but the
404 return code is set appropriately. If the matched portion of the line is empty,
405 nothing is output unless the file name or line number are being printed, in
406 which case they are shown on an otherwise empty line. This option is mutually
407 exclusive with \fB--file-offsets\fP and \fB--line-offsets\fP.
408 .TP
409 \fB-o\fP\fInumber\fP, \fB--only-matching\fP=\fInumber\fP
410 Show only the part of the line that matched the capturing parentheses of the
411 given number. Up to 32 capturing parentheses are supported. Because these
412 options can be given without an argument (see above), if an argument is
413 present, it must be given in the same shell item, for example, -o3 or
414 --only-matching=2. The comments given for the non-argument case above also
415 apply to this case. If the specified capturing parentheses do not exist in the
416 pattern, or were not set in the match, nothing is output unless the file name
417 or line number are being printed.
418 .TP
419 \fB-q\fP, \fB--quiet\fP
420 Work quietly, that is, display nothing except error messages. The exit
421 status indicates whether or not any matches were found.
422 .TP
423 \fB-r\fP, \fB--recursive\fP
424 If any given path is a directory, recursively scan the files it contains,
425 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
426 directory is read as a normal file; in some operating systems this gives an
427 immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
428 option to "recurse".
429 .TP
430 \fB--recursion-limit\fP=\fInumber\fP
431 See \fB--match-limit\fP above.
432 .TP
433 \fB-s\fP, \fB--no-messages\fP
434 Suppress error messages about non-existent or unreadable files. Such files are
435 quietly skipped. However, the return code is still 2, even if matches were
436 found in other files.
437 .TP
438 \fB-u\fP, \fB--utf-8\fP
439 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
440 with UTF-8 support. Both patterns and subject lines must be valid strings of
441 UTF-8 characters.
442 .TP
443 \fB-V\fP, \fB--version\fP
444 Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
445 used to the standard error stream.
446 .TP
447 \fB-v\fP, \fB--invert-match\fP
448 Invert the sense of the match, so that lines which do \fInot\fP match any of
449 the patterns are the ones that are found.
450 .TP
451 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
452 Force the patterns to match only whole words. This is equivalent to having \eb
453 at the start and end of the pattern.
454 .TP
455 \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
456 Force the patterns to be anchored (each must start matching at the beginning of
457 a line) and in addition, require them to match entire lines. This is
458 equivalent to having ^ and $ characters at the start and end of each
459 alternative branch in every pattern.
460 .
461 .
462 .SH "ENVIRONMENT VARIABLES"
463 .rs
464 .sp
465 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
466 order, for a locale. The first one that is set is used. This can be overridden
467 by the \fB--locale\fP option. If no locale is set, the PCRE library's default
468 (usually the "C" locale) is used.
469 .
470 .
471 .SH "NEWLINES"
472 .rs
473 .sp
474 The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
475 different newline conventions from the default. However, the setting of this
476 option does not affect the way in which \fBpcregrep\fP writes information to
477 the standard error and output streams. It uses the string "\en" in C
478 \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to
479 convert this to an appropriate sequence if the output is sent to a file.
480 .
481 .
482 .SH "OPTIONS COMPATIBILITY"
483 .rs
484 .sp
485 Many of the short and long forms of \fBpcregrep\fP's options are the same
486 as in the GNU \fBgrep\fP program (version 2.5.4). Any long option of the form
487 \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
488 (PCRE terminology). However, the \fB--file-offsets\fP, \fB--include-dir\fP,
489 \fB--line-offsets\fP, \fB--locale\fP, \fB--match-limit\fP, \fB-M\fP,
490 \fB--multiline\fP, \fB-N\fP, \fB--newline\fP, \fB--recursion-limit\fP,
491 \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP, as is the
492 use of the \fB--only-matching\fP option with a capturing parentheses number.
493 .P
494 Although most of the common options work the same way, a few are different in
495 \fBpcregrep\fP. For example, the \fB--include\fP option's argument is a glob
496 for GNU \fBgrep\fP, but a regular expression for \fBpcregrep\fP. If both the
497 \fB-c\fP and \fB-l\fP options are given, GNU grep lists only file names,
498 without counts, but \fBpcregrep\fP gives the counts.
499 .
500 .
501 .SH "OPTIONS WITH DATA"
502 .rs
503 .sp
504 There are four different ways in which an option with data can be specified.
505 If a short form option is used, the data may follow immediately, or (with one
506 exception) in the next command line item. For example:
507 .sp
508 -f/some/file
509 -f /some/file
510 .sp
511 The exception is the \fB-o\fP option, which may appear with or without data.
512 Because of this, if data is present, it must follow immediately in the same
513 item, for example -o3.
514 .P
515 If a long form option is used, the data may appear in the same command line
516 item, separated by an equals character, or (with two exceptions) it may appear
517 in the next command line item. For example:
518 .sp
519 --file=/some/file
520 --file /some/file
521 .sp
522 Note, however, that if you want to supply a file name beginning with ~ as data
523 in a shell command, and have the shell expand ~ to a home directory, you must
524 separate the file name from the option, because the shell does not treat ~
525 specially unless it is at the start of an item.
526 .P
527 The exceptions to the above are the \fB--colour\fP (or \fB--color\fP) and
528 \fB--only-matching\fP options, for which the data is optional. If one of these
529 options does have data, it must be given in the first form, using an equals
530 character. Otherwise \fBpcregrep\fP will assume that it has no data.
531 .
532 .
533 .SH "MATCHING ERRORS"
534 .rs
535 .sp
536 It is possible to supply a regular expression that takes a very long time to
537 fail to match certain lines. Such patterns normally involve nested indefinite
538 repeats, for example: (a+)*\ed when matched against a line of a's with no final
539 digit. The PCRE matching function has a resource limit that causes it to abort
540 in these circumstances. If this happens, \fBpcregrep\fP outputs an error
541 message and the line that caused the problem to the standard error stream. If
542 there are more than 20 such errors, \fBpcregrep\fP gives up.
543 .P
544 The \fB--match-limit\fP option of \fBpcregrep\fP can be used to set the overall
545 resource limit; there is a second option called \fB--recursion-limit\fP that
546 sets a limit on the amount of memory (usually stack) that is used (see the
547 discussion of these options above).
548 .
549 .
550 .SH DIAGNOSTICS
551 .rs
552 .sp
553 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
554 for syntax errors, overlong lines, non-existent or inaccessible files (even if
555 matches were found in other files) or too many matching errors. Using the
556 \fB-s\fP option to suppress error messages about inaccessible files does not
557 affect the return code.
558 .
559 .
560 .SH "SEE ALSO"
561 .rs
562 .sp
563 \fBpcrepattern\fP(3), \fBpcretest\fP(1).
564 .
565 .
566 .SH AUTHOR
567 .rs
568 .sp
569 .nf
570 Philip Hazel
571 University Computing Service
572 Cambridge CB2 3QH, England.
573 .fi
574 .
575 .
576 .SH REVISION
577 .rs
578 .sp
579 .nf
580 Last updated: 06 September 2011
581 Copyright (c) 1997-2011 University of Cambridge.
582 .fi

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