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1 nigel 49 .TH PCREGREP 1
2     .SH NAME
3     pcregrep - a grep with Perl-compatible regular expressions.
4     .SH SYNOPSIS
5 nigel 87 .B pcregrep [options] [long options] [pattern] [path1 path2 ...]
6 nigel 75 .
7 nigel 49 .SH DESCRIPTION
8 nigel 63 .rs
9     .sp
10 nigel 75 \fBpcregrep\fP searches files for character patterns, in the same way as other
11 nigel 49 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 nigel 63 .\" HREF
14 nigel 93 \fBpcrepattern\fP(3)
15 nigel 63 .\"
16 nigel 93 for a full description of syntax and semantics of the regular expressions
17     that PCRE supports.
18 nigel 75 .P
19 nigel 87 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 nigel 75 .P
30 nigel 87 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 nigel 77 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 nigel 87 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 nigel 77 \fBpcregrep\fP behaves. In particular, the \fB-M\fP option makes it possible to
46 nigel 91 search for patterns that span line boundaries. What defines a line boundary is
47     controlled by the \fB-N\fP (\fB--newline\fP) option.
48 nigel 75 .P
49 nigel 77 Patterns are limited to 8K or BUFSIZ characters, whichever is the greater.
50     BUFSIZ is defined in \fB<stdio.h>\fP.
51 nigel 87 .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 nigel 75 .
56 nigel 49 .SH OPTIONS
57 nigel 63 .rs
58 nigel 49 .TP 10
59 nigel 77 \fB--\fP
60     This terminate the list of options. It is useful if the next item on the
61 nigel 87 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 nigel 49 .TP
64 nigel 87 \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 nigel 77 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 nigel 87 guarantees to have up to 8K of following text available for context output.
71 nigel 77 .TP
72 nigel 87 \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 nigel 77 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 nigel 87 guarantees to have up to 8K of preceding text available for context output.
79 nigel 77 .TP
80 nigel 87 \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 nigel 77 This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
83     .TP
84 nigel 87 \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 nigel 49 .TP
90 nigel 87 \fB--colour\fP, \fB--color\fP
91     If this option is given without any data, it is equivalent to "--colour=auto".
92     If data is required, it must be given in the same shell item, separated by an
93     equals sign.
94     .TP
95     \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
96     This option specifies under what circumstances the part of a line that matched
97     a pattern should be coloured in the output. The value may be "never" (the
98     default), "always", or "auto". In the latter case, colouring happens only if
99     the standard output is connected to a terminal. The colour can be specified by
100     setting the environment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value
101     of this variable should be a string of two numbers, separated by a semicolon.
102     They are copied directly into the control string for setting colour on a
103     terminal, so it is your responsibility to ensure that they make sense. If
104     neither of the environment variables is set, the default is "1;31", which gives
105     red.
106     .TP
107     \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
108     If an input path is not a regular file or a directory, "action" specifies how
109     it is to be processed. Valid values are "read" (the default) or "skip"
110     (silently skip the path).
111     .TP
112     \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
113     If an input path is a directory, "action" specifies how it is to be processed.
114     Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP
115     option), or "skip" (silently skip the path). In the default case, directories
116     are read as if they were ordinary files. In some operating systems the effect
117     of reading a directory like this is an immediate end-of-file.
118     .TP
119     \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP,
120     \fB--regexp=\fP\fIpattern\fP Specify a pattern to be matched. This option can
121     be used multiple times in order to specify several patterns. It can also be
122     used as a way of specifying a single pattern that starts with a hyphen. When
123     \fB-e\fP is used, no argument pattern is taken from the command line; all
124     arguments are treated as file names. There is an overall maximum of 100
125     patterns. They are applied to each line in the order in which they are defined
126     until one matches (or fails to match if \fB-v\fP is used). If \fB-f\fP is used
127     with \fB-e\fP, the command line patterns are matched first, followed by the
128     patterns from the file, independent of the order in which these options are
129     specified. Note that multiple use of \fB-e\fP is not the same as a single
130     pattern with alternatives. For example, X|Y finds the first character in a line
131     that is X or Y, whereas if the two patterns are given separately,
132     \fBpcregrep\fP finds X if it is present, even if it follows Y in the line. It
133     finds Y only if there is no X in the line. This really matters only if you are
134     using \fB-o\fP to show the portion of the line that matched.
135     .TP
136 nigel 77 \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 nigel 87 \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 nigel 53 .TP
150 nigel 87 \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 nigel 49 .TP
161 nigel 87 \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 nigel 49 Ignore upper/lower case distinctions during comparisons.
180     .TP
181 nigel 77 \fB--include\fP=\fIpattern\fP
182     When \fBpcregrep\fP is searching the files in a directory as a consequence of
183 nigel 87 the \fB-r\fP (recursive search) option, only those files whose names match the
184 nigel 77 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 nigel 87 \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 nigel 77 .TP
193 nigel 87 \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 nigel 49 .TP
199 nigel 77 \fB--label\fP=\fIname\fP
200     This option supplies a name to be used for the standard input when file names
201 nigel 87 are being output. If not supplied, "(standard input)" is used. There is no
202 nigel 77 short form for this option.
203     .TP
204 nigel 87 \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 nigel 77 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 nigel 91 \fB-N\fP \fInewline-type\fP, \fB--newline=\fP\fInewline-type\fP
223 nigel 93 The PCRE library supports four different conventions for indicating
224 nigel 91 the ends of lines. They are the single-character sequences CR (carriage return)
225 nigel 93 and LF (linefeed), the two-character sequence CRLF, and an "any" convention, in
226     which any Unicode line ending sequence is assumed to end a line. The Unicode
227     sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
228     (formfeed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
229     PS (paragraph separator, U+0029).
230     .sp
231     When the PCRE library is built, a default line-ending sequence is specified.
232     This is normally the standard sequence for the operating system. Unless
233     otherwise specified by this option, \fBpcregrep\fP uses the library's default.
234     The possible values for this option are CR, LF, CRLF, or ANY. This makes it
235     possible to use \fBpcregrep\fP on files that have come from other environments
236     without having to modify their line endings. If the data that is being scanned
237     does not agree with the convention set by this option, \fBpcregrep\fP may
238     behave in strange ways.
239 nigel 91 .TP
240 nigel 87 \fB-n\fP, \fB--line-number\fP
241     Precede each output line by its line number in the file, followed by a colon
242     and a space for matching lines or a hyphen and a space for context lines. If
243     the filename is also being output, it precedes the line number.
244 nigel 49 .TP
245 nigel 87 \fB-o\fP, \fB--only-matching\fP
246     Show only the part of the line that matched a pattern. In this mode, no
247     context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are
248     ignored.
249 nigel 77 .TP
250 nigel 87 \fB-q\fP, \fB--quiet\fP
251     Work quietly, that is, display nothing except error messages. The exit
252     status indicates whether or not any matches were found.
253     .TP
254     \fB-r\fP, \fB--recursive\fP
255 nigel 77 If any given path is a directory, recursively scan the files it contains,
256 nigel 87 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
257     directory is read as a normal file; in some operating systems this gives an
258     immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
259     option to "recurse".
260 nigel 53 .TP
261 nigel 87 \fB-s\fP, \fB--no-messages\fP
262 nigel 77 Suppress error messages about non-existent or unreadable files. Such files are
263     quietly skipped. However, the return code is still 2, even if matches were
264     found in other files.
265 nigel 49 .TP
266 nigel 87 \fB-u\fP, \fB--utf-8\fP
267 nigel 63 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
268 nigel 87 with UTF-8 support. Both patterns and subject lines must be valid strings of
269     UTF-8 characters.
270 nigel 63 .TP
271 nigel 87 \fB-V\fP, \fB--version\fP
272 nigel 77 Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
273     used to the standard error stream.
274     .TP
275 nigel 87 \fB-v\fP, \fB--invert-match\fP
276     Invert the sense of the match, so that lines which do \fInot\fP match any of
277     the patterns are the ones that are found.
278 nigel 49 .TP
279 nigel 87 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
280     Force the patterns to match only whole words. This is equivalent to having \eb
281 nigel 77 at the start and end of the pattern.
282     .TP
283 ph10 148 \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
284 nigel 87 Force the patterns to be anchored (each must start matching at the beginning of
285     a line) and in addition, require them to match entire lines. This is
286 nigel 49 equivalent to having ^ and $ characters at the start and end of each
287 nigel 87 alternative branch in every pattern.
288 nigel 75 .
289 nigel 87 .
290     .SH "ENVIRONMENT VARIABLES"
291 nigel 63 .rs
292     .sp
293 nigel 87 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
294     order, for a locale. The first one that is set is used. This can be overridden
295     by the \fB--locale\fP option. If no locale is set, the PCRE library's default
296     (usually the "C" locale) is used.
297     .
298     .
299 nigel 91 .SH "NEWLINES"
300     .rs
301     .sp
302     The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
303     different newline conventions from the default. However, the setting of this
304     option does not affect the way in which \fBpcregrep\fP writes information to
305     the standard error and output streams. It uses the string "\en" in C
306     \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to
307     convert this to an appropriate sequence if the output is sent to a file.
308     .
309     .
310 nigel 87 .SH "OPTIONS COMPATIBILITY"
311     .rs
312 nigel 75 .sp
313 nigel 87 The majority of short and long forms of \fBpcregrep\fP's options are the same
314     as in the GNU \fBgrep\fP program. Any long option of the form
315     \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
316     (PCRE terminology). However, the \fB--locale\fP, \fB-M\fP, \fB--multiline\fP,
317     \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP.
318 nigel 77 .
319 nigel 87 .
320 nigel 77 .SH "OPTIONS WITH DATA"
321     .rs
322 nigel 75 .sp
323 nigel 77 There are four different ways in which an option with data can be specified.
324     If a short form option is used, the data may follow immediately, or in the next
325     command line item. For example:
326     .sp
327     -f/some/file
328     -f /some/file
329     .sp
330     If a long form option is used, the data may appear in the same command line
331 nigel 87 item, separated by an equals character, or (with one exception) it may appear
332     in the next command line item. For example:
333 nigel 77 .sp
334     --file=/some/file
335     --file /some/file
336     .sp
337 nigel 87 Note, however, that if you want to supply a file name beginning with ~ as data
338     in a shell command, and have the shell expand ~ to a home directory, you must
339     separate the file name from the option, because the shell does not treat ~
340     specially unless it is at the start of an item.
341     .P
342     The exception to the above is the \fB--colour\fP (or \fB--color\fP) option,
343     for which the data is optional. If this option does have data, it must be given
344     in the first form, using an equals character. Otherwise it will be assumed that
345     it has no data.
346 nigel 75 .
347 nigel 87 .
348 nigel 93 .SH "MATCHING ERRORS"
349 nigel 87 .rs
350     .sp
351     It is possible to supply a regular expression that takes a very long time to
352     fail to match certain lines. Such patterns normally involve nested indefinite
353     repeats, for example: (a+)*\ed when matched against a line of a's with no final
354     digit. The PCRE matching function has a resource limit that causes it to abort
355     in these circumstances. If this happens, \fBpcregrep\fP outputs an error
356     message and the line that caused the problem to the standard error stream. If
357     there are more than 20 such errors, \fBpcregrep\fP gives up.
358     .
359     .
360 nigel 49 .SH DIAGNOSTICS
361 nigel 63 .rs
362     .sp
363 nigel 49 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
364 nigel 77 for syntax errors and non-existent or inacessible files (even if matches were
365 nigel 87 found in other files) or too many matching errors. Using the \fB-s\fP option to
366     suppress error messages about inaccessble files does not affect the return
367     code.
368 nigel 75 .
369     .
370 nigel 93 .SH "SEE ALSO"
371     .rs
372     .sp
373     \fBpcrepattern\fP(3), \fBpcretest\fP(1).
374     .
375     .
376 nigel 49 .SH AUTHOR
377 nigel 63 .rs
378     .sp
379 ph10 99 .nf
380 nigel 77 Philip Hazel
381 nigel 63 University Computing Service
382 nigel 93 Cambridge CB2 3QH, England.
383 ph10 99 .fi
384     .
385     .
386     .SH REVISION
387     .rs
388     .sp
389     .nf
390     Last updated: 06 March 2007
391     Copyright (c) 1997-2007 University of Cambridge.
392     .fi

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