3 pcregrep - a grep with Perl-compatible regular expressions.
5 .B pcregrep [options] [long options] [pattern] [path1 path2 ...]
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
16 for a full description of syntax and semantics of the regular expressions
19 Patterns, whether supplied on the command line or in a separate file, are given
20 without delimiters. For example:
22 pcregrep Thursday /etc/motd
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.
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.
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.
40 pcregrep some-pattern /file1 - /file3
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.
49 Patterns are limited to 8K or BUFSIZ characters, whichever is the greater.
50 BUFSIZ is defined in \fB<stdio.h>\fP. When there is more than one pattern
51 (specified by the use of \fB-e\fP and/or \fB-f\fP), each pattern is applied to
52 each line in the order in which they are defined, except that all the \fB-e\fP
53 patterns are tried before the \fB-f\fP patterns.
55 By default, as soon as one pattern matches (or fails to match when \fB-v\fP is
56 used), no further patterns are considered. However, if \fB--colour\fP (or
57 \fB--color\fP) is used to colour the matching substrings, or if
58 \fB--only-matching\fP, \fB--file-offsets\fP, or \fB--line-offsets\fP is used to
59 output only the part of the line that matched (either shown literally, or as an
60 offset), scanning resumes immediately following the match, so that further
61 matches on the same line can be found. If there are multiple patterns, they are
62 all tried on the remainder of the line, but patterns that follow the one that
63 matched are not tried on the earlier part of the line.
65 This is the same behaviour as GNU grep, but it does mean that the order in
66 which multiple patterns are specified can affect the output when one of the
67 above options is used.
69 Patterns that can match an empty string are accepted, but empty string
70 matches are never recognized. An example is the pattern "(super)?(man)?", in
71 which all components are optional. This pattern finds all occurrences of both
72 "super" and "man"; the output differs from matching with "super|man" when only
73 the matching substrings are being shown.
75 If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set,
76 \fBpcregrep\fP uses the value to set a locale when calling the PCRE library.
77 The \fB--locale\fP option can be used to override this.
79 .SH "SUPPORT FOR COMPRESSED FILES"
82 It is possible to compile \fBpcregrep\fP so that it uses \fBlibz\fP or
83 \fBlibbz2\fP to read files whose names end in \fB.gz\fP or \fB.bz2\fP,
84 respectively. You can find out whether your binary has support for one or both
85 of these file types by running it with the \fB--help\fP option. If the
86 appropriate support is not present, files are treated as plain text. The
87 standard input is always so treated.
92 The order in which some of the options appear can affect the output. For
93 example, both the \fB-h\fP and \fB-l\fP options affect the printing of file
94 names. Whichever comes later in the command line will be the one that takes
98 This terminate the list of options. It is useful if the next item on the
99 command line starts with a hyphen but is not an option. This allows for the
100 processing of patterns and filenames that start with hyphens.
102 \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
103 Output \fInumber\fP lines of context after each matching line. If filenames
104 and/or line numbers are being output, a hyphen separator is used instead of a
105 colon for the context lines. A line containing "--" is output between each
106 group of lines, unless they are in fact contiguous in the input file. The value
107 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
108 guarantees to have up to 8K of following text available for context output.
110 \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
111 Output \fInumber\fP lines of context before each matching line. If filenames
112 and/or line numbers are being output, a hyphen separator is used instead of a
113 colon for the context lines. A line containing "--" is output between each
114 group of lines, unless they are in fact contiguous in the input file. The value
115 of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
116 guarantees to have up to 8K of preceding text available for context output.
118 \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
119 Output \fInumber\fP lines of context both before and after each matching line.
120 This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
122 \fB-c\fP, \fB--count\fP
123 Do not output individual lines from the files that are being scanned; instead
124 output the number of lines that would otherwise have been shown. If no lines
125 are selected, the number zero is output. If several files are are being
126 scanned, a count is output for each of them. However, if the
127 \fB--files-with-matches\fP option is also used, only those files whose counts
128 are greater than zero are listed. When \fB-c\fP is used, the \fB-A\fP,
129 \fB-B\fP, and \fB-C\fP options are ignored.
131 \fB--colour\fP, \fB--color\fP
132 If this option is given without any data, it is equivalent to "--colour=auto".
133 If data is required, it must be given in the same shell item, separated by an
136 \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
137 This option specifies under what circumstances the parts of a line that matched
138 a pattern should be coloured in the output. By default, the output is not
139 coloured. The value (which is optional, see above) may be "never", "always", or
140 "auto". In the latter case, colouring happens only if the standard output is
141 connected to a terminal. More resources are used when colouring is enabled,
142 because \fBpcregrep\fP has to search for all possible matches in a line, not
143 just one, in order to colour them all.
145 The colour that is used can be specified by setting the environment variable
146 PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
147 string of two numbers, separated by a semicolon. They are copied directly into
148 the control string for setting colour on a terminal, so it is your
149 responsibility to ensure that they make sense. If neither of the environment
150 variables is set, the default is "1;31", which gives red.
152 \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
153 If an input path is not a regular file or a directory, "action" specifies how
154 it is to be processed. Valid values are "read" (the default) or "skip"
155 (silently skip the path).
157 \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
158 If an input path is a directory, "action" specifies how it is to be processed.
159 Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP
160 option), or "skip" (silently skip the path). In the default case, directories
161 are read as if they were ordinary files. In some operating systems the effect
162 of reading a directory like this is an immediate end-of-file.
164 \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP, \fB--regexp=\fP\fIpattern\fP
165 Specify a pattern to be matched. This option can be used multiple times in
166 order to specify several patterns. It can also be used as a way of specifying a
167 single pattern that starts with a hyphen. When \fB-e\fP is used, no argument
168 pattern is taken from the command line; all arguments are treated as file
169 names. There is an overall maximum of 100 patterns. They are applied to each
170 line in the order in which they are defined until one matches (or fails to
171 match if \fB-v\fP is used). If \fB-f\fP is used with \fB-e\fP, the command line
172 patterns are matched first, followed by the patterns from the file, independent
173 of the order in which these options are specified. Note that multiple use of
174 \fB-e\fP is not the same as a single pattern with alternatives. For example,
175 X|Y finds the first character in a line that is X or Y, whereas if the two
176 patterns are given separately, \fBpcregrep\fP finds X if it is present, even if
177 it follows Y in the line. It finds Y only if there is no X in the line. This
178 really matters only if you are using \fB-o\fP to show the part(s) of the line
181 \fB--exclude\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, any regular files whose names match the
184 pattern are excluded. Subdirectories are not excluded by this option; they are
185 searched recursively, subject to the \fB--exclude_dir\fP and
186 \fB--include_dir\fP options. The pattern is a PCRE regular expression, and is
187 matched against the final component of the file name (not the entire path). If
188 a file name matches both \fB--include\fP and \fB--exclude\fP, it is excluded.
189 There is no short form for this option.
191 \fB--exclude_dir\fP=\fIpattern\fP
192 When \fBpcregrep\fP is searching the contents of a directory as a consequence
193 of the \fB-r\fP (recursive search) option, any subdirectories whose names match
194 the pattern are excluded. (Note that the \fP--exclude\fP option does not affect
195 subdirectories.) The pattern is a PCRE regular expression, and is matched
196 against the final component of the name (not the entire path). If a
197 subdirectory name matches both \fB--include_dir\fP and \fB--exclude_dir\fP, it
198 is excluded. There is no short form for this option.
200 \fB-F\fP, \fB--fixed-strings\fP
201 Interpret each pattern as a list of fixed strings, separated by newlines,
202 instead of as a regular expression. The \fB-w\fP (match as a word) and \fB-x\fP
203 (match whole line) options can be used with \fB-F\fP. They apply to each of the
204 fixed strings. A line is selected if any of the fixed strings are found in it
205 (subject to \fB-w\fP or \fB-x\fP, if present).
207 \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
208 Read a number of patterns from the file, one per line, and match them against
209 each line of input. A data line is output if any of the patterns match it. The
210 filename can be given as "-" to refer to the standard input. When \fB-f\fP is
211 used, patterns specified on the command line using \fB-e\fP may also be
212 present; they are tested before the file's patterns. However, no other pattern
213 is taken from the command line; all arguments are treated as file names. There
214 is an overall maximum of 100 patterns. Trailing white space is removed from
215 each line, and blank lines are ignored. An empty file contains no patterns and
216 therefore matches nothing. See also the comments about multiple patterns versus
217 a single pattern with alternatives in the description of \fB-e\fP above.
220 Instead of showing lines or parts of lines that match, show each match as an
221 offset from the start of the file and a length, separated by a comma. In this
222 mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP
223 options are ignored. If there is more than one match in a line, each of them is
224 shown separately. This option is mutually exclusive with \fB--line-offsets\fP
225 and \fB--only-matching\fP.
227 \fB-H\fP, \fB--with-filename\fP
228 Force the inclusion of the filename at the start of output lines when searching
229 a single file. By default, the filename is not shown in this case. For matching
230 lines, the filename is followed by a colon; for context lines, a hyphen
231 separator is used. If a line number is also being output, it follows the file
234 \fB-h\fP, \fB--no-filename\fP
235 Suppress the output filenames when searching multiple files. By default,
236 filenames are shown when multiple files are searched. For matching lines, the
237 filename is followed by a colon; for context lines, a hyphen separator is used.
238 If a line number is also being output, it follows the file name.
241 Output a help message, giving brief details of the command options and file
242 type support, and then exit.
244 \fB-i\fP, \fB--ignore-case\fP
245 Ignore upper/lower case distinctions during comparisons.
247 \fB--include\fP=\fIpattern\fP
248 When \fBpcregrep\fP is searching the files in a directory as a consequence of
249 the \fB-r\fP (recursive search) option, only those regular files whose names
250 match the pattern are included. Subdirectories are always included and searched
251 recursively, subject to the \fP--include_dir\fP and \fB--exclude_dir\fP
252 options. The pattern is a PCRE regular expression, and is matched against the
253 final component of the file name (not the entire path). If a file name matches
254 both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no short
255 form for this option.
257 \fB--include_dir\fP=\fIpattern\fP
258 When \fBpcregrep\fP is searching the contents of a directory as a consequence
259 of the \fB-r\fP (recursive search) option, only those subdirectories whose
260 names match the pattern are included. (Note that the \fB--include\fP option
261 does not affect subdirectories.) The pattern is a PCRE regular expression, and
262 is matched against the final component of the name (not the entire path). If a
263 subdirectory name matches both \fB--include_dir\fP and \fB--exclude_dir\fP, it
264 is excluded. There is no short form for this option.
266 \fB-L\fP, \fB--files-without-match\fP
267 Instead of outputting lines from the files, just output the names of the files
268 that do not contain any lines that would have been output. Each file name is
269 output once, on a separate line.
271 \fB-l\fP, \fB--files-with-matches\fP
272 Instead of outputting lines from the files, just output the names of the files
273 containing lines that would have been output. Each file name is output
274 once, on a separate line. Searching normally stops as soon as a matching line
275 is found in a file. However, if the \fB-c\fP (count) option is also used,
276 matching continues in order to obtain the correct count, and those files that
277 have at least one match are listed along with their counts. Using this option
278 with \fB-c\fP is a way of suppressing the listing of files with no matches.
280 \fB--label\fP=\fIname\fP
281 This option supplies a name to be used for the standard input when file names
282 are being output. If not supplied, "(standard input)" is used. There is no
283 short form for this option.
285 \fB--line-buffered\fP
286 When this option is given, input is read and processed line by line, and the
287 output is flushed after each write. By default, input is read in large chunks,
288 unless \fBpcregrep\fP can determine that it is reading from a terminal (which
289 is currently possible only in Unix environments). Output to terminal is
290 normally automatically flushed by the operating system. This option can be
291 useful when the input or output is attached to a pipe and you do not want
292 \fBpcregrep\fP to buffer up large amounts of data. However, its use will affect
293 performance, and the \fB-M\fP (multiline) option ceases to work.
296 Instead of showing lines or parts of lines that match, show each match as a
297 line number, the offset from the start of the line, and a length. The line
298 number is terminated by a colon (as usual; see the \fB-n\fP option), and the
299 offset and length are separated by a comma. In this mode, no context is shown.
300 That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are ignored. If there is
301 more than one match in a line, each of them is shown separately. This option is
302 mutually exclusive with \fB--file-offsets\fP and \fB--only-matching\fP.
304 \fB--locale\fP=\fIlocale-name\fP
305 This option specifies a locale to be used for pattern matching. It overrides
306 the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
307 locale is specified, the PCRE library's default (usually the "C" locale) is
308 used. There is no short form for this option.
310 \fB-M\fP, \fB--multiline\fP
311 Allow patterns to match more than one line. When this option is given, patterns
312 may usefully contain literal newline characters and internal occurrences of ^
313 and $ characters. The output for any one match may consist of more than one
314 line. When this option is set, the PCRE library is called in "multiline" mode.
315 There is a limit to the number of lines that can be matched, imposed by the way
316 that \fBpcregrep\fP buffers the input file as it scans it. However,
317 \fBpcregrep\fP ensures that at least 8K characters or the rest of the document
318 (whichever is the shorter) are available for forward matching, and similarly
319 the previous 8K characters (or all the previous characters, if fewer than 8K)
320 are guaranteed to be available for lookbehind assertions. This option does not
321 work when input is read line by line (see \fP--line-buffered\fP.)
323 \fB-N\fP \fInewline-type\fP, \fB--newline=\fP\fInewline-type\fP
324 The PCRE library supports five different conventions for indicating
325 the ends of lines. They are the single-character sequences CR (carriage return)
326 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
327 which recognizes any of the preceding three types, and an "any" convention, in
328 which any Unicode line ending sequence is assumed to end a line. The Unicode
329 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
330 (formfeed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
331 PS (paragraph separator, U+2029).
333 When the PCRE library is built, a default line-ending sequence is specified.
334 This is normally the standard sequence for the operating system. Unless
335 otherwise specified by this option, \fBpcregrep\fP uses the library's default.
336 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
337 makes it possible to use \fBpcregrep\fP on files that have come from other
338 environments without having to modify their line endings. If the data that is
339 being scanned does not agree with the convention set by this option,
340 \fBpcregrep\fP may behave in strange ways.
342 \fB-n\fP, \fB--line-number\fP
343 Precede each output line by its line number in the file, followed by a colon
344 for matching lines or a hyphen for context lines. If the filename is also being
345 output, it precedes the line number. This option is forced if
346 \fB--line-offsets\fP is used.
348 \fB-o\fP, \fB--only-matching\fP
349 Show only the part of the line that matched a pattern. In this mode, no
350 context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are
351 ignored. If there is more than one match in a line, each of them is shown
352 separately. If \fB-o\fP is combined with \fB-v\fP (invert the sense of the
353 match to find non-matching lines), no output is generated, but the return code
354 is set appropriately. This option is mutually exclusive with
355 \fB--file-offsets\fP and \fB--line-offsets\fP.
357 \fB-q\fP, \fB--quiet\fP
358 Work quietly, that is, display nothing except error messages. The exit
359 status indicates whether or not any matches were found.
361 \fB-r\fP, \fB--recursive\fP
362 If any given path is a directory, recursively scan the files it contains,
363 taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
364 directory is read as a normal file; in some operating systems this gives an
365 immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
368 \fB-s\fP, \fB--no-messages\fP
369 Suppress error messages about non-existent or unreadable files. Such files are
370 quietly skipped. However, the return code is still 2, even if matches were
371 found in other files.
373 \fB-u\fP, \fB--utf-8\fP
374 Operate in UTF-8 mode. This option is available only if PCRE has been compiled
375 with UTF-8 support. Both patterns and subject lines must be valid strings of
378 \fB-V\fP, \fB--version\fP
379 Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
380 used to the standard error stream.
382 \fB-v\fP, \fB--invert-match\fP
383 Invert the sense of the match, so that lines which do \fInot\fP match any of
384 the patterns are the ones that are found.
386 \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
387 Force the patterns to match only whole words. This is equivalent to having \eb
388 at the start and end of the pattern.
390 \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
391 Force the patterns to be anchored (each must start matching at the beginning of
392 a line) and in addition, require them to match entire lines. This is
393 equivalent to having ^ and $ characters at the start and end of each
394 alternative branch in every pattern.
397 .SH "ENVIRONMENT VARIABLES"
400 The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
401 order, for a locale. The first one that is set is used. This can be overridden
402 by the \fB--locale\fP option. If no locale is set, the PCRE library's default
403 (usually the "C" locale) is used.
409 The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
410 different newline conventions from the default. However, the setting of this
411 option does not affect the way in which \fBpcregrep\fP writes information to
412 the standard error and output streams. It uses the string "\en" in C
413 \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to
414 convert this to an appropriate sequence if the output is sent to a file.
417 .SH "OPTIONS COMPATIBILITY"
420 The majority of short and long forms of \fBpcregrep\fP's options are the same
421 as in the GNU \fBgrep\fP program. Any long option of the form
422 \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
423 (PCRE terminology). However, the \fB--locale\fP, \fB-M\fP, \fB--multiline\fP,
424 \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP. If both the
425 \fB-c\fP and \fB-l\fP options are given, GNU grep lists only file names,
426 without counts, but \fBpcregrep\fP gives the counts.
429 .SH "OPTIONS WITH DATA"
432 There are four different ways in which an option with data can be specified.
433 If a short form option is used, the data may follow immediately, or in the next
434 command line item. For example:
439 If a long form option is used, the data may appear in the same command line
440 item, separated by an equals character, or (with one exception) it may appear
441 in the next command line item. For example:
446 Note, however, that if you want to supply a file name beginning with ~ as data
447 in a shell command, and have the shell expand ~ to a home directory, you must
448 separate the file name from the option, because the shell does not treat ~
449 specially unless it is at the start of an item.
451 The exception to the above is the \fB--colour\fP (or \fB--color\fP) option,
452 for which the data is optional. If this option does have data, it must be given
453 in the first form, using an equals character. Otherwise it will be assumed that
457 .SH "MATCHING ERRORS"
460 It is possible to supply a regular expression that takes a very long time to
461 fail to match certain lines. Such patterns normally involve nested indefinite
462 repeats, for example: (a+)*\ed when matched against a line of a's with no final
463 digit. The PCRE matching function has a resource limit that causes it to abort
464 in these circumstances. If this happens, \fBpcregrep\fP outputs an error
465 message and the line that caused the problem to the standard error stream. If
466 there are more than 20 such errors, \fBpcregrep\fP gives up.
472 Exit status is 0 if any matches were found, 1 if no matches were found, and 2
473 for syntax errors and non-existent or inacessible files (even if matches were
474 found in other files) or too many matching errors. Using the \fB-s\fP option to
475 suppress error messages about inaccessble files does not affect the return
482 \fBpcrepattern\fP(3), \fBpcretest\fP(1).
490 University Computing Service
491 Cambridge CB2 3QH, England.
499 Last updated: 21 May 2010
500 Copyright (c) 1997-2010 University of Cambridge.
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