1PCRE2GREP(1) General Commands Manual PCRE2GREP(1)
2
6 pcre2grep - a grep with Perl-compatible regular expressions.
7
9 pcre2grep [options] [long options] [pattern] [path1 path2 ...]
10
12 pcre2grep searches files for character patterns, in the same way as
14 other grep commands do, but it uses the PCRE2 regular expression
15 library to support patterns that are compatible with the regular
16 expressions of Perl 5. See pcre2syntax(3) for a quick-reference summary
17 of pattern syntax, or pcre2pattern(3) for a full description of the
18 syntax and semantics of the regular expressions that PCRE2 supports.
19 Patterns, whether supplied on the command line or in a separate file,
21 are given without delimiters. For example:
22 pcre2grep Thursday /etc/motd
24 If you attempt to use delimiters (for example, by surrounding a pattern
26 with slashes, as is common in Perl scripts), they are interpreted as
27 part of the pattern. Quotes can of course be used to delimit patterns
28 on the command line because they are interpreted by the shell, and
29 indeed quotes are required if a pattern contains white space or shell
30 metacharacters.
31 The first argument that follows any option settings is treated as the
33 single pattern to be matched when neither -e nor -f is present. Con‐
34 versely, when one or both of these options are used to specify pat‐
35 terns, all arguments are treated as path names. At least one of -e, -f,
36 or an argument pattern must be provided.
37 If no files are specified, pcre2grep reads the standard input. The
39 standard input can also be referenced by a name consisting of a single
40 hyphen. For example:
41 pcre2grep some-pattern file1 - file3
43 Input files are searched line by line. By default, each line that
45 matches a pattern is copied to the standard output, and if there is
46 more than one file, the file name is output at the start of each line,
47 followed by a colon. However, there are options that can change how
48 pcre2grep behaves. In particular, the -M option makes it possible to
49 search for strings that span line boundaries. What defines a line
50 boundary is controlled by the -N (--newline) option.
51 The amount of memory used for buffering files that are being scanned is
53 controlled by parameters that can be set by the --buffer-size and
54 --max-buffer-size options. The first of these sets the size of buffer
55 that is obtained at the start of processing. If an input file contains
56 very long lines, a larger buffer may be needed; this is handled by
57 automatically extending the buffer, up to the limit specified by --max-
58 buffer-size. The default values for these parameters can be set when
59 pcre2grep is built; if nothing is specified, the defaults are set to
60 20KiB and 1MiB respectively. An error occurs if a line is too long and
61 the buffer can no longer be expanded.
62 The block of memory that is actually used is three times the "buffer
64 size", to allow for buffering "before" and "after" lines. If the buffer
65 size is too small, fewer than requested "before" and "after" lines may
66 be output.
67 Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the
69 greater. BUFSIZ is defined in <stdio.h>. When there is more than one
70 pattern (specified by the use of -e and/or -f), each pattern is applied
71 to each line in the order in which they are defined, except that all
72 the -e patterns are tried before the -f patterns.
73 By default, as soon as one pattern matches a line, no further patterns
75 are considered. However, if --colour (or --color) is used to colour the
76 matching substrings, or if --only-matching, --file-offsets, or --line-
77 offsets is used to output only the part of the line that matched
78 (either shown literally, or as an offset), scanning resumes immediately
79 following the match, so that further matches on the same line can be
80 found. If there are multiple patterns, they are all tried on the
81 remainder of the line, but patterns that follow the one that matched
82 are not tried on the earlier part of the line.
83 This behaviour means that the order in which multiple patterns are
85 specified can affect the output when one of the above options is used.
86 This is no longer the same behaviour as GNU grep, which now manages to
87 display earlier matches for later patterns (as long as there is no
88 overlap).
89 Patterns that can match an empty string are accepted, but empty string
91 matches are never recognized. An example is the pattern
92 "(super)?(man)?", in which all components are optional. This pattern
93 finds all occurrences of both "super" and "man"; the output differs
94 from matching with "super|man" when only the matching substrings are
95 being shown.
96 If the LC_ALL or LC_CTYPE environment variable is set, pcre2grep uses
98 the value to set a locale when calling the PCRE2 library. The --locale
99 option can be used to override this.
100
102 It is possible to compile pcre2grep so that it uses libz or libbz2 to
104 read compressed files whose names end in .gz or .bz2, respectively. You
105 can find out whether your pcre2grep binary has support for one or both
106 of these file types by running it with the --help option. If the appro‐
107 priate support is not present, all files are treated as plain text. The
108 standard input is always so treated. When input is from a compressed
109 .gz or .bz2 file, the --line-buffered option is ignored.
110
112 By default, a file that contains a binary zero byte within the first
114 1024 bytes is identified as a binary file, and is processed specially.
115 (GNU grep identifies binary files in this manner.) However, if the new‐
116 line type is specified as "nul", that is, the line terminator is a
117 binary zero, the test for a binary file is not applied. See the
118 --binary-files option for a means of changing the way binary files are
119 handled.
120
122 Patterns passed from the command line are strings that are terminated
124 by a binary zero, so cannot contain internal zeros. However, patterns
125 that are read from a file via the -f option may contain binary zeros.
126
128 The order in which some of the options appear can affect the output.
130 For example, both the -H and -l options affect the printing of file
131 names. Whichever comes later in the command line will be the one that
132 takes effect. Similarly, except where noted below, if an option is
133 given twice, the later setting is used. Numerical values for options
134 may be followed by K or M, to signify multiplication by 1024 or
135 1024*1024 respectively.
136 -- This terminates the list of options. It is useful if the next
138 item on the command line starts with a hyphen but is not an
139 option. This allows for the processing of patterns and file
140 names that start with hyphens.
141 -A number, --after-context=number
143 Output up to number lines of context after each matching
144 line. Fewer lines are output if the next match or the end of
145 the file is reached, or if the processing buffer size has
146 been set too small. If file names and/or line numbers are
147 being output, a hyphen separator is used instead of a colon
148 for the context lines. A line containing "--" is output
149 between each group of lines, unless they are in fact contigu‐
150 ous in the input file. The value of number is expected to be
151 relatively small. When -c is used, -A is ignored.
152 -a, --text
154 Treat binary files as text. This is equivalent to --binary-
155 files=text.
156 -B number, --before-context=number
158 Output up to number lines of context before each matching
159 line. Fewer lines are output if the previous match or the
160 start of the file is within number lines, or if the process‐
161 ing buffer size has been set too small. If file names and/or
162 line numbers are being output, a hyphen separator is used
163 instead of a colon for the context lines. A line containing
164 "--" is output between each group of lines, unless they are
165 in fact contiguous in the input file. The value of number is
166 expected to be relatively small. When -c is used, -B is
167 ignored.
168 --binary-files=word
170 Specify how binary files are to be processed. If the word is
171 "binary" (the default), pattern matching is performed on
172 binary files, but the only output is "Binary file <name>
173 matches" when a match succeeds. If the word is "text", which
174 is equivalent to the -a or --text option, binary files are
175 processed in the same way as any other file. In this case,
176 when a match succeeds, the output may be binary garbage,
177 which can have nasty effects if sent to a terminal. If the
178 word is "without-match", which is equivalent to the -I
179 option, binary files are not processed at all; they are
180 assumed not to be of interest and are skipped without causing
181 any output or affecting the return code.
182 --buffer-size=number
184 Set the parameter that controls how much memory is obtained
185 at the start of processing for buffering files that are being
186 scanned. See also --max-buffer-size below.
187 -C number, --context=number
189 Output number lines of context both before and after each
190 matching line. This is equivalent to setting both -A and -B
191 to the same value.
192 -c, --count
194 Do not output lines from the files that are being scanned;
195 instead output the number of lines that would have been
196 shown, either because they matched, or, if -v is set, because
197 they failed to match. By default, this count is exactly the
198 same as the number of lines that would have been output, but
199 if the -M (multiline) option is used (without -v), there may
200 be more suppressed lines than the count (that is, the number
201 of matches).
202 If no lines are selected, the number zero is output. If sev‐
204 eral files are are being scanned, a count is output for each
205 of them and the -t option can be used to cause a total to be
206 output at the end. However, if the --files-with-matches
207 option is also used, only those files whose counts are
208 greater than zero are listed. When -c is used, the -A, -B,
209 and -C options are ignored.
210 --colour, --color
212 If this option is given without any data, it is equivalent to
213 "--colour=auto". If data is required, it must be given in
214 the same shell item, separated by an equals sign.
215 --colour=value, --color=value
217 This option specifies under what circumstances the parts of a
218 line that matched a pattern should be coloured in the output.
219 By default, the output is not coloured. The value (which is
220 optional, see above) may be "never", "always", or "auto". In
221 the latter case, colouring happens only if the standard out‐
222 put is connected to a terminal. More resources are used when
223 colouring is enabled, because pcre2grep has to search for all
224 possible matches in a line, not just one, in order to colour
225 them all.
226 The colour that is used can be specified by setting one of
228 the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR,
229 PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that
230 order. If none of these are set, pcre2grep looks for
231 GREP_COLORS or GREP_COLOR (in that order). The value of the
232 variable should be a string of two numbers, separated by a
233 semicolon, except in the case of GREP_COLORS, which must
234 start with "ms=" or "mt=" followed by two semicolon-separated
235 colours, terminated by the end of the string or by a colon.
236 If GREP_COLORS does not start with "ms=" or "mt=" it is
237 ignored, and GREP_COLOR is checked.
238 If the string obtained from one of the above variables con‐
240 tains any characters other than semicolon or digits, the set‐
241 ting is ignored and the default colour is used. The string is
242 copied directly into the control string for setting colour on
243 a terminal, so it is your responsibility to ensure that the
244 values make sense. If no relevant environment variable is
245 set, the default is "1;31", which gives red.
246 -D action, --devices=action
248 If an input path is not a regular file or a directory,
249 "action" specifies how it is to be processed. Valid values
250 are "read" (the default) or "skip" (silently skip the path).
251 -d action, --directories=action
253 If an input path is a directory, "action" specifies how it is
254 to be processed. Valid values are "read" (the default in
255 non-Windows environments, for compatibility with GNU grep),
256 "recurse" (equivalent to the -r option), or "skip" (silently
257 skip the path, the default in Windows environments). In the
258 "read" case, directories are read as if they were ordinary
259 files. In some operating systems the effect of reading a
260 directory like this is an immediate end-of-file; in others it
261 may provoke an error.
262 --depth-limit=number
264 See --match-limit below.
265 -e pattern, --regex=pattern, --regexp=pattern
267 Specify a pattern to be matched. This option can be used mul‐
268 tiple times in order to specify several patterns. It can also
269 be used as a way of specifying a single pattern that starts
270 with a hyphen. When -e is used, no argument pattern is taken
271 from the command line; all arguments are treated as file
272 names. There is no limit to the number of patterns. They are
273 applied to each line in the order in which they are defined
274 until one matches.
275 If -f is used with -e, the command line patterns are matched
277 first, followed by the patterns from the file(s), independent
278 of the order in which these options are specified. Note that
279 multiple use of -e is not the same as a single pattern with
280 alternatives. For example, X|Y finds the first character in a
281 line that is X or Y, whereas if the two patterns are given
282 separately, with X first, pcre2grep finds X if it is present,
283 even if it follows Y in the line. It finds Y only if there is
284 no X in the line. This matters only if you are using -o or
285 --colo(u)r to show the part(s) of the line that matched.
286 --exclude=pattern
288 Files (but not directories) whose names match the pattern are
289 skipped without being processed. This applies to all files,
290 whether listed on the command line, obtained from --file-
291 list, or by scanning a directory. The pattern is a PCRE2 reg‐
292 ular expression, and is matched against the final component
293 of the file name, not the entire path. The -F, -w, and -x
294 options do not apply to this pattern. The option may be given
295 any number of times in order to specify multiple patterns. If
296 a file name matches both an --include and an --exclude pat‐
297 tern, it is excluded. There is no short form for this option.
298 --exclude-from=filename
300 Treat each non-empty line of the file as the data for an
301 --exclude option. What constitutes a newline when reading the
302 file is the operating system's default. The --newline option
303 has no effect on this option. This option may be given more
304 than once in order to specify a number of files to read.
305 --exclude-dir=pattern
307 Directories whose names match the pattern are skipped without
308 being processed, whatever the setting of the --recursive
309 option. This applies to all directories, whether listed on
310 the command line, obtained from --file-list, or by scanning a
311 parent directory. The pattern is a PCRE2 regular expression,
312 and is matched against the final component of the directory
313 name, not the entire path. The -F, -w, and -x options do not
314 apply to this pattern. The option may be given any number of
315 times in order to specify more than one pattern. If a direc‐
316 tory matches both --include-dir and --exclude-dir, it is
317 excluded. There is no short form for this option.
318 -F, --fixed-strings
320 Interpret each data-matching pattern as a list of fixed
321 strings, separated by newlines, instead of as a regular
322 expression. What constitutes a newline for this purpose is
323 controlled by the --newline option. The -w (match as a word)
324 and -x (match whole line) options can be used with -F. They
325 apply to each of the fixed strings. A line is selected if any
326 of the fixed strings are found in it (subject to -w or -x, if
327 present). This option applies only to the patterns that are
328 matched against the contents of files; it does not apply to
329 patterns specified by any of the --include or --exclude
330 options.
331 -f filename, --file=filename
333 Read patterns from the file, one per line, and match them
334 against each line of input. As is the case with patterns on
335 the command line, no delimiters should be used. What consti‐
336 tutes a newline when reading the file is the operating sys‐
337 tem's default interpretation of \n. The --newline option has
338 no effect on this option. Trailing white space is removed
339 from each line, and blank lines are ignored. An empty file
340 contains no patterns and therefore matches nothing. Patterns
341 read from a file in this way may contain binary zeros, which
342 are treated as ordinary data characters. See also the com‐
343 ments about multiple patterns versus a single pattern with
344 alternatives in the description of -e above.
345 If this option is given more than once, all the specified
347 files are read. A data line is output if any of the patterns
348 match it. A file name can be given as "-" to refer to the
349 standard input. When -f is used, patterns specified on the
350 command line using -e may also be present; they are tested
351 before the file's patterns. However, no other pattern is
352 taken from the command line; all arguments are treated as the
353 names of paths to be searched.
354 --file-list=filename
356 Read a list of files and/or directories that are to be
357 scanned from the given file, one per line. What constitutes a
358 newline when reading the file is the operating system's
359 default. Trailing white space is removed from each line, and
360 blank lines are ignored. These paths are processed before any
361 that are listed on the command line. The file name can be
362 given as "-" to refer to the standard input. If --file and
363 --file-list are both specified as "-", patterns are read
364 first. This is useful only when the standard input is a ter‐
365 minal, from which further lines (the list of files) can be
366 read after an end-of-file indication. If this option is given
367 more than once, all the specified files are read.
368 --file-offsets
370 Instead of showing lines or parts of lines that match, show
371 each match as an offset from the start of the file and a
372 length, separated by a comma. In this mode, no context is
373 shown. That is, the -A, -B, and -C options are ignored. If
374 there is more than one match in a line, each of them is shown
375 separately. This option is mutually exclusive with --output,
376 --line-offsets, and --only-matching.
377 -H, --with-filename
379 Force the inclusion of the file name at the start of output
380 lines when searching a single file. By default, the file name
381 is not shown in this case. For matching lines, the file name
382 is followed by a colon; for context lines, a hyphen separator
383 is used. If a line number is also being output, it follows
384 the file name. When the -M option causes a pattern to match
385 more than one line, only the first is preceded by the file
386 name. This option overrides any previous -h, -l, or -L
387 options.
388 -h, --no-filename
390 Suppress the output file names when searching multiple files.
391 By default, file names are shown when multiple files are
392 searched. For matching lines, the file name is followed by a
393 colon; for context lines, a hyphen separator is used. If a
394 line number is also being output, it follows the file name.
395 This option overrides any previous -H, -L, or -l options.
396 --heap-limit=number
398 See --match-limit below.
399 --help Output a help message, giving brief details of the command
401 options and file type support, and then exit. Anything else
402 on the command line is ignored.
403 -I Ignore binary files. This is equivalent to --binary-
405 files=without-match.
406 -i, --ignore-case
408 Ignore upper/lower case distinctions during comparisons.
409 --include=pattern
411 If any --include patterns are specified, the only files that
412 are processed are those that match one of the patterns (and
413 do not match an --exclude pattern). This option does not
414 affect directories, but it applies to all files, whether
415 listed on the command line, obtained from --file-list, or by
416 scanning a directory. The pattern is a PCRE2 regular expres‐
417 sion, and is matched against the final component of the file
418 name, not the entire path. The -F, -w, and -x options do not
419 apply to this pattern. The option may be given any number of
420 times. If a file name matches both an --include and an
421 --exclude pattern, it is excluded. There is no short form
422 for this option.
423 --include-from=filename
425 Treat each non-empty line of the file as the data for an
426 --include option. What constitutes a newline for this purpose
427 is the operating system's default. The --newline option has
428 no effect on this option. This option may be given any number
429 of times; all the files are read.
430 --include-dir=pattern
432 If any --include-dir patterns are specified, the only direc‐
433 tories that are processed are those that match one of the
434 patterns (and do not match an --exclude-dir pattern). This
435 applies to all directories, whether listed on the command
436 line, obtained from --file-list, or by scanning a parent
437 directory. The pattern is a PCRE2 regular expression, and is
438 matched against the final component of the directory name,
439 not the entire path. The -F, -w, and -x options do not apply
440 to this pattern. The option may be given any number of times.
441 If a directory matches both --include-dir and --exclude-dir,
442 it is excluded. There is no short form for this option.
443 -L, --files-without-match
445 Instead of outputting lines from the files, just output the
446 names of the files that do not contain any lines that would
447 have been output. Each file name is output once, on a sepa‐
448 rate line. This option overrides any previous -H, -h, or -l
449 options.
450 -l, --files-with-matches
452 Instead of outputting lines from the files, just output the
453 names of the files containing lines that would have been out‐
454 put. Each file name is output once, on a separate line.
455 Searching normally stops as soon as a matching line is found
456 in a file. However, if the -c (count) option is also used,
457 matching continues in order to obtain the correct count, and
458 those files that have at least one match are listed along
459 with their counts. Using this option with -c is a way of sup‐
460 pressing the listing of files with no matches. This opeion
461 overrides any previous -H, -h, or -L options.
462 --label=name
464 This option supplies a name to be used for the standard input
465 when file names are being output. If not supplied, "(standard
466 input)" is used. There is no short form for this option.
467 --line-buffered
469 When this option is given, non-compressed input is read and
470 processed line by line, and the output is flushed after each
471 write. By default, input is read in large chunks, unless
472 pcre2grep can determine that it is reading from a terminal
473 (which is currently possible only in Unix-like environments
474 or Windows). Output to terminal is normally automatically
475 flushed by the operating system. This option can be useful
476 when the input or output is attached to a pipe and you do not
477 want pcre2grep to buffer up large amounts of data. However,
478 its use will affect performance, and the -M (multiline)
479 option ceases to work. When input is from a compressed .gz or
480 .bz2 file, --line-buffered is ignored.
481 --line-offsets
483 Instead of showing lines or parts of lines that match, show
484 each match as a line number, the offset from the start of the
485 line, and a length. The line number is terminated by a colon
486 (as usual; see the -n option), and the offset and length are
487 separated by a comma. In this mode, no context is shown.
488 That is, the -A, -B, and -C options are ignored. If there is
489 more than one match in a line, each of them is shown sepa‐
490 rately. This option is mutually exclusive with --output,
491 --file-offsets, and --only-matching.
492 --locale=locale-name
494 This option specifies a locale to be used for pattern match‐
495 ing. It overrides the value in the LC_ALL or LC_CTYPE envi‐
496 ronment variables. If no locale is specified, the PCRE2
497 library's default (usually the "C" locale) is used. There is
498 no short form for this option.
499 --match-limit=number
501 Processing some regular expression patterns may take a very
502 long time to search for all possible matching strings. Others
503 may require a very large amount of memory. There are three
504 options that set resource limits for matching.
505 The --match-limit option provides a means of limiting comput‐
507 ing resource usage when processing patterns that are not
508 going to match, but which have a very large number of possi‐
509 bilities in their search trees. The classic example is a pat‐
510 tern that uses nested unlimited repeats. Internally, PCRE2
511 has a counter that is incremented each time around its main
512 processing loop. If the value set by --match-limit is
513 reached, an error occurs.
514 The --heap-limit option specifies, as a number of kibibytes
516 (units of 1024 bytes), the amount of heap memory that may be
517 used for matching. Heap memory is needed only if matching the
518 pattern requires a significant number of nested backtracking
519 points to be remembered. This parameter can be set to zero to
520 forbid the use of heap memory altogether.
521 The --depth-limit option limits the depth of nested back‐
523 tracking points, which indirectly limits the amount of memory
524 that is used. The amount of memory needed for each backtrack‐
525 ing point depends on the number of capturing parentheses in
526 the pattern, so the amount of memory that is used before this
527 limit acts varies from pattern to pattern. This limit is of
528 use only if it is set smaller than --match-limit.
529 There are no short forms for these options. The default lim‐
531 its can be set when the PCRE2 library is compiled; if they
532 are not specified, the defaults are very large and so effec‐
533 tively unlimited.
534 --max-buffer-size=number
536 This limits the expansion of the processing buffer, whose
537 initial size can be set by --buffer-size. The maximum buffer
538 size is silently forced to be no smaller than the starting
539 buffer size.
540 -M, --multiline
542 Allow patterns to match more than one line. When this option
543 is set, the PCRE2 library is called in "multiline" mode. This
544 allows a matched string to extend past the end of a line and
545 continue on one or more subsequent lines. Patterns used with
546 -M may usefully contain literal newline characters and inter‐
547 nal occurrences of ^ and $ characters. The output for a suc‐
548 cessful match may consist of more than one line. The first
549 line is the line in which the match started, and the last
550 line is the line in which the match ended. If the matched
551 string ends with a newline sequence, the output ends at the
552 end of that line. If -v is set, none of the lines in a
553 multi-line match are output. Once a match has been handled,
554 scanning restarts at the beginning of the line after the one
555 in which the match ended.
556 The newline sequence that separates multiple lines must be
558 matched as part of the pattern. For example, to find the
559 phrase "regular expression" in a file where "regular" might
560 be at the end of a line and "expression" at the start of the
561 next line, you could use this command:
562 pcre2grep -M 'regular\s+expression' <file>
564 The \s escape sequence matches any white space character,
566 including newlines, and is followed by + so as to match
567 trailing white space on the first line as well as possibly
568 handling a two-character newline sequence.
569 There is a limit to the number of lines that can be matched,
571 imposed by the way that pcre2grep buffers the input file as
572 it scans it. With a sufficiently large processing buffer,
573 this should not be a problem, but the -M option does not work
574 when input is read line by line (see --line-buffered.)
575 -N newline-type, --newline=newline-type
577 The PCRE2 library supports five different conventions for
578 indicating the ends of lines. They are the single-character
579 sequences CR (carriage return) and LF (linefeed), the two-
580 character sequence CRLF, an "anycrlf" convention, which rec‐
581 ognizes any of the preceding three types, and an "any" con‐
582 vention, in which any Unicode line ending sequence is assumed
583 to end a line. The Unicode sequences are the three just men‐
584 tioned, plus VT (vertical tab, U+000B), FF (form feed,
585 U+000C), NEL (next line, U+0085), LS (line separator,
586 U+2028), and PS (paragraph separator, U+2029).
587 When the PCRE2 library is built, a default line-ending
589 sequence is specified. This is normally the standard
590 sequence for the operating system. Unless otherwise specified
591 by this option, pcre2grep uses the library's default. The
592 possible values for this option are CR, LF, CRLF, ANYCRLF, or
593 ANY. This makes it possible to use pcre2grep to scan files
594 that have come from other environments without having to mod‐
595 ify their line endings. If the data that is being scanned
596 does not agree with the convention set by this option,
597 pcre2grep may behave in strange ways. Note that this option
598 does not apply to files specified by the -f, --exclude-from,
599 or --include-from options, which are expected to use the
600 operating system's standard newline sequence.
601 -n, --line-number
603 Precede each output line by its line number in the file, fol‐
604 lowed by a colon for matching lines or a hyphen for context
605 lines. If the file name is also being output, it precedes the
606 line number. When the -M option causes a pattern to match
607 more than one line, only the first is preceded by its line
608 number. This option is forced if --line-offsets is used.
609 --no-jit If the PCRE2 library is built with support for just-in-time
611 compiling (which speeds up matching), pcre2grep automatically
612 makes use of this, unless it was explicitly disabled at build
613 time. This option can be used to disable the use of JIT at
614 run time. It is provided for testing and working round prob‐
615 lems. It should never be needed in normal use.
616 -O text, --output=text
618 When there is a match, instead of outputting the whole line
619 that matched, output just the given text. This option is
620 mutually exclusive with --only-matching, --file-offsets, and
621 --line-offsets. Escape sequences starting with a dollar char‐
622 acter may be used to insert the contents of the matched part
623 of the line and/or captured substrings into the text.
624 $<digits> or ${<digits>} is replaced by the captured sub‐
626 string of the given decimal number; zero substitutes the
627 whole match. If the number is greater than the number of cap‐
628 turing substrings, or if the capture is unset, the replace‐
629 ment is empty.
630 $a is replaced by bell; $b by backspace; $e by escape; $f by
632 form feed; $n by newline; $r by carriage return; $t by tab;
633 $v by vertical tab.
634 $o<digits> is replaced by the character represented by the
636 given octal number; up to three digits are processed.
637 $x<digits> is replaced by the character represented by the
639 given hexadecimal number; up to two digits are processed.
640 Any other character is substituted by itself. In particular,
642 $$ is replaced by a single dollar.
643 -o, --only-matching
645 Show only the part of the line that matched a pattern instead
646 of the whole line. In this mode, no context is shown. That
647 is, the -A, -B, and -C options are ignored. If there is more
648 than one match in a line, each of them is shown separately,
649 on a separate line of output. If -o is combined with -v
650 (invert the sense of the match to find non-matching lines),
651 no output is generated, but the return code is set appropri‐
652 ately. If the matched portion of the line is empty, nothing
653 is output unless the file name or line number are being
654 printed, in which case they are shown on an otherwise empty
655 line. This option is mutually exclusive with --output,
656 --file-offsets and --line-offsets.
657 -onumber, --only-matching=number
659 Show only the part of the line that matched the capturing
660 parentheses of the given number. Up to 50 capturing parenthe‐
661 ses are supported by default. This limit can be changed via
662 the --om-capture option. A pattern may contain any number of
663 capturing parentheses, but only those whose number is within
664 the limit can be accessed by -o. An error occurs if the num‐
665 ber specified by -o is greater than the limit.
666 -o0 is the same as -o without a number. Because these options
668 can be given without an argument (see above), if an argument
669 is present, it must be given in the same shell item, for
670 example, -o3 or --only-matching=2. The comments given for the
671 non-argument case above also apply to this option. If the
672 specified capturing parentheses do not exist in the pattern,
673 or were not set in the match, nothing is output unless the
674 file name or line number are being output.
675 If this option is given multiple times, multiple substrings
677 are output for each match, in the order the options are
678 given, and all on one line. For example, -o3 -o1 -o3 causes
679 the substrings matched by capturing parentheses 3 and 1 and
680 then 3 again to be output. By default, there is no separator
681 (but see the next but one option).
682 --om-capture=number
684 Set the number of capturing parentheses that can be accessed
685 by -o. The default is 50.
686 --om-separator=text
688 Specify a separating string for multiple occurrences of -o.
689 The default is an empty string. Separating strings are never
690 coloured.
691 -q, --quiet
693 Work quietly, that is, display nothing except error messages.
694 The exit status indicates whether or not any matches were
695 found.
696 -r, --recursive
698 If any given path is a directory, recursively scan the files
699 it contains, taking note of any --include and --exclude set‐
700 tings. By default, a directory is read as a normal file; in
701 some operating systems this gives an immediate end-of-file.
702 This option is a shorthand for setting the -d option to
703 "recurse".
704 --recursion-limit=number
706 See --match-limit above.
707 -s, --no-messages
709 Suppress error messages about non-existent or unreadable
710 files. Such files are quietly skipped. However, the return
711 code is still 2, even if matches were found in other files.
712 -t, --total-count
714 This option is useful when scanning more than one file. If
715 used on its own, -t suppresses all output except for a grand
716 total number of matching lines (or non-matching lines if -v
717 is used) in all the files. If -t is used with -c, a grand
718 total is output except when the previous output is just one
719 line. In other words, it is not output when just one file's
720 count is listed. If file names are being output, the grand
721 total is preceded by "TOTAL:". Otherwise, it appears as just
722 another number. The -t option is ignored when used with -L
723 (list files without matches), because the grand total would
724 always be zero.
725 -u, --utf-8
727 Operate in UTF-8 mode. This option is available only if PCRE2
728 has been compiled with UTF-8 support. All patterns (including
729 those for any --exclude and --include options) and all sub‐
730 ject lines that are scanned must be valid strings of UTF-8
731 characters.
732 -V, --version
734 Write the version numbers of pcre2grep and the PCRE2 library
735 to the standard output and then exit. Anything else on the
736 command line is ignored.
737 -v, --invert-match
739 Invert the sense of the match, so that lines which do not
740 match any of the patterns are the ones that are found.
741 -w, --word-regex, --word-regexp
743 Force the patterns only to match "words". That is, there must
744 be a word boundary at the start and end of each matched
745 string. This is equivalent to having "\b(?:" at the start of
746 each pattern, and ")\b" at the end. This option applies only
747 to the patterns that are matched against the contents of
748 files; it does not apply to patterns specified by any of the
749 --include or --exclude options.
750 -x, --line-regex, --line-regexp
752 Force the patterns to start matching only at the beginnings
753 of lines, and in addition, require them to match entire
754 lines. In multiline mode the match may be more than one line.
755 This is equivalent to having "^(?:" at the start of each pat‐
756 tern and ")$" at the end. This option applies only to the
757 patterns that are matched against the contents of files; it
758 does not apply to patterns specified by any of the --include
759 or --exclude options.
760
762 The environment variables LC_ALL and LC_CTYPE are examined, in that
764 order, for a locale. The first one that is set is used. This can be
765 overridden by the --locale option. If no locale is set, the PCRE2
766 library's default (usually the "C" locale) is used.
767
769 The -N (--newline) option allows pcre2grep to scan files with different
771 newline conventions from the default. Any parts of the input files that
772 are written to the standard output are copied identically, with what‐
773 ever newline sequences they have in the input. However, the setting of
774 this option affects only the way scanned files are processed. It does
775 not affect the interpretation of files specified by the -f, --file-
776 list, --exclude-from, or --include-from options, nor does it affect the
777 way in which pcre2grep writes informational messages to the standard
778 error and output streams. For these it uses the string "\n" to indicate
779 newlines, relying on the C I/O library to convert this to an appropri‐
780 ate sequence.
781
783 Many of the short and long forms of pcre2grep's options are the same as
785 in the GNU grep program. Any long option of the form --xxx-regexp (GNU
786 terminology) is also available as --xxx-regex (PCRE2 terminology). How‐
787 ever, the --depth-limit, --file-list, --file-offsets, --heap-limit,
788 --include-dir, --line-offsets, --locale, --match-limit, -M, --multi‐
789 line, -N, --newline, --om-separator, --output, -u, and --utf-8 options
790 are specific to pcre2grep, as is the use of the --only-matching option
791 with a capturing parentheses number.
792 Although most of the common options work the same way, a few are dif‐
794 ferent in pcre2grep. For example, the --include option's argument is a
795 glob for GNU grep, but a regular expression for pcre2grep. If both the
796 -c and -l options are given, GNU grep lists only file names, without
797 counts, but pcre2grep gives the counts as well.
798
800 There are four different ways in which an option with data can be spec‐
802 ified. If a short form option is used, the data may follow immedi‐
803 ately, or (with one exception) in the next command line item. For exam‐
804 ple:
805 -f/some/file
807 -f /some/file
808 The exception is the -o option, which may appear with or without data.
810 Because of this, if data is present, it must follow immediately in the
811 same item, for example -o3.
812 If a long form option is used, the data may appear in the same command
814 line item, separated by an equals character, or (with two exceptions)
815 it may appear in the next command line item. For example:
816 --file=/some/file
818 --file /some/file
819 Note, however, that if you want to supply a file name beginning with ~
821 as data in a shell command, and have the shell expand ~ to a home
822 directory, you must separate the file name from the option, because the
823 shell does not treat ~ specially unless it is at the start of an item.
824 The exceptions to the above are the --colour (or --color) and --only-
826 matching options, for which the data is optional. If one of these
827 options does have data, it must be given in the first form, using an
828 equals character. Otherwise pcre2grep will assume that it has no data.
829
831 pcre2grep has, by default, support for calling external programs or
833 scripts or echoing specific strings during matching by making use of
834 PCRE2's callout facility. However, this support can be completely or
835 partially disabled when pcre2grep is built. You can find out whether
836 your binary has support for callouts by running it with the --help
837 option. If callout support is completely disabled, all callouts in pat‐
838 terns are ignored by pcre2grep. If the facility is partially disabled,
839 calling external programs is not supported, and callouts that request
840 it are ignored.
841 A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu‐
843 ment is either a number or a quoted string (see the pcre2callout docu‐
844 mentation for details). Numbered callouts are ignored by pcre2grep;
845 only callouts with string arguments are useful.
846 Calling external programs or scripts
848 This facility can be independently disabled when pcre2grep is built. It
850 is supported for Windows, where a call to _spawnvp() is used, for VMS,
851 where lib$spawn() is used, and for any other Unix-like environment
852 where fork() and execv() are available.
853 If the callout string does not start with a pipe (vertical bar) charac‐
855 ter, it is parsed into a list of substrings separated by pipe charac‐
856 ters. The first substring must be an executable name, with the follow‐
857 ing substrings specifying arguments:
858 executable_name|arg1|arg2|...
860 Any substring (including the executable name) may contain escape
862 sequences started by a dollar character: $<digits> or ${<digits>} is
863 replaced by the captured substring of the given decimal number, which
864 must be greater than zero. If the number is greater than the number of
865 capturing substrings, or if the capture is unset, the replacement is
866 empty.
867 Any other character is substituted by itself. In particular, $$ is
869 replaced by a single dollar and $| is replaced by a pipe character.
870 Here is an example:
871 echo -e "abcde\n12345" | pcre2grep \
873 '(?x)(.)(..(.))
874 (?C"/bin/echo|Arg1: [$1] [$2] [$3]|Arg2: $|${1}$| ($4)")()' -
875 Output:
877 Arg1: [a] [bcd] [d] Arg2: |a| ()
879 abcde
880 Arg1: [1] [234] [4] Arg2: |1| ()
881 12345
882 The parameters for the system call that is used to run the program or
884 script are zero-terminated strings. This means that binary zero charac‐
885 ters in the callout argument will cause premature termination of their
886 substrings, and therefore should not be present. Any syntax errors in
887 the string (for example, a dollar not followed by another character)
888 cause the callout to be ignored. If running the program fails for any
889 reason (including the non-existence of the executable), a local match‐
890 ing failure occurs and the matcher backtracks in the normal way.
891 Echoing a specific string
893 This facility is always available, provided that callouts were not com‐
895 pletely disabled when pcre2grep was built. If the callout string starts
896 with a pipe (vertical bar) character, the rest of the string is written
897 to the output, having been passed through the same escape processing as
898 text from the --output option. This provides a simple echoing facility
899 that avoids calling an external program or script. No terminator is
900 added to the string, so if you want a newline, you must include it
901 explicitly. Matching continues normally after the string is output. If
902 you want to see only the callout output but not any output from an
903 actual match, you should end the relevant pattern with (*FAIL).
904
906 It is possible to supply a regular expression that takes a very long
908 time to fail to match certain lines. Such patterns normally involve
909 nested indefinite repeats, for example: (a+)*\d when matched against a
910 line of a's with no final digit. The PCRE2 matching function has a
911 resource limit that causes it to abort in these circumstances. If this
912 happens, pcre2grep outputs an error message and the line that caused
913 the problem to the standard error stream. If there are more than 20
914 such errors, pcre2grep gives up.
915 The --match-limit option of pcre2grep can be used to set the overall
917 resource limit. There are also other limits that affect the amount of
918 memory used during matching; see the discussion of --heap-limit and
919 --depth-limit above.
920
922 Exit status is 0 if any matches were found, 1 if no matches were found,
924 and 2 for syntax errors, overlong lines, non-existent or inaccessible
925 files (even if matches were found in other files) or too many matching
926 errors. Using the -s option to suppress error messages about inaccessi‐
927 ble files does not affect the return code.
928 When run under VMS, the return code is placed in the symbol
930 PCRE2GREP_RC because VMS does not distinguish between exit(0) and
931 exit(1).
932
934 pcre2pattern(3), pcre2syntax(3), pcre2callout(3).
936
938 Philip Hazel
940 University Computing Service
941 Cambridge, England.
942
944 Last updated: 24 November 2018
946 Copyright (c) 1997-2018 University of Cambridge.
947PCRE2 10.33 24 November 2018 PCRE2GREP(1)