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 matched 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 However, if the newline type is specified as NUL, that is, the line
116 terminator is a binary zero, the test for a binary file is not applied.
117 See the --binary-files option for a means of changing the way binary
118 files are handled.
119
121 Patterns passed from the command line are strings that are terminated
123 by a binary zero, so cannot contain internal zeros. However, patterns
124 that are read from a file via the -f option may contain binary zeros.
125
127 The order in which some of the options appear can affect the output.
129 For example, both the -H and -l options affect the printing of file
130 names. Whichever comes later in the command line will be the one that
131 takes effect. Similarly, except where noted below, if an option is
132 given twice, the later setting is used. Numerical values for options
133 may be followed by K or M, to signify multiplication by 1024 or
134 1024*1024 respectively.
135 -- This terminates the list of options. It is useful if the next
137 item on the command line starts with a hyphen but is not an
138 option. This allows for the processing of patterns and file
139 names that start with hyphens.
140 -A number, --after-context=number
142 Output up to number lines of context after each matching
143 line. Fewer lines are output if the next match or the end of
144 the file is reached, or if the processing buffer size has
145 been set too small. If file names and/or line numbers are
146 being output, a hyphen separator is used instead of a colon
147 for the context lines. A line containing "--" is output
148 between each group of lines, unless they are in fact contigu‐
149 ous in the input file. The value of number is expected to be
150 relatively small. When -c is used, -A is ignored.
151 -a, --text
153 Treat binary files as text. This is equivalent to --binary-
154 files=text.
155 -B number, --before-context=number
157 Output up to number lines of context before each matching
158 line. Fewer lines are output if the previous match or the
159 start of the file is within number lines, or if the process‐
160 ing buffer size has been set too small. If file names and/or
161 line numbers are being output, a hyphen separator is used
162 instead of a colon for the context lines. A line containing
163 "--" is output between each group of lines, unless they are
164 in fact contiguous in the input file. The value of number is
165 expected to be relatively small. When -c is used, -B is
166 ignored.
167 --binary-files=word
169 Specify how binary files are to be processed. If the word is
170 "binary" (the default), pattern matching is performed on
171 binary files, but the only output is "Binary file <name>
172 matches" when a match succeeds. If the word is "text", which
173 is equivalent to the -a or --text option, binary files are
174 processed in the same way as any other file. In this case,
175 when a match succeeds, the output may be binary garbage,
176 which can have nasty effects if sent to a terminal. If the
177 word is "without-match", which is equivalent to the -I
178 option, binary files are not processed at all; they are
179 assumed not to be of interest and are skipped without causing
180 any output or affecting the return code.
181 --buffer-size=number
183 Set the parameter that controls how much memory is obtained
184 at the start of processing for buffering files that are being
185 scanned. See also --max-buffer-size below.
186 -C number, --context=number
188 Output number lines of context both before and after each
189 matching line. This is equivalent to setting both -A and -B
190 to the same value.
191 -c, --count
193 Do not output lines from the files that are being scanned;
194 instead output the number of lines that would have been
195 shown, either because they matched, or, if -v is set, because
196 they failed to match. By default, this count is exactly the
197 same as the number of lines that would have been output, but
198 if the -M (multiline) option is used (without -v), there may
199 be more suppressed lines than the count (that is, the number
200 of matches).
201 If no lines are selected, the number zero is output. If sev‐
203 eral files are are being scanned, a count is output for each
204 of them and the -t option can be used to cause a total to be
205 output at the end. However, if the --files-with-matches
206 option is also used, only those files whose counts are
207 greater than zero are listed. When -c is used, the -A, -B,
208 and -C options are ignored.
209 --colour, --color
211 If this option is given without any data, it is equivalent to
212 "--colour=auto". If data is required, it must be given in
213 the same shell item, separated by an equals sign.
214 --colour=value, --color=value
216 This option specifies under what circumstances the parts of a
217 line that matched a pattern should be coloured in the output.
218 By default, the output is not coloured. The value (which is
219 optional, see above) may be "never", "always", or "auto". In
220 the latter case, colouring happens only if the standard out‐
221 put is connected to a terminal. More resources are used when
222 colouring is enabled, because pcre2grep has to search for all
223 possible matches in a line, not just one, in order to colour
224 them all.
225 The colour that is used can be specified by setting one of
227 the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR,
228 PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that
229 order. If none of these are set, pcre2grep looks for
230 GREP_COLORS or GREP_COLOR (in that order). The value of the
231 variable should be a string of two numbers, separated by a
232 semicolon, except in the case of GREP_COLORS, which must
233 start with "ms=" or "mt=" followed by two semicolon-separated
234 colours, terminated by the end of the string or by a colon.
235 If GREP_COLORS does not start with "ms=" or "mt=" it is
236 ignored, and GREP_COLOR is checked.
237 If the string obtained from one of the above variables con‐
239 tains any characters other than semicolon or digits, the set‐
240 ting is ignored and the default colour is used. The string is
241 copied directly into the control string for setting colour on
242 a terminal, so it is your responsibility to ensure that the
243 values make sense. If no relevant environment variable is
244 set, the default is "1;31", which gives red.
245 -D action, --devices=action
247 If an input path is not a regular file or a directory,
248 "action" specifies how it is to be processed. Valid values
249 are "read" (the default) or "skip" (silently skip the path).
250 -d action, --directories=action
252 If an input path is a directory, "action" specifies how it is
253 to be processed. Valid values are "read" (the default in
254 non-Windows environments, for compatibility with GNU grep),
255 "recurse" (equivalent to the -r option), or "skip" (silently
256 skip the path, the default in Windows environments). In the
257 "read" case, directories are read as if they were ordinary
258 files. In some operating systems the effect of reading a
259 directory like this is an immediate end-of-file; in others it
260 may provoke an error.
261 --depth-limit=number
263 See --match-limit below.
264 -e pattern, --regex=pattern, --regexp=pattern
266 Specify a pattern to be matched. This option can be used mul‐
267 tiple times in order to specify several patterns. It can also
268 be used as a way of specifying a single pattern that starts
269 with a hyphen. When -e is used, no argument pattern is taken
270 from the command line; all arguments are treated as file
271 names. There is no limit to the number of patterns. They are
272 applied to each line in the order in which they are defined
273 until one matches.
274 If -f is used with -e, the command line patterns are matched
276 first, followed by the patterns from the file(s), independent
277 of the order in which these options are specified. Note that
278 multiple use of -e is not the same as a single pattern with
279 alternatives. For example, X|Y finds the first character in a
280 line that is X or Y, whereas if the two patterns are given
281 separately, with X first, pcre2grep finds X if it is present,
282 even if it follows Y in the line. It finds Y only if there is
283 no X in the line. This matters only if you are using -o or
284 --colo(u)r to show the part(s) of the line that matched.
285 --exclude=pattern
287 Files (but not directories) whose names match the pattern are
288 skipped without being processed. This applies to all files,
289 whether listed on the command line, obtained from --file-
290 list, or by scanning a directory. The pattern is a PCRE2 reg‐
291 ular expression, and is matched against the final component
292 of the file name, not the entire path. The -F, -w, and -x
293 options do not apply to this pattern. The option may be given
294 any number of times in order to specify multiple patterns. If
295 a file name matches both an --include and an --exclude pat‐
296 tern, it is excluded. There is no short form for this option.
297 --exclude-from=filename
299 Treat each non-empty line of the file as the data for an
300 --exclude option. What constitutes a newline when reading the
301 file is the operating system's default. The --newline option
302 has no effect on this option. This option may be given more
303 than once in order to specify a number of files to read.
304 --exclude-dir=pattern
306 Directories whose names match the pattern are skipped without
307 being processed, whatever the setting of the --recursive
308 option. This applies to all directories, whether listed on
309 the command line, obtained from --file-list, or by scanning a
310 parent directory. The pattern is a PCRE2 regular expression,
311 and is matched against the final component of the directory
312 name, not the entire path. The -F, -w, and -x options do not
313 apply to this pattern. The option may be given any number of
314 times in order to specify more than one pattern. If a direc‐
315 tory matches both --include-dir and --exclude-dir, it is
316 excluded. There is no short form for this option.
317 -F, --fixed-strings
319 Interpret each data-matching pattern as a list of fixed
320 strings, separated by newlines, instead of as a regular
321 expression. What constitutes a newline for this purpose is
322 controlled by the --newline option. The -w (match as a word)
323 and -x (match whole line) options can be used with -F. They
324 apply to each of the fixed strings. A line is selected if any
325 of the fixed strings are found in it (subject to -w or -x, if
326 present). This option applies only to the patterns that are
327 matched against the contents of files; it does not apply to
328 patterns specified by any of the --include or --exclude
329 options.
330 -f filename, --file=filename
332 Read patterns from the file, one per line, and match them
333 against each line of input. As is the case with patterns on
334 the command line, no delimiters should be used. What consti‐
335 tutes a newline when reading the file is the operating sys‐
336 tem's default interpretation of \n. The --newline option has
337 no effect on this option. Trailing white space is removed
338 from each line, and blank lines are ignored. An empty file
339 contains no patterns and therefore matches nothing. Patterns
340 read from a file in this way may contain binary zeros, which
341 are treated as ordinary data characters. See also the com‐
342 ments about multiple patterns versus a single pattern with
343 alternatives in the description of -e above.
344 If this option is given more than once, all the specified
346 files are read. A data line is output if any of the patterns
347 match it. A file name can be given as "-" to refer to the
348 standard input. When -f is used, patterns specified on the
349 command line using -e may also be present; they are tested
350 before the file's patterns. However, no other pattern is
351 taken from the command line; all arguments are treated as the
352 names of paths to be searched.
353 --file-list=filename
355 Read a list of files and/or directories that are to be
356 scanned from the given file, one per line. What constitutes a
357 newline when reading the file is the operating system's
358 default. Trailing white space is removed from each line, and
359 blank lines are ignored. These paths are processed before any
360 that are listed on the command line. The file name can be
361 given as "-" to refer to the standard input. If --file and
362 --file-list are both specified as "-", patterns are read
363 first. This is useful only when the standard input is a ter‐
364 minal, from which further lines (the list of files) can be
365 read after an end-of-file indication. If this option is given
366 more than once, all the specified files are read.
367 --file-offsets
369 Instead of showing lines or parts of lines that match, show
370 each match as an offset from the start of the file and a
371 length, separated by a comma. In this mode, no context is
372 shown. That is, the -A, -B, and -C options are ignored. If
373 there is more than one match in a line, each of them is shown
374 separately. This option is mutually exclusive with --output,
375 --line-offsets, and --only-matching.
376 -H, --with-filename
378 Force the inclusion of the file name at the start of output
379 lines when searching a single file. By default, the file name
380 is not shown in this case. For matching lines, the file name
381 is followed by a colon; for context lines, a hyphen separator
382 is used. If a line number is also being output, it follows
383 the file name. When the -M option causes a pattern to match
384 more than one line, only the first is preceded by the file
385 name. This option overrides any previous -h, -l, or -L
386 options.
387 -h, --no-filename
389 Suppress the output file names when searching multiple files.
390 By default, file names are shown when multiple files are
391 searched. For matching lines, the file name is followed by a
392 colon; for context lines, a hyphen separator is used. If a
393 line number is also being output, it follows the file name.
394 This option overrides any previous -H, -L, or -l options.
395 --heap-limit=number
397 See --match-limit below.
398 --help Output a help message, giving brief details of the command
400 options and file type support, and then exit. Anything else
401 on the command line is ignored.
402 -I Ignore binary files. This is equivalent to --binary-
404 files=without-match.
405 -i, --ignore-case
407 Ignore upper/lower case distinctions during comparisons.
408 --include=pattern
410 If any --include patterns are specified, the only files that
411 are processed are those whose names match one of the patterns
412 and do not match an --exclude pattern. This option does not
413 affect directories, but it applies to all files, whether
414 listed on the command line, obtained from --file-list, or by
415 scanning a directory. The pattern is a PCRE2 regular expres‐
416 sion, and is matched against the final component of the file
417 name, not the entire path. The -F, -w, and -x options do not
418 apply to this pattern. The option may be given any number of
419 times. If a file name matches both an --include and an
420 --exclude pattern, it is excluded. There is no short form
421 for this option.
422 --include-from=filename
424 Treat each non-empty line of the file as the data for an
425 --include option. What constitutes a newline for this purpose
426 is the operating system's default. The --newline option has
427 no effect on this option. This option may be given any number
428 of times; all the files are read.
429 --include-dir=pattern
431 If any --include-dir patterns are specified, the only direc‐
432 tories that are processed are those whose names match one of
433 the patterns and do not match an --exclude-dir pattern. This
434 applies to all directories, whether listed on the command
435 line, obtained from --file-list, or by scanning a parent
436 directory. The pattern is a PCRE2 regular expression, and is
437 matched against the final component of the directory name,
438 not the entire path. The -F, -w, and -x options do not apply
439 to this pattern. The option may be given any number of times.
440 If a directory matches both --include-dir and --exclude-dir,
441 it is excluded. There is no short form for this option.
442 -L, --files-without-match
444 Instead of outputting lines from the files, just output the
445 names of the files that do not contain any lines that would
446 have been output. Each file name is output once, on a sepa‐
447 rate line. This option overrides any previous -H, -h, or -l
448 options.
449 -l, --files-with-matches
451 Instead of outputting lines from the files, just output the
452 names of the files containing lines that would have been out‐
453 put. Each file name is output once, on a separate line.
454 Searching normally stops as soon as a matching line is found
455 in a file. However, if the -c (count) option is also used,
456 matching continues in order to obtain the correct count, and
457 those files that have at least one match are listed along
458 with their counts. Using this option with -c is a way of sup‐
459 pressing the listing of files with no matches that occurs
460 with -c on its own. This option overrides any previous -H,
461 -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 or
474 Windows. Output to terminal is normally automatically flushed
475 by the operating system. This option can be useful when the
476 input or output is attached to a pipe and you do not want
477 pcre2grep to buffer up large amounts of data. However, its
478 use will affect performance, and the -M (multiline) option
479 ceases to work. When input is from a compressed .gz or .bz2
480 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 -M, --multiline
501 Allow patterns to match more than one line. When this option
502 is set, the PCRE2 library is called in "multiline" mode. This
503 allows a matched string to extend past the end of a line and
504 continue on one or more subsequent lines. Patterns used with
505 -M may usefully contain literal newline characters and inter‐
506 nal occurrences of ^ and $ characters. The output for a suc‐
507 cessful match may consist of more than one line. The first
508 line is the line in which the match started, and the last
509 line is the line in which the match ended. If the matched
510 string ends with a newline sequence, the output ends at the
511 end of that line. If -v is set, none of the lines in a
512 multi-line match are output. Once a match has been handled,
513 scanning restarts at the beginning of the line after the one
514 in which the match ended.
515 The newline sequence that separates multiple lines must be
517 matched as part of the pattern. For example, to find the
518 phrase "regular expression" in a file where "regular" might
519 be at the end of a line and "expression" at the start of the
520 next line, you could use this command:
521 pcre2grep -M 'regular\s+expression' <file>
523 The \s escape sequence matches any white space character,
525 including newlines, and is followed by + so as to match
526 trailing white space on the first line as well as possibly
527 handling a two-character newline sequence.
528 There is a limit to the number of lines that can be matched,
530 imposed by the way that pcre2grep buffers the input file as
531 it scans it. With a sufficiently large processing buffer,
532 this should not be a problem, but the -M option does not work
533 when input is read line by line (see --line-buffered.)
534 -m number, --max-count=number
536 Stop processing after finding number matching lines, or non-
537 matching lines if -v is also set. Any trailing context lines
538 are output after the final match. In multiline mode, each
539 multiline match counts as just one line for this purpose. If
540 this limit is reached when reading the standard input from a
541 regular file, the file is left positioned just after the last
542 matching line. If -c is also set, the count that is output
543 is never greater than number. This option has no effect if
544 used with -L, -l, or -q, or when just checking for a match in
545 a binary file.
546 --match-limit=number
548 Processing some regular expression patterns may take a very
549 long time to search for all possible matching strings. Others
550 may require a very large amount of memory. There are three
551 options that set resource limits for matching.
552 The --match-limit option provides a means of limiting comput‐
554 ing resource usage when processing patterns that are not
555 going to match, but which have a very large number of possi‐
556 bilities in their search trees. The classic example is a pat‐
557 tern that uses nested unlimited repeats. Internally, PCRE2
558 has a counter that is incremented each time around its main
559 processing loop. If the value set by --match-limit is
560 reached, an error occurs.
561 The --heap-limit option specifies, as a number of kibibytes
563 (units of 1024 bytes), the amount of heap memory that may be
564 used for matching. Heap memory is needed only if matching the
565 pattern requires a significant number of nested backtracking
566 points to be remembered. This parameter can be set to zero to
567 forbid the use of heap memory altogether.
568 The --depth-limit option limits the depth of nested back‐
570 tracking points, which indirectly limits the amount of memory
571 that is used. The amount of memory needed for each backtrack‐
572 ing point depends on the number of capturing parentheses in
573 the pattern, so the amount of memory that is used before this
574 limit acts varies from pattern to pattern. This limit is of
575 use only if it is set smaller than --match-limit.
576 There are no short forms for these options. The default lim‐
578 its can be set when the PCRE2 library is compiled; if they
579 are not specified, the defaults are very large and so effec‐
580 tively unlimited.
581 --max-buffer-size=number
583 This limits the expansion of the processing buffer, whose
584 initial size can be set by --buffer-size. The maximum buffer
585 size is silently forced to be no smaller than the starting
586 buffer size.
587 -N newline-type, --newline=newline-type
589 Six different conventions for indicating the ends of lines in
590 scanned files are supported. For example:
591 pcre2grep -N CRLF 'some pattern' <file>
593 The newline type may be specified in upper, lower, or mixed
595 case. If the newline type is NUL, lines are separated by
596 binary zero characters. The other types are the single-char‐
597 acter sequences CR (carriage return) and LF (linefeed), the
598 two-character sequence CRLF, an "anycrlf" type, which recog‐
599 nizes any of the preceding three types, and an "any" type,
600 for which any Unicode line ending sequence is assumed to end
601 a line. The Unicode sequences are the three just mentioned,
602 plus VT (vertical tab, U+000B), FF (form feed, U+000C), NEL
603 (next line, U+0085), LS (line separator, U+2028), and PS
604 (paragraph separator, U+2029).
605 When the PCRE2 library is built, a default line-ending
607 sequence is specified. This is normally the standard
608 sequence for the operating system. Unless otherwise specified
609 by this option, pcre2grep uses the library's default.
610 This option makes it possible to use pcre2grep to scan files
612 that have come from other environments without having to mod‐
613 ify their line endings. If the data that is being scanned
614 does not agree with the convention set by this option,
615 pcre2grep may behave in strange ways. Note that this option
616 does not apply to files specified by the -f, --exclude-from,
617 or --include-from options, which are expected to use the
618 operating system's standard newline sequence.
619 -n, --line-number
621 Precede each output line by its line number in the file, fol‐
622 lowed by a colon for matching lines or a hyphen for context
623 lines. If the file name is also being output, it precedes the
624 line number. When the -M option causes a pattern to match
625 more than one line, only the first is preceded by its line
626 number. This option is forced if --line-offsets is used.
627 --no-jit If the PCRE2 library is built with support for just-in-time
629 compiling (which speeds up matching), pcre2grep automatically
630 makes use of this, unless it was explicitly disabled at build
631 time. This option can be used to disable the use of JIT at
632 run time. It is provided for testing and working round prob‐
633 lems. It should never be needed in normal use.
634 -O text, --output=text
636 When there is a match, instead of outputting the line that
637 matched, output just the text specified in this option, fol‐
638 lowed by an operating-system standard newline. In this mode,
639 no context is shown. That is, the -A, -B, and -C options are
640 ignored. The --newline option has no effect on this option,
641 which is mutually exclusive with --only-matching, --file-off‐
642 sets, and --line-offsets. However, like --only-matching, if
643 there is more than one match in a line, each of them causes a
644 line of output.
645 Escape sequences starting with a dollar character may be used
647 to insert the contents of the matched part of the line and/or
648 captured substrings into the text.
649 $<digits> or ${<digits>} is replaced by the captured sub‐
651 string of the given decimal number; zero substitutes the
652 whole match. If the number is greater than the number of cap‐
653 turing substrings, or if the capture is unset, the replace‐
654 ment is empty.
655 $a is replaced by bell; $b by backspace; $e by escape; $f by
657 form feed; $n by newline; $r by carriage return; $t by tab;
658 $v by vertical tab.
659 $o<digits> or $o{<digits>} is replaced by the character whose
661 code point is the given octal number. In the first form, up
662 to three octal digits are processed. When more digits are
663 needed in Unicode mode to specify a wide character, the sec‐
664 ond form must be used.
665 $x<digits> or $x{<digits>} is replaced by the character rep‐
667 resented by the given hexadecimal number. In the first form,
668 up to two hexadecimal digits are processed. When more digits
669 are needed in Unicode mode to specify a wide character, the
670 second form must be used.
671 Any other character is substituted by itself. In particular,
673 $$ is replaced by a single dollar.
674 -o, --only-matching
676 Show only the part of the line that matched a pattern instead
677 of the whole line. In this mode, no context is shown. That
678 is, the -A, -B, and -C options are ignored. If there is more
679 than one match in a line, each of them is shown separately,
680 on a separate line of output. If -o is combined with -v
681 (invert the sense of the match to find non-matching lines),
682 no output is generated, but the return code is set appropri‐
683 ately. If the matched portion of the line is empty, nothing
684 is output unless the file name or line number are being
685 printed, in which case they are shown on an otherwise empty
686 line. This option is mutually exclusive with --output,
687 --file-offsets and --line-offsets.
688 -onumber, --only-matching=number
690 Show only the part of the line that matched the capturing
691 parentheses of the given number. Up to 50 capturing parenthe‐
692 ses are supported by default. This limit can be changed via
693 the --om-capture option. A pattern may contain any number of
694 capturing parentheses, but only those whose number is within
695 the limit can be accessed by -o. An error occurs if the num‐
696 ber specified by -o is greater than the limit.
697 -o0 is the same as -o without a number. Because these options
699 can be given without an argument (see above), if an argument
700 is present, it must be given in the same shell item, for
701 example, -o3 or --only-matching=2. The comments given for the
702 non-argument case above also apply to this option. If the
703 specified capturing parentheses do not exist in the pattern,
704 or were not set in the match, nothing is output unless the
705 file name or line number are being output.
706 If this option is given multiple times, multiple substrings
708 are output for each match, in the order the options are
709 given, and all on one line. For example, -o3 -o1 -o3 causes
710 the substrings matched by capturing parentheses 3 and 1 and
711 then 3 again to be output. By default, there is no separator
712 (but see the next but one option).
713 --om-capture=number
715 Set the number of capturing parentheses that can be accessed
716 by -o. The default is 50.
717 --om-separator=text
719 Specify a separating string for multiple occurrences of -o.
720 The default is an empty string. Separating strings are never
721 coloured.
722 -q, --quiet
724 Work quietly, that is, display nothing except error messages.
725 The exit status indicates whether or not any matches were
726 found.
727 -r, --recursive
729 If any given path is a directory, recursively scan the files
730 it contains, taking note of any --include and --exclude set‐
731 tings. By default, a directory is read as a normal file; in
732 some operating systems this gives an immediate end-of-file.
733 This option is a shorthand for setting the -d option to
734 "recurse".
735 --recursion-limit=number
737 This is an obsolete synonym for --depth-limit. See --match-
738 limit above for details.
739 -s, --no-messages
741 Suppress error messages about non-existent or unreadable
742 files. Such files are quietly skipped. However, the return
743 code is still 2, even if matches were found in other files.
744 -t, --total-count
746 This option is useful when scanning more than one file. If
747 used on its own, -t suppresses all output except for a grand
748 total number of matching lines (or non-matching lines if -v
749 is used) in all the files. If -t is used with -c, a grand
750 total is output except when the previous output is just one
751 line. In other words, it is not output when just one file's
752 count is listed. If file names are being output, the grand
753 total is preceded by "TOTAL:". Otherwise, it appears as just
754 another number. The -t option is ignored when used with -L
755 (list files without matches), because the grand total would
756 always be zero.
757 -u, --utf Operate in UTF-8 mode. This option is available only if PCRE2
759 has been compiled with UTF-8 support. All patterns (including
760 those for any --exclude and --include options) and all lines
761 that are scanned must be valid strings of UTF-8 characters.
762 If an invalid UTF-8 string is encountered, an error occurs.
763 -U, --utf-allow-invalid
765 As --utf, but in addition subject lines may contain invalid
766 UTF-8 code unit sequences. These can never form part of any
767 pattern match. Patterns themselves, however, must still be
768 valid UTF-8 strings. This facility allows valid UTF-8 strings
769 to be sought within arbitrary byte sequences in executable or
770 other binary files. For more details about matching in non-
771 valid UTF-8 strings, see the pcre2unicode(3) documentation.
772 -V, --version
774 Write the version numbers of pcre2grep and the PCRE2 library
775 to the standard output and then exit. Anything else on the
776 command line is ignored.
777 -v, --invert-match
779 Invert the sense of the match, so that lines which do not
780 match any of the patterns are the ones that are found. When
781 this option is set, options such as --only-matching and
782 --output, which specify parts of a match that are to be out‐
783 put, are ignored.
784 -w, --word-regex, --word-regexp
786 Force the patterns only to match "words". That is, there must
787 be a word boundary at the start and end of each matched
788 string. This is equivalent to having "\b(?:" at the start of
789 each pattern, and ")\b" at the end. This option applies only
790 to the patterns that are matched against the contents of
791 files; it does not apply to patterns specified by any of the
792 --include or --exclude options.
793 -x, --line-regex, --line-regexp
795 Force the patterns to start matching only at the beginnings
796 of lines, and in addition, require them to match entire
797 lines. In multiline mode the match may be more than one line.
798 This is equivalent to having "^(?:" at the start of each pat‐
799 tern and ")$" at the end. This option applies only to the
800 patterns that are matched against the contents of files; it
801 does not apply to patterns specified by any of the --include
802 or --exclude options.
803
805 The environment variables LC_ALL and LC_CTYPE are examined, in that
807 order, for a locale. The first one that is set is used. This can be
808 overridden by the --locale option. If no locale is set, the PCRE2
809 library's default (usually the "C" locale) is used.
810
812 The -N (--newline) option allows pcre2grep to scan files with newline
814 conventions that differ from the default. This option affects only the
815 way scanned files are processed. It does not affect the interpretation
816 of files specified by the -f, --file-list, --exclude-from, or
817 --include-from options.
818 Any parts of the scanned input files that are written to the standard
820 output are copied with whatever newline sequences they have in the
821 input. However, if the final line of a file is output, and it does not
822 end with a newline sequence, a newline sequence is added. If the new‐
823 line setting is CR, LF, CRLF or NUL, that line ending is output; for
824 the other settings (ANYCRLF or ANY) a single NL is used.
825 The newline setting does not affect the way in which pcre2grep writes
827 newlines in informational messages to the standard output and error
828 streams. Under Windows, the standard output is set to be binary, so
829 that "\r\n" at the ends of output lines that are copied from the input
830 is not converted to "\r\r\n" by the C I/O library. This means that any
831 messages written to the standard output must end with "\r\n". For all
832 other operating systems, and for all messages to the standard error
833 stream, "\n" is used.
834
836 Many of the short and long forms of pcre2grep's options are the same as
838 in the GNU grep program. Any long option of the form --xxx-regexp (GNU
839 terminology) is also available as --xxx-regex (PCRE2 terminology). How‐
840 ever, the --depth-limit, --file-list, --file-offsets, --heap-limit,
841 --include-dir, --line-offsets, --locale, --match-limit, -M, --multi‐
842 line, -N, --newline, --om-separator, --output, -u, --utf, -U, and
843 --utf-allow-invalid options are specific to pcre2grep, as is the use of
844 the --only-matching option with a capturing parentheses number.
845 Although most of the common options work the same way, a few are dif‐
847 ferent in pcre2grep. For example, the --include option's argument is a
848 glob for GNU grep, but a regular expression for pcre2grep. If both the
849 -c and -l options are given, GNU grep lists only file names, without
850 counts, but pcre2grep gives the counts as well.
851
853 There are four different ways in which an option with data can be spec‐
855 ified. If a short form option is used, the data may follow immedi‐
856 ately, or (with one exception) in the next command line item. For exam‐
857 ple:
858 -f/some/file
860 -f /some/file
861 The exception is the -o option, which may appear with or without data.
863 Because of this, if data is present, it must follow immediately in the
864 same item, for example -o3.
865 If a long form option is used, the data may appear in the same command
867 line item, separated by an equals character, or (with two exceptions)
868 it may appear in the next command line item. For example:
869 --file=/some/file
871 --file /some/file
872 Note, however, that if you want to supply a file name beginning with ~
874 as data in a shell command, and have the shell expand ~ to a home
875 directory, you must separate the file name from the option, because the
876 shell does not treat ~ specially unless it is at the start of an item.
877 The exceptions to the above are the --colour (or --color) and --only-
879 matching options, for which the data is optional. If one of these
880 options does have data, it must be given in the first form, using an
881 equals character. Otherwise pcre2grep will assume that it has no data.
882
884 pcre2grep has, by default, support for calling external programs or
886 scripts or echoing specific strings during matching by making use of
887 PCRE2's callout facility. However, this support can be completely or
888 partially disabled when pcre2grep is built. You can find out whether
889 your binary has support for callouts by running it with the --help
890 option. If callout support is completely disabled, all callouts in pat‐
891 terns are ignored by pcre2grep. If the facility is partially disabled,
892 calling external programs is not supported, and callouts that request
893 it are ignored.
894 A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu‐
896 ment is either a number or a quoted string (see the pcre2callout docu‐
897 mentation for details). Numbered callouts are ignored by pcre2grep;
898 only callouts with string arguments are useful.
899 Echoing a specific string
901 Starting the callout string with a pipe character invokes an echoing
903 facility that avoids calling an external program or script. This facil‐
904 ity is always available, provided that callouts were not completely
905 disabled when pcre2grep was built. The rest of the callout string is
906 processed as a zero-terminated string, which means it should not con‐
907 tain any internal binary zeros. It is written to the output, having
908 first been passed through the same escape processing as text from the
909 --output (-O) option (see above). However, $0 cannot be used to insert
910 a matched substring because the match is still in progress. Instead,
911 the single character '0' is inserted. Any syntax errors in the string
912 (for example, a dollar not followed by another character) causes the
913 callout to be ignored. No terminator is added to the output string, so
914 if you want a newline, you must include it explicitly using the escape
915 $n. For example:
916 pcre2grep '(.)(..(.))(?C"|[$1] [$2] [$3]$n")' <some file>
918 Matching continues normally after the string is output. If you want to
920 see only the callout output but not any output from an actual match,
921 you should end the pattern with (*FAIL).
922 Calling external programs or scripts
924 This facility can be independently disabled when pcre2grep is built. It
926 is supported for Windows, where a call to _spawnvp() is used, for VMS,
927 where lib$spawn() is used, and for any Unix-like environment where
928 fork() and execv() are available.
929 If the callout string does not start with a pipe (vertical bar) charac‐
931 ter, it is parsed into a list of substrings separated by pipe charac‐
932 ters. The first substring must be an executable name, with the follow‐
933 ing substrings specifying arguments:
934 executable_name|arg1|arg2|...
936 Any substring (including the executable name) may contain escape
938 sequences started by a dollar character. These are the same as for the
939 --output (-O) option documented above, except that $0 cannot insert the
940 matched string because the match is still in progress. Instead, the
941 character '0' is inserted. If you need a literal dollar or pipe charac‐
942 ter in any substring, use $$ or $| respectively. Here is an example:
943 echo -e "abcde\n12345" | pcre2grep \
945 '(?x)(.)(..(.))
946 (?C"/bin/echo|Arg1: [$1] [$2] [$3]|Arg2: $|${1}$| ($4)")()' -
947 Output:
949 Arg1: [a] [bcd] [d] Arg2: |a| ()
951 abcde
952 Arg1: [1] [234] [4] Arg2: |1| ()
953 12345
954 The parameters for the system call that is used to run the program or
956 script are zero-terminated strings. This means that binary zero charac‐
957 ters in the callout argument will cause premature termination of their
958 substrings, and therefore should not be present. Any syntax errors in
959 the string (for example, a dollar not followed by another character)
960 causes the callout to be ignored. If running the program fails for any
961 reason (including the non-existence of the executable), a local match‐
962 ing failure occurs and the matcher backtracks in the normal way.
963
965 It is possible to supply a regular expression that takes a very long
967 time to fail to match certain lines. Such patterns normally involve
968 nested indefinite repeats, for example: (a+)*\d when matched against a
969 line of a's with no final digit. The PCRE2 matching function has a
970 resource limit that causes it to abort in these circumstances. If this
971 happens, pcre2grep outputs an error message and the line that caused
972 the problem to the standard error stream. If there are more than 20
973 such errors, pcre2grep gives up.
974 The --match-limit option of pcre2grep can be used to set the overall
976 resource limit. There are also other limits that affect the amount of
977 memory used during matching; see the discussion of --heap-limit and
978 --depth-limit above.
979
981 Exit status is 0 if any matches were found, 1 if no matches were found,
983 and 2 for syntax errors, overlong lines, non-existent or inaccessible
984 files (even if matches were found in other files) or too many matching
985 errors. Using the -s option to suppress error messages about inaccessi‐
986 ble files does not affect the return code.
987 When run under VMS, the return code is placed in the symbol
989 PCRE2GREP_RC because VMS does not distinguish between exit(0) and
990 exit(1).
991
993 pcre2pattern(3), pcre2syntax(3), pcre2callout(3), pcre2unicode(3).
995
997 Philip Hazel
999 University Computing Service
1000 Cambridge, England.
1001
1003 Last updated: 04 October 2020
1005 Copyright (c) 1997-2020 University of Cambridge.
1006PCRE2 10.36 04 October 2020 PCRE2GREP(1)