1 PCRE2GREP(1) General Commands Manual PCRE2GREP(1)
6 pcre2grep - a grep with Perl-compatible regular expressions.
9 pcre2grep [options] [long options] [pattern] [path1 path2 ...]
14 pcre2grep searches files for character patterns, in the same way as
15 other grep commands do, but it uses the PCRE2 regular expression
16 library to support patterns that are compatible with the regular
17 expressions of Perl 5. See pcre2syntax(3) for a quick-reference summary
18 of pattern syntax, or pcre2pattern(3) for a full description of the
19 syntax and semantics of the regular expressions that PCRE2 supports.
21 Patterns, whether supplied on the command line or in a separate file,
22 are given without delimiters. For example:
24 pcre2grep Thursday /etc/motd
26 If you attempt to use delimiters (for example, by surrounding a pattern
27 with slashes, as is common in Perl scripts), they are interpreted as
28 part of the pattern. Quotes can of course be used to delimit patterns
29 on the command line because they are interpreted by the shell, and
30 indeed quotes are required if a pattern contains white space or shell
33 The first argument that follows any option settings is treated as the
34 single pattern to be matched when neither -e nor -f is present. Con-
35 versely, when one or both of these options are used to specify pat-
36 terns, all arguments are treated as path names. At least one of -e, -f,
37 or an argument pattern must be provided.
39 If no files are specified, pcre2grep reads the standard input. The
40 standard input can also be referenced by a name consisting of a single
43 pcre2grep some-pattern file1 - file3
45 Input files are searched line by line. By default, each line that
46 matches a pattern is copied to the standard output, and if there is
47 more than one file, the file name is output at the start of each line,
48 followed by a colon. However, there are options that can change how
49 pcre2grep behaves. In particular, the -M option makes it possible to
50 search for strings that span line boundaries. What defines a line
51 boundary is controlled by the -N (--newline) option.
53 The amount of memory used for buffering files that are being scanned is
54 controlled by parameters that can be set by the --buffer-size and
55 --max-buffer-size options. The first of these sets the size of buffer
56 that is obtained at the start of processing. If an input file contains
57 very long lines, a larger buffer may be needed; this is handled by
58 automatically extending the buffer, up to the limit specified by --max-
59 buffer-size. The default values for these parameters can be set when
60 pcre2grep is built; if nothing is specified, the defaults are set to
61 20KiB and 1MiB respectively. An error occurs if a line is too long and
62 the buffer can no longer be expanded.
64 The block of memory that is actually used is three times the "buffer
65 size", to allow for buffering "before" and "after" lines. If the buffer
66 size is too small, fewer than requested "before" and "after" lines may
69 Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the
70 greater. BUFSIZ is defined in <stdio.h>. When there is more than one
71 pattern (specified by the use of -e and/or -f), each pattern is applied
72 to each line in the order in which they are defined, except that all
73 the -e patterns are tried before the -f patterns.
75 By default, as soon as one pattern matches a line, no further patterns
76 are considered. However, if --colour (or --color) is used to colour the
77 matching substrings, or if --only-matching, --file-offsets, or --line-
78 offsets is used to output only the part of the line that matched
79 (either shown literally, or as an offset), scanning resumes immediately
80 following the match, so that further matches on the same line can be
81 found. If there are multiple patterns, they are all tried on the
82 remainder of the line, but patterns that follow the one that matched
83 are not tried on the earlier part of the line.
85 This behaviour means that the order in which multiple patterns are
86 specified can affect the output when one of the above options is used.
87 This is no longer the same behaviour as GNU grep, which now manages to
88 display earlier matches for later patterns (as long as there is no
91 Patterns that can match an empty string are accepted, but empty string
92 matches are never recognized. An example is the pattern
93 "(super)?(man)?", in which all components are optional. This pattern
94 finds all occurrences of both "super" and "man"; the output differs
95 from matching with "super|man" when only the matching substrings are
98 If the LC_ALL or LC_CTYPE environment variable is set, pcre2grep uses
99 the value to set a locale when calling the PCRE2 library. The --locale
100 option can be used to override this.
103 SUPPORT FOR COMPRESSED FILES
105 It is possible to compile pcre2grep so that it uses libz or libbz2 to
106 read compressed files whose names end in .gz or .bz2, respectively. You
107 can find out whether your pcre2grep binary has support for one or both
108 of these file types by running it with the --help option. If the appro-
109 priate support is not present, all files are treated as plain text. The
110 standard input is always so treated. When input is from a compressed
111 .gz or .bz2 file, the --line-buffered option is ignored.
116 By default, a file that contains a binary zero byte within the first
117 1024 bytes is identified as a binary file, and is processed specially.
118 (GNU grep identifies binary files in this manner.) However, if the new-
119 line type is specified as "nul", that is, the line terminator is a
120 binary zero, the test for a binary file is not applied. See the
121 --binary-files option for a means of changing the way binary files are
125 BINARY ZEROS IN PATTERNS
127 Patterns passed from the command line are strings that are terminated
128 by a binary zero, so cannot contain internal zeros. However, patterns
129 that are read from a file via the -f option may contain binary zeros.
134 The order in which some of the options appear can affect the output.
135 For example, both the -H and -l options affect the printing of file
136 names. Whichever comes later in the command line will be the one that
137 takes effect. Similarly, except where noted below, if an option is
138 given twice, the later setting is used. Numerical values for options
139 may be followed by K or M, to signify multiplication by 1024 or
140 1024*1024 respectively.
142 -- This terminates the list of options. It is useful if the next
143 item on the command line starts with a hyphen but is not an
144 option. This allows for the processing of patterns and file
145 names that start with hyphens.
147 -A number, --after-context=number
148 Output up to number lines of context after each matching
149 line. Fewer lines are output if the next match or the end of
150 the file is reached, or if the processing buffer size has
151 been set too small. If file names and/or line numbers are
152 being output, a hyphen separator is used instead of a colon
153 for the context lines. A line containing "--" is output
154 between each group of lines, unless they are in fact contigu-
155 ous in the input file. The value of number is expected to be
156 relatively small. When -c is used, -A is ignored.
159 Treat binary files as text. This is equivalent to --binary-
162 -B number, --before-context=number
163 Output up to number lines of context before each matching
164 line. Fewer lines are output if the previous match or the
165 start of the file is within number lines, or if the process-
166 ing buffer size has been set too small. If file names and/or
167 line numbers are being output, a hyphen separator is used
168 instead of a colon for the context lines. A line containing
169 "--" is output between each group of lines, unless they are
170 in fact contiguous in the input file. The value of number is
171 expected to be relatively small. When -c is used, -B is
175 Specify how binary files are to be processed. If the word is
176 "binary" (the default), pattern matching is performed on
177 binary files, but the only output is "Binary file <name>
178 matches" when a match succeeds. If the word is "text", which
179 is equivalent to the -a or --text option, binary files are
180 processed in the same way as any other file. In this case,
181 when a match succeeds, the output may be binary garbage,
182 which can have nasty effects if sent to a terminal. If the
183 word is "without-match", which is equivalent to the -I
184 option, binary files are not processed at all; they are
185 assumed not to be of interest and are skipped without causing
186 any output or affecting the return code.
189 Set the parameter that controls how much memory is obtained
190 at the start of processing for buffering files that are being
191 scanned. See also --max-buffer-size below.
193 -C number, --context=number
194 Output number lines of context both before and after each
195 matching line. This is equivalent to setting both -A and -B
199 Do not output lines from the files that are being scanned;
200 instead output the number of lines that would have been
201 shown, either because they matched, or, if -v is set, because
202 they failed to match. By default, this count is exactly the
203 same as the number of lines that would have been output, but
204 if the -M (multiline) option is used (without -v), there may
205 be more suppressed lines than the count (that is, the number
208 If no lines are selected, the number zero is output. If sev-
209 eral files are are being scanned, a count is output for each
210 of them and the -t option can be used to cause a total to be
211 output at the end. However, if the --files-with-matches
212 option is also used, only those files whose counts are
213 greater than zero are listed. When -c is used, the -A, -B,
214 and -C options are ignored.
217 If this option is given without any data, it is equivalent to
218 "--colour=auto". If data is required, it must be given in
219 the same shell item, separated by an equals sign.
221 --colour=value, --color=value
222 This option specifies under what circumstances the parts of a
223 line that matched a pattern should be coloured in the output.
224 By default, the output is not coloured. The value (which is
225 optional, see above) may be "never", "always", or "auto". In
226 the latter case, colouring happens only if the standard out-
227 put is connected to a terminal. More resources are used when
228 colouring is enabled, because pcre2grep has to search for all
229 possible matches in a line, not just one, in order to colour
232 The colour that is used can be specified by setting one of
233 the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR,
234 PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that
235 order. If none of these are set, pcre2grep looks for
236 GREP_COLORS or GREP_COLOR (in that order). The value of the
237 variable should be a string of two numbers, separated by a
238 semicolon, except in the case of GREP_COLORS, which must
239 start with "ms=" or "mt=" followed by two semicolon-separated
240 colours, terminated by the end of the string or by a colon.
241 If GREP_COLORS does not start with "ms=" or "mt=" it is
242 ignored, and GREP_COLOR is checked.
244 If the string obtained from one of the above variables con-
245 tains any characters other than semicolon or digits, the set-
246 ting is ignored and the default colour is used. The string is
247 copied directly into the control string for setting colour on
248 a terminal, so it is your responsibility to ensure that the
249 values make sense. If no relevant environment variable is
250 set, the default is "1;31", which gives red.
252 -D action, --devices=action
253 If an input path is not a regular file or a directory,
254 "action" specifies how it is to be processed. Valid values
255 are "read" (the default) or "skip" (silently skip the path).
257 -d action, --directories=action
258 If an input path is a directory, "action" specifies how it is
259 to be processed. Valid values are "read" (the default in
260 non-Windows environments, for compatibility with GNU grep),
261 "recurse" (equivalent to the -r option), or "skip" (silently
262 skip the path, the default in Windows environments). In the
263 "read" case, directories are read as if they were ordinary
264 files. In some operating systems the effect of reading a
265 directory like this is an immediate end-of-file; in others it
266 may provoke an error.
269 See --match-limit below.
271 -e pattern, --regex=pattern, --regexp=pattern
272 Specify a pattern to be matched. This option can be used mul-
273 tiple times in order to specify several patterns. It can also
274 be used as a way of specifying a single pattern that starts
275 with a hyphen. When -e is used, no argument pattern is taken
276 from the command line; all arguments are treated as file
277 names. There is no limit to the number of patterns. They are
278 applied to each line in the order in which they are defined
281 If -f is used with -e, the command line patterns are matched
282 first, followed by the patterns from the file(s), independent
283 of the order in which these options are specified. Note that
284 multiple use of -e is not the same as a single pattern with
285 alternatives. For example, X|Y finds the first character in a
286 line that is X or Y, whereas if the two patterns are given
287 separately, with X first, pcre2grep finds X if it is present,
288 even if it follows Y in the line. It finds Y only if there is
289 no X in the line. This matters only if you are using -o or
290 --colo(u)r to show the part(s) of the line that matched.
293 Files (but not directories) whose names match the pattern are
294 skipped without being processed. This applies to all files,
295 whether listed on the command line, obtained from --file-
296 list, or by scanning a directory. The pattern is a PCRE2 reg-
297 ular expression, and is matched against the final component
298 of the file name, not the entire path. The -F, -w, and -x
299 options do not apply to this pattern. The option may be given
300 any number of times in order to specify multiple patterns. If
301 a file name matches both an --include and an --exclude pat-
302 tern, it is excluded. There is no short form for this option.
304 --exclude-from=filename
305 Treat each non-empty line of the file as the data for an
306 --exclude option. What constitutes a newline when reading the
307 file is the operating system's default. The --newline option
308 has no effect on this option. This option may be given more
309 than once in order to specify a number of files to read.
311 --exclude-dir=pattern
312 Directories whose names match the pattern are skipped without
313 being processed, whatever the setting of the --recursive
314 option. This applies to all directories, whether listed on
315 the command line, obtained from --file-list, or by scanning a
316 parent directory. The pattern is a PCRE2 regular expression,
317 and is matched against the final component of the directory
318 name, not the entire path. The -F, -w, and -x options do not
319 apply to this pattern. The option may be given any number of
320 times in order to specify more than one pattern. If a direc-
321 tory matches both --include-dir and --exclude-dir, it is
322 excluded. There is no short form for this option.
325 Interpret each data-matching pattern as a list of fixed
326 strings, separated by newlines, instead of as a regular
327 expression. What constitutes a newline for this purpose is
328 controlled by the --newline option. The -w (match as a word)
329 and -x (match whole line) options can be used with -F. They
330 apply to each of the fixed strings. A line is selected if any
331 of the fixed strings are found in it (subject to -w or -x, if
332 present). This option applies only to the patterns that are
333 matched against the contents of files; it does not apply to
334 patterns specified by any of the --include or --exclude
337 -f filename, --file=filename
338 Read patterns from the file, one per line, and match them
339 against each line of input. As is the case with patterns on
340 the command line, no delimiters should be used. What consti-
341 tutes a newline when reading the file is the operating sys-
342 tem's default interpretation of \n. The --newline option has
343 no effect on this option. Trailing white space is removed
344 from each line, and blank lines are ignored. An empty file
345 contains no patterns and therefore matches nothing. Patterns
346 read from a file in this way may contain binary zeros, which
347 are treated as ordinary data characters. See also the com-
348 ments about multiple patterns versus a single pattern with
349 alternatives in the description of -e above.
351 If this option is given more than once, all the specified
352 files are read. A data line is output if any of the patterns
353 match it. A file name can be given as "-" to refer to the
354 standard input. When -f is used, patterns specified on the
355 command line using -e may also be present; they are tested
356 before the file's patterns. However, no other pattern is
357 taken from the command line; all arguments are treated as the
358 names of paths to be searched.
361 Read a list of files and/or directories that are to be
362 scanned from the given file, one per line. What constitutes a
363 newline when reading the file is the operating system's
364 default. Trailing white space is removed from each line, and
365 blank lines are ignored. These paths are processed before any
366 that are listed on the command line. The file name can be
367 given as "-" to refer to the standard input. If --file and
368 --file-list are both specified as "-", patterns are read
369 first. This is useful only when the standard input is a ter-
370 minal, from which further lines (the list of files) can be
371 read after an end-of-file indication. If this option is given
372 more than once, all the specified files are read.
375 Instead of showing lines or parts of lines that match, show
376 each match as an offset from the start of the file and a
377 length, separated by a comma. In this mode, no context is
378 shown. That is, the -A, -B, and -C options are ignored. If
379 there is more than one match in a line, each of them is shown
380 separately. This option is mutually exclusive with --output,
381 --line-offsets, and --only-matching.
384 Force the inclusion of the file name at the start of output
385 lines when searching a single file. By default, the file name
386 is not shown in this case. For matching lines, the file name
387 is followed by a colon; for context lines, a hyphen separator
388 is used. If a line number is also being output, it follows
389 the file name. When the -M option causes a pattern to match
390 more than one line, only the first is preceded by the file
391 name. This option overrides any previous -h, -l, or -L
395 Suppress the output file names when searching multiple files.
396 By default, file names are shown when multiple files are
397 searched. For matching lines, the file name is followed by a
398 colon; for context lines, a hyphen separator is used. If a
399 line number is also being output, it follows the file name.
400 This option overrides any previous -H, -L, or -l options.
403 See --match-limit below.
405 --help Output a help message, giving brief details of the command
406 options and file type support, and then exit. Anything else
407 on the command line is ignored.
409 -I Ignore binary files. This is equivalent to --binary-
413 Ignore upper/lower case distinctions during comparisons.
416 If any --include patterns are specified, the only files that
417 are processed are those that match one of the patterns (and
418 do not match an --exclude pattern). This option does not
419 affect directories, but it applies to all files, whether
420 listed on the command line, obtained from --file-list, or by
421 scanning a directory. The pattern is a PCRE2 regular expres-
422 sion, and is matched against the final component of the file
423 name, not the entire path. The -F, -w, and -x options do not
424 apply to this pattern. The option may be given any number of
425 times. If a file name matches both an --include and an
426 --exclude pattern, it is excluded. There is no short form
429 --include-from=filename
430 Treat each non-empty line of the file as the data for an
431 --include option. What constitutes a newline for this purpose
432 is the operating system's default. The --newline option has
433 no effect on this option. This option may be given any number
434 of times; all the files are read.
436 --include-dir=pattern
437 If any --include-dir patterns are specified, the only direc-
438 tories that are processed are those that match one of the
439 patterns (and do not match an --exclude-dir pattern). This
440 applies to all directories, whether listed on the command
441 line, obtained from --file-list, or by scanning a parent
442 directory. The pattern is a PCRE2 regular expression, and is
443 matched against the final component of the directory name,
444 not the entire path. The -F, -w, and -x options do not apply
445 to this pattern. The option may be given any number of times.
446 If a directory matches both --include-dir and --exclude-dir,
447 it is excluded. There is no short form for this option.
449 -L, --files-without-match
450 Instead of outputting lines from the files, just output the
451 names of the files that do not contain any lines that would
452 have been output. Each file name is output once, on a sepa-
453 rate line. This option overrides any previous -H, -h, or -l
456 -l, --files-with-matches
457 Instead of outputting lines from the files, just output the
458 names of the files containing lines that would have been out-
459 put. Each file name is output once, on a separate line.
460 Searching normally stops as soon as a matching line is found
461 in a file. However, if the -c (count) option is also used,
462 matching continues in order to obtain the correct count, and
463 those files that have at least one match are listed along
464 with their counts. Using this option with -c is a way of sup-
465 pressing the listing of files with no matches. This opeion
466 overrides any previous -H, -h, or -L options.
469 This option supplies a name to be used for the standard input
470 when file names are being output. If not supplied, "(standard
471 input)" is used. There is no short form for this option.
474 When this option is given, non-compressed input is read and
475 processed line by line, and the output is flushed after each
476 write. By default, input is read in large chunks, unless
477 pcre2grep can determine that it is reading from a terminal
478 (which is currently possible only in Unix-like environments
479 or Windows). Output to terminal is normally automatically
480 flushed by the operating system. This option can be useful
481 when the input or output is attached to a pipe and you do not
482 want pcre2grep to buffer up large amounts of data. However,
483 its use will affect performance, and the -M (multiline)
484 option ceases to work. When input is from a compressed .gz or
485 .bz2 file, --line-buffered is ignored.
488 Instead of showing lines or parts of lines that match, show
489 each match as a line number, the offset from the start of the
490 line, and a length. The line number is terminated by a colon
491 (as usual; see the -n option), and the offset and length are
492 separated by a comma. In this mode, no context is shown.
493 That is, the -A, -B, and -C options are ignored. If there is
494 more than one match in a line, each of them is shown sepa-
495 rately. This option is mutually exclusive with --output,
496 --file-offsets, and --only-matching.
499 This option specifies a locale to be used for pattern match-
500 ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
501 ronment variables. If no locale is specified, the PCRE2
502 library's default (usually the "C" locale) is used. There is
503 no short form for this option.
506 Processing some regular expression patterns may take a very
507 long time to search for all possible matching strings. Others
508 may require a very large amount of memory. There are three
509 options that set resource limits for matching.
511 The --match-limit option provides a means of limiting comput-
512 ing resource usage when processing patterns that are not
513 going to match, but which have a very large number of possi-
514 bilities in their search trees. The classic example is a pat-
515 tern that uses nested unlimited repeats. Internally, PCRE2
516 has a counter that is incremented each time around its main
517 processing loop. If the value set by --match-limit is
518 reached, an error occurs.
520 The --heap-limit option specifies, as a number of kibibytes
521 (units of 1024 bytes), the amount of heap memory that may be
522 used for matching. Heap memory is needed only if matching the
523 pattern requires a significant number of nested backtracking
524 points to be remembered. This parameter can be set to zero to
525 forbid the use of heap memory altogether.
527 The --depth-limit option limits the depth of nested back-
528 tracking points, which indirectly limits the amount of memory
529 that is used. The amount of memory needed for each backtrack-
530 ing point depends on the number of capturing parentheses in
531 the pattern, so the amount of memory that is used before this
532 limit acts varies from pattern to pattern. This limit is of
533 use only if it is set smaller than --match-limit.
535 There are no short forms for these options. The default lim-
536 its can be set when the PCRE2 library is compiled; if they
537 are not specified, the defaults are very large and so effec-
540 --max-buffer-size=number
541 This limits the expansion of the processing buffer, whose
542 initial size can be set by --buffer-size. The maximum buffer
543 size is silently forced to be no smaller than the starting
547 Allow patterns to match more than one line. When this option
548 is set, the PCRE2 library is called in "multiline" mode. This
549 allows a matched string to extend past the end of a line and
550 continue on one or more subsequent lines. Patterns used with
551 -M may usefully contain literal newline characters and inter-
552 nal occurrences of ^ and $ characters. The output for a suc-
553 cessful match may consist of more than one line. The first
554 line is the line in which the match started, and the last
555 line is the line in which the match ended. If the matched
556 string ends with a newline sequence, the output ends at the
557 end of that line. If -v is set, none of the lines in a
558 multi-line match are output. Once a match has been handled,
559 scanning restarts at the beginning of the line after the one
560 in which the match ended.
562 The newline sequence that separates multiple lines must be
563 matched as part of the pattern. For example, to find the
564 phrase "regular expression" in a file where "regular" might
565 be at the end of a line and "expression" at the start of the
566 next line, you could use this command:
568 pcre2grep -M 'regular\s+expression' <file>
570 The \s escape sequence matches any white space character,
571 including newlines, and is followed by + so as to match
572 trailing white space on the first line as well as possibly
573 handling a two-character newline sequence.
575 There is a limit to the number of lines that can be matched,
576 imposed by the way that pcre2grep buffers the input file as
577 it scans it. With a sufficiently large processing buffer,
578 this should not be a problem, but the -M option does not work
579 when input is read line by line (see --line-buffered.)
581 -N newline-type, --newline=newline-type
582 The PCRE2 library supports five different conventions for
583 indicating the ends of lines. They are the single-character
584 sequences CR (carriage return) and LF (linefeed), the two-
585 character sequence CRLF, an "anycrlf" convention, which rec-
586 ognizes any of the preceding three types, and an "any" con-
587 vention, in which any Unicode line ending sequence is assumed
588 to end a line. The Unicode sequences are the three just men-
589 tioned, plus VT (vertical tab, U+000B), FF (form feed,
590 U+000C), NEL (next line, U+0085), LS (line separator,
591 U+2028), and PS (paragraph separator, U+2029).
593 When the PCRE2 library is built, a default line-ending
594 sequence is specified. This is normally the standard
595 sequence for the operating system. Unless otherwise specified
596 by this option, pcre2grep uses the library's default. The
597 possible values for this option are CR, LF, CRLF, ANYCRLF, or
598 ANY. This makes it possible to use pcre2grep to scan files
599 that have come from other environments without having to mod-
600 ify their line endings. If the data that is being scanned
601 does not agree with the convention set by this option,
602 pcre2grep may behave in strange ways. Note that this option
603 does not apply to files specified by the -f, --exclude-from,
604 or --include-from options, which are expected to use the
605 operating system's standard newline sequence.
608 Precede each output line by its line number in the file, fol-
609 lowed by a colon for matching lines or a hyphen for context
610 lines. If the file name is also being output, it precedes the
611 line number. When the -M option causes a pattern to match
612 more than one line, only the first is preceded by its line
613 number. This option is forced if --line-offsets is used.
615 --no-jit If the PCRE2 library is built with support for just-in-time
616 compiling (which speeds up matching), pcre2grep automatically
617 makes use of this, unless it was explicitly disabled at build
618 time. This option can be used to disable the use of JIT at
619 run time. It is provided for testing and working round prob-
620 lems. It should never be needed in normal use.
622 -O text, --output=text
623 When there is a match, instead of outputting the whole line
624 that matched, output just the given text. This option is
625 mutually exclusive with --only-matching, --file-offsets, and
626 --line-offsets. Escape sequences starting with a dollar char-
627 acter may be used to insert the contents of the matched part
628 of the line and/or captured substrings into the text.
630 $<digits> or ${<digits>} is replaced by the captured sub-
631 string of the given decimal number; zero substitutes the
632 whole match. If the number is greater than the number of cap-
633 turing substrings, or if the capture is unset, the replace-
636 $a is replaced by bell; $b by backspace; $e by escape; $f by
637 form feed; $n by newline; $r by carriage return; $t by tab;
640 $o<digits> is replaced by the character represented by the
641 given octal number; up to three digits are processed.
643 $x<digits> is replaced by the character represented by the
644 given hexadecimal number; up to two digits are processed.
646 Any other character is substituted by itself. In particular,
647 $$ is replaced by a single dollar.
650 Show only the part of the line that matched a pattern instead
651 of the whole line. In this mode, no context is shown. That
652 is, the -A, -B, and -C options are ignored. If there is more
653 than one match in a line, each of them is shown separately,
654 on a separate line of output. If -o is combined with -v
655 (invert the sense of the match to find non-matching lines),
656 no output is generated, but the return code is set appropri-
657 ately. If the matched portion of the line is empty, nothing
658 is output unless the file name or line number are being
659 printed, in which case they are shown on an otherwise empty
660 line. This option is mutually exclusive with --output,
661 --file-offsets and --line-offsets.
663 -onumber, --only-matching=number
664 Show only the part of the line that matched the capturing
665 parentheses of the given number. Up to 32 capturing parenthe-
666 ses are supported, and -o0 is equivalent to -o without a num-
667 ber. Because these options can be given without an argument
668 (see above), if an argument is present, it must be given in
669 the same shell item, for example, -o3 or --only-matching=2.
670 The comments given for the non-argument case above also apply
671 to this option. If the specified capturing parentheses do not
672 exist in the pattern, or were not set in the match, nothing
673 is output unless the file name or line number are being out-
676 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 option).
684 Specify a separating string for multiple occurrences of -o.
685 The default is an empty string. Separating strings are never
689 Work quietly, that is, display nothing except error messages.
690 The exit status indicates whether or not any matches were
694 If any given path is a directory, recursively scan the files
695 it contains, taking note of any --include and --exclude set-
696 tings. By default, a directory is read as a normal file; in
697 some operating systems this gives an immediate end-of-file.
698 This option is a shorthand for setting the -d option to
701 --recursion-limit=number
702 See --match-limit above.
705 Suppress error messages about non-existent or unreadable
706 files. Such files are quietly skipped. However, the return
707 code is still 2, even if matches were found in other files.
710 This option is useful when scanning more than one file. If
711 used on its own, -t suppresses all output except for a grand
712 total number of matching lines (or non-matching lines if -v
713 is used) in all the files. If -t is used with -c, a grand
714 total is output except when the previous output is just one
715 line. In other words, it is not output when just one file's
716 count is listed. If file names are being output, the grand
717 total is preceded by "TOTAL:". Otherwise, it appears as just
718 another number. The -t option is ignored when used with -L
719 (list files without matches), because the grand total would
723 Operate in UTF-8 mode. This option is available only if PCRE2
724 has been compiled with UTF-8 support. All patterns (including
725 those for any --exclude and --include options) and all sub-
726 ject lines that are scanned must be valid strings of UTF-8
730 Write the version numbers of pcre2grep and the PCRE2 library
731 to the standard output and then exit. Anything else on the
732 command line is ignored.
735 Invert the sense of the match, so that lines which do not
736 match any of the patterns are the ones that are found.
738 -w, --word-regex, --word-regexp
739 Force the patterns only to match "words". That is, there must
740 be a word boundary at the start and end of each matched
741 string. This is equivalent to having "\b(?:" at the start of
742 each pattern, and ")\b" at the end. This option applies only
743 to the patterns that are matched against the contents of
744 files; it does not apply to patterns specified by any of the
745 --include or --exclude options.
747 -x, --line-regex, --line-regexp
748 Force the patterns to start matching only at the beginnings
749 of lines, and in addition, require them to match entire
750 lines. In multiline mode the match may be more than one line.
751 This is equivalent to having "^(?:" at the start of each pat-
752 tern and ")$" at the end. This option applies only to the
753 patterns that are matched against the contents of files; it
754 does not apply to patterns specified by any of the --include
755 or --exclude options.
758 ENVIRONMENT VARIABLES
760 The environment variables LC_ALL and LC_CTYPE are examined, in that
761 order, for a locale. The first one that is set is used. This can be
762 overridden by the --locale option. If no locale is set, the PCRE2
763 library's default (usually the "C" locale) is used.
768 The -N (--newline) option allows pcre2grep to scan files with different
769 newline conventions from the default. Any parts of the input files that
770 are written to the standard output are copied identically, with what-
771 ever newline sequences they have in the input. However, the setting of
772 this option affects only the way scanned files are processed. It does
773 not affect the interpretation of files specified by the -f, --file-
774 list, --exclude-from, or --include-from options, nor does it affect the
775 way in which pcre2grep writes informational messages to the standard
776 error and output streams. For these it uses the string "\n" to indicate
777 newlines, relying on the C I/O library to convert this to an appropri-
781 OPTIONS COMPATIBILITY
783 Many of the short and long forms of pcre2grep's options are the same as
784 in the GNU grep program. Any long option of the form --xxx-regexp (GNU
785 terminology) is also available as --xxx-regex (PCRE2 terminology). How-
786 ever, the --depth-limit, --file-list, --file-offsets, --heap-limit,
787 --include-dir, --line-offsets, --locale, --match-limit, -M, --multi-
788 line, -N, --newline, --om-separator, --output, -u, and --utf-8 options
789 are specific to pcre2grep, as is the use of the --only-matching option
790 with a capturing parentheses number.
792 Although most of the common options work the same way, a few are dif-
793 ferent in pcre2grep. For example, the --include option's argument is a
794 glob for GNU grep, but a regular expression for pcre2grep. If both the
795 -c and -l options are given, GNU grep lists only file names, without
796 counts, but pcre2grep gives the counts as well.
801 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-
809 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.
813 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:
820 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.
825 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.
831 USING PCRE2'S CALLOUT FACILITY
833 pcre2grep has, by default, support for calling external programs or
834 scripts or echoing specific strings during matching by making use of
835 PCRE2's callout facility. However, this support can be disabled when
836 pcre2grep is built. You can find out whether your binary has support
837 for callouts by running it with the --help option. If the support is
838 not enabled, all callouts in patterns are ignored by pcre2grep.
840 A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu-
841 ment is either a number or a quoted string (see the pcre2callout docu-
842 mentation for details). Numbered callouts are ignored by pcre2grep;
843 only callouts with string arguments are useful.
845 Calling external programs or scripts
847 If the callout string does not start with a pipe (vertical bar) charac-
848 ter, it is parsed into a list of substrings separated by pipe charac-
849 ters. The first substring must be an executable name, with the follow-
850 ing substrings specifying arguments:
852 executable_name|arg1|arg2|...
854 Any substring (including the executable name) may contain escape
855 sequences started by a dollar character: $<digits> or ${<digits>} is
856 replaced by the captured substring of the given decimal number, which
857 must be greater than zero. If the number is greater than the number of
858 capturing substrings, or if the capture is unset, the replacement is
861 Any other character is substituted by itself. In particular, $$ is
862 replaced by a single dollar and $| is replaced by a pipe character.
865 echo -e "abcde\n12345" | pcre2grep \
867 (?C"/bin/echo|Arg1: [$1] [$2] [$3]|Arg2: $|${1}$| ($4)")()' -
871 Arg1: [a] [bcd] [d] Arg2: |a| ()
873 Arg1: [1] [234] [4] Arg2: |1| ()
876 The parameters for the execv() system call that is used to run the pro-
877 gram or script are zero-terminated strings. This means that binary zero
878 characters in the callout argument will cause premature termination of
879 their substrings, and therefore should not be present. Any syntax
880 errors in the string (for example, a dollar not followed by another
881 character) cause the callout to be ignored. If running the program
882 fails for any reason (including the non-existence of the executable), a
883 local matching failure occurs and the matcher backtracks in the normal
886 Echoing a specific string
888 If the callout string starts with a pipe (vertical bar) character, the
889 rest of the string is written to the output, having been passed through
890 the same escape processing as text from the --output option. This pro-
891 vides a simple echoing facility that avoids calling an external program
892 or script. No terminator is added to the string, so if you want a new-
893 line, you must include it explicitly. Matching continues normally
894 after the string is output. If you want to see only the callout output
895 but not any output from an actual match, you should end the relevant
896 pattern with (*FAIL).
901 It is possible to supply a regular expression that takes a very long
902 time to fail to match certain lines. Such patterns normally involve
903 nested indefinite repeats, for example: (a+)*\d when matched against a
904 line of a's with no final digit. The PCRE2 matching function has a
905 resource limit that causes it to abort in these circumstances. If this
906 happens, pcre2grep outputs an error message and the line that caused
907 the problem to the standard error stream. If there are more than 20
908 such errors, pcre2grep gives up.
910 The --match-limit option of pcre2grep can be used to set the overall
911 resource limit. There are also other limits that affect the amount of
912 memory used during matching; see the discussion of --heap-limit and
918 Exit status is 0 if any matches were found, 1 if no matches were found,
919 and 2 for syntax errors, overlong lines, non-existent or inaccessible
920 files (even if matches were found in other files) or too many matching
921 errors. Using the -s option to suppress error messages about inaccessi-
922 ble files does not affect the return code.
924 When run under VMS, the return code is placed in the symbol
925 PCRE2GREP_RC because VMS does not distinguish between exit(0) and
931 pcre2pattern(3), pcre2syntax(3), pcre2callout(3).
937 University Computing Service
943 Last updated: 24 February 2018
944 Copyright (c) 1997-2018 University of Cambridge.
projects / ossec-hids.git / blob