1 PCRE2GREP(1) General Commands Manual PCRE2GREP(1) 2 3 4 5 NAME 6 pcre2grep - a grep with Perl-compatible regular expressions. 7 8 SYNOPSIS 9 pcre2grep [options] [long options] [pattern] [path1 path2 ...] 10 11 12 DESCRIPTION 13 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. 20 21 Patterns, whether supplied on the command line or in a separate file, 22 are given without delimiters. For example: 23 24 pcre2grep Thursday /etc/motd 25 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 31 metacharacters. 32 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. 38 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 41 hyphen. For example: 42 43 pcre2grep some-pattern file1 - file3 44 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. 52 53 The amount of memory used for buffering files that are being scanned is 54 controlled by a parameter that can be set by the --buffer-size option. 55 The default value for this parameter is specified when pcre2grep is 56 built, with the default default being 20K. A block of memory three 57 times this size is used (to allow for buffering "before" and "after" 58 lines). An error occurs if a line overflows the buffer. 59 60 Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the 61 greater. BUFSIZ is defined in <stdio.h>. When there is more than one 62 pattern (specified by the use of -e and/or -f), each pattern is applied 63 to each line in the order in which they are defined, except that all 64 the -e patterns are tried before the -f patterns. 65 66 By default, as soon as one pattern matches a line, no further patterns 67 are considered. However, if --colour (or --color) is used to colour the 68 matching substrings, or if --only-matching, --file-offsets, or --line- 69 offsets is used to output only the part of the line that matched 70 (either shown literally, or as an offset), scanning resumes immediately 71 following the match, so that further matches on the same line can be 72 found. If there are multiple patterns, they are all tried on the 73 remainder of the line, but patterns that follow the one that matched 74 are not tried on the earlier part of the line. 75 76 This behaviour means that the order in which multiple patterns are 77 specified can affect the output when one of the above options is used. 78 This is no longer the same behaviour as GNU grep, which now manages to 79 display earlier matches for later patterns (as long as there is no 80 overlap). 81 82 Patterns that can match an empty string are accepted, but empty string 83 matches are never recognized. An example is the pattern 84 "(super)?(man)?", in which all components are optional. This pattern 85 finds all occurrences of both "super" and "man"; the output differs 86 from matching with "super|man" when only the matching substrings are 87 being shown. 88 89 If the LC_ALL or LC_CTYPE environment variable is set, pcre2grep uses 90 the value to set a locale when calling the PCRE2 library. The --locale 91 option can be used to override this. 92 93 94 SUPPORT FOR COMPRESSED FILES 95 96 It is possible to compile pcre2grep so that it uses libz or libbz2 to 97 read files whose names end in .gz or .bz2, respectively. You can find 98 out whether your binary has support for one or both of these file types 99 by running it with the --help option. If the appropriate support is not 100 present, files are treated as plain text. The standard input is always 101 so treated. 102 103 104 BINARY FILES 105 106 By default, a file that contains a binary zero byte within the first 107 1024 bytes is identified as a binary file, and is processed specially. 108 (GNU grep also identifies binary files in this manner.) See the 109 --binary-files option for a means of changing the way binary files are 110 handled. 111 112 113 OPTIONS 114 115 The order in which some of the options appear can affect the output. 116 For example, both the -h and -l options affect the printing of file 117 names. Whichever comes later in the command line will be the one that 118 takes effect. Similarly, except where noted below, if an option is 119 given twice, the later setting is used. Numerical values for options 120 may be followed by K or M, to signify multiplication by 1024 or 121 1024*1024 respectively. 122 123 -- This terminates the list of options. It is useful if the next 124 item on the command line starts with a hyphen but is not an 125 option. This allows for the processing of patterns and file 126 names that start with hyphens. 127 128 -A number, --after-context=number 129 Output number lines of context after each matching line. If 130 file names and/or line numbers are being output, a hyphen 131 separator is used instead of a colon for the context lines. A 132 line containing "--" is output between each group of lines, 133 unless they are in fact contiguous in the input file. The 134 value of number is expected to be relatively small. However, 135 pcre2grep guarantees to have up to 8K of following text 136 available for context output. 137 138 -a, --text 139 Treat binary files as text. This is equivalent to --binary- 140 files=text. 141 142 -B number, --before-context=number 143 Output number lines of context before each matching line. If 144 file names and/or line numbers are being output, a hyphen 145 separator is used instead of a colon for the context lines. A 146 line containing "--" is output between each group of lines, 147 unless they are in fact contiguous in the input file. The 148 value of number is expected to be relatively small. However, 149 pcre2grep guarantees to have up to 8K of preceding text 150 available for context output. 151 152 --binary-files=word 153 Specify how binary files are to be processed. If the word is 154 "binary" (the default), pattern matching is performed on 155 binary files, but the only output is "Binary file <name> 156 matches" when a match succeeds. If the word is "text", which 157 is equivalent to the -a or --text option, binary files are 158 processed in the same way as any other file. In this case, 159 when a match succeeds, the output may be binary garbage, 160 which can have nasty effects if sent to a terminal. If the 161 word is "without-match", which is equivalent to the -I 162 option, binary files are not processed at all; they are 163 assumed not to be of interest and are skipped without causing 164 any output or affecting the return code. 165 166 --buffer-size=number 167 Set the parameter that controls how much memory is used for 168 buffering files that are being scanned. 169 170 -C number, --context=number 171 Output number lines of context both before and after each 172 matching line. This is equivalent to setting both -A and -B 173 to the same value. 174 175 -c, --count 176 Do not output lines from the files that are being scanned; 177 instead output the number of matches (or non-matches if -v is 178 used) that would otherwise have caused lines to be shown. By 179 default, this count is the same as the number of suppressed 180 lines, but if the -M (multiline) option is used (without -v), 181 there may be more suppressed lines than the number of 182 matches. 183 184 If no lines are selected, the number zero is output. If sev- 185 eral files are are being scanned, a count is output for each 186 of them. However, if the --files-with-matches option is also 187 used, only those files whose counts are greater than zero are 188 listed. When -c is used, the -A, -B, and -C options are 189 ignored. 190 191 --colour, --color 192 If this option is given without any data, it is equivalent to 193 "--colour=auto". If data is required, it must be given in 194 the same shell item, separated by an equals sign. 195 196 --colour=value, --color=value 197 This option specifies under what circumstances the parts of a 198 line that matched a pattern should be coloured in the output. 199 By default, the output is not coloured. The value (which is 200 optional, see above) may be "never", "always", or "auto". In 201 the latter case, colouring happens only if the standard out- 202 put is connected to a terminal. More resources are used when 203 colouring is enabled, because pcre2grep has to search for all 204 possible matches in a line, not just one, in order to colour 205 them all. 206 207 The colour that is used can be specified by setting the envi- 208 ronment variable PCRE2GREP_COLOUR or PCRE2GREP_COLOR. The 209 value of this variable should be a string of two numbers, 210 separated by a semicolon. They are copied directly into the 211 control string for setting colour on a terminal, so it is 212 your responsibility to ensure that they make sense. If nei- 213 ther of the environment variables is set, the default is 214 "1;31", which gives red. 215 216 -D action, --devices=action 217 If an input path is not a regular file or a directory, 218 "action" specifies how it is to be processed. Valid values 219 are "read" (the default) or "skip" (silently skip the path). 220 221 -d action, --directories=action 222 If an input path is a directory, "action" specifies how it is 223 to be processed. Valid values are "read" (the default in 224 non-Windows environments, for compatibility with GNU grep), 225 "recurse" (equivalent to the -r option), or "skip" (silently 226 skip the path, the default in Windows environments). In the 227 "read" case, directories are read as if they were ordinary 228 files. In some operating systems the effect of reading a 229 directory like this is an immediate end-of-file; in others it 230 may provoke an error. 231 232 -e pattern, --regex=pattern, --regexp=pattern 233 Specify a pattern to be matched. This option can be used mul- 234 tiple times in order to specify several patterns. It can also 235 be used as a way of specifying a single pattern that starts 236 with a hyphen. When -e is used, no argument pattern is taken 237 from the command line; all arguments are treated as file 238 names. There is no limit to the number of patterns. They are 239 applied to each line in the order in which they are defined 240 until one matches. 241 242 If -f is used with -e, the command line patterns are matched 243 first, followed by the patterns from the file(s), independent 244 of the order in which these options are specified. Note that 245 multiple use of -e is not the same as a single pattern with 246 alternatives. For example, X|Y finds the first character in a 247 line that is X or Y, whereas if the two patterns are given 248 separately, with X first, pcre2grep finds X if it is present, 249 even if it follows Y in the line. It finds Y only if there is 250 no X in the line. This matters only if you are using -o or 251 --colo(u)r to show the part(s) of the line that matched. 252 253 --exclude=pattern 254 Files (but not directories) whose names match the pattern are 255 skipped without being processed. This applies to all files, 256 whether listed on the command line, obtained from --file- 257 list, or by scanning a directory. The pattern is a PCRE2 reg- 258 ular expression, and is matched against the final component 259 of the file name, not the entire path. The -F, -w, and -x 260 options do not apply to this pattern. The option may be given 261 any number of times in order to specify multiple patterns. If 262 a file name matches both an --include and an --exclude pat- 263 tern, it is excluded. There is no short form for this option. 264 265 --exclude-from=filename 266 Treat each non-empty line of the file as the data for an 267 --exclude option. What constitutes a newline when reading the 268 file is the operating system's default. The --newline option 269 has no effect on this option. This option may be given more 270 than once in order to specify a number of files to read. 271 272 --exclude-dir=pattern 273 Directories whose names match the pattern are skipped without 274 being processed, whatever the setting of the --recursive 275 option. This applies to all directories, whether listed on 276 the command line, obtained from --file-list, or by scanning a 277 parent directory. The pattern is a PCRE2 regular expression, 278 and is matched against the final component of the directory 279 name, not the entire path. The -F, -w, and -x options do not 280 apply to this pattern. The option may be given any number of 281 times in order to specify more than one pattern. If a direc- 282 tory matches both --include-dir and --exclude-dir, it is 283 excluded. There is no short form for this option. 284 285 -F, --fixed-strings 286 Interpret each data-matching pattern as a list of fixed 287 strings, separated by newlines, instead of as a regular 288 expression. What constitutes a newline for this purpose is 289 controlled by the --newline option. The -w (match as a word) 290 and -x (match whole line) options can be used with -F. They 291 apply to each of the fixed strings. A line is selected if any 292 of the fixed strings are found in it (subject to -w or -x, if 293 present). This option applies only to the patterns that are 294 matched against the contents of files; it does not apply to 295 patterns specified by any of the --include or --exclude 296 options. 297 298 -f filename, --file=filename 299 Read patterns from the file, one per line, and match them 300 against each line of input. What constitutes a newline when 301 reading the file is the operating system's default. The 302 --newline option has no effect on this option. Trailing white 303 space is removed from each line, and blank lines are ignored. 304 An empty file contains no patterns and therefore matches 305 nothing. See also the comments about multiple patterns versus 306 a single pattern with alternatives in the description of -e 307 above. 308 309 If this option is given more than once, all the specified 310 files are read. A data line is output if any of the patterns 311 match it. A file name can be given as "-" to refer to the 312 standard input. When -f is used, patterns specified on the 313 command line using -e may also be present; they are tested 314 before the file's patterns. However, no other pattern is 315 taken from the command line; all arguments are treated as the 316 names of paths to be searched. 317 318 --file-list=filename 319 Read a list of files and/or directories that are to be 320 scanned from the given file, one per line. Trailing white 321 space is removed from each line, and blank lines are ignored. 322 These paths are processed before any that are listed on the 323 command line. The file name can be given as "-" to refer to 324 the standard input. If --file and --file-list are both spec- 325 ified as "-", patterns are read first. This is useful only 326 when the standard input is a terminal, from which further 327 lines (the list of files) can be read after an end-of-file 328 indication. If this option is given more than once, all the 329 specified files are read. 330 331 --file-offsets 332 Instead of showing lines or parts of lines that match, show 333 each match as an offset from the start of the file and a 334 length, separated by a comma. In this mode, no context is 335 shown. That is, the -A, -B, and -C options are ignored. If 336 there is more than one match in a line, each of them is shown 337 separately. This option is mutually exclusive with --line- 338 offsets and --only-matching. 339 340 -H, --with-filename 341 Force the inclusion of the file name at the start of output 342 lines when searching a single file. By default, the file name 343 is not shown in this case. For matching lines, the file name 344 is followed by a colon; for context lines, a hyphen separator 345 is used. If a line number is also being output, it follows 346 the file name. When the -M option causes a pattern to match 347 more than one line, only the first is preceded by the file 348 name. 349 350 -h, --no-filename 351 Suppress the output file names when searching multiple files. 352 By default, file names are shown when multiple files are 353 searched. For matching lines, the file name is followed by a 354 colon; for context lines, a hyphen separator is used. If a 355 line number is also being output, it follows the file name. 356 357 --help Output a help message, giving brief details of the command 358 options and file type support, and then exit. Anything else 359 on the command line is ignored. 360 361 -I Ignore binary files. This is equivalent to --binary- 362 files=without-match. 363 364 -i, --ignore-case 365 Ignore upper/lower case distinctions during comparisons. 366 367 --include=pattern 368 If any --include patterns are specified, the only files that 369 are processed are those that match one of the patterns (and 370 do not match an --exclude pattern). This option does not 371 affect directories, but it applies to all files, whether 372 listed on the command line, obtained from --file-list, or by 373 scanning a directory. The pattern is a PCRE2 regular expres- 374 sion, and is matched against the final component of the file 375 name, not the entire path. The -F, -w, and -x options do not 376 apply to this pattern. The option may be given any number of 377 times. If a file name matches both an --include and an 378 --exclude pattern, it is excluded. There is no short form 379 for this option. 380 381 --include-from=filename 382 Treat each non-empty line of the file as the data for an 383 --include option. What constitutes a newline for this purpose 384 is the operating system's default. The --newline option has 385 no effect on this option. This option may be given any number 386 of times; all the files are read. 387 388 --include-dir=pattern 389 If any --include-dir patterns are specified, the only direc- 390 tories that are processed are those that match one of the 391 patterns (and do not match an --exclude-dir pattern). This 392 applies to all directories, whether listed on the command 393 line, obtained from --file-list, or by scanning a parent 394 directory. The pattern is a PCRE2 regular expression, and is 395 matched against the final component of the directory name, 396 not the entire path. The -F, -w, and -x options do not apply 397 to this pattern. The option may be given any number of times. 398 If a directory matches both --include-dir and --exclude-dir, 399 it is excluded. There is no short form for this option. 400 401 -L, --files-without-match 402 Instead of outputting lines from the files, just output the 403 names of the files that do not contain any lines that would 404 have been output. Each file name is output once, on a sepa- 405 rate line. 406 407 -l, --files-with-matches 408 Instead of outputting lines from the files, just output the 409 names of the files containing lines that would have been out- 410 put. Each file name is output once, on a separate line. 411 Searching normally stops as soon as a matching line is found 412 in a file. However, if the -c (count) option is also used, 413 matching continues in order to obtain the correct count, and 414 those files that have at least one match are listed along 415 with their counts. Using this option with -c is a way of sup- 416 pressing the listing of files with no matches. 417 418 --label=name 419 This option supplies a name to be used for the standard input 420 when file names are being output. If not supplied, "(standard 421 input)" is used. There is no short form for this option. 422 423 --line-buffered 424 When this option is given, input is read and processed line 425 by line, and the output is flushed after each write. By 426 default, input is read in large chunks, unless pcre2grep can 427 determine that it is reading from a terminal (which is cur- 428 rently possible only in Unix-like environments). Output to 429 terminal is normally automatically flushed by the operating 430 system. This option can be useful when the input or output is 431 attached to a pipe and you do not want pcre2grep to buffer up 432 large amounts of data. However, its use will affect perfor- 433 mance, and the -M (multiline) option ceases to work. 434 435 --line-offsets 436 Instead of showing lines or parts of lines that match, show 437 each match as a line number, the offset from the start of the 438 line, and a length. The line number is terminated by a colon 439 (as usual; see the -n option), and the offset and length are 440 separated by a comma. In this mode, no context is shown. 441 That is, the -A, -B, and -C options are ignored. If there is 442 more than one match in a line, each of them is shown sepa- 443 rately. This option is mutually exclusive with --file-offsets 444 and --only-matching. 445 446 --locale=locale-name 447 This option specifies a locale to be used for pattern match- 448 ing. It overrides the value in the LC_ALL or LC_CTYPE envi- 449 ronment variables. If no locale is specified, the PCRE2 450 library's default (usually the "C" locale) is used. There is 451 no short form for this option. 452 453 --match-limit=number 454 Processing some regular expression patterns can require a 455 very large amount of memory, leading in some cases to a pro- 456 gram crash if not enough is available. Other patterns may 457 take a very long time to search for all possible matching 458 strings. The pcre2_match() function that is called by 459 pcre2grep to do the matching has two parameters that can 460 limit the resources that it uses. 461 462 The --match-limit option provides a means of limiting 463 resource usage when processing patterns that are not going to 464 match, but which have a very large number of possibilities in 465 their search trees. The classic example is a pattern that 466 uses nested unlimited repeats. Internally, PCRE2 uses a func- 467 tion called match() which it calls repeatedly (sometimes 468 recursively). The limit set by --match-limit is imposed on 469 the number of times this function is called during a match, 470 which has the effect of limiting the amount of backtracking 471 that can take place. 472 473 The --recursion-limit option is similar to --match-limit, but 474 instead of limiting the total number of times that match() is 475 called, it limits the depth of recursive calls, which in turn 476 limits the amount of memory that can be used. The recursion 477 depth is a smaller number than the total number of calls, 478 because not all calls to match() are recursive. This limit is 479 of use only if it is set smaller than --match-limit. 480 481 There are no short forms for these options. The default set- 482 tings are specified when the PCRE2 library is compiled, with 483 the default default being 10 million. 484 485 -M, --multiline 486 Allow patterns to match more than one line. When this option 487 is given, patterns may usefully contain literal newline char- 488 acters and internal occurrences of ^ and $ characters. The 489 output for a successful match may consist of more than one 490 line. The first is the line in which the match started, and 491 the last is the line in which the match ended. If the matched 492 string ends with a newline sequence the output ends at the 493 end of that line. 494 495 When this option is set, the PCRE2 library is called in "mul- 496 tiline" mode. This allows a matched string to extend past the 497 end of a line and continue on one or more subsequent lines. 498 However, pcre2grep still processes the input line by line. 499 Once a match has been handled, scanning restarts at the 500 beginning of the next line, just as it does when -M is not 501 present. This means that it is possible for the second or 502 subsequent lines in a multiline match to be output again as 503 part of another match. 504 505 The newline sequence that separates multiple lines must be 506 matched as part of the pattern. For example, to find the 507 phrase "regular expression" in a file where "regular" might 508 be at the end of a line and "expression" at the start of the 509 next line, you could use this command: 510 511 pcre2grep -M 'regular\s+expression' <file> 512 513 The \s escape sequence matches any white space character, 514 including newlines, and is followed by + so as to match 515 trailing white space on the first line as well as possibly 516 handling a two-character newline sequence. 517 518 There is a limit to the number of lines that can be matched, 519 imposed by the way that pcre2grep buffers the input file as 520 it scans it. However, pcre2grep ensures that at least 8K 521 characters or the rest of the file (whichever is the shorter) 522 are available for forward matching, and similarly the previ- 523 ous 8K characters (or all the previous characters, if fewer 524 than 8K) are guaranteed to be available for lookbehind asser- 525 tions. The -M option does not work when input is read line by 526 line (see --line-buffered.) 527 528 -N newline-type, --newline=newline-type 529 The PCRE2 library supports five different conventions for 530 indicating the ends of lines. They are the single-character 531 sequences CR (carriage return) and LF (linefeed), the two- 532 character sequence CRLF, an "anycrlf" convention, which rec- 533 ognizes any of the preceding three types, and an "any" con- 534 vention, in which any Unicode line ending sequence is assumed 535 to end a line. The Unicode sequences are the three just men- 536 tioned, plus VT (vertical tab, U+000B), FF (form feed, 537 U+000C), NEL (next line, U+0085), LS (line separator, 538 U+2028), and PS (paragraph separator, U+2029). 539 540 When the PCRE2 library is built, a default line-ending 541 sequence is specified. This is normally the standard 542 sequence for the operating system. Unless otherwise specified 543 by this option, pcre2grep uses the library's default. The 544 possible values for this option are CR, LF, CRLF, ANYCRLF, or 545 ANY. This makes it possible to use pcre2grep to scan files 546 that have come from other environments without having to mod- 547 ify their line endings. If the data that is being scanned 548 does not agree with the convention set by this option, 549 pcre2grep may behave in strange ways. Note that this option 550 does not apply to files specified by the -f, --exclude-from, 551 or --include-from options, which are expected to use the 552 operating system's standard newline sequence. 553 554 -n, --line-number 555 Precede each output line by its line number in the file, fol- 556 lowed by a colon for matching lines or a hyphen for context 557 lines. If the file name is also being output, it precedes the 558 line number. When the -M option causes a pattern to match 559 more than one line, only the first is preceded by its line 560 number. This option is forced if --line-offsets is used. 561 562 --no-jit If the PCRE2 library is built with support for just-in-time 563 compiling (which speeds up matching), pcre2grep automatically 564 makes use of this, unless it was explicitly disabled at build 565 time. This option can be used to disable the use of JIT at 566 run time. It is provided for testing and working round prob- 567 lems. It should never be needed in normal use. 568 569 -o, --only-matching 570 Show only the part of the line that matched a pattern instead 571 of the whole line. In this mode, no context is shown. That 572 is, the -A, -B, and -C options are ignored. If there is more 573 than one match in a line, each of them is shown separately. 574 If -o is combined with -v (invert the sense of the match to 575 find non-matching lines), no output is generated, but the 576 return code is set appropriately. If the matched portion of 577 the line is empty, nothing is output unless the file name or 578 line number are being printed, in which case they are shown 579 on an otherwise empty line. This option is mutually exclusive 580 with --file-offsets and --line-offsets. 581 582 -onumber, --only-matching=number 583 Show only the part of the line that matched the capturing 584 parentheses of the given number. Up to 32 capturing parenthe- 585 ses are supported, and -o0 is equivalent to -o without a num- 586 ber. Because these options can be given without an argument 587 (see above), if an argument is present, it must be given in 588 the same shell item, for example, -o3 or --only-matching=2. 589 The comments given for the non-argument case above also apply 590 to this case. If the specified capturing parentheses do not 591 exist in the pattern, or were not set in the match, nothing 592 is output unless the file name or line number are being out- 593 put. 594 595 If this option is given multiple times, multiple substrings 596 are output, in the order the options are given. For example, 597 -o3 -o1 -o3 causes the substrings matched by capturing paren- 598 theses 3 and 1 and then 3 again to be output. By default, 599 there is no separator (but see the next option). 600 601 --om-separator=text 602 Specify a separating string for multiple occurrences of -o. 603 The default is an empty string. Separating strings are never 604 coloured. 605 606 -q, --quiet 607 Work quietly, that is, display nothing except error messages. 608 The exit status indicates whether or not any matches were 609 found. 610 611 -r, --recursive 612 If any given path is a directory, recursively scan the files 613 it contains, taking note of any --include and --exclude set- 614 tings. By default, a directory is read as a normal file; in 615 some operating systems this gives an immediate end-of-file. 616 This option is a shorthand for setting the -d option to 617 "recurse". 618 619 --recursion-limit=number 620 See --match-limit above. 621 622 -s, --no-messages 623 Suppress error messages about non-existent or unreadable 624 files. Such files are quietly skipped. However, the return 625 code is still 2, even if matches were found in other files. 626 627 -u, --utf-8 628 Operate in UTF-8 mode. This option is available only if PCRE2 629 has been compiled with UTF-8 support. All patterns (including 630 those for any --exclude and --include options) and all sub- 631 ject lines that are scanned must be valid strings of UTF-8 632 characters. 633 634 -V, --version 635 Write the version numbers of pcre2grep and the PCRE2 library 636 to the standard output and then exit. Anything else on the 637 command line is ignored. 638 639 -v, --invert-match 640 Invert the sense of the match, so that lines which do not 641 match any of the patterns are the ones that are found. 642 643 -w, --word-regex, --word-regexp 644 Force the patterns to match only whole words. This is equiva- 645 lent to having \b at the start and end of the pattern. This 646 option applies only to the patterns that are matched against 647 the contents of files; it does not apply to patterns speci- 648 fied by any of the --include or --exclude options. 649 650 -x, --line-regex, --line-regexp 651 Force the patterns to be anchored (each must start matching 652 at the beginning of a line) and in addition, require them to 653 match entire lines. This is equivalent to having ^ and $ 654 characters at the start and end of each alternative top-level 655 branch in every pattern. This option applies only to the pat- 656 terns that are matched against the contents of files; it does 657 not apply to patterns specified by any of the --include or 658 --exclude options. 659 660 661 ENVIRONMENT VARIABLES 662 663 The environment variables LC_ALL and LC_CTYPE are examined, in that 664 order, for a locale. The first one that is set is used. This can be 665 overridden by the --locale option. If no locale is set, the PCRE2 666 library's default (usually the "C" locale) is used. 667 668 669 NEWLINES 670 671 The -N (--newline) option allows pcre2grep to scan files with different 672 newline conventions from the default. Any parts of the input files that 673 are written to the standard output are copied identically, with what- 674 ever newline sequences they have in the input. However, the setting of 675 this option does not affect the interpretation of files specified by 676 the -f, --exclude-from, or --include-from options, which are assumed to 677 use the operating system's standard newline sequence, nor does it 678 affect the way in which pcre2grep writes informational messages to the 679 standard error and output streams. For these it uses the string "\n" to 680 indicate newlines, relying on the C I/O library to convert this to an 681 appropriate sequence. 682 683 684 OPTIONS COMPATIBILITY 685 686 Many of the short and long forms of pcre2grep's options are the same as 687 in the GNU grep program. Any long option of the form --xxx-regexp (GNU 688 terminology) is also available as --xxx-regex (PCRE2 terminology). How- 689 ever, the --file-list, --file-offsets, --include-dir, --line-offsets, 690 --locale, --match-limit, -M, --multiline, -N, --newline, --om-separa- 691 tor, --recursion-limit, -u, and --utf-8 options are specific to 692 pcre2grep, as is the use of the --only-matching option with a capturing 693 parentheses number. 694 695 Although most of the common options work the same way, a few are dif- 696 ferent in pcre2grep. For example, the --include option's argument is a 697 glob for GNU grep, but a regular expression for pcre2grep. If both the 698 -c and -l options are given, GNU grep lists only file names, without 699 counts, but pcre2grep gives the counts as well. 700 701 702 OPTIONS WITH DATA 703 704 There are four different ways in which an option with data can be spec- 705 ified. If a short form option is used, the data may follow immedi- 706 ately, or (with one exception) in the next command line item. For exam- 707 ple: 708 709 -f/some/file 710 -f /some/file 711 712 The exception is the -o option, which may appear with or without data. 713 Because of this, if data is present, it must follow immediately in the 714 same item, for example -o3. 715 716 If a long form option is used, the data may appear in the same command 717 line item, separated by an equals character, or (with two exceptions) 718 it may appear in the next command line item. For example: 719 720 --file=/some/file 721 --file /some/file 722 723 Note, however, that if you want to supply a file name beginning with ~ 724 as data in a shell command, and have the shell expand ~ to a home 725 directory, you must separate the file name from the option, because the 726 shell does not treat ~ specially unless it is at the start of an item. 727 728 The exceptions to the above are the --colour (or --color) and --only- 729 matching options, for which the data is optional. If one of these 730 options does have data, it must be given in the first form, using an 731 equals character. Otherwise pcre2grep will assume that it has no data. 732 733 734 CALLING EXTERNAL SCRIPTS 735 736 On non-Windows systems, pcre2grep has, by default, support for calling 737 external programs or scripts during matching by making use of PCRE2's 738 callout facility. However, this support can be disabled when pcre2grep 739 is built. You can find out whether your binary has support for call- 740 outs by running it with the --help option. If the support is not 741 enabled, all callouts in patterns are ignored by pcre2grep. 742 743 A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu- 744 ment is either a number or a quoted string (see the pcre2callout docu- 745 mentation for details). Numbered callouts are ignored by pcre2grep. 746 String arguments are parsed as a list of substrings separated by pipe 747 (vertical bar) characters. The first substring must be an executable 748 name, with the following substrings specifying arguments: 749 750 executable_name|arg1|arg2|... 751 752 Any substring (including the executable name) may contain escape 753 sequences started by a dollar character: $<digits> or ${<digits>} is 754 replaced by the captured substring of the given decimal number, which 755 must be greater than zero. If the number is greater than the number of 756 capturing substrings, or if the capture is unset, the replacement is 757 empty. 758 759 Any other character is substituted by itself. In particular, $$ is 760 replaced by a single dollar and $| is replaced by a pipe character. 761 Here is an example: 762 763 echo -e "abcde\n12345" | pcre2grep \ 764 '(?x)(.)(..(.)) 765 (?C"/bin/echo|Arg1: [$1] [$2] [$3]|Arg2: $|${1}$| ($4)")()' - 766 767 Output: 768 769 Arg1: [a] [bcd] [d] Arg2: |a| () 770 abcde 771 Arg1: [1] [234] [4] Arg2: |1| () 772 12345 773 774 The parameters for the execv() system call that is used to run the pro- 775 gram or script are zero-terminated strings. This means that binary zero 776 characters in the callout argument will cause premature termination of 777 their substrings, and therefore should not be present. Any syntax 778 errors in the string (for example, a dollar not followed by another 779 character) cause the callout to be ignored. If running the program 780 fails for any reason (including the non-existence of the executable), a 781 local matching failure occurs and the matcher backtracks in the normal 782 way. 783 784 785 MATCHING ERRORS 786 787 It is possible to supply a regular expression that takes a very long 788 time to fail to match certain lines. Such patterns normally involve 789 nested indefinite repeats, for example: (a+)*\d when matched against a 790 line of a's with no final digit. The PCRE2 matching function has a 791 resource limit that causes it to abort in these circumstances. If this 792 happens, pcre2grep outputs an error message and the line that caused 793 the problem to the standard error stream. If there are more than 20 794 such errors, pcre2grep gives up. 795 796 The --match-limit option of pcre2grep can be used to set the overall 797 resource limit; there is a second option called --recursion-limit that 798 sets a limit on the amount of memory (usually stack) that is used (see 799 the discussion of these options above). 800 801 802 DIAGNOSTICS 803 804 Exit status is 0 if any matches were found, 1 if no matches were found, 805 and 2 for syntax errors, overlong lines, non-existent or inaccessible 806 files (even if matches were found in other files) or too many matching 807 errors. Using the -s option to suppress error messages about inaccessi- 808 ble files does not affect the return code. 809 810 811 SEE ALSO 812 813 pcre2pattern(3), pcre2syntax(3), pcre2callout(3). 814 815 816 AUTHOR 817 818 Philip Hazel 819 University Computing Service 820 Cambridge, England. 821 822 823 REVISION 824 825 Last updated: 19 June 2016 826 Copyright (c) 1997-2016 University of Cambridge. 827
