1 PCREGREP(1) General Commands Manual PCREGREP(1) 2 3 4 5 NAME 6 pcregrep - a grep with Perl-compatible regular expressions. 7 8 SYNOPSIS 9 pcregrep [options] [long options] [pattern] [path1 path2 ...] 10 11 12 DESCRIPTION 13 14 pcregrep searches files for character patterns, in the same way as 15 other grep commands do, but it uses the PCRE regular expression library 16 to support patterns that are compatible with the regular expressions of 17 Perl 5. See pcresyntax(3) for a quick-reference summary of pattern syn- 18 tax, or pcrepattern(3) for a full description of the syntax and seman- 19 tics of the regular expressions that PCRE supports. 20 21 Patterns, whether supplied on the command line or in a separate file, 22 are given without delimiters. For example: 23 24 pcregrep 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, pcregrep reads the standard input. The stan- 40 dard input can also be referenced by a name consisting of a single 41 hyphen. For example: 42 43 pcregrep some-pattern /file1 - /file3 44 45 By default, each line that matches a pattern is copied to the standard 46 output, and if there is more than one file, the file name is output at 47 the start of each line, followed by a colon. However, there are options 48 that can change how pcregrep behaves. In particular, the -M option 49 makes it possible to search for patterns that span line boundaries. 50 What defines a line boundary is controlled by the -N (--newline) 51 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 pcregrep 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, pcregrep uses 90 the value to set a locale when calling the PCRE 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 pcregrep 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 filenames and/or line numbers are being output, a hyphen sep- 131 arator 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 pcregrep guarantees to have up to 8K of following text avail- 136 able 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 filenames and/or line numbers are being output, a hyphen sep- 145 arator 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 pcregrep guarantees to have up to 8K of preceding text avail- 150 able 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. 164 165 --buffer-size=number 166 Set the parameter that controls how much memory is used for 167 buffering files that are being scanned. 168 169 -C number, --context=number 170 Output number lines of context both before and after each 171 matching line. This is equivalent to setting both -A and -B 172 to the same value. 173 174 -c, --count 175 Do not output individual lines from the files that are being 176 scanned; instead output the number of lines that would other- 177 wise have been shown. If no lines are selected, the number 178 zero is output. If several files are are being scanned, a 179 count is output for each of them. However, if the --files- 180 with-matches option is also used, only those files whose 181 counts are greater than zero are listed. When -c is used, the 182 -A, -B, and -C options are ignored. 183 184 --colour, --color 185 If this option is given without any data, it is equivalent to 186 "--colour=auto". If data is required, it must be given in 187 the same shell item, separated by an equals sign. 188 189 --colour=value, --color=value 190 This option specifies under what circumstances the parts of a 191 line that matched a pattern should be coloured in the output. 192 By default, the output is not coloured. The value (which is 193 optional, see above) may be "never", "always", or "auto". In 194 the latter case, colouring happens only if the standard out- 195 put is connected to a terminal. More resources are used when 196 colouring is enabled, because pcregrep has to search for all 197 possible matches in a line, not just one, in order to colour 198 them all. 199 200 The colour that is used can be specified by setting the envi- 201 ronment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value 202 of this variable should be a string of two numbers, separated 203 by a semicolon. They are copied directly into the control 204 string for setting colour on a terminal, so it is your 205 responsibility to ensure that they make sense. If neither of 206 the environment variables is set, the default is "1;31", 207 which gives red. 208 209 -D action, --devices=action 210 If an input path is not a regular file or a directory, 211 "action" specifies how it is to be processed. Valid values 212 are "read" (the default) or "skip" (silently skip the path). 213 214 -d action, --directories=action 215 If an input path is a directory, "action" specifies how it is 216 to be processed. Valid values are "read" (the default in 217 non-Windows environments, for compatibility with GNU grep), 218 "recurse" (equivalent to the -r option), or "skip" (silently 219 skip the path, the default in Windows environments). In the 220 "read" case, directories are read as if they were ordinary 221 files. In some operating systems the effect of reading a 222 directory like this is an immediate end-of-file; in others it 223 may provoke an error. 224 225 -e pattern, --regex=pattern, --regexp=pattern 226 Specify a pattern to be matched. This option can be used mul- 227 tiple times in order to specify several patterns. It can also 228 be used as a way of specifying a single pattern that starts 229 with a hyphen. When -e is used, no argument pattern is taken 230 from the command line; all arguments are treated as file 231 names. There is no limit to the number of patterns. They are 232 applied to each line in the order in which they are defined 233 until one matches. 234 235 If -f is used with -e, the command line patterns are matched 236 first, followed by the patterns from the file(s), independent 237 of the order in which these options are specified. Note that 238 multiple use of -e is not the same as a single pattern with 239 alternatives. For example, X|Y finds the first character in a 240 line that is X or Y, whereas if the two patterns are given 241 separately, with X first, pcregrep finds X if it is present, 242 even if it follows Y in the line. It finds Y only if there is 243 no X in the line. This matters only if you are using -o or 244 --colo(u)r to show the part(s) of the line that matched. 245 246 --exclude=pattern 247 Files (but not directories) whose names match the pattern are 248 skipped without being processed. This applies to all files, 249 whether listed on the command line, obtained from --file- 250 list, or by scanning a directory. The pattern is a PCRE regu- 251 lar expression, and is matched against the final component of 252 the file name, not the entire path. The -F, -w, and -x 253 options do not apply to this pattern. The option may be given 254 any number of times in order to specify multiple patterns. If 255 a file name matches both an --include and an --exclude pat- 256 tern, it is excluded. There is no short form for this option. 257 258 --exclude-from=filename 259 Treat each non-empty line of the file as the data for an 260 --exclude option. What constitutes a newline when reading the 261 file is the operating system's default. The --newline option 262 has no effect on this option. This option may be given more 263 than once in order to specify a number of files to read. 264 265 --exclude-dir=pattern 266 Directories whose names match the pattern are skipped without 267 being processed, whatever the setting of the --recursive 268 option. This applies to all directories, whether listed on 269 the command line, obtained from --file-list, or by scanning a 270 parent directory. The pattern is a PCRE regular expression, 271 and is matched against the final component of the directory 272 name, not the entire path. The -F, -w, and -x options do not 273 apply to this pattern. The option may be given any number of 274 times in order to specify more than one pattern. If a direc- 275 tory matches both --include-dir and --exclude-dir, it is 276 excluded. There is no short form for this option. 277 278 -F, --fixed-strings 279 Interpret each data-matching pattern as a list of fixed 280 strings, separated by newlines, instead of as a regular 281 expression. What constitutes a newline for this purpose is 282 controlled by the --newline option. The -w (match as a word) 283 and -x (match whole line) options can be used with -F. They 284 apply to each of the fixed strings. A line is selected if any 285 of the fixed strings are found in it (subject to -w or -x, if 286 present). This option applies only to the patterns that are 287 matched against the contents of files; it does not apply to 288 patterns specified by any of the --include or --exclude 289 options. 290 291 -f filename, --file=filename 292 Read patterns from the file, one per line, and match them 293 against each line of input. What constitutes a newline when 294 reading the file is the operating system's default. The 295 --newline option has no effect on this option. Trailing white 296 space is removed from each line, and blank lines are ignored. 297 An empty file contains no patterns and therefore matches 298 nothing. See also the comments about multiple patterns versus 299 a single pattern with alternatives in the description of -e 300 above. 301 302 If this option is given more than once, all the specified 303 files are read. A data line is output if any of the patterns 304 match it. A filename can be given as "-" to refer to the 305 standard input. When -f is used, patterns specified on the 306 command line using -e may also be present; they are tested 307 before the file's patterns. However, no other pattern is 308 taken from the command line; all arguments are treated as the 309 names of paths to be searched. 310 311 --file-list=filename 312 Read a list of files and/or directories that are to be 313 scanned from the given file, one per line. Trailing white 314 space is removed from each line, and blank lines are ignored. 315 These paths are processed before any that are listed on the 316 command line. The filename can be given as "-" to refer to 317 the standard input. If --file and --file-list are both spec- 318 ified as "-", patterns are read first. This is useful only 319 when the standard input is a terminal, from which further 320 lines (the list of files) can be read after an end-of-file 321 indication. If this option is given more than once, all the 322 specified files are read. 323 324 --file-offsets 325 Instead of showing lines or parts of lines that match, show 326 each match as an offset from the start of the file and a 327 length, separated by a comma. In this mode, no context is 328 shown. That is, the -A, -B, and -C options are ignored. If 329 there is more than one match in a line, each of them is shown 330 separately. This option is mutually exclusive with --line- 331 offsets and --only-matching. 332 333 -H, --with-filename 334 Force the inclusion of the filename at the start of output 335 lines when searching a single file. By default, the filename 336 is not shown in this case. For matching lines, the filename 337 is followed by a colon; for context lines, a hyphen separator 338 is used. If a line number is also being output, it follows 339 the file name. 340 341 -h, --no-filename 342 Suppress the output filenames when searching multiple files. 343 By default, filenames are shown when multiple files are 344 searched. For matching lines, the filename is followed by a 345 colon; for context lines, a hyphen separator is used. If a 346 line number is also being output, it follows the file name. 347 348 --help Output a help message, giving brief details of the command 349 options and file type support, and then exit. Anything else 350 on the command line is ignored. 351 352 -I Treat binary files as never matching. This is equivalent to 353 --binary-files=without-match. 354 355 -i, --ignore-case 356 Ignore upper/lower case distinctions during comparisons. 357 358 --include=pattern 359 If any --include patterns are specified, the only files that 360 are processed are those that match one of the patterns (and 361 do not match an --exclude pattern). This option does not 362 affect directories, but it applies to all files, whether 363 listed on the command line, obtained from --file-list, or by 364 scanning a directory. The pattern is a PCRE regular expres- 365 sion, and is matched against the final component of the file 366 name, not the entire path. The -F, -w, and -x options do not 367 apply to this pattern. The option may be given any number of 368 times. If a file name matches both an --include and an 369 --exclude pattern, it is excluded. There is no short form 370 for this option. 371 372 --include-from=filename 373 Treat each non-empty line of the file as the data for an 374 --include option. What constitutes a newline for this purpose 375 is the operating system's default. The --newline option has 376 no effect on this option. This option may be given any number 377 of times; all the files are read. 378 379 --include-dir=pattern 380 If any --include-dir patterns are specified, the only direc- 381 tories that are processed are those that match one of the 382 patterns (and do not match an --exclude-dir pattern). This 383 applies to all directories, whether listed on the command 384 line, obtained from --file-list, or by scanning a parent 385 directory. The pattern is a PCRE regular expression, and is 386 matched against the final component of the directory name, 387 not the entire path. The -F, -w, and -x options do not apply 388 to this pattern. The option may be given any number of times. 389 If a directory matches both --include-dir and --exclude-dir, 390 it is excluded. There is no short form for this option. 391 392 -L, --files-without-match 393 Instead of outputting lines from the files, just output the 394 names of the files that do not contain any lines that would 395 have been output. Each file name is output once, on a sepa- 396 rate line. 397 398 -l, --files-with-matches 399 Instead of outputting lines from the files, just output the 400 names of the files containing lines that would have been out- 401 put. Each file name is output once, on a separate line. 402 Searching normally stops as soon as a matching line is found 403 in a file. However, if the -c (count) option is also used, 404 matching continues in order to obtain the correct count, and 405 those files that have at least one match are listed along 406 with their counts. Using this option with -c is a way of sup- 407 pressing the listing of files with no matches. 408 409 --label=name 410 This option supplies a name to be used for the standard input 411 when file names are being output. If not supplied, "(standard 412 input)" is used. There is no short form for this option. 413 414 --line-buffered 415 When this option is given, input is read and processed line 416 by line, and the output is flushed after each write. By 417 default, input is read in large chunks, unless pcregrep can 418 determine that it is reading from a terminal (which is cur- 419 rently possible only in Unix-like environments). Output to 420 terminal is normally automatically flushed by the operating 421 system. This option can be useful when the input or output is 422 attached to a pipe and you do not want pcregrep to buffer up 423 large amounts of data. However, its use will affect perfor- 424 mance, and the -M (multiline) option ceases to work. 425 426 --line-offsets 427 Instead of showing lines or parts of lines that match, show 428 each match as a line number, the offset from the start of the 429 line, and a length. The line number is terminated by a colon 430 (as usual; see the -n option), and the offset and length are 431 separated by a comma. In this mode, no context is shown. 432 That is, the -A, -B, and -C options are ignored. If there is 433 more than one match in a line, each of them is shown sepa- 434 rately. This option is mutually exclusive with --file-offsets 435 and --only-matching. 436 437 --locale=locale-name 438 This option specifies a locale to be used for pattern match- 439 ing. It overrides the value in the LC_ALL or LC_CTYPE envi- 440 ronment variables. If no locale is specified, the PCRE 441 library's default (usually the "C" locale) is used. There is 442 no short form for this option. 443 444 --match-limit=number 445 Processing some regular expression patterns can require a 446 very large amount of memory, leading in some cases to a pro- 447 gram crash if not enough is available. Other patterns may 448 take a very long time to search for all possible matching 449 strings. The pcre_exec() function that is called by pcregrep 450 to do the matching has two parameters that can limit the 451 resources that it uses. 452 453 The --match-limit option provides a means of limiting 454 resource usage when processing patterns that are not going to 455 match, but which have a very large number of possibilities in 456 their search trees. The classic example is a pattern that 457 uses nested unlimited repeats. Internally, PCRE uses a func- 458 tion called match() which it calls repeatedly (sometimes 459 recursively). The limit set by --match-limit is imposed on 460 the number of times this function is called during a match, 461 which has the effect of limiting the amount of backtracking 462 that can take place. 463 464 The --recursion-limit option is similar to --match-limit, but 465 instead of limiting the total number of times that match() is 466 called, it limits the depth of recursive calls, which in turn 467 limits the amount of memory that can be used. The recursion 468 depth is a smaller number than the total number of calls, 469 because not all calls to match() are recursive. This limit is 470 of use only if it is set smaller than --match-limit. 471 472 There are no short forms for these options. The default set- 473 tings are specified when the PCRE library is compiled, with 474 the default default being 10 million. 475 476 -M, --multiline 477 Allow patterns to match more than one line. When this option 478 is given, patterns may usefully contain literal newline char- 479 acters and internal occurrences of ^ and $ characters. The 480 output for a successful match may consist of more than one 481 line, the last of which is the one in which the match ended. 482 If the matched string ends with a newline sequence the output 483 ends at the end of that line. 484 485 When this option is set, the PCRE library is called in "mul- 486 tiline" mode. There is a limit to the number of lines that 487 can be matched, imposed by the way that pcregrep buffers the 488 input file as it scans it. However, pcregrep ensures that at 489 least 8K characters or the rest of the document (whichever is 490 the shorter) are available for forward matching, and simi- 491 larly the previous 8K characters (or all the previous charac- 492 ters, if fewer than 8K) are guaranteed to be available for 493 lookbehind assertions. This option does not work when input 494 is read line by line (see --line-buffered.) 495 496 -N newline-type, --newline=newline-type 497 The PCRE library supports five different conventions for 498 indicating the ends of lines. They are the single-character 499 sequences CR (carriage return) and LF (linefeed), the two- 500 character sequence CRLF, an "anycrlf" convention, which rec- 501 ognizes any of the preceding three types, and an "any" con- 502 vention, in which any Unicode line ending sequence is assumed 503 to end a line. The Unicode sequences are the three just men- 504 tioned, plus VT (vertical tab, U+000B), FF (form feed, 505 U+000C), NEL (next line, U+0085), LS (line separator, 506 U+2028), and PS (paragraph separator, U+2029). 507 508 When the PCRE library is built, a default line-ending 509 sequence is specified. This is normally the standard 510 sequence for the operating system. Unless otherwise specified 511 by this option, pcregrep uses the library's default. The 512 possible values for this option are CR, LF, CRLF, ANYCRLF, or 513 ANY. This makes it possible to use pcregrep to scan files 514 that have come from other environments without having to mod- 515 ify their line endings. If the data that is being scanned 516 does not agree with the convention set by this option, pcre- 517 grep may behave in strange ways. Note that this option does 518 not apply to files specified by the -f, --exclude-from, or 519 --include-from options, which are expected to use the operat- 520 ing system's standard newline sequence. 521 522 -n, --line-number 523 Precede each output line by its line number in the file, fol- 524 lowed by a colon for matching lines or a hyphen for context 525 lines. If the filename is also being output, it precedes the 526 line number. This option is forced if --line-offsets is used. 527 528 --no-jit If the PCRE library is built with support for just-in-time 529 compiling (which speeds up matching), pcregrep automatically 530 makes use of this, unless it was explicitly disabled at build 531 time. This option can be used to disable the use of JIT at 532 run time. It is provided for testing and working round prob- 533 lems. It should never be needed in normal use. 534 535 -o, --only-matching 536 Show only the part of the line that matched a pattern instead 537 of the whole line. In this mode, no context is shown. That 538 is, the -A, -B, and -C options are ignored. If there is more 539 than one match in a line, each of them is shown separately. 540 If -o is combined with -v (invert the sense of the match to 541 find non-matching lines), no output is generated, but the 542 return code is set appropriately. If the matched portion of 543 the line is empty, nothing is output unless the file name or 544 line number are being printed, in which case they are shown 545 on an otherwise empty line. This option is mutually exclusive 546 with --file-offsets and --line-offsets. 547 548 -onumber, --only-matching=number 549 Show only the part of the line that matched the capturing 550 parentheses of the given number. Up to 32 capturing parenthe- 551 ses are supported, and -o0 is equivalent to -o without a num- 552 ber. Because these options can be given without an argument 553 (see above), if an argument is present, it must be given in 554 the same shell item, for example, -o3 or --only-matching=2. 555 The comments given for the non-argument case above also apply 556 to this case. If the specified capturing parentheses do not 557 exist in the pattern, or were not set in the match, nothing 558 is output unless the file name or line number are being 559 printed. 560 561 If this option is given multiple times, multiple substrings 562 are output, in the order the options are given. For example, 563 -o3 -o1 -o3 causes the substrings matched by capturing paren- 564 theses 3 and 1 and then 3 again to be output. By default, 565 there is no separator (but see the next option). 566 567 --om-separator=text 568 Specify a separating string for multiple occurrences of -o. 569 The default is an empty string. Separating strings are never 570 coloured. 571 572 -q, --quiet 573 Work quietly, that is, display nothing except error messages. 574 The exit status indicates whether or not any matches were 575 found. 576 577 -r, --recursive 578 If any given path is a directory, recursively scan the files 579 it contains, taking note of any --include and --exclude set- 580 tings. By default, a directory is read as a normal file; in 581 some operating systems this gives an immediate end-of-file. 582 This option is a shorthand for setting the -d option to 583 "recurse". 584 585 --recursion-limit=number 586 See --match-limit above. 587 588 -s, --no-messages 589 Suppress error messages about non-existent or unreadable 590 files. Such files are quietly skipped. However, the return 591 code is still 2, even if matches were found in other files. 592 593 -u, --utf-8 594 Operate in UTF-8 mode. This option is available only if PCRE 595 has been compiled with UTF-8 support. All patterns (including 596 those for any --exclude and --include options) and all sub- 597 ject lines that are scanned must be valid strings of UTF-8 598 characters. 599 600 -V, --version 601 Write the version numbers of pcregrep and the PCRE library to 602 the standard output and then exit. Anything else on the com- 603 mand line is ignored. 604 605 -v, --invert-match 606 Invert the sense of the match, so that lines which do not 607 match any of the patterns are the ones that are found. 608 609 -w, --word-regex, --word-regexp 610 Force the patterns to match only whole words. This is equiva- 611 lent to having \b at the start and end of the pattern. This 612 option applies only to the patterns that are matched against 613 the contents of files; it does not apply to patterns speci- 614 fied by any of the --include or --exclude options. 615 616 -x, --line-regex, --line-regexp 617 Force the patterns to be anchored (each must start matching 618 at the beginning of a line) and in addition, require them to 619 match entire lines. This is equivalent to having ^ and $ 620 characters at the start and end of each alternative branch in 621 every pattern. This option applies only to the patterns that 622 are matched against the contents of files; it does not apply 623 to patterns specified by any of the --include or --exclude 624 options. 625 626 627 ENVIRONMENT VARIABLES 628 629 The environment variables LC_ALL and LC_CTYPE are examined, in that 630 order, for a locale. The first one that is set is used. This can be 631 overridden by the --locale option. If no locale is set, the PCRE 632 library's default (usually the "C" locale) is used. 633 634 635 NEWLINES 636 637 The -N (--newline) option allows pcregrep to scan files with different 638 newline conventions from the default. Any parts of the input files that 639 are written to the standard output are copied identically, with what- 640 ever newline sequences they have in the input. However, the setting of 641 this option does not affect the interpretation of files specified by 642 the -f, --exclude-from, or --include-from options, which are assumed to 643 use the operating system's standard newline sequence, nor does it 644 affect the way in which pcregrep writes informational messages to the 645 standard error and output streams. For these it uses the string "\n" to 646 indicate newlines, relying on the C I/O library to convert this to an 647 appropriate sequence. 648 649 650 OPTIONS COMPATIBILITY 651 652 Many of the short and long forms of pcregrep's options are the same as 653 in the GNU grep program. Any long option of the form --xxx-regexp (GNU 654 terminology) is also available as --xxx-regex (PCRE terminology). How- 655 ever, the --file-list, --file-offsets, --include-dir, --line-offsets, 656 --locale, --match-limit, -M, --multiline, -N, --newline, --om-separa- 657 tor, --recursion-limit, -u, and --utf-8 options are specific to pcre- 658 grep, as is the use of the --only-matching option with a capturing 659 parentheses number. 660 661 Although most of the common options work the same way, a few are dif- 662 ferent in pcregrep. For example, the --include option's argument is a 663 glob for GNU grep, but a regular expression for pcregrep. If both the 664 -c and -l options are given, GNU grep lists only file names, without 665 counts, but pcregrep gives the counts. 666 667 668 OPTIONS WITH DATA 669 670 There are four different ways in which an option with data can be spec- 671 ified. If a short form option is used, the data may follow immedi- 672 ately, or (with one exception) in the next command line item. For exam- 673 ple: 674 675 -f/some/file 676 -f /some/file 677 678 The exception is the -o option, which may appear with or without data. 679 Because of this, if data is present, it must follow immediately in the 680 same item, for example -o3. 681 682 If a long form option is used, the data may appear in the same command 683 line item, separated by an equals character, or (with two exceptions) 684 it may appear in the next command line item. For example: 685 686 --file=/some/file 687 --file /some/file 688 689 Note, however, that if you want to supply a file name beginning with ~ 690 as data in a shell command, and have the shell expand ~ to a home 691 directory, you must separate the file name from the option, because the 692 shell does not treat ~ specially unless it is at the start of an item. 693 694 The exceptions to the above are the --colour (or --color) and --only- 695 matching options, for which the data is optional. If one of these 696 options does have data, it must be given in the first form, using an 697 equals character. Otherwise pcregrep will assume that it has no data. 698 699 700 MATCHING ERRORS 701 702 It is possible to supply a regular expression that takes a very long 703 time to fail to match certain lines. Such patterns normally involve 704 nested indefinite repeats, for example: (a+)*\d when matched against a 705 line of a's with no final digit. The PCRE matching function has a 706 resource limit that causes it to abort in these circumstances. If this 707 happens, pcregrep outputs an error message and the line that caused the 708 problem to the standard error stream. If there are more than 20 such 709 errors, pcregrep gives up. 710 711 The --match-limit option of pcregrep can be used to set the overall 712 resource limit; there is a second option called --recursion-limit that 713 sets a limit on the amount of memory (usually stack) that is used (see 714 the discussion of these options above). 715 716 717 DIAGNOSTICS 718 719 Exit status is 0 if any matches were found, 1 if no matches were found, 720 and 2 for syntax errors, overlong lines, non-existent or inaccessible 721 files (even if matches were found in other files) or too many matching 722 errors. Using the -s option to suppress error messages about inaccessi- 723 ble files does not affect the return code. 724 725 726 SEE ALSO 727 728 pcrepattern(3), pcresyntax(3), pcretest(1). 729 730 731 AUTHOR 732 733 Philip Hazel 734 University Computing Service 735 Cambridge CB2 3QH, England. 736 737 738 REVISION 739 740 Last updated: 03 April 2014 741 Copyright (c) 1997-2014 University of Cambridge. 742
