1 <html> 2 <head> 3 <title>pcre2grep specification</title> 4 </head> 5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB"> 6 <h1>pcre2grep man page</h1> 7 <p> 8 Return to the <a href="index.html">PCRE2 index page</a>. 9 </p> 10 <p> 11 This page is part of the PCRE2 HTML documentation. It was generated 12 automatically from the original man page. If there is any nonsense in it, 13 please consult the man page, in case the conversion went wrong. 14 <br> 15 <ul> 16 <li><a name="TOC1" href="#SEC1">SYNOPSIS</a> 17 <li><a name="TOC2" href="#SEC2">DESCRIPTION</a> 18 <li><a name="TOC3" href="#SEC3">SUPPORT FOR COMPRESSED FILES</a> 19 <li><a name="TOC4" href="#SEC4">BINARY FILES</a> 20 <li><a name="TOC5" href="#SEC5">BINARY ZEROS IN PATTERNS</a> 21 <li><a name="TOC6" href="#SEC6">OPTIONS</a> 22 <li><a name="TOC7" href="#SEC7">ENVIRONMENT VARIABLES</a> 23 <li><a name="TOC8" href="#SEC8">NEWLINES</a> 24 <li><a name="TOC9" href="#SEC9">OPTIONS COMPATIBILITY</a> 25 <li><a name="TOC10" href="#SEC10">OPTIONS WITH DATA</a> 26 <li><a name="TOC11" href="#SEC11">USING PCRE2'S CALLOUT FACILITY</a> 27 <li><a name="TOC12" href="#SEC12">MATCHING ERRORS</a> 28 <li><a name="TOC13" href="#SEC13">DIAGNOSTICS</a> 29 <li><a name="TOC14" href="#SEC14">SEE ALSO</a> 30 <li><a name="TOC15" href="#SEC15">AUTHOR</a> 31 <li><a name="TOC16" href="#SEC16">REVISION</a> 32 </ul> 33 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br> 34 <P> 35 <b>pcre2grep [options] [long options] [pattern] [path1 path2 ...]</b> 36 </P> 37 <br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br> 38 <P> 39 <b>pcre2grep</b> searches files for character patterns, in the same way as other 40 grep commands do, but it uses the PCRE2 regular expression library to support 41 patterns that are compatible with the regular expressions of Perl 5. See 42 <a href="pcre2syntax.html"><b>pcre2syntax</b>(3)</a> 43 for a quick-reference summary of pattern syntax, or 44 <a href="pcre2pattern.html"><b>pcre2pattern</b>(3)</a> 45 for a full description of the syntax and semantics of the regular expressions 46 that PCRE2 supports. 47 </P> 48 <P> 49 Patterns, whether supplied on the command line or in a separate file, are given 50 without delimiters. For example: 51 <pre> 52 pcre2grep Thursday /etc/motd 53 </pre> 54 If you attempt to use delimiters (for example, by surrounding a pattern with 55 slashes, as is common in Perl scripts), they are interpreted as part of the 56 pattern. Quotes can of course be used to delimit patterns on the command line 57 because they are interpreted by the shell, and indeed quotes are required if a 58 pattern contains white space or shell metacharacters. 59 </P> 60 <P> 61 The first argument that follows any option settings is treated as the single 62 pattern to be matched when neither <b>-e</b> nor <b>-f</b> is present. 63 Conversely, when one or both of these options are used to specify patterns, all 64 arguments are treated as path names. At least one of <b>-e</b>, <b>-f</b>, or an 65 argument pattern must be provided. 66 </P> 67 <P> 68 If no files are specified, <b>pcre2grep</b> reads the standard input. The 69 standard input can also be referenced by a name consisting of a single hyphen. 70 For example: 71 <pre> 72 pcre2grep some-pattern file1 - file3 73 </pre> 74 Input files are searched line by line. By default, each line that matches a 75 pattern is copied to the standard output, and if there is more than one file, 76 the file name is output at the start of each line, followed by a colon. 77 However, there are options that can change how <b>pcre2grep</b> behaves. In 78 particular, the <b>-M</b> option makes it possible to search for strings that 79 span line boundaries. What defines a line boundary is controlled by the 80 <b>-N</b> (<b>--newline</b>) option. 81 </P> 82 <P> 83 The amount of memory used for buffering files that are being scanned is 84 controlled by parameters that can be set by the <b>--buffer-size</b> and 85 <b>--max-buffer-size</b> options. The first of these sets the size of buffer 86 that is obtained at the start of processing. If an input file contains very 87 long lines, a larger buffer may be needed; this is handled by automatically 88 extending the buffer, up to the limit specified by <b>--max-buffer-size</b>. The 89 default values for these parameters can be set when <b>pcre2grep</b> is 90 built; if nothing is specified, the defaults are set to 20KiB and 1MiB 91 respectively. An error occurs if a line is too long and the buffer can no 92 longer be expanded. 93 </P> 94 <P> 95 The block of memory that is actually used is three times the "buffer size", to 96 allow for buffering "before" and "after" lines. If the buffer size is too 97 small, fewer than requested "before" and "after" lines may be output. 98 </P> 99 <P> 100 Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the greater. 101 BUFSIZ is defined in <b><stdio.h></b>. When there is more than one pattern 102 (specified by the use of <b>-e</b> and/or <b>-f</b>), each pattern is applied to 103 each line in the order in which they are defined, except that all the <b>-e</b> 104 patterns are tried before the <b>-f</b> patterns. 105 </P> 106 <P> 107 By default, as soon as one pattern matches a line, no further patterns are 108 considered. However, if <b>--colour</b> (or <b>--color</b>) is used to colour the 109 matching substrings, or if <b>--only-matching</b>, <b>--file-offsets</b>, or 110 <b>--line-offsets</b> is used to output only the part of the line that matched 111 (either shown literally, or as an offset), scanning resumes immediately 112 following the match, so that further matches on the same line can be found. If 113 there are multiple patterns, they are all tried on the remainder of the line, 114 but patterns that follow the one that matched are not tried on the earlier part 115 of the line. 116 </P> 117 <P> 118 This behaviour means that the order in which multiple patterns are specified 119 can affect the output when one of the above options is used. This is no longer 120 the same behaviour as GNU grep, which now manages to display earlier matches 121 for later patterns (as long as there is no overlap). 122 </P> 123 <P> 124 Patterns that can match an empty string are accepted, but empty string 125 matches are never recognized. An example is the pattern "(super)?(man)?", in 126 which all components are optional. This pattern finds all occurrences of both 127 "super" and "man"; the output differs from matching with "super|man" when only 128 the matching substrings are being shown. 129 </P> 130 <P> 131 If the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variable is set, 132 <b>pcre2grep</b> uses the value to set a locale when calling the PCRE2 library. 133 The <b>--locale</b> option can be used to override this. 134 </P> 135 <br><a name="SEC3" href="#TOC1">SUPPORT FOR COMPRESSED FILES</a><br> 136 <P> 137 It is possible to compile <b>pcre2grep</b> so that it uses <b>libz</b> or 138 <b>libbz2</b> to read compressed files whose names end in <b>.gz</b> or 139 <b>.bz2</b>, respectively. You can find out whether your <b>pcre2grep</b> binary 140 has support for one or both of these file types by running it with the 141 <b>--help</b> option. If the appropriate support is not present, all files are 142 treated as plain text. The standard input is always so treated. When input is 143 from a compressed .gz or .bz2 file, the <b>--line-buffered</b> option is 144 ignored. 145 </P> 146 <br><a name="SEC4" href="#TOC1">BINARY FILES</a><br> 147 <P> 148 By default, a file that contains a binary zero byte within the first 1024 bytes 149 is identified as a binary file, and is processed specially. (GNU grep 150 identifies binary files in this manner.) However, if the newline type is 151 specified as "nul", that is, the line terminator is a binary zero, the test for 152 a binary file is not applied. See the <b>--binary-files</b> option for a means 153 of changing the way binary files are handled. 154 </P> 155 <br><a name="SEC5" href="#TOC1">BINARY ZEROS IN PATTERNS</a><br> 156 <P> 157 Patterns passed from the command line are strings that are terminated by a 158 binary zero, so cannot contain internal zeros. However, patterns that are read 159 from a file via the <b>-f</b> option may contain binary zeros. 160 </P> 161 <br><a name="SEC6" href="#TOC1">OPTIONS</a><br> 162 <P> 163 The order in which some of the options appear can affect the output. For 164 example, both the <b>-H</b> and <b>-l</b> options affect the printing of file 165 names. Whichever comes later in the command line will be the one that takes 166 effect. Similarly, except where noted below, if an option is given twice, the 167 later setting is used. Numerical values for options may be followed by K or M, 168 to signify multiplication by 1024 or 1024*1024 respectively. 169 </P> 170 <P> 171 <b>--</b> 172 This terminates the list of options. It is useful if the next item on the 173 command line starts with a hyphen but is not an option. This allows for the 174 processing of patterns and file names that start with hyphens. 175 </P> 176 <P> 177 <b>-A</b> <i>number</i>, <b>--after-context=</b><i>number</i> 178 Output up to <i>number</i> lines of context after each matching line. Fewer 179 lines are output if the next match or the end of the file is reached, or if the 180 processing buffer size has been set too small. If file names and/or line 181 numbers are being output, a hyphen separator is used instead of a colon for the 182 context lines. A line containing "--" is output between each group of lines, 183 unless they are in fact contiguous in the input file. The value of <i>number</i> 184 is expected to be relatively small. When <b>-c</b> is used, <b>-A</b> is ignored. 185 </P> 186 <P> 187 <b>-a</b>, <b>--text</b> 188 Treat binary files as text. This is equivalent to 189 <b>--binary-files</b>=<i>text</i>. 190 </P> 191 <P> 192 <b>-B</b> <i>number</i>, <b>--before-context=</b><i>number</i> 193 Output up to <i>number</i> lines of context before each matching line. Fewer 194 lines are output if the previous match or the start of the file is within 195 <i>number</i> lines, or if the processing buffer size has been set too small. If 196 file names and/or line numbers are being output, a hyphen separator is used 197 instead of a colon for the context lines. A line containing "--" is output 198 between each group of lines, unless they are in fact contiguous in the input 199 file. The value of <i>number</i> is expected to be relatively small. When 200 <b>-c</b> is used, <b>-B</b> is ignored. 201 </P> 202 <P> 203 <b>--binary-files=</b><i>word</i> 204 Specify how binary files are to be processed. If the word is "binary" (the 205 default), pattern matching is performed on binary files, but the only output is 206 "Binary file <name> matches" when a match succeeds. If the word is "text", 207 which is equivalent to the <b>-a</b> or <b>--text</b> option, binary files are 208 processed in the same way as any other file. In this case, when a match 209 succeeds, the output may be binary garbage, which can have nasty effects if 210 sent to a terminal. If the word is "without-match", which is equivalent to the 211 <b>-I</b> option, binary files are not processed at all; they are assumed not to 212 be of interest and are skipped without causing any output or affecting the 213 return code. 214 </P> 215 <P> 216 <b>--buffer-size=</b><i>number</i> 217 Set the parameter that controls how much memory is obtained at the start of 218 processing for buffering files that are being scanned. See also 219 <b>--max-buffer-size</b> below. 220 </P> 221 <P> 222 <b>-C</b> <i>number</i>, <b>--context=</b><i>number</i> 223 Output <i>number</i> lines of context both before and after each matching line. 224 This is equivalent to setting both <b>-A</b> and <b>-B</b> to the same value. 225 </P> 226 <P> 227 <b>-c</b>, <b>--count</b> 228 Do not output lines from the files that are being scanned; instead output the 229 number of lines that would have been shown, either because they matched, or, if 230 <b>-v</b> is set, because they failed to match. By default, this count is 231 exactly the same as the number of lines that would have been output, but if the 232 <b>-M</b> (multiline) option is used (without <b>-v</b>), there may be more 233 suppressed lines than the count (that is, the number of matches). 234 <br> 235 <br> 236 If no lines are selected, the number zero is output. If several files are are 237 being scanned, a count is output for each of them and the <b>-t</b> option can 238 be used to cause a total to be output at the end. However, if the 239 <b>--files-with-matches</b> option is also used, only those files whose counts 240 are greater than zero are listed. When <b>-c</b> is used, the <b>-A</b>, 241 <b>-B</b>, and <b>-C</b> options are ignored. 242 </P> 243 <P> 244 <b>--colour</b>, <b>--color</b> 245 If this option is given without any data, it is equivalent to "--colour=auto". 246 If data is required, it must be given in the same shell item, separated by an 247 equals sign. 248 </P> 249 <P> 250 <b>--colour=</b><i>value</i>, <b>--color=</b><i>value</i> 251 This option specifies under what circumstances the parts of a line that matched 252 a pattern should be coloured in the output. By default, the output is not 253 coloured. The value (which is optional, see above) may be "never", "always", or 254 "auto". In the latter case, colouring happens only if the standard output is 255 connected to a terminal. More resources are used when colouring is enabled, 256 because <b>pcre2grep</b> has to search for all possible matches in a line, not 257 just one, in order to colour them all. 258 <br> 259 <br> 260 The colour that is used can be specified by setting one of the environment 261 variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR, PCREGREP_COLOUR, or 262 PCREGREP_COLOR, which are checked in that order. If none of these are set, 263 <b>pcre2grep</b> looks for GREP_COLORS or GREP_COLOR (in that order). The value 264 of the variable should be a string of two numbers, separated by a semicolon, 265 except in the case of GREP_COLORS, which must start with "ms=" or "mt=" 266 followed by two semicolon-separated colours, terminated by the end of the 267 string or by a colon. If GREP_COLORS does not start with "ms=" or "mt=" it is 268 ignored, and GREP_COLOR is checked. 269 <br> 270 <br> 271 If the string obtained from one of the above variables contains any characters 272 other than semicolon or digits, the setting is ignored and the default colour 273 is used. The string is copied directly into the control string for setting 274 colour on a terminal, so it is your responsibility to ensure that the values 275 make sense. If no relevant environment variable is set, the default is "1;31", 276 which gives red. 277 </P> 278 <P> 279 <b>-D</b> <i>action</i>, <b>--devices=</b><i>action</i> 280 If an input path is not a regular file or a directory, "action" specifies how 281 it is to be processed. Valid values are "read" (the default) or "skip" 282 (silently skip the path). 283 </P> 284 <P> 285 <b>-d</b> <i>action</i>, <b>--directories=</b><i>action</i> 286 If an input path is a directory, "action" specifies how it is to be processed. 287 Valid values are "read" (the default in non-Windows environments, for 288 compatibility with GNU grep), "recurse" (equivalent to the <b>-r</b> option), or 289 "skip" (silently skip the path, the default in Windows environments). In the 290 "read" case, directories are read as if they were ordinary files. In some 291 operating systems the effect of reading a directory like this is an immediate 292 end-of-file; in others it may provoke an error. 293 </P> 294 <P> 295 <b>--depth-limit</b>=<i>number</i> 296 See <b>--match-limit</b> below. 297 </P> 298 <P> 299 <b>-e</b> <i>pattern</i>, <b>--regex=</b><i>pattern</i>, <b>--regexp=</b><i>pattern</i> 300 Specify a pattern to be matched. This option can be used multiple times in 301 order to specify several patterns. It can also be used as a way of specifying a 302 single pattern that starts with a hyphen. When <b>-e</b> is used, no argument 303 pattern is taken from the command line; all arguments are treated as file 304 names. There is no limit to the number of patterns. They are applied to each 305 line in the order in which they are defined until one matches. 306 <br> 307 <br> 308 If <b>-f</b> is used with <b>-e</b>, the command line patterns are matched first, 309 followed by the patterns from the file(s), independent of the order in which 310 these options are specified. Note that multiple use of <b>-e</b> is not the same 311 as a single pattern with alternatives. For example, X|Y finds the first 312 character in a line that is X or Y, whereas if the two patterns are given 313 separately, with X first, <b>pcre2grep</b> finds X if it is present, even if it 314 follows Y in the line. It finds Y only if there is no X in the line. This 315 matters only if you are using <b>-o</b> or <b>--colo(u)r</b> to show the part(s) 316 of the line that matched. 317 </P> 318 <P> 319 <b>--exclude</b>=<i>pattern</i> 320 Files (but not directories) whose names match the pattern are skipped without 321 being processed. This applies to all files, whether listed on the command line, 322 obtained from <b>--file-list</b>, or by scanning a directory. The pattern is a 323 PCRE2 regular expression, and is matched against the final component of the 324 file name, not the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do 325 not apply to this pattern. The option may be given any number of times in order 326 to specify multiple patterns. If a file name matches both an <b>--include</b> 327 and an <b>--exclude</b> pattern, it is excluded. There is no short form for this 328 option. 329 </P> 330 <P> 331 <b>--exclude-from=</b><i>filename</i> 332 Treat each non-empty line of the file as the data for an <b>--exclude</b> 333 option. What constitutes a newline when reading the file is the operating 334 system's default. The <b>--newline</b> option has no effect on this option. This 335 option may be given more than once in order to specify a number of files to 336 read. 337 </P> 338 <P> 339 <b>--exclude-dir</b>=<i>pattern</i> 340 Directories whose names match the pattern are skipped without being processed, 341 whatever the setting of the <b>--recursive</b> option. This applies to all 342 directories, whether listed on the command line, obtained from 343 <b>--file-list</b>, or by scanning a parent directory. The pattern is a PCRE2 344 regular expression, and is matched against the final component of the directory 345 name, not the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not 346 apply to this pattern. The option may be given any number of times in order to 347 specify more than one pattern. If a directory matches both <b>--include-dir</b> 348 and <b>--exclude-dir</b>, it is excluded. There is no short form for this 349 option. 350 </P> 351 <P> 352 <b>-F</b>, <b>--fixed-strings</b> 353 Interpret each data-matching pattern as a list of fixed strings, separated by 354 newlines, instead of as a regular expression. What constitutes a newline for 355 this purpose is controlled by the <b>--newline</b> option. The <b>-w</b> (match 356 as a word) and <b>-x</b> (match whole line) options can be used with <b>-F</b>. 357 They apply to each of the fixed strings. A line is selected if any of the fixed 358 strings are found in it (subject to <b>-w</b> or <b>-x</b>, if present). This 359 option applies only to the patterns that are matched against the contents of 360 files; it does not apply to patterns specified by any of the <b>--include</b> or 361 <b>--exclude</b> options. 362 </P> 363 <P> 364 <b>-f</b> <i>filename</i>, <b>--file=</b><i>filename</i> 365 Read patterns from the file, one per line, and match them against each line of 366 input. As is the case with patterns on the command line, no delimiters should 367 be used. What constitutes a newline when reading the file is the operating 368 system's default interpretation of \n. The <b>--newline</b> option has no 369 effect on this option. Trailing white space is removed from each line, and 370 blank lines are ignored. An empty file contains no patterns and therefore 371 matches nothing. Patterns read from a file in this way may contain binary 372 zeros, which are treated as ordinary data characters. See also the comments 373 about multiple patterns versus a single pattern with alternatives in the 374 description of <b>-e</b> above. 375 <br> 376 <br> 377 If this option is given more than once, all the specified files are read. A 378 data line is output if any of the patterns match it. A file name can be given 379 as "-" to refer to the standard input. When <b>-f</b> is used, patterns 380 specified on the command line using <b>-e</b> may also be present; they are 381 tested before the file's patterns. However, no other pattern is taken from the 382 command line; all arguments are treated as the names of paths to be searched. 383 </P> 384 <P> 385 <b>--file-list</b>=<i>filename</i> 386 Read a list of files and/or directories that are to be scanned from the given 387 file, one per line. What constitutes a newline when reading the file is the 388 operating system's default. Trailing white space is removed from each line, and 389 blank lines are ignored. These paths are processed before any that are listed 390 on the command line. The file name can be given as "-" to refer to the standard 391 input. If <b>--file</b> and <b>--file-list</b> are both specified as "-", 392 patterns are read first. This is useful only when the standard input is a 393 terminal, from which further lines (the list of files) can be read after an 394 end-of-file indication. If this option is given more than once, all the 395 specified files are read. 396 </P> 397 <P> 398 <b>--file-offsets</b> 399 Instead of showing lines or parts of lines that match, show each match as an 400 offset from the start of the file and a length, separated by a comma. In this 401 mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b> 402 options are ignored. If there is more than one match in a line, each of them is 403 shown separately. This option is mutually exclusive with <b>--output</b>, 404 <b>--line-offsets</b>, and <b>--only-matching</b>. 405 </P> 406 <P> 407 <b>-H</b>, <b>--with-filename</b> 408 Force the inclusion of the file name at the start of output lines when 409 searching a single file. By default, the file name is not shown in this case. 410 For matching lines, the file name is followed by a colon; for context lines, a 411 hyphen separator is used. If a line number is also being output, it follows the 412 file name. When the <b>-M</b> option causes a pattern to match more than one 413 line, only the first is preceded by the file name. This option overrides any 414 previous <b>-h</b>, <b>-l</b>, or <b>-L</b> options. 415 </P> 416 <P> 417 <b>-h</b>, <b>--no-filename</b> 418 Suppress the output file names when searching multiple files. By default, 419 file names are shown when multiple files are searched. For matching lines, the 420 file name is followed by a colon; for context lines, a hyphen separator is used. 421 If a line number is also being output, it follows the file name. This option 422 overrides any previous <b>-H</b>, <b>-L</b>, or <b>-l</b> options. 423 </P> 424 <P> 425 <b>--heap-limit</b>=<i>number</i> 426 See <b>--match-limit</b> below. 427 </P> 428 <P> 429 <b>--help</b> 430 Output a help message, giving brief details of the command options and file 431 type support, and then exit. Anything else on the command line is 432 ignored. 433 </P> 434 <P> 435 <b>-I</b> 436 Ignore binary files. This is equivalent to 437 <b>--binary-files</b>=<i>without-match</i>. 438 </P> 439 <P> 440 <b>-i</b>, <b>--ignore-case</b> 441 Ignore upper/lower case distinctions during comparisons. 442 </P> 443 <P> 444 <b>--include</b>=<i>pattern</i> 445 If any <b>--include</b> patterns are specified, the only files that are 446 processed are those that match one of the patterns (and do not match an 447 <b>--exclude</b> pattern). This option does not affect directories, but it 448 applies to all files, whether listed on the command line, obtained from 449 <b>--file-list</b>, or by scanning a directory. The pattern is a PCRE2 regular 450 expression, and is matched against the final component of the file name, not 451 the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not apply to 452 this pattern. The option may be given any number of times. If a file name 453 matches both an <b>--include</b> and an <b>--exclude</b> pattern, it is excluded. 454 There is no short form for this option. 455 </P> 456 <P> 457 <b>--include-from=</b><i>filename</i> 458 Treat each non-empty line of the file as the data for an <b>--include</b> 459 option. What constitutes a newline for this purpose is the operating system's 460 default. The <b>--newline</b> option has no effect on this option. This option 461 may be given any number of times; all the files are read. 462 </P> 463 <P> 464 <b>--include-dir</b>=<i>pattern</i> 465 If any <b>--include-dir</b> patterns are specified, the only directories that 466 are processed are those that match one of the patterns (and do not match an 467 <b>--exclude-dir</b> pattern). This applies to all directories, whether listed 468 on the command line, obtained from <b>--file-list</b>, or by scanning a parent 469 directory. The pattern is a PCRE2 regular expression, and is matched against 470 the final component of the directory name, not the entire path. The <b>-F</b>, 471 <b>-w</b>, and <b>-x</b> options do not apply to this pattern. The option may be 472 given any number of times. If a directory matches both <b>--include-dir</b> and 473 <b>--exclude-dir</b>, it is excluded. There is no short form for this option. 474 </P> 475 <P> 476 <b>-L</b>, <b>--files-without-match</b> 477 Instead of outputting lines from the files, just output the names of the files 478 that do not contain any lines that would have been output. Each file name is 479 output once, on a separate line. This option overrides any previous <b>-H</b>, 480 <b>-h</b>, or <b>-l</b> options. 481 </P> 482 <P> 483 <b>-l</b>, <b>--files-with-matches</b> 484 Instead of outputting lines from the files, just output the names of the files 485 containing lines that would have been output. Each file name is output once, on 486 a separate line. Searching normally stops as soon as a matching line is found 487 in a file. However, if the <b>-c</b> (count) option is also used, matching 488 continues in order to obtain the correct count, and those files that have at 489 least one match are listed along with their counts. Using this option with 490 <b>-c</b> is a way of suppressing the listing of files with no matches. This 491 opeion overrides any previous <b>-H</b>, <b>-h</b>, or <b>-L</b> options. 492 </P> 493 <P> 494 <b>--label</b>=<i>name</i> 495 This option supplies a name to be used for the standard input when file names 496 are being output. If not supplied, "(standard input)" is used. There is no 497 short form for this option. 498 </P> 499 <P> 500 <b>--line-buffered</b> 501 When this option is given, non-compressed input is read and processed line by 502 line, and the output is flushed after each write. By default, input is read in 503 large chunks, unless <b>pcre2grep</b> can determine that it is reading from a 504 terminal (which is currently possible only in Unix-like environments or 505 Windows). Output to terminal is normally automatically flushed by the operating 506 system. This option can be useful when the input or output is attached to a 507 pipe and you do not want <b>pcre2grep</b> to buffer up large amounts of data. 508 However, its use will affect performance, and the <b>-M</b> (multiline) option 509 ceases to work. When input is from a compressed .gz or .bz2 file, 510 <b>--line-buffered</b> is ignored. 511 </P> 512 <P> 513 <b>--line-offsets</b> 514 Instead of showing lines or parts of lines that match, show each match as a 515 line number, the offset from the start of the line, and a length. The line 516 number is terminated by a colon (as usual; see the <b>-n</b> option), and the 517 offset and length are separated by a comma. In this mode, no context is shown. 518 That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b> options are ignored. If there is 519 more than one match in a line, each of them is shown separately. This option is 520 mutually exclusive with <b>--output</b>, <b>--file-offsets</b>, and 521 <b>--only-matching</b>. 522 </P> 523 <P> 524 <b>--locale</b>=<i>locale-name</i> 525 This option specifies a locale to be used for pattern matching. It overrides 526 the value in the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variables. If no 527 locale is specified, the PCRE2 library's default (usually the "C" locale) is 528 used. There is no short form for this option. 529 </P> 530 <P> 531 <b>--match-limit</b>=<i>number</i> 532 Processing some regular expression patterns may take a very long time to search 533 for all possible matching strings. Others may require a very large amount of 534 memory. There are three options that set resource limits for matching. 535 <br> 536 <br> 537 The <b>--match-limit</b> option provides a means of limiting computing resource 538 usage when processing patterns that are not going to match, but which have a 539 very large number of possibilities in their search trees. The classic example 540 is a pattern that uses nested unlimited repeats. Internally, PCRE2 has a 541 counter that is incremented each time around its main processing loop. If the 542 value set by <b>--match-limit</b> is reached, an error occurs. 543 <br> 544 <br> 545 The <b>--heap-limit</b> option specifies, as a number of kibibytes (units of 546 1024 bytes), the amount of heap memory that may be used for matching. Heap 547 memory is needed only if matching the pattern requires a significant number of 548 nested backtracking points to be remembered. This parameter can be set to zero 549 to forbid the use of heap memory altogether. 550 <br> 551 <br> 552 The <b>--depth-limit</b> option limits the depth of nested backtracking points, 553 which indirectly limits the amount of memory that is used. The amount of memory 554 needed for each backtracking point depends on the number of capturing 555 parentheses in the pattern, so the amount of memory that is used before this 556 limit acts varies from pattern to pattern. This limit is of use only if it is 557 set smaller than <b>--match-limit</b>. 558 <br> 559 <br> 560 There are no short forms for these options. The default limits can be set 561 when the PCRE2 library is compiled; if they are not specified, the defaults 562 are very large and so effectively unlimited. 563 </P> 564 <P> 565 \fB--max-buffer-size=<i>number</i> 566 This limits the expansion of the processing buffer, whose initial size can be 567 set by <b>--buffer-size</b>. The maximum buffer size is silently forced to be no 568 smaller than the starting buffer size. 569 </P> 570 <P> 571 <b>-M</b>, <b>--multiline</b> 572 Allow patterns to match more than one line. When this option is set, the PCRE2 573 library is called in "multiline" mode. This allows a matched string to extend 574 past the end of a line and continue on one or more subsequent lines. Patterns 575 used with <b>-M</b> may usefully contain literal newline characters and internal 576 occurrences of ^ and $ characters. The output for a successful match may 577 consist of more than one line. The first line is the line in which the match 578 started, and the last line is the line in which the match ended. If the matched 579 string ends with a newline sequence, the output ends at the end of that line. 580 If <b>-v</b> is set, none of the lines in a multi-line match are output. Once a 581 match has been handled, scanning restarts at the beginning of the line after 582 the one in which the match ended. 583 <br> 584 <br> 585 The newline sequence that separates multiple lines must be matched as part of 586 the pattern. For example, to find the phrase "regular expression" in a file 587 where "regular" might be at the end of a line and "expression" at the start of 588 the next line, you could use this command: 589 <pre> 590 pcre2grep -M 'regular\s+expression' <file> 591 </pre> 592 The \s escape sequence matches any white space character, including newlines, 593 and is followed by + so as to match trailing white space on the first line as 594 well as possibly handling a two-character newline sequence. 595 <br> 596 <br> 597 There is a limit to the number of lines that can be matched, imposed by the way 598 that <b>pcre2grep</b> buffers the input file as it scans it. With a sufficiently 599 large processing buffer, this should not be a problem, but the <b>-M</b> option 600 does not work when input is read line by line (see \fP--line-buffered\fP.) 601 </P> 602 <P> 603 <b>-N</b> <i>newline-type</i>, <b>--newline</b>=<i>newline-type</i> 604 The PCRE2 library supports five different conventions for indicating 605 the ends of lines. They are the single-character sequences CR (carriage return) 606 and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention, 607 which recognizes any of the preceding three types, and an "any" convention, in 608 which any Unicode line ending sequence is assumed to end a line. The Unicode 609 sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF 610 (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and 611 PS (paragraph separator, U+2029). 612 <br> 613 <br> 614 When the PCRE2 library is built, a default line-ending sequence is specified. 615 This is normally the standard sequence for the operating system. Unless 616 otherwise specified by this option, <b>pcre2grep</b> uses the library's default. 617 The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This 618 makes it possible to use <b>pcre2grep</b> to scan files that have come from 619 other environments without having to modify their line endings. If the data 620 that is being scanned does not agree with the convention set by this option, 621 <b>pcre2grep</b> may behave in strange ways. Note that this option does not 622 apply to files specified by the <b>-f</b>, <b>--exclude-from</b>, or 623 <b>--include-from</b> options, which are expected to use the operating system's 624 standard newline sequence. 625 </P> 626 <P> 627 <b>-n</b>, <b>--line-number</b> 628 Precede each output line by its line number in the file, followed by a colon 629 for matching lines or a hyphen for context lines. If the file name is also 630 being output, it precedes the line number. When the <b>-M</b> option causes a 631 pattern to match more than one line, only the first is preceded by its line 632 number. This option is forced if <b>--line-offsets</b> is used. 633 </P> 634 <P> 635 <b>--no-jit</b> 636 If the PCRE2 library is built with support for just-in-time compiling (which 637 speeds up matching), <b>pcre2grep</b> automatically makes use of this, unless it 638 was explicitly disabled at build time. This option can be used to disable the 639 use of JIT at run time. It is provided for testing and working round problems. 640 It should never be needed in normal use. 641 </P> 642 <P> 643 <b>-O</b> <i>text</i>, <b>--output</b>=<i>text</i> 644 When there is a match, instead of outputting the whole line that matched, 645 output just the given text. This option is mutually exclusive with 646 <b>--only-matching</b>, <b>--file-offsets</b>, and <b>--line-offsets</b>. Escape 647 sequences starting with a dollar character may be used to insert the contents 648 of the matched part of the line and/or captured substrings into the text. 649 <br> 650 <br> 651 $<digits> or ${<digits>} is replaced by the captured 652 substring of the given decimal number; zero substitutes the whole match. If 653 the number is greater than the number of capturing substrings, or if the 654 capture is unset, the replacement is empty. 655 <br> 656 <br> 657 $a is replaced by bell; $b by backspace; $e by escape; $f by form feed; $n by 658 newline; $r by carriage return; $t by tab; $v by vertical tab. 659 <br> 660 <br> 661 $o<digits> is replaced by the character represented by the given octal 662 number; up to three digits are processed. 663 <br> 664 <br> 665 $x<digits> is replaced by the character represented by the given hexadecimal 666 number; up to two digits are processed. 667 <br> 668 <br> 669 Any other character is substituted by itself. In particular, $$ is replaced by 670 a single dollar. 671 </P> 672 <P> 673 <b>-o</b>, <b>--only-matching</b> 674 Show only the part of the line that matched a pattern instead of the whole 675 line. In this mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and 676 <b>-C</b> options are ignored. If there is more than one match in a line, each 677 of them is shown separately, on a separate line of output. If <b>-o</b> is 678 combined with <b>-v</b> (invert the sense of the match to find non-matching 679 lines), no output is generated, but the return code is set appropriately. If 680 the matched portion of the line is empty, nothing is output unless the file 681 name or line number are being printed, in which case they are shown on an 682 otherwise empty line. This option is mutually exclusive with <b>--output</b>, 683 <b>--file-offsets</b> and <b>--line-offsets</b>. 684 </P> 685 <P> 686 <b>-o</b><i>number</i>, <b>--only-matching</b>=<i>number</i> 687 Show only the part of the line that matched the capturing parentheses of the 688 given number. Up to 32 capturing parentheses are supported, and -o0 is 689 equivalent to <b>-o</b> without a number. Because these options can be given 690 without an argument (see above), if an argument is present, it must be given in 691 the same shell item, for example, -o3 or --only-matching=2. The comments given 692 for the non-argument case above also apply to this option. If the specified 693 capturing parentheses do not exist in the pattern, or were not set in the 694 match, nothing is output unless the file name or line number are being output. 695 <br> 696 <br> 697 If this option is given multiple times, multiple substrings are output for each 698 match, in the order the options are given, and all on one line. For example, 699 -o3 -o1 -o3 causes the substrings matched by capturing parentheses 3 and 1 and 700 then 3 again to be output. By default, there is no separator (but see the next 701 option). 702 </P> 703 <P> 704 <b>--om-separator</b>=<i>text</i> 705 Specify a separating string for multiple occurrences of <b>-o</b>. The default 706 is an empty string. Separating strings are never coloured. 707 </P> 708 <P> 709 <b>-q</b>, <b>--quiet</b> 710 Work quietly, that is, display nothing except error messages. The exit 711 status indicates whether or not any matches were found. 712 </P> 713 <P> 714 <b>-r</b>, <b>--recursive</b> 715 If any given path is a directory, recursively scan the files it contains, 716 taking note of any <b>--include</b> and <b>--exclude</b> settings. By default, a 717 directory is read as a normal file; in some operating systems this gives an 718 immediate end-of-file. This option is a shorthand for setting the <b>-d</b> 719 option to "recurse". 720 </P> 721 <P> 722 <b>--recursion-limit</b>=<i>number</i> 723 See <b>--match-limit</b> above. 724 </P> 725 <P> 726 <b>-s</b>, <b>--no-messages</b> 727 Suppress error messages about non-existent or unreadable files. Such files are 728 quietly skipped. However, the return code is still 2, even if matches were 729 found in other files. 730 </P> 731 <P> 732 <b>-t</b>, <b>--total-count</b> 733 This option is useful when scanning more than one file. If used on its own, 734 <b>-t</b> suppresses all output except for a grand total number of matching 735 lines (or non-matching lines if <b>-v</b> is used) in all the files. If <b>-t</b> 736 is used with <b>-c</b>, a grand total is output except when the previous output 737 is just one line. In other words, it is not output when just one file's count 738 is listed. If file names are being output, the grand total is preceded by 739 "TOTAL:". Otherwise, it appears as just another number. The <b>-t</b> option is 740 ignored when used with <b>-L</b> (list files without matches), because the grand 741 total would always be zero. 742 </P> 743 <P> 744 <b>-u</b>, <b>--utf-8</b> 745 Operate in UTF-8 mode. This option is available only if PCRE2 has been compiled 746 with UTF-8 support. All patterns (including those for any <b>--exclude</b> and 747 <b>--include</b> options) and all subject lines that are scanned must be valid 748 strings of UTF-8 characters. 749 </P> 750 <P> 751 <b>-V</b>, <b>--version</b> 752 Write the version numbers of <b>pcre2grep</b> and the PCRE2 library to the 753 standard output and then exit. Anything else on the command line is 754 ignored. 755 </P> 756 <P> 757 <b>-v</b>, <b>--invert-match</b> 758 Invert the sense of the match, so that lines which do <i>not</i> match any of 759 the patterns are the ones that are found. 760 </P> 761 <P> 762 <b>-w</b>, <b>--word-regex</b>, <b>--word-regexp</b> 763 Force the patterns only to match "words". That is, there must be a word 764 boundary at the start and end of each matched string. This is equivalent to 765 having "\b(?:" at the start of each pattern, and ")\b" at the end. This 766 option applies only to the patterns that are matched against the contents of 767 files; it does not apply to patterns specified by any of the <b>--include</b> or 768 <b>--exclude</b> options. 769 </P> 770 <P> 771 <b>-x</b>, <b>--line-regex</b>, <b>--line-regexp</b> 772 Force the patterns to start matching only at the beginnings of lines, and in 773 addition, require them to match entire lines. In multiline mode the match may 774 be more than one line. This is equivalent to having "^(?:" at the start of each 775 pattern and ")$" at the end. This option applies only to the patterns that are 776 matched against the contents of files; it does not apply to patterns specified 777 by any of the <b>--include</b> or <b>--exclude</b> options. 778 </P> 779 <br><a name="SEC7" href="#TOC1">ENVIRONMENT VARIABLES</a><br> 780 <P> 781 The environment variables <b>LC_ALL</b> and <b>LC_CTYPE</b> are examined, in that 782 order, for a locale. The first one that is set is used. This can be overridden 783 by the <b>--locale</b> option. If no locale is set, the PCRE2 library's default 784 (usually the "C" locale) is used. 785 </P> 786 <br><a name="SEC8" href="#TOC1">NEWLINES</a><br> 787 <P> 788 The <b>-N</b> (<b>--newline</b>) option allows <b>pcre2grep</b> to scan files with 789 different newline conventions from the default. Any parts of the input files 790 that are written to the standard output are copied identically, with whatever 791 newline sequences they have in the input. However, the setting of this option 792 affects only the way scanned files are processed. It does not affect the 793 interpretation of files specified by the <b>-f</b>, <b>--file-list</b>, 794 <b>--exclude-from</b>, or <b>--include-from</b> options, nor does it affect the 795 way in which <b>pcre2grep</b> writes informational messages to the standard 796 error and output streams. For these it uses the string "\n" to indicate 797 newlines, relying on the C I/O library to convert this to an appropriate 798 sequence. 799 </P> 800 <br><a name="SEC9" href="#TOC1">OPTIONS COMPATIBILITY</a><br> 801 <P> 802 Many of the short and long forms of <b>pcre2grep</b>'s options are the same 803 as in the GNU <b>grep</b> program. Any long option of the form 804 <b>--xxx-regexp</b> (GNU terminology) is also available as <b>--xxx-regex</b> 805 (PCRE2 terminology). However, the <b>--depth-limit</b>, <b>--file-list</b>, 806 <b>--file-offsets</b>, <b>--heap-limit</b>, <b>--include-dir</b>, 807 <b>--line-offsets</b>, <b>--locale</b>, <b>--match-limit</b>, <b>-M</b>, 808 <b>--multiline</b>, <b>-N</b>, <b>--newline</b>, <b>--om-separator</b>, 809 <b>--output</b>, <b>-u</b>, and <b>--utf-8</b> options are specific to 810 <b>pcre2grep</b>, as is the use of the <b>--only-matching</b> option with a 811 capturing parentheses number. 812 </P> 813 <P> 814 Although most of the common options work the same way, a few are different in 815 <b>pcre2grep</b>. For example, the <b>--include</b> option's argument is a glob 816 for GNU <b>grep</b>, but a regular expression for <b>pcre2grep</b>. If both the 817 <b>-c</b> and <b>-l</b> options are given, GNU grep lists only file names, 818 without counts, but <b>pcre2grep</b> gives the counts as well. 819 </P> 820 <br><a name="SEC10" href="#TOC1">OPTIONS WITH DATA</a><br> 821 <P> 822 There are four different ways in which an option with data can be specified. 823 If a short form option is used, the data may follow immediately, or (with one 824 exception) in the next command line item. For example: 825 <pre> 826 -f/some/file 827 -f /some/file 828 </pre> 829 The exception is the <b>-o</b> option, which may appear with or without data. 830 Because of this, if data is present, it must follow immediately in the same 831 item, for example -o3. 832 </P> 833 <P> 834 If a long form option is used, the data may appear in the same command line 835 item, separated by an equals character, or (with two exceptions) it may appear 836 in the next command line item. For example: 837 <pre> 838 --file=/some/file 839 --file /some/file 840 </pre> 841 Note, however, that if you want to supply a file name beginning with ~ as data 842 in a shell command, and have the shell expand ~ to a home directory, you must 843 separate the file name from the option, because the shell does not treat ~ 844 specially unless it is at the start of an item. 845 </P> 846 <P> 847 The exceptions to the above are the <b>--colour</b> (or <b>--color</b>) and 848 <b>--only-matching</b> options, for which the data is optional. If one of these 849 options does have data, it must be given in the first form, using an equals 850 character. Otherwise <b>pcre2grep</b> will assume that it has no data. 851 </P> 852 <br><a name="SEC11" href="#TOC1">USING PCRE2'S CALLOUT FACILITY</a><br> 853 <P> 854 <b>pcre2grep</b> has, by default, support for calling external programs or 855 scripts or echoing specific strings during matching by making use of PCRE2's 856 callout facility. However, this support can be disabled when <b>pcre2grep</b> is 857 built. You can find out whether your binary has support for callouts by running 858 it with the <b>--help</b> option. If the support is not enabled, all callouts in 859 patterns are ignored by <b>pcre2grep</b>. 860 </P> 861 <P> 862 A callout in a PCRE2 pattern is of the form (?C<arg>) where the argument is 863 either a number or a quoted string (see the 864 <a href="pcre2callout.html"><b>pcre2callout</b></a> 865 documentation for details). Numbered callouts are ignored by <b>pcre2grep</b>; 866 only callouts with string arguments are useful. 867 </P> 868 <br><b> 869 Calling external programs or scripts 870 </b><br> 871 <P> 872 If the callout string does not start with a pipe (vertical bar) character, it 873 is parsed into a list of substrings separated by pipe characters. The first 874 substring must be an executable name, with the following substrings specifying 875 arguments: 876 <pre> 877 executable_name|arg1|arg2|... 878 </pre> 879 Any substring (including the executable name) may contain escape sequences 880 started by a dollar character: $<digits> or ${<digits>} is replaced by the 881 captured substring of the given decimal number, which must be greater than 882 zero. If the number is greater than the number of capturing substrings, or if 883 the capture is unset, the replacement is empty. 884 </P> 885 <P> 886 Any other character is substituted by itself. In particular, $$ is replaced by 887 a single dollar and $| is replaced by a pipe character. Here is an example: 888 <pre> 889 echo -e "abcde\n12345" | pcre2grep \ 890 '(?x)(.)(..(.)) 891 (?C"/bin/echo|Arg1: [$1] [$2] [$3]|Arg2: $|${1}$| ($4)")()' - 892 893 Output: 894 895 Arg1: [a] [bcd] [d] Arg2: |a| () 896 abcde 897 Arg1: [1] [234] [4] Arg2: |1| () 898 12345 899 </pre> 900 The parameters for the <b>execv()</b> system call that is used to run the 901 program or script are zero-terminated strings. This means that binary zero 902 characters in the callout argument will cause premature termination of their 903 substrings, and therefore should not be present. Any syntax errors in the 904 string (for example, a dollar not followed by another character) cause the 905 callout to be ignored. If running the program fails for any reason (including 906 the non-existence of the executable), a local matching failure occurs and the 907 matcher backtracks in the normal way. 908 </P> 909 <br><b> 910 Echoing a specific string 911 </b><br> 912 <P> 913 If the callout string starts with a pipe (vertical bar) character, the rest of 914 the string is written to the output, having been passed through the same escape 915 processing as text from the --output option. This provides a simple echoing 916 facility that avoids calling an external program or script. No terminator is 917 added to the string, so if you want a newline, you must include it explicitly. 918 Matching continues normally after the string is output. If you want to see only 919 the callout output but not any output from an actual match, you should end the 920 relevant pattern with (*FAIL). 921 </P> 922 <br><a name="SEC12" href="#TOC1">MATCHING ERRORS</a><br> 923 <P> 924 It is possible to supply a regular expression that takes a very long time to 925 fail to match certain lines. Such patterns normally involve nested indefinite 926 repeats, for example: (a+)*\d when matched against a line of a's with no final 927 digit. The PCRE2 matching function has a resource limit that causes it to abort 928 in these circumstances. If this happens, <b>pcre2grep</b> outputs an error 929 message and the line that caused the problem to the standard error stream. If 930 there are more than 20 such errors, <b>pcre2grep</b> gives up. 931 </P> 932 <P> 933 The <b>--match-limit</b> option of <b>pcre2grep</b> can be used to set the 934 overall resource limit. There are also other limits that affect the amount of 935 memory used during matching; see the discussion of <b>--heap-limit</b> and 936 <b>--depth-limit</b> above. 937 </P> 938 <br><a name="SEC13" href="#TOC1">DIAGNOSTICS</a><br> 939 <P> 940 Exit status is 0 if any matches were found, 1 if no matches were found, and 2 941 for syntax errors, overlong lines, non-existent or inaccessible files (even if 942 matches were found in other files) or too many matching errors. Using the 943 <b>-s</b> option to suppress error messages about inaccessible files does not 944 affect the return code. 945 </P> 946 <P> 947 When run under VMS, the return code is placed in the symbol PCRE2GREP_RC 948 because VMS does not distinguish between exit(0) and exit(1). 949 </P> 950 <br><a name="SEC14" href="#TOC1">SEE ALSO</a><br> 951 <P> 952 <b>pcre2pattern</b>(3), <b>pcre2syntax</b>(3), <b>pcre2callout</b>(3). 953 </P> 954 <br><a name="SEC15" href="#TOC1">AUTHOR</a><br> 955 <P> 956 Philip Hazel 957 <br> 958 University Computing Service 959 <br> 960 Cambridge, England. 961 <br> 962 </P> 963 <br><a name="SEC16" href="#TOC1">REVISION</a><br> 964 <P> 965 Last updated: 24 February 2018 966 <br> 967 Copyright © 1997-2018 University of Cambridge. 968 <br> 969 <p> 970 Return to the <a href="index.html">PCRE2 index page</a>. 971 </p> 972
