Annotation of embedaddon/pcre/doc/html/pcregrep.html, revision 1.1.1.3
1.1 misho 1: <html>
2: <head>
3: <title>pcregrep specification</title>
4: </head>
5: <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6: <h1>pcregrep man page</h1>
7: <p>
8: Return to the <a href="index.html">PCRE index page</a>.
9: </p>
10: <p>
11: This page is part of the PCRE HTML documentation. It was generated automatically
12: from the original man page. If there is any nonsense in it, please consult the
13: 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>
1.1.1.2 misho 19: <li><a name="TOC4" href="#SEC4">BINARY FILES</a>
20: <li><a name="TOC5" href="#SEC5">OPTIONS</a>
21: <li><a name="TOC6" href="#SEC6">ENVIRONMENT VARIABLES</a>
22: <li><a name="TOC7" href="#SEC7">NEWLINES</a>
23: <li><a name="TOC8" href="#SEC8">OPTIONS COMPATIBILITY</a>
24: <li><a name="TOC9" href="#SEC9">OPTIONS WITH DATA</a>
25: <li><a name="TOC10" href="#SEC10">MATCHING ERRORS</a>
26: <li><a name="TOC11" href="#SEC11">DIAGNOSTICS</a>
27: <li><a name="TOC12" href="#SEC12">SEE ALSO</a>
28: <li><a name="TOC13" href="#SEC13">AUTHOR</a>
29: <li><a name="TOC14" href="#SEC14">REVISION</a>
1.1 misho 30: </ul>
31: <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
32: <P>
33: <b>pcregrep [options] [long options] [pattern] [path1 path2 ...]</b>
34: </P>
35: <br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
36: <P>
37: <b>pcregrep</b> searches files for character patterns, in the same way as other
38: grep commands do, but it uses the PCRE regular expression library to support
39: patterns that are compatible with the regular expressions of Perl 5. See
40: <a href="pcrepattern.html"><b>pcrepattern</b>(3)</a>
41: for a full description of syntax and semantics of the regular expressions
42: that PCRE supports.
43: </P>
44: <P>
45: Patterns, whether supplied on the command line or in a separate file, are given
46: without delimiters. For example:
47: <pre>
48: pcregrep Thursday /etc/motd
49: </pre>
50: If you attempt to use delimiters (for example, by surrounding a pattern with
51: slashes, as is common in Perl scripts), they are interpreted as part of the
52: pattern. Quotes can of course be used to delimit patterns on the command line
1.1.1.3 ! misho 53: because they are interpreted by the shell, and indeed quotes are required if a
1.1 misho 54: pattern contains white space or shell metacharacters.
55: </P>
56: <P>
57: The first argument that follows any option settings is treated as the single
58: pattern to be matched when neither <b>-e</b> nor <b>-f</b> is present.
59: Conversely, when one or both of these options are used to specify patterns, all
60: arguments are treated as path names. At least one of <b>-e</b>, <b>-f</b>, or an
61: argument pattern must be provided.
62: </P>
63: <P>
64: If no files are specified, <b>pcregrep</b> reads the standard input. The
65: standard input can also be referenced by a name consisting of a single hyphen.
66: For example:
67: <pre>
68: pcregrep some-pattern /file1 - /file3
69: </pre>
70: By default, each line that matches a pattern is copied to the standard
71: output, and if there is more than one file, the file name is output at the
72: start of each line, followed by a colon. However, there are options that can
73: change how <b>pcregrep</b> behaves. In particular, the <b>-M</b> option makes it
74: possible to search for patterns that span line boundaries. What defines a line
75: boundary is controlled by the <b>-N</b> (<b>--newline</b>) option.
76: </P>
77: <P>
78: The amount of memory used for buffering files that are being scanned is
79: controlled by a parameter that can be set by the <b>--buffer-size</b> option.
80: The default value for this parameter is specified when <b>pcregrep</b> is built,
81: with the default default being 20K. A block of memory three times this size is
82: used (to allow for buffering "before" and "after" lines). An error occurs if a
83: line overflows the buffer.
84: </P>
85: <P>
1.1.1.3 ! misho 86: Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the greater.
! 87: BUFSIZ is defined in <b><stdio.h></b>. When there is more than one pattern
! 88: (specified by the use of <b>-e</b> and/or <b>-f</b>), each pattern is applied to
! 89: each line in the order in which they are defined, except that all the <b>-e</b>
! 90: patterns are tried before the <b>-f</b> patterns.
! 91: </P>
! 92: <P>
! 93: By default, as soon as one pattern matches a line, no further patterns are
! 94: considered. However, if <b>--colour</b> (or <b>--color</b>) is used to colour the
! 95: matching substrings, or if <b>--only-matching</b>, <b>--file-offsets</b>, or
! 96: <b>--line-offsets</b> is used to output only the part of the line that matched
! 97: (either shown literally, or as an offset), scanning resumes immediately
! 98: following the match, so that further matches on the same line can be found. If
! 99: there are multiple patterns, they are all tried on the remainder of the line,
! 100: but patterns that follow the one that matched are not tried on the earlier part
! 101: of the line.
! 102: </P>
! 103: <P>
! 104: This behaviour means that the order in which multiple patterns are specified
! 105: can affect the output when one of the above options is used. This is no longer
! 106: the same behaviour as GNU grep, which now manages to display earlier matches
! 107: for later patterns (as long as there is no overlap).
1.1 misho 108: </P>
109: <P>
110: Patterns that can match an empty string are accepted, but empty string
111: matches are never recognized. An example is the pattern "(super)?(man)?", in
112: which all components are optional. This pattern finds all occurrences of both
113: "super" and "man"; the output differs from matching with "super|man" when only
114: the matching substrings are being shown.
115: </P>
116: <P>
117: If the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variable is set,
118: <b>pcregrep</b> uses the value to set a locale when calling the PCRE library.
119: The <b>--locale</b> option can be used to override this.
120: </P>
121: <br><a name="SEC3" href="#TOC1">SUPPORT FOR COMPRESSED FILES</a><br>
122: <P>
123: It is possible to compile <b>pcregrep</b> so that it uses <b>libz</b> or
124: <b>libbz2</b> to read files whose names end in <b>.gz</b> or <b>.bz2</b>,
125: respectively. You can find out whether your binary has support for one or both
126: of these file types by running it with the <b>--help</b> option. If the
127: appropriate support is not present, files are treated as plain text. The
128: standard input is always so treated.
129: </P>
1.1.1.2 misho 130: <br><a name="SEC4" href="#TOC1">BINARY FILES</a><br>
131: <P>
132: By default, a file that contains a binary zero byte within the first 1024 bytes
133: is identified as a binary file, and is processed specially. (GNU grep also
134: identifies binary files in this manner.) See the <b>--binary-files</b> option
135: for a means of changing the way binary files are handled.
136: </P>
137: <br><a name="SEC5" href="#TOC1">OPTIONS</a><br>
1.1 misho 138: <P>
139: The order in which some of the options appear can affect the output. For
140: example, both the <b>-h</b> and <b>-l</b> options affect the printing of file
141: names. Whichever comes later in the command line will be the one that takes
1.1.1.3 ! misho 142: effect. Similarly, except where noted below, if an option is given twice, the
! 143: later setting is used. Numerical values for options may be followed by K or M,
! 144: to signify multiplication by 1024 or 1024*1024 respectively.
1.1 misho 145: </P>
146: <P>
147: <b>--</b>
148: This terminates the list of options. It is useful if the next item on the
149: command line starts with a hyphen but is not an option. This allows for the
150: processing of patterns and filenames that start with hyphens.
151: </P>
152: <P>
153: <b>-A</b> <i>number</i>, <b>--after-context=</b><i>number</i>
154: Output <i>number</i> lines of context after each matching line. If filenames
155: and/or line numbers are being output, a hyphen separator is used instead of a
156: colon for the context lines. A line containing "--" is output between each
157: group of lines, unless they are in fact contiguous in the input file. The value
158: of <i>number</i> is expected to be relatively small. However, <b>pcregrep</b>
159: guarantees to have up to 8K of following text available for context output.
160: </P>
161: <P>
1.1.1.2 misho 162: <b>-a</b>, <b>--text</b>
163: Treat binary files as text. This is equivalent to
164: <b>--binary-files</b>=<i>text</i>.
165: </P>
166: <P>
1.1 misho 167: <b>-B</b> <i>number</i>, <b>--before-context=</b><i>number</i>
168: Output <i>number</i> lines of context before each matching line. If filenames
169: and/or line numbers are being output, a hyphen separator is used instead of a
170: colon for the context lines. A line containing "--" is output between each
171: group of lines, unless they are in fact contiguous in the input file. The value
172: of <i>number</i> is expected to be relatively small. However, <b>pcregrep</b>
173: guarantees to have up to 8K of preceding text available for context output.
174: </P>
175: <P>
1.1.1.2 misho 176: <b>--binary-files=</b><i>word</i>
177: Specify how binary files are to be processed. If the word is "binary" (the
178: default), pattern matching is performed on binary files, but the only output is
179: "Binary file <name> matches" when a match succeeds. If the word is "text",
180: which is equivalent to the <b>-a</b> or <b>--text</b> option, binary files are
181: processed in the same way as any other file. In this case, when a match
182: succeeds, the output may be binary garbage, which can have nasty effects if
183: sent to a terminal. If the word is "without-match", which is equivalent to the
184: <b>-I</b> option, binary files are not processed at all; they are assumed not to
185: be of interest.
186: </P>
187: <P>
1.1 misho 188: <b>--buffer-size=</b><i>number</i>
189: Set the parameter that controls how much memory is used for buffering files
190: that are being scanned.
191: </P>
192: <P>
193: <b>-C</b> <i>number</i>, <b>--context=</b><i>number</i>
194: Output <i>number</i> lines of context both before and after each matching line.
195: This is equivalent to setting both <b>-A</b> and <b>-B</b> to the same value.
196: </P>
197: <P>
198: <b>-c</b>, <b>--count</b>
199: Do not output individual lines from the files that are being scanned; instead
200: output the number of lines that would otherwise have been shown. If no lines
201: are selected, the number zero is output. If several files are are being
202: scanned, a count is output for each of them. However, if the
203: <b>--files-with-matches</b> option is also used, only those files whose counts
204: are greater than zero are listed. When <b>-c</b> is used, the <b>-A</b>,
205: <b>-B</b>, and <b>-C</b> options are ignored.
206: </P>
207: <P>
208: <b>--colour</b>, <b>--color</b>
209: If this option is given without any data, it is equivalent to "--colour=auto".
210: If data is required, it must be given in the same shell item, separated by an
211: equals sign.
212: </P>
213: <P>
214: <b>--colour=</b><i>value</i>, <b>--color=</b><i>value</i>
215: This option specifies under what circumstances the parts of a line that matched
216: a pattern should be coloured in the output. By default, the output is not
217: coloured. The value (which is optional, see above) may be "never", "always", or
218: "auto". In the latter case, colouring happens only if the standard output is
219: connected to a terminal. More resources are used when colouring is enabled,
220: because <b>pcregrep</b> has to search for all possible matches in a line, not
221: just one, in order to colour them all.
222: <br>
223: <br>
224: The colour that is used can be specified by setting the environment variable
225: PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
226: string of two numbers, separated by a semicolon. They are copied directly into
227: the control string for setting colour on a terminal, so it is your
228: responsibility to ensure that they make sense. If neither of the environment
229: variables is set, the default is "1;31", which gives red.
230: </P>
231: <P>
232: <b>-D</b> <i>action</i>, <b>--devices=</b><i>action</i>
233: If an input path is not a regular file or a directory, "action" specifies how
234: it is to be processed. Valid values are "read" (the default) or "skip"
235: (silently skip the path).
236: </P>
237: <P>
238: <b>-d</b> <i>action</i>, <b>--directories=</b><i>action</i>
239: If an input path is a directory, "action" specifies how it is to be processed.
1.1.1.3 ! misho 240: Valid values are "read" (the default in non-Windows environments, for
! 241: compatibility with GNU grep), "recurse" (equivalent to the <b>-r</b> option), or
! 242: "skip" (silently skip the path, the default in Windows environments). In the
! 243: "read" case, directories are read as if they were ordinary files. In some
! 244: operating systems the effect of reading a directory like this is an immediate
! 245: end-of-file; in others it may provoke an error.
1.1 misho 246: </P>
247: <P>
248: <b>-e</b> <i>pattern</i>, <b>--regex=</b><i>pattern</i>, <b>--regexp=</b><i>pattern</i>
249: Specify a pattern to be matched. This option can be used multiple times in
250: order to specify several patterns. It can also be used as a way of specifying a
251: single pattern that starts with a hyphen. When <b>-e</b> is used, no argument
252: pattern is taken from the command line; all arguments are treated as file
1.1.1.3 ! misho 253: names. There is no limit to the number of patterns. They are applied to each
! 254: line in the order in which they are defined until one matches.
! 255: <br>
! 256: <br>
! 257: If <b>-f</b> is used with <b>-e</b>, the command line patterns are matched first,
! 258: followed by the patterns from the file(s), independent of the order in which
! 259: these options are specified. Note that multiple use of <b>-e</b> is not the same
! 260: as a single pattern with alternatives. For example, X|Y finds the first
! 261: character in a line that is X or Y, whereas if the two patterns are given
! 262: separately, with X first, <b>pcregrep</b> finds X if it is present, even if it
! 263: follows Y in the line. It finds Y only if there is no X in the line. This
! 264: matters only if you are using <b>-o</b> or <b>--colo(u)r</b> to show the part(s)
! 265: of the line that matched.
1.1 misho 266: </P>
267: <P>
268: <b>--exclude</b>=<i>pattern</i>
1.1.1.3 ! misho 269: Files (but not directories) whose names match the pattern are skipped without
! 270: being processed. This applies to all files, whether listed on the command line,
! 271: obtained from <b>--file-list</b>, or by scanning a directory. The pattern is a
! 272: PCRE regular expression, and is matched against the final component of the file
! 273: name, not the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not
! 274: apply to this pattern. The option may be given any number of times in order to
! 275: specify multiple patterns. If a file name matches both an <b>--include</b>
! 276: and an <b>--exclude</b> pattern, it is excluded. There is no short form for this
! 277: option.
! 278: </P>
! 279: <P>
! 280: <b>--exclude-from=</b><i>filename</i>
! 281: Treat each non-empty line of the file as the data for an <b>--exclude</b>
! 282: option. What constitutes a newline when reading the file is the operating
! 283: system's default. The <b>--newline</b> option has no effect on this option. This
! 284: option may be given more than once in order to specify a number of files to
! 285: read.
1.1 misho 286: </P>
287: <P>
288: <b>--exclude-dir</b>=<i>pattern</i>
1.1.1.3 ! misho 289: Directories whose names match the pattern are skipped without being processed,
! 290: whatever the setting of the <b>--recursive</b> option. This applies to all
! 291: directories, whether listed on the command line, obtained from
! 292: <b>--file-list</b>, or by scanning a parent directory. The pattern is a PCRE
! 293: regular expression, and is matched against the final component of the directory
! 294: name, not the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not
! 295: apply to this pattern. The option may be given any number of times in order to
! 296: specify more than one pattern. If a directory matches both <b>--include-dir</b>
! 297: and <b>--exclude-dir</b>, it is excluded. There is no short form for this
! 298: option.
1.1 misho 299: </P>
300: <P>
301: <b>-F</b>, <b>--fixed-strings</b>
1.1.1.3 ! misho 302: Interpret each data-matching pattern as a list of fixed strings, separated by
! 303: newlines, instead of as a regular expression. What constitutes a newline for
! 304: this purpose is controlled by the <b>--newline</b> option. The <b>-w</b> (match
! 305: as a word) and <b>-x</b> (match whole line) options can be used with <b>-F</b>.
! 306: They apply to each of the fixed strings. A line is selected if any of the fixed
! 307: strings are found in it (subject to <b>-w</b> or <b>-x</b>, if present). This
! 308: option applies only to the patterns that are matched against the contents of
! 309: files; it does not apply to patterns specified by any of the <b>--include</b> or
! 310: <b>--exclude</b> options.
1.1 misho 311: </P>
312: <P>
313: <b>-f</b> <i>filename</i>, <b>--file=</b><i>filename</i>
1.1.1.3 ! misho 314: Read patterns from the file, one per line, and match them against
! 315: each line of input. What constitutes a newline when reading the file is the
! 316: operating system's default. The <b>--newline</b> option has no effect on this
! 317: option. Trailing white space is removed from each line, and blank lines are
! 318: ignored. An empty file contains no patterns and therefore matches nothing. See
! 319: also the comments about multiple patterns versus a single pattern with
! 320: alternatives in the description of <b>-e</b> above.
! 321: <br>
! 322: <br>
! 323: If this option is given more than once, all the specified files are
! 324: read. A data line is output if any of the patterns match it. A filename can
! 325: be given as "-" to refer to the standard input. When <b>-f</b> is used, patterns
! 326: specified on the command line using <b>-e</b> may also be present; they are
! 327: tested before the file's patterns. However, no other pattern is taken from the
! 328: command line; all arguments are treated as the names of paths to be searched.
1.1.1.2 misho 329: </P>
330: <P>
331: <b>--file-list</b>=<i>filename</i>
1.1.1.3 ! misho 332: Read a list of files and/or directories that are to be scanned from the given
! 333: file, one per line. Trailing white space is removed from each line, and blank
! 334: lines are ignored. These paths are processed before any that are listed on the
! 335: command line. The filename can be given as "-" to refer to the standard input.
! 336: If <b>--file</b> and <b>--file-list</b> are both specified as "-", patterns are
! 337: read first. This is useful only when the standard input is a terminal, from
! 338: which further lines (the list of files) can be read after an end-of-file
! 339: indication. If this option is given more than once, all the specified files are
! 340: read.
1.1 misho 341: </P>
342: <P>
343: <b>--file-offsets</b>
344: Instead of showing lines or parts of lines that match, show each match as an
345: offset from the start of the file and a length, separated by a comma. In this
346: mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b>
347: options are ignored. If there is more than one match in a line, each of them is
348: shown separately. This option is mutually exclusive with <b>--line-offsets</b>
349: and <b>--only-matching</b>.
350: </P>
351: <P>
352: <b>-H</b>, <b>--with-filename</b>
353: Force the inclusion of the filename at the start of output lines when searching
354: a single file. By default, the filename is not shown in this case. For matching
355: lines, the filename is followed by a colon; for context lines, a hyphen
356: separator is used. If a line number is also being output, it follows the file
357: name.
358: </P>
359: <P>
360: <b>-h</b>, <b>--no-filename</b>
361: Suppress the output filenames when searching multiple files. By default,
362: filenames are shown when multiple files are searched. For matching lines, the
363: filename is followed by a colon; for context lines, a hyphen separator is used.
364: If a line number is also being output, it follows the file name.
365: </P>
366: <P>
367: <b>--help</b>
368: Output a help message, giving brief details of the command options and file
1.1.1.3 ! misho 369: type support, and then exit. Anything else on the command line is
! 370: ignored.
1.1 misho 371: </P>
372: <P>
1.1.1.2 misho 373: <b>-I</b>
374: Treat binary files as never matching. This is equivalent to
375: <b>--binary-files</b>=<i>without-match</i>.
376: </P>
377: <P>
1.1 misho 378: <b>-i</b>, <b>--ignore-case</b>
379: Ignore upper/lower case distinctions during comparisons.
380: </P>
381: <P>
382: <b>--include</b>=<i>pattern</i>
1.1.1.3 ! misho 383: If any <b>--include</b> patterns are specified, the only files that are
! 384: processed are those that match one of the patterns (and do not match an
! 385: <b>--exclude</b> pattern). This option does not affect directories, but it
! 386: applies to all files, whether listed on the command line, obtained from
! 387: <b>--file-list</b>, or by scanning a directory. The pattern is a PCRE regular
! 388: expression, and is matched against the final component of the file name, not
! 389: the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not apply to
! 390: this pattern. The option may be given any number of times. If a file name
! 391: matches both an <b>--include</b> and an <b>--exclude</b> pattern, it is excluded.
! 392: There is no short form for this option.
! 393: </P>
! 394: <P>
! 395: <b>--include-from=</b><i>filename</i>
! 396: Treat each non-empty line of the file as the data for an <b>--include</b>
! 397: option. What constitutes a newline for this purpose is the operating system's
! 398: default. The <b>--newline</b> option has no effect on this option. This option
! 399: may be given any number of times; all the files are read.
1.1 misho 400: </P>
401: <P>
402: <b>--include-dir</b>=<i>pattern</i>
1.1.1.3 ! misho 403: If any <b>--include-dir</b> patterns are specified, the only directories that
! 404: are processed are those that match one of the patterns (and do not match an
! 405: <b>--exclude-dir</b> pattern). This applies to all directories, whether listed
! 406: on the command line, obtained from <b>--file-list</b>, or by scanning a parent
! 407: directory. The pattern is a PCRE regular expression, and is matched against the
! 408: final component of the directory name, not the entire path. The <b>-F</b>,
! 409: <b>-w</b>, and <b>-x</b> options do not apply to this pattern. The option may be
! 410: given any number of times. If a directory matches both <b>--include-dir</b> and
! 411: <b>--exclude-dir</b>, it is excluded. There is no short form for this option.
1.1 misho 412: </P>
413: <P>
414: <b>-L</b>, <b>--files-without-match</b>
415: Instead of outputting lines from the files, just output the names of the files
416: that do not contain any lines that would have been output. Each file name is
417: output once, on a separate line.
418: </P>
419: <P>
420: <b>-l</b>, <b>--files-with-matches</b>
421: Instead of outputting lines from the files, just output the names of the files
422: containing lines that would have been output. Each file name is output
423: once, on a separate line. Searching normally stops as soon as a matching line
424: is found in a file. However, if the <b>-c</b> (count) option is also used,
425: matching continues in order to obtain the correct count, and those files that
426: have at least one match are listed along with their counts. Using this option
427: with <b>-c</b> is a way of suppressing the listing of files with no matches.
428: </P>
429: <P>
430: <b>--label</b>=<i>name</i>
431: This option supplies a name to be used for the standard input when file names
432: are being output. If not supplied, "(standard input)" is used. There is no
433: short form for this option.
434: </P>
435: <P>
436: <b>--line-buffered</b>
437: When this option is given, input is read and processed line by line, and the
438: output is flushed after each write. By default, input is read in large chunks,
439: unless <b>pcregrep</b> can determine that it is reading from a terminal (which
1.1.1.3 ! misho 440: is currently possible only in Unix-like environments). Output to terminal is
1.1 misho 441: normally automatically flushed by the operating system. This option can be
442: useful when the input or output is attached to a pipe and you do not want
443: <b>pcregrep</b> to buffer up large amounts of data. However, its use will affect
444: performance, and the <b>-M</b> (multiline) option ceases to work.
445: </P>
446: <P>
447: <b>--line-offsets</b>
448: Instead of showing lines or parts of lines that match, show each match as a
449: line number, the offset from the start of the line, and a length. The line
450: number is terminated by a colon (as usual; see the <b>-n</b> option), and the
451: offset and length are separated by a comma. In this mode, no context is shown.
452: That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b> options are ignored. If there is
453: more than one match in a line, each of them is shown separately. This option is
454: mutually exclusive with <b>--file-offsets</b> and <b>--only-matching</b>.
455: </P>
456: <P>
457: <b>--locale</b>=<i>locale-name</i>
458: This option specifies a locale to be used for pattern matching. It overrides
459: the value in the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variables. If no
460: locale is specified, the PCRE library's default (usually the "C" locale) is
461: used. There is no short form for this option.
462: </P>
463: <P>
464: <b>--match-limit</b>=<i>number</i>
465: Processing some regular expression patterns can require a very large amount of
466: memory, leading in some cases to a program crash if not enough is available.
467: Other patterns may take a very long time to search for all possible matching
468: strings. The <b>pcre_exec()</b> function that is called by <b>pcregrep</b> to do
469: the matching has two parameters that can limit the resources that it uses.
470: <br>
471: <br>
472: The <b>--match-limit</b> option provides a means of limiting resource usage
473: when processing patterns that are not going to match, but which have a very
474: large number of possibilities in their search trees. The classic example is a
475: pattern that uses nested unlimited repeats. Internally, PCRE uses a function
476: called <b>match()</b> which it calls repeatedly (sometimes recursively). The
477: limit set by <b>--match-limit</b> is imposed on the number of times this
478: function is called during a match, which has the effect of limiting the amount
479: of backtracking that can take place.
480: <br>
481: <br>
482: The <b>--recursion-limit</b> option is similar to <b>--match-limit</b>, but
483: instead of limiting the total number of times that <b>match()</b> is called, it
484: limits the depth of recursive calls, which in turn limits the amount of memory
485: that can be used. The recursion depth is a smaller number than the total number
486: of calls, because not all calls to <b>match()</b> are recursive. This limit is
487: of use only if it is set smaller than <b>--match-limit</b>.
488: <br>
489: <br>
490: There are no short forms for these options. The default settings are specified
491: when the PCRE library is compiled, with the default default being 10 million.
492: </P>
493: <P>
494: <b>-M</b>, <b>--multiline</b>
495: Allow patterns to match more than one line. When this option is given, patterns
496: may usefully contain literal newline characters and internal occurrences of ^
497: and $ characters. The output for a successful match may consist of more than
498: one line, the last of which is the one in which the match ended. If the matched
499: string ends with a newline sequence the output ends at the end of that line.
500: <br>
501: <br>
502: When this option is set, the PCRE library is called in "multiline" mode.
503: There is a limit to the number of lines that can be matched, imposed by the way
504: that <b>pcregrep</b> buffers the input file as it scans it. However,
505: <b>pcregrep</b> ensures that at least 8K characters or the rest of the document
506: (whichever is the shorter) are available for forward matching, and similarly
507: the previous 8K characters (or all the previous characters, if fewer than 8K)
508: are guaranteed to be available for lookbehind assertions. This option does not
509: work when input is read line by line (see \fP--line-buffered\fP.)
510: </P>
511: <P>
512: <b>-N</b> <i>newline-type</i>, <b>--newline</b>=<i>newline-type</i>
513: The PCRE library supports five different conventions for indicating
514: the ends of lines. They are the single-character sequences CR (carriage return)
515: and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
516: which recognizes any of the preceding three types, and an "any" convention, in
517: which any Unicode line ending sequence is assumed to end a line. The Unicode
518: sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
519: (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
520: PS (paragraph separator, U+2029).
521: <br>
522: <br>
523: When the PCRE library is built, a default line-ending sequence is specified.
524: This is normally the standard sequence for the operating system. Unless
525: otherwise specified by this option, <b>pcregrep</b> uses the library's default.
526: The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
1.1.1.3 ! misho 527: makes it possible to use <b>pcregrep</b> to scan files that have come from other
1.1 misho 528: environments without having to modify their line endings. If the data that is
529: being scanned does not agree with the convention set by this option,
1.1.1.3 ! misho 530: <b>pcregrep</b> may behave in strange ways. Note that this option does not
! 531: apply to files specified by the <b>-f</b>, <b>--exclude-from</b>, or
! 532: <b>--include-from</b> options, which are expected to use the operating system's
! 533: standard newline sequence.
1.1 misho 534: </P>
535: <P>
536: <b>-n</b>, <b>--line-number</b>
537: Precede each output line by its line number in the file, followed by a colon
538: for matching lines or a hyphen for context lines. If the filename is also being
539: output, it precedes the line number. This option is forced if
540: <b>--line-offsets</b> is used.
541: </P>
542: <P>
543: <b>--no-jit</b>
544: If the PCRE library is built with support for just-in-time compiling (which
545: speeds up matching), <b>pcregrep</b> automatically makes use of this, unless it
546: was explicitly disabled at build time. This option can be used to disable the
547: use of JIT at run time. It is provided for testing and working round problems.
548: It should never be needed in normal use.
549: </P>
550: <P>
551: <b>-o</b>, <b>--only-matching</b>
552: Show only the part of the line that matched a pattern instead of the whole
553: line. In this mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and
554: <b>-C</b> options are ignored. If there is more than one match in a line, each
555: of them is shown separately. If <b>-o</b> is combined with <b>-v</b> (invert the
556: sense of the match to find non-matching lines), no output is generated, but the
557: return code is set appropriately. If the matched portion of the line is empty,
558: nothing is output unless the file name or line number are being printed, in
559: which case they are shown on an otherwise empty line. This option is mutually
560: exclusive with <b>--file-offsets</b> and <b>--line-offsets</b>.
561: </P>
562: <P>
563: <b>-o</b><i>number</i>, <b>--only-matching</b>=<i>number</i>
564: Show only the part of the line that matched the capturing parentheses of the
1.1.1.3 ! misho 565: given number. Up to 32 capturing parentheses are supported, and -o0 is
! 566: equivalent to <b>-o</b> without a number. Because these options can be given
! 567: without an argument (see above), if an argument is present, it must be given in
! 568: the same shell item, for example, -o3 or --only-matching=2. The comments given
! 569: for the non-argument case above also apply to this case. If the specified
! 570: capturing parentheses do not exist in the pattern, or were not set in the
! 571: match, nothing is output unless the file name or line number are being printed.
! 572: <br>
! 573: <br>
! 574: If this option is given multiple times, multiple substrings are output, in the
! 575: order the options are given. For example, -o3 -o1 -o3 causes the substrings
! 576: matched by capturing parentheses 3 and 1 and then 3 again to be output. By
! 577: default, there is no separator (but see the next option).
! 578: </P>
! 579: <P>
! 580: <b>--om-separator</b>=<i>text</i>
! 581: Specify a separating string for multiple occurrences of <b>-o</b>. The default
! 582: is an empty string. Separating strings are never coloured.
1.1 misho 583: </P>
584: <P>
585: <b>-q</b>, <b>--quiet</b>
586: Work quietly, that is, display nothing except error messages. The exit
587: status indicates whether or not any matches were found.
588: </P>
589: <P>
590: <b>-r</b>, <b>--recursive</b>
591: If any given path is a directory, recursively scan the files it contains,
592: taking note of any <b>--include</b> and <b>--exclude</b> settings. By default, a
593: directory is read as a normal file; in some operating systems this gives an
594: immediate end-of-file. This option is a shorthand for setting the <b>-d</b>
595: option to "recurse".
596: </P>
597: <P>
598: <b>--recursion-limit</b>=<i>number</i>
599: See <b>--match-limit</b> above.
600: </P>
601: <P>
602: <b>-s</b>, <b>--no-messages</b>
603: Suppress error messages about non-existent or unreadable files. Such files are
604: quietly skipped. However, the return code is still 2, even if matches were
605: found in other files.
606: </P>
607: <P>
608: <b>-u</b>, <b>--utf-8</b>
609: Operate in UTF-8 mode. This option is available only if PCRE has been compiled
1.1.1.3 ! misho 610: with UTF-8 support. All patterns (including those for any <b>--exclude</b> and
! 611: <b>--include</b> options) and all subject lines that are scanned must be valid
! 612: strings of UTF-8 characters.
1.1 misho 613: </P>
614: <P>
615: <b>-V</b>, <b>--version</b>
1.1.1.3 ! misho 616: Write the version numbers of <b>pcregrep</b> and the PCRE library to the
! 617: standard output and then exit. Anything else on the command line is
! 618: ignored.
1.1 misho 619: </P>
620: <P>
621: <b>-v</b>, <b>--invert-match</b>
622: Invert the sense of the match, so that lines which do <i>not</i> match any of
623: the patterns are the ones that are found.
624: </P>
625: <P>
626: <b>-w</b>, <b>--word-regex</b>, <b>--word-regexp</b>
627: Force the patterns to match only whole words. This is equivalent to having \b
1.1.1.3 ! misho 628: at the start and end of the pattern. This option applies only to the patterns
! 629: that are matched against the contents of files; it does not apply to patterns
! 630: specified by any of the <b>--include</b> or <b>--exclude</b> options.
1.1 misho 631: </P>
632: <P>
633: <b>-x</b>, <b>--line-regex</b>, <b>--line-regexp</b>
634: Force the patterns to be anchored (each must start matching at the beginning of
1.1.1.3 ! misho 635: a line) and in addition, require them to match entire lines. This is equivalent
! 636: to having ^ and $ characters at the start and end of each alternative branch in
! 637: every pattern. This option applies only to the patterns that are matched
! 638: against the contents of files; it does not apply to patterns specified by any
! 639: of the <b>--include</b> or <b>--exclude</b> options.
1.1 misho 640: </P>
1.1.1.2 misho 641: <br><a name="SEC6" href="#TOC1">ENVIRONMENT VARIABLES</a><br>
1.1 misho 642: <P>
643: The environment variables <b>LC_ALL</b> and <b>LC_CTYPE</b> are examined, in that
644: order, for a locale. The first one that is set is used. This can be overridden
645: by the <b>--locale</b> option. If no locale is set, the PCRE library's default
646: (usually the "C" locale) is used.
647: </P>
1.1.1.2 misho 648: <br><a name="SEC7" href="#TOC1">NEWLINES</a><br>
1.1 misho 649: <P>
650: The <b>-N</b> (<b>--newline</b>) option allows <b>pcregrep</b> to scan files with
1.1.1.3 ! misho 651: different newline conventions from the default. Any parts of the input files
! 652: that are written to the standard output are copied identically, with whatever
! 653: newline sequences they have in the input. However, the setting of this option
! 654: does not affect the interpretation of files specified by the <b>-f</b>,
! 655: <b>--exclude-from</b>, or <b>--include-from</b> options, which are assumed to use
! 656: the operating system's standard newline sequence, nor does it affect the way in
! 657: which <b>pcregrep</b> writes informational messages to the standard error and
! 658: output streams. For these it uses the string "\n" to indicate newlines,
! 659: relying on the C I/O library to convert this to an appropriate sequence.
1.1 misho 660: </P>
1.1.1.2 misho 661: <br><a name="SEC8" href="#TOC1">OPTIONS COMPATIBILITY</a><br>
1.1 misho 662: <P>
663: Many of the short and long forms of <b>pcregrep</b>'s options are the same
1.1.1.2 misho 664: as in the GNU <b>grep</b> program. Any long option of the form
1.1 misho 665: <b>--xxx-regexp</b> (GNU terminology) is also available as <b>--xxx-regex</b>
1.1.1.2 misho 666: (PCRE terminology). However, the <b>--file-list</b>, <b>--file-offsets</b>,
667: <b>--include-dir</b>, <b>--line-offsets</b>, <b>--locale</b>, <b>--match-limit</b>,
1.1.1.3 ! misho 668: <b>-M</b>, <b>--multiline</b>, <b>-N</b>, <b>--newline</b>, <b>--om-separator</b>,
1.1.1.2 misho 669: <b>--recursion-limit</b>, <b>-u</b>, and <b>--utf-8</b> options are specific to
670: <b>pcregrep</b>, as is the use of the <b>--only-matching</b> option with a
671: capturing parentheses number.
1.1 misho 672: </P>
673: <P>
674: Although most of the common options work the same way, a few are different in
675: <b>pcregrep</b>. For example, the <b>--include</b> option's argument is a glob
676: for GNU <b>grep</b>, but a regular expression for <b>pcregrep</b>. If both the
677: <b>-c</b> and <b>-l</b> options are given, GNU grep lists only file names,
678: without counts, but <b>pcregrep</b> gives the counts.
679: </P>
1.1.1.2 misho 680: <br><a name="SEC9" href="#TOC1">OPTIONS WITH DATA</a><br>
1.1 misho 681: <P>
682: There are four different ways in which an option with data can be specified.
683: If a short form option is used, the data may follow immediately, or (with one
684: exception) in the next command line item. For example:
685: <pre>
686: -f/some/file
687: -f /some/file
688: </pre>
689: The exception is the <b>-o</b> option, which may appear with or without data.
690: Because of this, if data is present, it must follow immediately in the same
691: item, for example -o3.
692: </P>
693: <P>
694: If a long form option is used, the data may appear in the same command line
695: item, separated by an equals character, or (with two exceptions) it may appear
696: in the next command line item. For example:
697: <pre>
698: --file=/some/file
699: --file /some/file
700: </pre>
701: Note, however, that if you want to supply a file name beginning with ~ as data
702: in a shell command, and have the shell expand ~ to a home directory, you must
703: separate the file name from the option, because the shell does not treat ~
704: specially unless it is at the start of an item.
705: </P>
706: <P>
707: The exceptions to the above are the <b>--colour</b> (or <b>--color</b>) and
708: <b>--only-matching</b> options, for which the data is optional. If one of these
709: options does have data, it must be given in the first form, using an equals
710: character. Otherwise <b>pcregrep</b> will assume that it has no data.
711: </P>
1.1.1.2 misho 712: <br><a name="SEC10" href="#TOC1">MATCHING ERRORS</a><br>
1.1 misho 713: <P>
714: It is possible to supply a regular expression that takes a very long time to
715: fail to match certain lines. Such patterns normally involve nested indefinite
716: repeats, for example: (a+)*\d when matched against a line of a's with no final
717: digit. The PCRE matching function has a resource limit that causes it to abort
718: in these circumstances. If this happens, <b>pcregrep</b> outputs an error
719: message and the line that caused the problem to the standard error stream. If
720: there are more than 20 such errors, <b>pcregrep</b> gives up.
721: </P>
722: <P>
723: The <b>--match-limit</b> option of <b>pcregrep</b> can be used to set the overall
724: resource limit; there is a second option called <b>--recursion-limit</b> that
725: sets a limit on the amount of memory (usually stack) that is used (see the
726: discussion of these options above).
727: </P>
1.1.1.2 misho 728: <br><a name="SEC11" href="#TOC1">DIAGNOSTICS</a><br>
1.1 misho 729: <P>
730: Exit status is 0 if any matches were found, 1 if no matches were found, and 2
731: for syntax errors, overlong lines, non-existent or inaccessible files (even if
732: matches were found in other files) or too many matching errors. Using the
733: <b>-s</b> option to suppress error messages about inaccessible files does not
734: affect the return code.
735: </P>
1.1.1.2 misho 736: <br><a name="SEC12" href="#TOC1">SEE ALSO</a><br>
1.1 misho 737: <P>
1.1.1.3 ! misho 738: <b>pcrepattern</b>(3), <b>pcresyntax</b>(3), <b>pcretest</b>(1).
1.1 misho 739: </P>
1.1.1.2 misho 740: <br><a name="SEC13" href="#TOC1">AUTHOR</a><br>
1.1 misho 741: <P>
742: Philip Hazel
743: <br>
744: University Computing Service
745: <br>
746: Cambridge CB2 3QH, England.
747: <br>
748: </P>
1.1.1.2 misho 749: <br><a name="SEC14" href="#TOC1">REVISION</a><br>
1.1 misho 750: <P>
1.1.1.3 ! misho 751: Last updated: 13 September 2012
1.1 misho 752: <br>
1.1.1.2 misho 753: Copyright © 1997-2012 University of Cambridge.
1.1 misho 754: <br>
755: <p>
756: Return to the <a href="index.html">PCRE index page</a>.
757: </p>
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