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1.1 misho 1: .TH PCREGREP 1
2: .SH NAME
3: pcregrep - a grep with Perl-compatible regular expressions.
4: .SH SYNOPSIS
5: .B pcregrep [options] [long options] [pattern] [path1 path2 ...]
6: .
7: .SH DESCRIPTION
8: .rs
9: .sp
10: \fBpcregrep\fP searches files for character patterns, in the same way as other
11: grep commands do, but it uses the PCRE regular expression library to support
12: patterns that are compatible with the regular expressions of Perl 5. See
13: .\" HREF
14: \fBpcrepattern\fP(3)
15: .\"
16: for a full description of syntax and semantics of the regular expressions
17: that PCRE supports.
18: .P
19: Patterns, whether supplied on the command line or in a separate file, are given
20: without delimiters. For example:
21: .sp
22: pcregrep Thursday /etc/motd
23: .sp
24: If you attempt to use delimiters (for example, by surrounding a pattern with
25: slashes, as is common in Perl scripts), they are interpreted as part of the
26: pattern. Quotes can of course be used to delimit patterns on the command line
27: because they are interpreted by the shell, and indeed they are required if a
28: pattern contains white space or shell metacharacters.
29: .P
30: The first argument that follows any option settings is treated as the single
31: pattern to be matched when neither \fB-e\fP nor \fB-f\fP is present.
32: Conversely, when one or both of these options are used to specify patterns, all
33: arguments are treated as path names. At least one of \fB-e\fP, \fB-f\fP, or an
34: argument pattern must be provided.
35: .P
36: If no files are specified, \fBpcregrep\fP reads the standard input. The
37: standard input can also be referenced by a name consisting of a single hyphen.
38: For example:
39: .sp
40: pcregrep some-pattern /file1 - /file3
41: .sp
42: By default, each line that matches a pattern is copied to the standard
43: output, and if there is more than one file, the file name is output at the
44: start of each line, followed by a colon. However, there are options that can
45: change how \fBpcregrep\fP behaves. In particular, the \fB-M\fP option makes it
46: possible to search for patterns that span line boundaries. What defines a line
47: boundary is controlled by the \fB-N\fP (\fB--newline\fP) option.
48: .P
49: The amount of memory used for buffering files that are being scanned is
50: controlled by a parameter that can be set by the \fB--buffer-size\fP option.
51: The default value for this parameter is specified when \fBpcregrep\fP is built,
52: with the default default being 20K. A block of memory three times this size is
53: used (to allow for buffering "before" and "after" lines). An error occurs if a
54: line overflows the buffer.
55: .P
56: Patterns are limited to 8K or BUFSIZ bytes, whichever is the greater. BUFSIZ is
57: defined in \fB<stdio.h>\fP. When there is more than one pattern (specified by
58: the use of \fB-e\fP and/or \fB-f\fP), each pattern is applied to each line in
59: the order in which they are defined, except that all the \fB-e\fP patterns are
60: tried before the \fB-f\fP patterns.
61: .P
62: By default, as soon as one pattern matches (or fails to match when \fB-v\fP is
63: used), no further patterns are considered. However, if \fB--colour\fP (or
64: \fB--color\fP) is used to colour the matching substrings, or if
65: \fB--only-matching\fP, \fB--file-offsets\fP, or \fB--line-offsets\fP is used to
66: output only the part of the line that matched (either shown literally, or as an
67: offset), scanning resumes immediately following the match, so that further
68: matches on the same line can be found. If there are multiple patterns, they are
69: all tried on the remainder of the line, but patterns that follow the one that
70: matched are not tried on the earlier part of the line.
71: .P
72: This is the same behaviour as GNU grep, but it does mean that the order in
73: which multiple patterns are specified can affect the output when one of the
74: above options is used.
75: .P
76: Patterns that can match an empty string are accepted, but empty string
77: matches are never recognized. An example is the pattern "(super)?(man)?", in
78: which all components are optional. This pattern finds all occurrences of both
79: "super" and "man"; the output differs from matching with "super|man" when only
80: the matching substrings are being shown.
81: .P
82: If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set,
83: \fBpcregrep\fP uses the value to set a locale when calling the PCRE library.
84: The \fB--locale\fP option can be used to override this.
85: .
86: .
87: .SH "SUPPORT FOR COMPRESSED FILES"
88: .rs
89: .sp
90: It is possible to compile \fBpcregrep\fP so that it uses \fBlibz\fP or
91: \fBlibbz2\fP to read files whose names end in \fB.gz\fP or \fB.bz2\fP,
92: respectively. You can find out whether your binary has support for one or both
93: of these file types by running it with the \fB--help\fP option. If the
94: appropriate support is not present, files are treated as plain text. The
95: standard input is always so treated.
96: .
97: .
98: .SH OPTIONS
99: .rs
100: .sp
101: The order in which some of the options appear can affect the output. For
102: example, both the \fB-h\fP and \fB-l\fP options affect the printing of file
103: names. Whichever comes later in the command line will be the one that takes
104: effect. Numerical values for options may be followed by K or M, to signify
105: multiplication by 1024 or 1024*1024 respectively.
106: .TP 10
107: \fB--\fP
108: This terminates the list of options. It is useful if the next item on the
109: command line starts with a hyphen but is not an option. This allows for the
110: processing of patterns and filenames that start with hyphens.
111: .TP
112: \fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
113: Output \fInumber\fP lines of context after each matching line. If filenames
114: and/or line numbers are being output, a hyphen separator is used instead of a
115: colon for the context lines. A line containing "--" is output between each
116: group of lines, unless they are in fact contiguous in the input file. The value
117: of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
118: guarantees to have up to 8K of following text available for context output.
119: .TP
120: \fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
121: Output \fInumber\fP lines of context before each matching line. If filenames
122: and/or line numbers are being output, a hyphen separator is used instead of a
123: colon for the context lines. A line containing "--" is output between each
124: group of lines, unless they are in fact contiguous in the input file. The value
125: of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
126: guarantees to have up to 8K of preceding text available for context output.
127: .TP
128: \fB--buffer-size=\fP\fInumber\fP
129: Set the parameter that controls how much memory is used for buffering files
130: that are being scanned.
131: .TP
132: \fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
133: Output \fInumber\fP lines of context both before and after each matching line.
134: This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
135: .TP
136: \fB-c\fP, \fB--count\fP
137: Do not output individual lines from the files that are being scanned; instead
138: output the number of lines that would otherwise have been shown. If no lines
139: are selected, the number zero is output. If several files are are being
140: scanned, a count is output for each of them. However, if the
141: \fB--files-with-matches\fP option is also used, only those files whose counts
142: are greater than zero are listed. When \fB-c\fP is used, the \fB-A\fP,
143: \fB-B\fP, and \fB-C\fP options are ignored.
144: .TP
145: \fB--colour\fP, \fB--color\fP
146: If this option is given without any data, it is equivalent to "--colour=auto".
147: If data is required, it must be given in the same shell item, separated by an
148: equals sign.
149: .TP
150: \fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
151: This option specifies under what circumstances the parts of a line that matched
152: a pattern should be coloured in the output. By default, the output is not
153: coloured. The value (which is optional, see above) may be "never", "always", or
154: "auto". In the latter case, colouring happens only if the standard output is
155: connected to a terminal. More resources are used when colouring is enabled,
156: because \fBpcregrep\fP has to search for all possible matches in a line, not
157: just one, in order to colour them all.
158: .sp
159: The colour that is used can be specified by setting the environment variable
160: PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
161: string of two numbers, separated by a semicolon. They are copied directly into
162: the control string for setting colour on a terminal, so it is your
163: responsibility to ensure that they make sense. If neither of the environment
164: variables is set, the default is "1;31", which gives red.
165: .TP
166: \fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
167: If an input path is not a regular file or a directory, "action" specifies how
168: it is to be processed. Valid values are "read" (the default) or "skip"
169: (silently skip the path).
170: .TP
171: \fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
172: If an input path is a directory, "action" specifies how it is to be processed.
173: Valid values are "read" (the default), "recurse" (equivalent to the \fB-r\fP
174: option), or "skip" (silently skip the path). In the default case, directories
175: are read as if they were ordinary files. In some operating systems the effect
176: of reading a directory like this is an immediate end-of-file.
177: .TP
178: \fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP, \fB--regexp=\fP\fIpattern\fP
179: Specify a pattern to be matched. This option can be used multiple times in
180: order to specify several patterns. It can also be used as a way of specifying a
181: single pattern that starts with a hyphen. When \fB-e\fP is used, no argument
182: pattern is taken from the command line; all arguments are treated as file
183: names. There is an overall maximum of 100 patterns. They are applied to each
184: line in the order in which they are defined until one matches (or fails to
185: match if \fB-v\fP is used). If \fB-f\fP is used with \fB-e\fP, the command line
186: patterns are matched first, followed by the patterns from the file, independent
187: of the order in which these options are specified. Note that multiple use of
188: \fB-e\fP is not the same as a single pattern with alternatives. For example,
189: X|Y finds the first character in a line that is X or Y, whereas if the two
190: patterns are given separately, \fBpcregrep\fP finds X if it is present, even if
191: it follows Y in the line. It finds Y only if there is no X in the line. This
192: really matters only if you are using \fB-o\fP to show the part(s) of the line
193: that matched.
194: .TP
195: \fB--exclude\fP=\fIpattern\fP
196: When \fBpcregrep\fP is searching the files in a directory as a consequence of
197: the \fB-r\fP (recursive search) option, any regular files whose names match the
198: pattern are excluded. Subdirectories are not excluded by this option; they are
199: searched recursively, subject to the \fB--exclude-dir\fP and
200: \fB--include_dir\fP options. The pattern is a PCRE regular expression, and is
201: matched against the final component of the file name (not the entire path). If
202: a file name matches both \fB--include\fP and \fB--exclude\fP, it is excluded.
203: There is no short form for this option.
204: .TP
205: \fB--exclude-dir\fP=\fIpattern\fP
206: When \fBpcregrep\fP is searching the contents of a directory as a consequence
207: of the \fB-r\fP (recursive search) option, any subdirectories whose names match
208: the pattern are excluded. (Note that the \fP--exclude\fP option does not affect
209: subdirectories.) The pattern is a PCRE regular expression, and is matched
210: against the final component of the name (not the entire path). If a
211: subdirectory name matches both \fB--include-dir\fP and \fB--exclude-dir\fP, it
212: is excluded. There is no short form for this option.
213: .TP
214: \fB-F\fP, \fB--fixed-strings\fP
215: Interpret each pattern as a list of fixed strings, separated by newlines,
216: instead of as a regular expression. The \fB-w\fP (match as a word) and \fB-x\fP
217: (match whole line) options can be used with \fB-F\fP. They apply to each of the
218: fixed strings. A line is selected if any of the fixed strings are found in it
219: (subject to \fB-w\fP or \fB-x\fP, if present).
220: .TP
221: \fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
222: Read a number of patterns from the file, one per line, and match them against
223: each line of input. A data line is output if any of the patterns match it. The
224: filename can be given as "-" to refer to the standard input. When \fB-f\fP is
225: used, patterns specified on the command line using \fB-e\fP may also be
226: present; they are tested before the file's patterns. However, no other pattern
227: is taken from the command line; all arguments are treated as file names. There
228: is an overall maximum of 100 patterns. Trailing white space is removed from
229: each line, and blank lines are ignored. An empty file contains no patterns and
230: therefore matches nothing. See also the comments about multiple patterns versus
231: a single pattern with alternatives in the description of \fB-e\fP above.
232: .TP
233: \fB--file-offsets\fP
234: Instead of showing lines or parts of lines that match, show each match as an
235: offset from the start of the file and a length, separated by a comma. In this
236: mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP
237: options are ignored. If there is more than one match in a line, each of them is
238: shown separately. This option is mutually exclusive with \fB--line-offsets\fP
239: and \fB--only-matching\fP.
240: .TP
241: \fB-H\fP, \fB--with-filename\fP
242: Force the inclusion of the filename at the start of output lines when searching
243: a single file. By default, the filename is not shown in this case. For matching
244: lines, the filename is followed by a colon; for context lines, a hyphen
245: separator is used. If a line number is also being output, it follows the file
246: name.
247: .TP
248: \fB-h\fP, \fB--no-filename\fP
249: Suppress the output filenames when searching multiple files. By default,
250: filenames are shown when multiple files are searched. For matching lines, the
251: filename is followed by a colon; for context lines, a hyphen separator is used.
252: If a line number is also being output, it follows the file name.
253: .TP
254: \fB--help\fP
255: Output a help message, giving brief details of the command options and file
256: type support, and then exit.
257: .TP
258: \fB-i\fP, \fB--ignore-case\fP
259: Ignore upper/lower case distinctions during comparisons.
260: .TP
261: \fB--include\fP=\fIpattern\fP
262: When \fBpcregrep\fP is searching the files in a directory as a consequence of
263: the \fB-r\fP (recursive search) option, only those regular files whose names
264: match the pattern are included. Subdirectories are always included and searched
265: recursively, subject to the \fP--include-dir\fP and \fB--exclude-dir\fP
266: options. The pattern is a PCRE regular expression, and is matched against the
267: final component of the file name (not the entire path). If a file name matches
268: both \fB--include\fP and \fB--exclude\fP, it is excluded. There is no short
269: form for this option.
270: .TP
271: \fB--include-dir\fP=\fIpattern\fP
272: When \fBpcregrep\fP is searching the contents of a directory as a consequence
273: of the \fB-r\fP (recursive search) option, only those subdirectories whose
274: names match the pattern are included. (Note that the \fB--include\fP option
275: does not affect subdirectories.) The pattern is a PCRE regular expression, and
276: is matched against the final component of the name (not the entire path). If a
277: subdirectory name matches both \fB--include-dir\fP and \fB--exclude-dir\fP, it
278: is excluded. There is no short form for this option.
279: .TP
280: \fB-L\fP, \fB--files-without-match\fP
281: Instead of outputting lines from the files, just output the names of the files
282: that do not contain any lines that would have been output. Each file name is
283: output once, on a separate line.
284: .TP
285: \fB-l\fP, \fB--files-with-matches\fP
286: Instead of outputting lines from the files, just output the names of the files
287: containing lines that would have been output. Each file name is output
288: once, on a separate line. Searching normally stops as soon as a matching line
289: is found in a file. However, if the \fB-c\fP (count) option is also used,
290: matching continues in order to obtain the correct count, and those files that
291: have at least one match are listed along with their counts. Using this option
292: with \fB-c\fP is a way of suppressing the listing of files with no matches.
293: .TP
294: \fB--label\fP=\fIname\fP
295: This option supplies a name to be used for the standard input when file names
296: are being output. If not supplied, "(standard input)" is used. There is no
297: short form for this option.
298: .TP
299: \fB--line-buffered\fP
300: When this option is given, input is read and processed line by line, and the
301: output is flushed after each write. By default, input is read in large chunks,
302: unless \fBpcregrep\fP can determine that it is reading from a terminal (which
303: is currently possible only in Unix environments). Output to terminal is
304: normally automatically flushed by the operating system. This option can be
305: useful when the input or output is attached to a pipe and you do not want
306: \fBpcregrep\fP to buffer up large amounts of data. However, its use will affect
307: performance, and the \fB-M\fP (multiline) option ceases to work.
308: .TP
309: \fB--line-offsets\fP
310: Instead of showing lines or parts of lines that match, show each match as a
311: line number, the offset from the start of the line, and a length. The line
312: number is terminated by a colon (as usual; see the \fB-n\fP option), and the
313: offset and length are separated by a comma. In this mode, no context is shown.
314: That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are ignored. If there is
315: more than one match in a line, each of them is shown separately. This option is
316: mutually exclusive with \fB--file-offsets\fP and \fB--only-matching\fP.
317: .TP
318: \fB--locale\fP=\fIlocale-name\fP
319: This option specifies a locale to be used for pattern matching. It overrides
320: the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
321: locale is specified, the PCRE library's default (usually the "C" locale) is
322: used. There is no short form for this option.
323: .TP
324: \fB--match-limit\fP=\fInumber\fP
325: Processing some regular expression patterns can require a very large amount of
326: memory, leading in some cases to a program crash if not enough is available.
327: Other patterns may take a very long time to search for all possible matching
328: strings. The \fBpcre_exec()\fP function that is called by \fBpcregrep\fP to do
329: the matching has two parameters that can limit the resources that it uses.
330: .sp
331: The \fB--match-limit\fP option provides a means of limiting resource usage
332: when processing patterns that are not going to match, but which have a very
333: large number of possibilities in their search trees. The classic example is a
334: pattern that uses nested unlimited repeats. Internally, PCRE uses a function
335: called \fBmatch()\fP which it calls repeatedly (sometimes recursively). The
336: limit set by \fB--match-limit\fP is imposed on the number of times this
337: function is called during a match, which has the effect of limiting the amount
338: of backtracking that can take place.
339: .sp
340: The \fB--recursion-limit\fP option is similar to \fB--match-limit\fP, but
341: instead of limiting the total number of times that \fBmatch()\fP is called, it
342: limits the depth of recursive calls, which in turn limits the amount of memory
343: that can be used. The recursion depth is a smaller number than the total number
344: of calls, because not all calls to \fBmatch()\fP are recursive. This limit is
345: of use only if it is set smaller than \fB--match-limit\fP.
346: .sp
347: There are no short forms for these options. The default settings are specified
348: when the PCRE library is compiled, with the default default being 10 million.
349: .TP
350: \fB-M\fP, \fB--multiline\fP
351: Allow patterns to match more than one line. When this option is given, patterns
352: may usefully contain literal newline characters and internal occurrences of ^
353: and $ characters. The output for a successful match may consist of more than
354: one line, the last of which is the one in which the match ended. If the matched
355: string ends with a newline sequence the output ends at the end of that line.
356: .sp
357: When this option is set, the PCRE library is called in "multiline" mode.
358: There is a limit to the number of lines that can be matched, imposed by the way
359: that \fBpcregrep\fP buffers the input file as it scans it. However,
360: \fBpcregrep\fP ensures that at least 8K characters or the rest of the document
361: (whichever is the shorter) are available for forward matching, and similarly
362: the previous 8K characters (or all the previous characters, if fewer than 8K)
363: are guaranteed to be available for lookbehind assertions. This option does not
364: work when input is read line by line (see \fP--line-buffered\fP.)
365: .TP
366: \fB-N\fP \fInewline-type\fP, \fB--newline\fP=\fInewline-type\fP
367: The PCRE library supports five different conventions for indicating
368: the ends of lines. They are the single-character sequences CR (carriage return)
369: and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
370: which recognizes any of the preceding three types, and an "any" convention, in
371: which any Unicode line ending sequence is assumed to end a line. The Unicode
372: sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
373: (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
374: PS (paragraph separator, U+2029).
375: .sp
376: When the PCRE library is built, a default line-ending sequence is specified.
377: This is normally the standard sequence for the operating system. Unless
378: otherwise specified by this option, \fBpcregrep\fP uses the library's default.
379: The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
380: makes it possible to use \fBpcregrep\fP on files that have come from other
381: environments without having to modify their line endings. If the data that is
382: being scanned does not agree with the convention set by this option,
383: \fBpcregrep\fP may behave in strange ways.
384: .TP
385: \fB-n\fP, \fB--line-number\fP
386: Precede each output line by its line number in the file, followed by a colon
387: for matching lines or a hyphen for context lines. If the filename is also being
388: output, it precedes the line number. This option is forced if
389: \fB--line-offsets\fP is used.
390: .TP
391: \fB--no-jit\fP
392: If the PCRE library is built with support for just-in-time compiling (which
393: speeds up matching), \fBpcregrep\fP automatically makes use of this, unless it
394: was explicitly disabled at build time. This option can be used to disable the
395: use of JIT at run time. It is provided for testing and working round problems.
396: It should never be needed in normal use.
397: .TP
398: \fB-o\fP, \fB--only-matching\fP
399: Show only the part of the line that matched a pattern instead of the whole
400: line. In this mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and
401: \fB-C\fP options are ignored. If there is more than one match in a line, each
402: of them is shown separately. If \fB-o\fP is combined with \fB-v\fP (invert the
403: sense of the match to find non-matching lines), no output is generated, but the
404: return code is set appropriately. If the matched portion of the line is empty,
405: nothing is output unless the file name or line number are being printed, in
406: which case they are shown on an otherwise empty line. This option is mutually
407: exclusive with \fB--file-offsets\fP and \fB--line-offsets\fP.
408: .TP
409: \fB-o\fP\fInumber\fP, \fB--only-matching\fP=\fInumber\fP
410: Show only the part of the line that matched the capturing parentheses of the
411: given number. Up to 32 capturing parentheses are supported. Because these
412: options can be given without an argument (see above), if an argument is
413: present, it must be given in the same shell item, for example, -o3 or
414: --only-matching=2. The comments given for the non-argument case above also
415: apply to this case. If the specified capturing parentheses do not exist in the
416: pattern, or were not set in the match, nothing is output unless the file name
417: or line number are being printed.
418: .TP
419: \fB-q\fP, \fB--quiet\fP
420: Work quietly, that is, display nothing except error messages. The exit
421: status indicates whether or not any matches were found.
422: .TP
423: \fB-r\fP, \fB--recursive\fP
424: If any given path is a directory, recursively scan the files it contains,
425: taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
426: directory is read as a normal file; in some operating systems this gives an
427: immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
428: option to "recurse".
429: .TP
430: \fB--recursion-limit\fP=\fInumber\fP
431: See \fB--match-limit\fP above.
432: .TP
433: \fB-s\fP, \fB--no-messages\fP
434: Suppress error messages about non-existent or unreadable files. Such files are
435: quietly skipped. However, the return code is still 2, even if matches were
436: found in other files.
437: .TP
438: \fB-u\fP, \fB--utf-8\fP
439: Operate in UTF-8 mode. This option is available only if PCRE has been compiled
440: with UTF-8 support. Both patterns and subject lines must be valid strings of
441: UTF-8 characters.
442: .TP
443: \fB-V\fP, \fB--version\fP
444: Write the version numbers of \fBpcregrep\fP and the PCRE library that is being
445: used to the standard error stream.
446: .TP
447: \fB-v\fP, \fB--invert-match\fP
448: Invert the sense of the match, so that lines which do \fInot\fP match any of
449: the patterns are the ones that are found.
450: .TP
451: \fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
452: Force the patterns to match only whole words. This is equivalent to having \eb
453: at the start and end of the pattern.
454: .TP
455: \fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
456: Force the patterns to be anchored (each must start matching at the beginning of
457: a line) and in addition, require them to match entire lines. This is
458: equivalent to having ^ and $ characters at the start and end of each
459: alternative branch in every pattern.
460: .
461: .
462: .SH "ENVIRONMENT VARIABLES"
463: .rs
464: .sp
465: The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
466: order, for a locale. The first one that is set is used. This can be overridden
467: by the \fB--locale\fP option. If no locale is set, the PCRE library's default
468: (usually the "C" locale) is used.
469: .
470: .
471: .SH "NEWLINES"
472: .rs
473: .sp
474: The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
475: different newline conventions from the default. However, the setting of this
476: option does not affect the way in which \fBpcregrep\fP writes information to
477: the standard error and output streams. It uses the string "\en" in C
478: \fBprintf()\fP calls to indicate newlines, relying on the C I/O library to
479: convert this to an appropriate sequence if the output is sent to a file.
480: .
481: .
482: .SH "OPTIONS COMPATIBILITY"
483: .rs
484: .sp
485: Many of the short and long forms of \fBpcregrep\fP's options are the same
486: as in the GNU \fBgrep\fP program (version 2.5.4). Any long option of the form
487: \fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
488: (PCRE terminology). However, the \fB--file-offsets\fP, \fB--include-dir\fP,
489: \fB--line-offsets\fP, \fB--locale\fP, \fB--match-limit\fP, \fB-M\fP,
490: \fB--multiline\fP, \fB-N\fP, \fB--newline\fP, \fB--recursion-limit\fP,
491: \fB-u\fP, and \fB--utf-8\fP options are specific to \fBpcregrep\fP, as is the
492: use of the \fB--only-matching\fP option with a capturing parentheses number.
493: .P
494: Although most of the common options work the same way, a few are different in
495: \fBpcregrep\fP. For example, the \fB--include\fP option's argument is a glob
496: for GNU \fBgrep\fP, but a regular expression for \fBpcregrep\fP. If both the
497: \fB-c\fP and \fB-l\fP options are given, GNU grep lists only file names,
498: without counts, but \fBpcregrep\fP gives the counts.
499: .
500: .
501: .SH "OPTIONS WITH DATA"
502: .rs
503: .sp
504: There are four different ways in which an option with data can be specified.
505: If a short form option is used, the data may follow immediately, or (with one
506: exception) in the next command line item. For example:
507: .sp
508: -f/some/file
509: -f /some/file
510: .sp
511: The exception is the \fB-o\fP option, which may appear with or without data.
512: Because of this, if data is present, it must follow immediately in the same
513: item, for example -o3.
514: .P
515: If a long form option is used, the data may appear in the same command line
516: item, separated by an equals character, or (with two exceptions) it may appear
517: in the next command line item. For example:
518: .sp
519: --file=/some/file
520: --file /some/file
521: .sp
522: Note, however, that if you want to supply a file name beginning with ~ as data
523: in a shell command, and have the shell expand ~ to a home directory, you must
524: separate the file name from the option, because the shell does not treat ~
525: specially unless it is at the start of an item.
526: .P
527: The exceptions to the above are the \fB--colour\fP (or \fB--color\fP) and
528: \fB--only-matching\fP options, for which the data is optional. If one of these
529: options does have data, it must be given in the first form, using an equals
530: character. Otherwise \fBpcregrep\fP will assume that it has no data.
531: .
532: .
533: .SH "MATCHING ERRORS"
534: .rs
535: .sp
536: It is possible to supply a regular expression that takes a very long time to
537: fail to match certain lines. Such patterns normally involve nested indefinite
538: repeats, for example: (a+)*\ed when matched against a line of a's with no final
539: digit. The PCRE matching function has a resource limit that causes it to abort
540: in these circumstances. If this happens, \fBpcregrep\fP outputs an error
541: message and the line that caused the problem to the standard error stream. If
542: there are more than 20 such errors, \fBpcregrep\fP gives up.
543: .P
544: The \fB--match-limit\fP option of \fBpcregrep\fP can be used to set the overall
545: resource limit; there is a second option called \fB--recursion-limit\fP that
546: sets a limit on the amount of memory (usually stack) that is used (see the
547: discussion of these options above).
548: .
549: .
550: .SH DIAGNOSTICS
551: .rs
552: .sp
553: Exit status is 0 if any matches were found, 1 if no matches were found, and 2
554: for syntax errors, overlong lines, non-existent or inaccessible files (even if
555: matches were found in other files) or too many matching errors. Using the
556: \fB-s\fP option to suppress error messages about inaccessible files does not
557: affect the return code.
558: .
559: .
560: .SH "SEE ALSO"
561: .rs
562: .sp
563: \fBpcrepattern\fP(3), \fBpcretest\fP(1).
564: .
565: .
566: .SH AUTHOR
567: .rs
568: .sp
569: .nf
570: Philip Hazel
571: University Computing Service
572: Cambridge CB2 3QH, England.
573: .fi
574: .
575: .
576: .SH REVISION
577: .rs
578: .sp
579: .nf
580: Last updated: 06 September 2011
581: Copyright (c) 1997-2011 University of Cambridge.
582: .fi

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