trunk/doc/pcregrep.txt

PCREGREP(1)                                                        PCREGREP(1)


NAME
       pcregrep - a grep with Perl-compatible regular expressions.


SYNOPSIS
       pcregrep [options] [long options] [pattern] [path1 path2 ...]


DESCRIPTION

       pcregrep  searches  files  for  character  patterns, in the same way as
       other grep commands do, but it uses the PCRE regular expression library
       to support patterns that are compatible with the regular expressions of
       Perl 5. See pcrepattern(3) for a full description of syntax and  seman-
       tics of the regular expressions that PCRE supports.

       Patterns,  whether  supplied on the command line or in a separate file,
       are given without delimiters. For example:

         pcregrep Thursday /etc/motd

       If you attempt to use delimiters (for example, by surrounding a pattern
       with  slashes,  as  is common in Perl scripts), they are interpreted as
       part of the pattern. Quotes can of course be used on the  command  line
       because they are interpreted by the shell, and indeed they are required
       if a pattern contains white space or shell metacharacters.

       The first argument that follows any option settings is treated  as  the
       single  pattern  to be matched when neither -e nor -f is present.  Con-
       versely, when one or both of these options are  used  to  specify  pat-
       terns, all arguments are treated as path names. At least one of -e, -f,
       or an argument pattern must be provided.

       If no files are specified, pcregrep reads the standard input. The stan-
       dard  input  can  also  be  referenced by a name consisting of a single
       hyphen.  For example:

         pcregrep some-pattern /file1 - /file3

       By default, each line that matches the pattern is copied to  the  stan-
       dard  output, and if there is more than one file, the file name is out-
       put at the start of each line. However,  there  are  options  that  can
       change how pcregrep behaves. In particular, the -M option makes it pos-
       sible to search for patterns that span line boundaries. What defines  a
       line boundary is controlled by the -N (--newline) option.

       Patterns  are  limited  to  8K  or  BUFSIZ characters, whichever is the
       greater.  BUFSIZ is defined in <stdio.h>.

       If the LC_ALL or LC_CTYPE environment variable is  set,  pcregrep  uses
       the  value to set a locale when calling the PCRE library.  The --locale
       option can be used to override this.


OPTIONS

       --        This terminate the list of options. It is useful if the  next
                 item  on  the command line starts with a hyphen but is not an
                 option. This allows for the processing of patterns and  file-
                 names that start with hyphens.

       -A number, --after-context=number
                 Output  number  lines of context after each matching line. If
                 filenames and/or line numbers are being output, a hyphen sep-
                 arator  is  used  instead of a colon for the context lines. A
                 line containing "--" is output between each group  of  lines,
                 unless  they  are  in  fact contiguous in the input file. The
                 value of number is expected to be relatively small.  However,
                 pcregrep guarantees to have up to 8K of following text avail-
                 able for context output.

       -B number, --before-context=number
                 Output number lines of context before each matching line.  If
                 filenames and/or line numbers are being output, a hyphen sep-
                 arator is used instead of a colon for the  context  lines.  A
                 line  containing  "--" is output between each group of lines,
                 unless they are in fact contiguous in  the  input  file.  The
                 value  of number is expected to be relatively small. However,
                 pcregrep guarantees to have up to 8K of preceding text avail-
                 able for context output.

       -C number, --context=number
                 Output  number  lines  of  context both before and after each
                 matching line.  This is equivalent to setting both -A and  -B
                 to the same value.

       -c, --count
                 Do  not  output individual lines; instead just output a count
                 of the number of lines that would otherwise have been output.
                 If  several  files  are  given, a count is output for each of
                 them. In this mode, the -A, -B, and -C options are ignored.

       --colour, --color
                 If this option is given without any data, it is equivalent to
                 "--colour=auto".   If  data  is required, it must be given in
                 the same shell item, separated by an equals sign.

       --colour=value, --color=value
                 This option specifies under what circumstances the part of  a
                 line that matched a pattern should be coloured in the output.
                 The value may be "never" (the default), "always", or  "auto".
                 In  the  latter  case, colouring happens only if the standard
                 output is connected to a terminal. The colour can  be  speci-
                 fied  by  setting the environment variable PCREGREP_COLOUR or
                 PCREGREP_COLOR. The value of this variable should be a string
                 of  two  numbers,  separated by a semicolon.  They are copied
                 directly into the control string for setting colour on a ter-
                 minal,  so it is your responsibility to ensure that they make
                 sense. If neither of the environment variables  is  set,  the
                 default is "1;31", which gives red.

       -D action, --devices=action
                 If  an  input  path  is  not  a  regular file or a directory,
                 "action" specifies how it is to be  processed.  Valid  values
                 are  "read" (the default) or "skip" (silently skip the path).

       -d action, --directories=action
                 If an input path is a directory, "action" specifies how it is
                 to  be  processed.   Valid  values  are "read" (the default),
                 "recurse" (equivalent to the -r option), or "skip"  (silently
                 skip  the path). In the default case, directories are read as
                 if they were ordinary files. In some  operating  systems  the
                 effect  of reading a directory like this is an immediate end-
                 of-file.

       -e pattern, --regex=pattern,
                 --regexp=pattern Specify a pattern to be matched. This option
                 can  be  used multiple times in order to specify several pat-
                 terns. It can also be used as a way of  specifying  a  single
                 pattern  that starts with a hyphen. When -e is used, no argu-
                 ment pattern is taken from the command  line;  all  arguments
                 are treated as file names. There is an overall maximum of 100
                 patterns. They are applied to each line in the order in which
                 they  are  defined until one matches (or fails to match if -v
                 is used). If -f is used with -e, the  command  line  patterns
                 are  matched  first,  followed by the patterns from the file,
                 independent of the order in which these  options  are  speci-
                 fied.  Note that multiple use of -e is not the same as a sin-
                 gle pattern with alternatives. For  example,  X|Y  finds  the
                 first  character in a line that is X or Y, whereas if the two
                 patterns are given separately, pcregrep  finds  X  if  it  is
                 present, even if it follows Y in the line. It finds Y only if
                 there is no X in the line. This really matters  only  if  you
                 are using -o to show the portion of the line that matched.

       --exclude=pattern
                 When pcregrep is searching the files in a directory as a con-
                 sequence of the -r (recursive search) option, any files whose
                 names  match  the pattern are excluded. The pattern is a PCRE
                 regular expression. If a file name matches both --include and
                 --exclude,  it  is  excluded. There is no short form for this
                 option.

       -F, --fixed-strings
                 Interpret each pattern as a list of fixed strings,  separated
                 by  newlines,  instead  of  as  a  regular expression. The -w
                 (match as a word) and -x (match whole line)  options  can  be
                 used with -F. They apply to each of the fixed strings. A line
                 is selected if any of the fixed strings are found in it (sub-
                 ject to -w or -x, if present).

       -f filename, --file=filename
                 Read  a  number  of patterns from the file, one per line, and
                 match them against each line of input. A data line is  output
                 if any of the patterns match it. The filename can be given as
                 "-" to refer to the standard input. When -f is used, patterns
                 specified  on  the command line using -e may also be present;
                 they are tested before the file's patterns. However, no other
                 pattern  is  taken  from  the command line; all arguments are
                 treated as file names. There is an  overall  maximum  of  100
                 patterns. Trailing white space is removed from each line, and
                 blank lines are ignored. An empty file contains  no  patterns
                 and therefore matches nothing.

       -H, --with-filename
                 Force  the  inclusion  of the filename at the start of output
                 lines when searching a single file. By default, the  filename
                 is  not  shown in this case. For matching lines, the filename
                 is followed by a colon and a  space;  for  context  lines,  a
                 hyphen separator is used. If a line number is also being out-
                 put, it follows the file name without a space.

       -h, --no-filename
                 Suppress the output filenames when searching multiple  files.
                 By  default,  filenames  are  shown  when  multiple files are
                 searched. For matching lines, the filename is followed  by  a
                 colon  and  a space; for context lines, a hyphen separator is
                 used. If a line number is also being output, it  follows  the
                 file name without a space.

       --help    Output a brief help message and exit.

       -i, --ignore-case
                 Ignore upper/lower case distinctions during comparisons.

       --include=pattern
                 When pcregrep is searching the files in a directory as a con-
                 sequence of the -r  (recursive  search)  option,  only  those
                 files whose names match the pattern are included. The pattern
                 is a PCRE regular expression. If a  file  name  matches  both
                 --include  and  --exclude,  it is excluded. There is no short
                 form for this option.

       -L, --files-without-match
                 Instead of outputting lines from the files, just  output  the
                 names  of  the files that do not contain any lines that would
                 have been output. Each file name is output once, on  a  sepa-
                 rate line.

       -l, --files-with-matches
                 Instead  of  outputting lines from the files, just output the
                 names of the files containing lines that would have been out-
                 put.  Each  file  name  is  output  once, on a separate line.
                 Searching stops as soon as a matching  line  is  found  in  a
                 file.

       --label=name
                 This option supplies a name to be used for the standard input
                 when file names are being output. If not supplied, "(standard
                 input)" is used. There is no short form for this option.

       --locale=locale-name
                 This  option specifies a locale to be used for pattern match-
                 ing. It overrides the value in the LC_ALL or  LC_CTYPE  envi-
                 ronment  variables.  If  no  locale  is  specified,  the PCRE
                 library's default (usually the "C" locale) is used. There  is
                 no short form for this option.

       -M, --multiline
                 Allow  patterns to match more than one line. When this option
                 is given, patterns may usefully contain literal newline char-
                 acters  and  internal  occurrences of ^ and $ characters. The
                 output for any one match may consist of more than  one  line.
                 When  this option is set, the PCRE library is called in "mul-
                 tiline" mode.  There is a limit to the number of  lines  that
                 can  be matched, imposed by the way that pcregrep buffers the
                 input file as it scans it. However, pcregrep ensures that  at
                 least 8K characters or the rest of the document (whichever is
                 the shorter) are available for forward  matching,  and  simi-
                 larly the previous 8K characters (or all the previous charac-
                 ters, if fewer than 8K) are guaranteed to  be  available  for
                 lookbehind assertions.

       -N newline-type, --newline=newline-type
                 The  PCRE  library  supports  four  different conventions for
                 indicating the ends of lines. They are  the  single-character
                 sequences  CR  (carriage  return) and LF (linefeed), the two-
                 character sequence CRLF, and an "any"  convention,  in  which
                 any  Unicode  line  ending sequence is assumed to end a line.
                 The Unicode sequences are the three just mentioned,  plus  VT
                 (vertical  tab,  U+000B),  FF  (formfeed,  U+000C), NEL (next
                 line, U+0085), LS (line separator, U+2028), and PS (paragraph
                 separator, U+0029).

                 When  the  PCRE  library  is  built,  a  default  line-ending
                 sequence  is  specified.   This  is  normally  the   standard
                 sequence for the operating system. Unless otherwise specified
                 by this option, pcregrep uses  the  library's  default.   The
                 possible  values  for  this  option are CR, LF, CRLF, or ANY.
                 This makes it possible to use pcregrep  on  files  that  have
                 come  from  other environments without having to modify their
                 line endings. If the data that  is  being  scanned  does  not
                 agree  with  the  convention set by this option, pcregrep may
                 behave in strange ways.

       -n, --line-number
                 Precede each output line by its line number in the file, fol-
                 lowed  by  a colon and a space for matching lines or a hyphen
                 and a space for context lines. If the filename is also  being
                 output, it precedes the line number.

       -o, --only-matching
                 Show  only  the  part  of the line that matched a pattern. In
                 this mode, no context is shown. That is, the -A, -B,  and  -C
                 options are ignored.

       -q, --quiet
                 Work quietly, that is, display nothing except error messages.
                 The exit status indicates whether or  not  any  matches  were
                 found.

       -r, --recursive
                 If  any given path is a directory, recursively scan the files
                 it contains, taking note of any --include and --exclude  set-
                 tings.  By  default, a directory is read as a normal file; in
                 some operating systems this gives an  immediate  end-of-file.
                 This  option  is  a  shorthand  for  setting the -d option to
                 "recurse".

       -s, --no-messages
                 Suppress error  messages  about  non-existent  or  unreadable
                 files.  Such  files  are quietly skipped. However, the return
                 code is still 2, even if matches were found in other files.

       -u, --utf-8
                 Operate in UTF-8 mode. This option is available only if  PCRE
                 has  been compiled with UTF-8 support. Both patterns and sub-
                 ject lines must be valid strings of UTF-8 characters.

       -V, --version
                 Write the version numbers of pcregrep and  the  PCRE  library
                 that is being used to the standard error stream.

       -v, --invert-match
                 Invert  the  sense  of  the match, so that lines which do not
                 match any of the patterns are the ones that are found.

       -w, --word-regex, --word-regexp
                 Force the patterns to match only whole words. This is equiva-
                 lent to having \b at the start and end of the pattern.

       -x, --line-regex, --line-regexp
                 Force  the  patterns to be anchored (each must start matching
                 at the beginning of a line) and in addition, require them  to
                 match  entire  lines.  This  is  equivalent to having ^ and $
                 characters at the start and end of each alternative branch in
                 every pattern.


ENVIRONMENT VARIABLES

       The  environment  variables  LC_ALL  and LC_CTYPE are examined, in that
       order, for a locale. The first one that is set is  used.  This  can  be
       overridden  by  the  --locale  option.  If  no  locale is set, the PCRE
       library's default (usually the "C" locale) is used.


NEWLINES

       The -N (--newline) option allows pcregrep to scan files with  different
       newline  conventions  from  the  default.  However, the setting of this
       option does not affect the way in which pcregrep writes information  to
       the  standard  error  and  output streams. It uses the string "\n" in C
       printf() calls to indicate newlines, relying on the C  I/O  library  to
       convert  this  to  an  appropriate  sequence if the output is sent to a
       file.


OPTIONS COMPATIBILITY

       The majority of short and long forms of pcregrep's options are the same
       as  in  the  GNU grep program. Any long option of the form --xxx-regexp
       (GNU terminology) is also available as --xxx-regex (PCRE  terminology).
       However,  the  --locale,  -M,  --multiline, -u, and --utf-8 options are
       specific to pcregrep.


OPTIONS WITH DATA

       There are four different ways in which an option with data can be spec-
       ified.   If  a  short  form option is used, the data may follow immedi-
       ately, or in the next command line item. For example:

         -f/some/file
         -f /some/file

       If a long form option is used, the data may appear in the same  command
       line item, separated by an equals character, or (with one exception) it
       may appear in the next command line item. For example:

         --file=/some/file
         --file /some/file

       Note, however, that if you want to supply a file name beginning with  ~
       as  data  in  a  shell  command,  and have the shell expand ~ to a home
       directory, you must separate the file name from the option, because the
       shell  does not treat ~ specially unless it is at the start of an item.

       The exception to the above is the --colour  (or  --color)  option,  for
       which  the  data is optional. If this option does have data, it must be
       given in the first form, using an equals character. Otherwise  it  will
       be assumed that it has no data.


MATCHING ERRORS

       It  is  possible  to supply a regular expression that takes a very long
       time to fail to match certain lines.  Such  patterns  normally  involve
       nested  indefinite repeats, for example: (a+)*\d when matched against a
       line of a's with no final digit.  The  PCRE  matching  function  has  a
       resource  limit that causes it to abort in these circumstances. If this
       happens, pcregrep outputs an error message and the line that caused the
       problem  to  the  standard error stream. If there are more than 20 such
       errors, pcregrep gives up.


DIAGNOSTICS

       Exit status is 0 if any matches were found, 1 if no matches were found,
       and  2 for syntax errors and non-existent or inacessible files (even if
       matches were found in other files) or too many matching  errors.  Using
       the  -s  option to suppress error messages about inaccessble files does
       not affect the return code.


SEE ALSO

       pcrepattern(3), pcretest(1).


AUTHOR

       Philip Hazel
       University Computing Service
       Cambridge CB2 3QH, England.


REVISION

       Last updated: 06 March 2007
       Copyright (c) 1997-2007 University of Cambridge.
1	PCREGREP(1) PCREGREP(1)
2
3
4	NAME
5	pcregrep - a grep with Perl-compatible regular expressions.
6
7
8	SYNOPSIS
9	pcregrep [options] [long options] [pattern] [path1 path2 ...]
10
11
12	DESCRIPTION
13
14	pcregrep searches files for character patterns, in the same way as
15	other grep commands do, but it uses the PCRE regular expression library
16	to support patterns that are compatible with the regular expressions of
17	Perl 5. See pcrepattern(3) for a full description of syntax and seman-
18	tics of the regular expressions that PCRE supports.
19
20	Patterns, whether supplied on the command line or in a separate file,
21	are given without delimiters. For example:
22
23	pcregrep Thursday /etc/motd
24
25	If you attempt to use delimiters (for example, by surrounding a pattern
26	with slashes, as is common in Perl scripts), they are interpreted as
27	part of the pattern. Quotes can of course be used on the command line
28	because they are interpreted by the shell, and indeed they are required
29	if a pattern contains white space or shell metacharacters.
30
31	The first argument that follows any option settings is treated as the
32	single pattern to be matched when neither -e nor -f is present. Con-
33	versely, when one or both of these options are used to specify pat-
34	terns, all arguments are treated as path names. At least one of -e, -f,
35	or an argument pattern must be provided.
36
37	If no files are specified, pcregrep reads the standard input. The stan-
38	dard input can also be referenced by a name consisting of a single
39	hyphen. For example:
40
41	pcregrep some-pattern /file1 - /file3
42
43	By default, each line that matches the pattern is copied to the stan-
44	dard output, and if there is more than one file, the file name is out-
45	put at the start of each line. However, there are options that can
46	change how pcregrep behaves. In particular, the -M option makes it pos-
47	sible to search for patterns that span line boundaries. What defines a
48	line boundary is controlled by the -N (--newline) option.
49
50	Patterns are limited to 8K or BUFSIZ characters, whichever is the
51	greater. BUFSIZ is defined in <stdio.h>.
52
53	If the LC_ALL or LC_CTYPE environment variable is set, pcregrep uses
54	the value to set a locale when calling the PCRE library. The --locale
55	option can be used to override this.
56
57
58	OPTIONS
59
60	-- This terminate the list of options. It is useful if the next
61	item on the command line starts with a hyphen but is not an
62	option. This allows for the processing of patterns and file-
63	names that start with hyphens.
64
65	-A number, --after-context=number
66	Output number lines of context after each matching line. If
67	filenames and/or line numbers are being output, a hyphen sep-
68	arator is used instead of a colon for the context lines. A
69	line containing "--" is output between each group of lines,
70	unless they are in fact contiguous in the input file. The
71	value of number is expected to be relatively small. However,
72	pcregrep guarantees to have up to 8K of following text avail-
73	able for context output.
74
75	-B number, --before-context=number
76	Output number lines of context before each matching line. If
77	filenames and/or line numbers are being output, a hyphen sep-
78	arator is used instead of a colon for the context lines. A
79	line containing "--" is output between each group of lines,
80	unless they are in fact contiguous in the input file. The
81	value of number is expected to be relatively small. However,
82	pcregrep guarantees to have up to 8K of preceding text avail-
83	able for context output.
84
85	-C number, --context=number
86	Output number lines of context both before and after each
87	matching line. This is equivalent to setting both -A and -B
88	to the same value.
89
90	-c, --count
91	Do not output individual lines; instead just output a count
92	of the number of lines that would otherwise have been output.
93	If several files are given, a count is output for each of
94	them. In this mode, the -A, -B, and -C options are ignored.
95
96	--colour, --color
97	If this option is given without any data, it is equivalent to
98	"--colour=auto". If data is required, it must be given in
99	the same shell item, separated by an equals sign.
100
101	--colour=value, --color=value
102	This option specifies under what circumstances the part of a
103	line that matched a pattern should be coloured in the output.
104	The value may be "never" (the default), "always", or "auto".
105	In the latter case, colouring happens only if the standard
106	output is connected to a terminal. The colour can be speci-
107	fied by setting the environment variable PCREGREP_COLOUR or
108	PCREGREP_COLOR. The value of this variable should be a string
109	of two numbers, separated by a semicolon. They are copied
110	directly into the control string for setting colour on a ter-
111	minal, so it is your responsibility to ensure that they make
112	sense. If neither of the environment variables is set, the
113	default is "1;31", which gives red.
114
115	-D action, --devices=action
116	If an input path is not a regular file or a directory,
117	"action" specifies how it is to be processed. Valid values
118	are "read" (the default) or "skip" (silently skip the path).
119
120	-d action, --directories=action
121	If an input path is a directory, "action" specifies how it is
122	to be processed. Valid values are "read" (the default),
123	"recurse" (equivalent to the -r option), or "skip" (silently
124	skip the path). In the default case, directories are read as
125	if they were ordinary files. In some operating systems the
126	effect of reading a directory like this is an immediate end-
127	of-file.
128
129	-e pattern, --regex=pattern,
130	--regexp=pattern Specify a pattern to be matched. This option
131	can be used multiple times in order to specify several pat-
132	terns. It can also be used as a way of specifying a single
133	pattern that starts with a hyphen. When -e is used, no argu-
134	ment pattern is taken from the command line; all arguments
135	are treated as file names. There is an overall maximum of 100
136	patterns. They are applied to each line in the order in which
137	they are defined until one matches (or fails to match if -v
138	is used). If -f is used with -e, the command line patterns
139	are matched first, followed by the patterns from the file,
140	independent of the order in which these options are speci-
141	fied. Note that multiple use of -e is not the same as a sin-
142	gle pattern with alternatives. For example, X\|Y finds the
143	first character in a line that is X or Y, whereas if the two
144	patterns are given separately, pcregrep finds X if it is
145	present, even if it follows Y in the line. It finds Y only if
146	there is no X in the line. This really matters only if you
147	are using -o to show the portion of the line that matched.
148
149	--exclude=pattern
150	When pcregrep is searching the files in a directory as a con-
151	sequence of the -r (recursive search) option, any files whose
152	names match the pattern are excluded. The pattern is a PCRE
153	regular expression. If a file name matches both --include and
154	--exclude, it is excluded. There is no short form for this
155	option.
156
157	-F, --fixed-strings
158	Interpret each pattern as a list of fixed strings, separated
159	by newlines, instead of as a regular expression. The -w
160	(match as a word) and -x (match whole line) options can be
161	used with -F. They apply to each of the fixed strings. A line
162	is selected if any of the fixed strings are found in it (sub-
163	ject to -w or -x, if present).
164
165	-f filename, --file=filename
166	Read a number of patterns from the file, one per line, and
167	match them against each line of input. A data line is output
168	if any of the patterns match it. The filename can be given as
169	"-" to refer to the standard input. When -f is used, patterns
170	specified on the command line using -e may also be present;
171	they are tested before the file's patterns. However, no other
172	pattern is taken from the command line; all arguments are
173	treated as file names. There is an overall maximum of 100
174	patterns. Trailing white space is removed from each line, and
175	blank lines are ignored. An empty file contains no patterns
176	and therefore matches nothing.
177
178	-H, --with-filename
179	Force the inclusion of the filename at the start of output
180	lines when searching a single file. By default, the filename
181	is not shown in this case. For matching lines, the filename
182	is followed by a colon and a space; for context lines, a
183	hyphen separator is used. If a line number is also being out-
184	put, it follows the file name without a space.
185
186	-h, --no-filename
187	Suppress the output filenames when searching multiple files.
188	By default, filenames are shown when multiple files are
189	searched. For matching lines, the filename is followed by a
190	colon and a space; for context lines, a hyphen separator is
191	used. If a line number is also being output, it follows the
192	file name without a space.
193
194	--help Output a brief help message and exit.
195
196	-i, --ignore-case
197	Ignore upper/lower case distinctions during comparisons.
198
199	--include=pattern
200	When pcregrep is searching the files in a directory as a con-
201	sequence of the -r (recursive search) option, only those
202	files whose names match the pattern are included. The pattern
203	is a PCRE regular expression. If a file name matches both
204	--include and --exclude, it is excluded. There is no short
205	form for this option.
206
207	-L, --files-without-match
208	Instead of outputting lines from the files, just output the
209	names of the files that do not contain any lines that would
210	have been output. Each file name is output once, on a sepa-
211	rate line.
212
213	-l, --files-with-matches
214	Instead of outputting lines from the files, just output the
215	names of the files containing lines that would have been out-
216	put. Each file name is output once, on a separate line.
217	Searching stops as soon as a matching line is found in a
218	file.
219
220	--label=name
221	This option supplies a name to be used for the standard input
222	when file names are being output. If not supplied, "(standard
223	input)" is used. There is no short form for this option.
224
225	--locale=locale-name
226	This option specifies a locale to be used for pattern match-
227	ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
228	ronment variables. If no locale is specified, the PCRE
229	library's default (usually the "C" locale) is used. There is
230	no short form for this option.
231
232	-M, --multiline
233	Allow patterns to match more than one line. When this option
234	is given, patterns may usefully contain literal newline char-
235	acters and internal occurrences of ^ and $ characters. The
236	output for any one match may consist of more than one line.
237	When this option is set, the PCRE library is called in "mul-
238	tiline" mode. There is a limit to the number of lines that
239	can be matched, imposed by the way that pcregrep buffers the
240	input file as it scans it. However, pcregrep ensures that at
241	least 8K characters or the rest of the document (whichever is
242	the shorter) are available for forward matching, and simi-
243	larly the previous 8K characters (or all the previous charac-
244	ters, if fewer than 8K) are guaranteed to be available for
245	lookbehind assertions.
246
247	-N newline-type, --newline=newline-type
248	The PCRE library supports four different conventions for
249	indicating the ends of lines. They are the single-character
250	sequences CR (carriage return) and LF (linefeed), the two-
251	character sequence CRLF, and an "any" convention, in which
252	any Unicode line ending sequence is assumed to end a line.
253	The Unicode sequences are the three just mentioned, plus VT
254	(vertical tab, U+000B), FF (formfeed, U+000C), NEL (next
255	line, U+0085), LS (line separator, U+2028), and PS (paragraph
256	separator, U+0029).
257
258	When the PCRE library is built, a default line-ending
259	sequence is specified. This is normally the standard
260	sequence for the operating system. Unless otherwise specified
261	by this option, pcregrep uses the library's default. The
262	possible values for this option are CR, LF, CRLF, or ANY.
263	This makes it possible to use pcregrep on files that have
264	come from other environments without having to modify their
265	line endings. If the data that is being scanned does not
266	agree with the convention set by this option, pcregrep may
267	behave in strange ways.
268
269	-n, --line-number
270	Precede each output line by its line number in the file, fol-
271	lowed by a colon and a space for matching lines or a hyphen
272	and a space for context lines. If the filename is also being
273	output, it precedes the line number.
274
275	-o, --only-matching
276	Show only the part of the line that matched a pattern. In
277	this mode, no context is shown. That is, the -A, -B, and -C
278	options are ignored.
279
280	-q, --quiet
281	Work quietly, that is, display nothing except error messages.
282	The exit status indicates whether or not any matches were
283	found.
284
285	-r, --recursive
286	If any given path is a directory, recursively scan the files
287	it contains, taking note of any --include and --exclude set-
288	tings. By default, a directory is read as a normal file; in
289	some operating systems this gives an immediate end-of-file.
290	This option is a shorthand for setting the -d option to
291	"recurse".
292
293	-s, --no-messages
294	Suppress error messages about non-existent or unreadable
295	files. Such files are quietly skipped. However, the return
296	code is still 2, even if matches were found in other files.
297
298	-u, --utf-8
299	Operate in UTF-8 mode. This option is available only if PCRE
300	has been compiled with UTF-8 support. Both patterns and sub-
301	ject lines must be valid strings of UTF-8 characters.
302
303	-V, --version
304	Write the version numbers of pcregrep and the PCRE library
305	that is being used to the standard error stream.
306
307	-v, --invert-match
308	Invert the sense of the match, so that lines which do not
309	match any of the patterns are the ones that are found.
310
311	-w, --word-regex, --word-regexp
312	Force the patterns to match only whole words. This is equiva-
313	lent to having \b at the start and end of the pattern.
314
315	-x, --line-regex, --line-regexp
316	Force the patterns to be anchored (each must start matching
317	at the beginning of a line) and in addition, require them to
318	match entire lines. This is equivalent to having ^ and $
319	characters at the start and end of each alternative branch in
320	every pattern.
321
322
323	ENVIRONMENT VARIABLES
324
325	The environment variables LC_ALL and LC_CTYPE are examined, in that
326	order, for a locale. The first one that is set is used. This can be
327	overridden by the --locale option. If no locale is set, the PCRE
328	library's default (usually the "C" locale) is used.
329
330
331	NEWLINES
332
333	The -N (--newline) option allows pcregrep to scan files with different
334	newline conventions from the default. However, the setting of this
335	option does not affect the way in which pcregrep writes information to
336	the standard error and output streams. It uses the string "\n" in C
337	printf() calls to indicate newlines, relying on the C I/O library to
338	convert this to an appropriate sequence if the output is sent to a
339	file.
340
341
342	OPTIONS COMPATIBILITY
343
344	The majority of short and long forms of pcregrep's options are the same
345	as in the GNU grep program. Any long option of the form --xxx-regexp
346	(GNU terminology) is also available as --xxx-regex (PCRE terminology).
347	However, the --locale, -M, --multiline, -u, and --utf-8 options are
348	specific to pcregrep.
349
350
351	OPTIONS WITH DATA
352
353	There are four different ways in which an option with data can be spec-
354	ified. If a short form option is used, the data may follow immedi-
355	ately, or in the next command line item. For example:
356
357	-f/some/file
358	-f /some/file
359
360	If a long form option is used, the data may appear in the same command
361	line item, separated by an equals character, or (with one exception) it
362	may appear in the next command line item. For example:
363
364	--file=/some/file
365	--file /some/file
366
367	Note, however, that if you want to supply a file name beginning with ~
368	as data in a shell command, and have the shell expand ~ to a home
369	directory, you must separate the file name from the option, because the
370	shell does not treat ~ specially unless it is at the start of an item.
371
372	The exception to the above is the --colour (or --color) option, for
373	which the data is optional. If this option does have data, it must be
374	given in the first form, using an equals character. Otherwise it will
375	be assumed that it has no data.
376
377
378	MATCHING ERRORS
379
380	It is possible to supply a regular expression that takes a very long
381	time to fail to match certain lines. Such patterns normally involve
382	nested indefinite repeats, for example: (a+)*\d when matched against a
383	line of a's with no final digit. The PCRE matching function has a
384	resource limit that causes it to abort in these circumstances. If this
385	happens, pcregrep outputs an error message and the line that caused the
386	problem to the standard error stream. If there are more than 20 such
387	errors, pcregrep gives up.
388
389
390	DIAGNOSTICS
391
392	Exit status is 0 if any matches were found, 1 if no matches were found,
393	and 2 for syntax errors and non-existent or inacessible files (even if
394	matches were found in other files) or too many matching errors. Using
395	the -s option to suppress error messages about inaccessble files does
396	not affect the return code.
397
398
399	SEE ALSO
400
401	pcrepattern(3), pcretest(1).
402
403
404	AUTHOR
405
406	Philip Hazel
407	University Computing Service
408	Cambridge CB2 3QH, England.
409
410
411	REVISION
412
413	Last updated: 06 March 2007
414	Copyright (c) 1997-2007 University of Cambridge.
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