pcregrep
(1)
Name
pcregrep - compatible regular expressions.
Synopsis
pcregrep [options] [long options] [pattern] [path1
Description
User Commands PCREGREP(1)
NAME
pcregrep - a grep with Perl-compatible regular expressions.
SYNOPSIS
pcregrep [options] [long options] [pattern] [path1
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 semantics of the regu-
lar expressions that PCRE supports.
Patterns, whether supplied on the command line or in a sepa-
rate file, are given without delimiters. For example:
pcregrep Thursday /etc/motd
If you attempt to use delimiters (for example, by surround-
ing a pattern with slashes, as is common in Perl scripts),
they are interpreted as part of the pattern. Quotes can of
course be used to delimit patterns 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. Conversely, when one or both of these
options are used to specify patterns, all arguments are
treated as path names. At least one of -e, -f, or an argu-
ment pattern must be provided.
If no files are specified, pcregrep reads the standard
input. The standard 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 a pattern is copied to
the standard output, and if there is more than one file, the
file name is output at the start of each line, followed by a
colon. However, there are options that can change how pcre-
grep behaves. In particular, the -M option makes it possible
to search for patterns that span line boundaries. What
defines a line boundary is controlled by the -N (--newline)
option.
The amount of memory used for buffering files that are being
scanned is controlled by a parameter that can be set by the
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--buffer-size option. The default value for this parameter
is specified when pcregrep is built, with the default
default being 20K. A block of memory three times this size
is used (to allow for buffering "before" and "after" lines).
An error occurs if a line overflows the buffer.
Patterns are limited to 8K or BUFSIZ bytes, whichever is the
greater. BUFSIZ is defined in <stdio.h>. When there is more
than one pattern (specified by the use of -e and/or -f),
each pattern is applied to each line in the order in which
they are defined, except that all the -e patterns are tried
before the -f patterns.
By default, as soon as one pattern matches (or fails to
match when -v is used), no further patterns are considered.
However, if --colour (or --color) is used to colour the
matching substrings, or if --only-matching, --file-offsets,
or --line-offsets is used to output only the part of the
line that matched (either shown literally, or as an offset),
scanning resumes immediately following the match, so that
further matches on the same line can be found. If there are
multiple patterns, they are all tried on the remainder of
the line, but patterns that follow the one that matched are
not tried on the earlier part of the line.
This is the same behaviour as GNU grep, but it does mean
that the order in which multiple patterns are specified can
affect the output when one of the above options is used.
Patterns that can match an empty string are accepted, but
empty string matches are never recognized. An example is the
pattern "(super)?(man)?", in which all components are
optional. This pattern finds all occurrences of both "super"
and "man"; the output differs from matching with "super|man"
when only the matching substrings are being shown.
If the LC_ALL or LC_CTYPE environment variable is set, pcre-
grep uses the value to set a locale when calling the PCRE
library. The --locale option can be used to override this.
SUPPORT FOR COMPRESSED FILES
It is possible to compile pcregrep so that it uses libz or
libbz2 to read files whose names end in .gz or .bz2, respec-
tively. You can find out whether your binary has support for
one or both of these file types by running it with the
--help option. If the appropriate support is not present,
files are treated as plain text. The standard input is
always so treated.
OPTIONS
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The order in which some of the options appear can affect the
output. For example, both the -h and -l options affect the
printing of file names. Whichever comes later in the command
line will be the one that takes effect. Numerical values for
options may be followed by K or M, to signify multiplication
by 1024 or 1024*1024 respectively.
-- This terminates 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 filenames 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 separator 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 available for context output.
-B number, --before-context=number
Output number lines of context before each match-
ing line. If filenames and/or line numbers are
being output, a hyphen separator is used instead
of a colon for the context lines. A line contain-
ing "--" 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 rela-
tively small. However, pcregrep guarantees to have
up to 8K of preceding text available for context
output.
--buffer-size=number
Set the parameter that controls how much memory is
used for buffering files that are being scanned.
-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 from the files that
are being scanned; instead output the number of
lines that would otherwise have been shown. If no
lines are selected, the number zero is output. If
several files are are being scanned, a count is
output for each of them. However, if the --files-
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with-matches option is also used, only those files
whose counts are greater than zero are listed.
When -c is used, 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
parts of a line that matched a pattern should be
coloured in the output. By default, the output is
not coloured. The value (which is optional, see
above) may be "never", "always", or "auto". In the
latter case, colouring happens only if the stan-
dard output is connected to a terminal. More
resources are used when colouring is enabled,
because pcregrep has to search for all possible
matches in a line, not just one, in order to
colour them all.
The colour that is used can be specified by set-
ting the environment variable PCREGREP_COLOUR or
PCREGREP_COLOR. The value of this variable should
be a string of two numbers, separated by a semi-
colon. They are copied directly into the control
string for setting colour on a terminal, 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 direc-
tory, "action" specifies how it is to be pro-
cessed. Valid values are "read" (the default) or
"skip" (silently skip the path).
-d action, --directories=action
If an input path is a directory, "action" speci-
fies 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
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be used multiple times in order to specify several
patterns. It can also be used as a way of specify-
ing a single pattern that starts with a hyphen.
When -e is used, no argument 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 specified. Note that multiple use of -e is not
the same as a single 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 part(s) of the line that matched.
--exclude=pattern
When pcregrep is searching the files in a direc-
tory as a consequence of the -r (recursive search)
option, any regular files whose names match the
pattern are excluded. Subdirectories are not
excluded by this option; they are searched recur-
sively, subject to the --exclude-dir and
--include_dir options. The pattern is a PCRE regu-
lar expression, and is matched against the final
component of the file name (not the entire path).
If a file name matches both --include and
--exclude, it is excluded. There is no short form
for this option.
--exclude-dir=pattern
When pcregrep is searching the contents of a
directory as a consequence of the -r (recursive
search) option, any subdirectories whose names
match the pattern are excluded. (Note that the
--exclude option does not affect subdirectories.)
The pattern is a PCRE regular expression, and is
matched against the final component of the name
(not the entire path). If a subdirectory name
matches both --include-dir and --exclude-dir, 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
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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 (subject 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 pat-
terns. However, no other pattern is taken from the
command line; all arguments are treated as file
names. There is an overall maximum of 100 pat-
terns. Trailing white space is removed from each
line, and blank lines are ignored. An empty file
contains no patterns and therefore matches noth-
ing. See also the comments about multiple patterns
versus a single pattern with alternatives in the
description of -e above.
--file-offsets
Instead of showing lines or parts of lines that
match, show each match as an offset from the start
of the file and a length, separated by a comma. In
this mode, no context is shown. That is, the -A,
-B, and -C options are ignored. If there is more
than one match in a line, each of them is shown
separately. This option is mutually exclusive with
--line-offsets and --only-matching.
-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; for context lines, a hyphen separator is
used. If a line number is also being output, it
follows the file name.
-h, --no-filename
Suppress the output filenames when searching mul-
tiple files. By default, filenames are shown when
multiple files are searched. For matching lines,
the filename is followed by a colon; for context
lines, a hyphen separator is used. If a line num-
ber is also being output, it follows the file
name.
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--help Output a help message, giving brief details of the
command options and file type support, and then
exit.
-i, --ignore-case
Ignore upper/lower case distinctions during com-
parisons.
--include=pattern
When pcregrep is searching the files in a direc-
tory as a consequence of the -r (recursive search)
option, only those regular files whose names match
the pattern are included. Subdirectories are
always included and searched recursively, subject
to the --include-dir and --exclude-dir options.
The pattern is a PCRE regular expression, and is
matched against the final component of the file
name (not the entire path). If a file name matches
both --include and --exclude, it is excluded.
There is no short form for this option.
--include-dir=pattern
When pcregrep is searching the contents of a
directory as a consequence of the -r (recursive
search) option, only those subdirectories whose
names match the pattern are included. (Note that
the --include option does not affect subdirecto-
ries.) The pattern is a PCRE regular expression,
and is matched against the final component of the
name (not the entire path). If a subdirectory name
matches both --include-dir and --exclude-dir, 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 separate 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 output. Each file name is
output once, on a separate line. Searching nor-
mally stops as soon as a matching line is found in
a file. However, if the -c (count) option is also
used, matching continues in order to obtain the
correct count, and those files that have at least
one match are listed along with their counts.
Using this option with -c is a way of suppressing
the listing of files with no matches.
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--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.
--line-buffered
When this option is given, input is read and pro-
cessed line by line, and the output is flushed
after each write. By default, input is read in
large chunks, unless pcregrep can determine that
it is reading from a terminal (which is currently
possible only in Unix environments). Output to
terminal is normally automatically flushed by the
operating system. This option can be useful when
the input or output is attached to a pipe and you
do not want pcregrep to buffer up large amounts of
data. However, its use will affect performance,
and the -M (multiline) option ceases to work.
--line-offsets
Instead of showing lines or parts of lines that
match, show each match as a line number, the off-
set from the start of the line, and a length. The
line number is terminated by a colon (as usual;
see the -n option), and the offset and length are
separated by a comma. In this mode, no context is
shown. That is, the -A, -B, and -C options are
ignored. If there is more than one match in a
line, each of them is shown separately. This
option is mutually exclusive with --file-offsets
and --only-matching.
--locale=locale-name
This option specifies a locale to be used for pat-
tern matching. It overrides the value in the
LC_ALL or LC_CTYPE environment 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.
--match-limit=number
Processing some regular expression patterns can
require a very large amount of memory, leading in
some cases to a program crash if not enough is
available. Other patterns may take a very long
time to search for all possible matching strings.
The pcre_exec() function that is called by pcre-
grep to do the matching has two parameters that
can limit the resources that it uses.
The --match-limit option provides a means of
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limiting resource usage when processing patterns
that are not going to match, but which have a very
large number of possibilities in their search
trees. The classic example is a pattern that uses
nested unlimited repeats. Internally, PCRE uses a
function called match() which it calls repeatedly
(sometimes recursively). The limit set by --match-
limit is imposed on the number of times this func-
tion is called during a match, which has the
effect of limiting the amount of backtracking that
can take place.
The --recursion-limit option is similar to
--match-limit, but instead of limiting the total
number of times that match() is called, it limits
the depth of recursive calls, which in turn limits
the amount of memory that can be used. The recur-
sion depth is a smaller number than the total num-
ber of calls, because not all calls to match() are
recursive. This limit is of use only if it is set
smaller than --match-limit.
There are no short forms for these options. The
default settings are specified when the PCRE
library is compiled, with the default default
being 10 million.
-M, --multiline
Allow patterns to match more than one line. When
this option is given, patterns may usefully con-
tain literal newline characters and internal
occurrences of ^ and $ characters. The output for
a successful match may consist of more than one
line, the last of which is the one in which the
match ended. If the matched string ends with a
newline sequence the output ends at the end of
that line.
When this option is set, the PCRE library is
called in "multiline" 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 for-
ward matching, and similarly the previous 8K char-
acters (or all the previous characters, if fewer
than 8K) are guaranteed to be available for look-
behind assertions. This option does not work when
input is read line by line (see --line-buffered.)
-N newline-type, --newline=newline-type
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The PCRE library supports five different conven-
tions for indicating the ends of lines. They are
the single-character sequences CR (carriage
return) and LF (linefeed), the two-character
sequence CRLF, an "anycrlf" convention, which rec-
ognizes any of the preceding three types, 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 (form feed, U+000C),
NEL (next line, U+0085), LS (line separator,
U+2028), and PS (paragraph separator, U+2029).
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, pcre-
grep uses the library's default. The possible
values for this option are CR, LF, CRLF, ANYCRLF,
or ANY. This makes it possible to use pcregrep on
files that have come from other environments with-
out 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, followed by a colon for matching lines or a
hyphen for context lines. If the filename is also
being output, it precedes the line number. This
option is forced if --line-offsets is used.
--no-jit If the PCRE library is built with support for
just-in-time compiling (which speeds up matching),
pcregrep automatically makes use of this, unless
it was explicitly disabled at build time. This
option can be used to disable the use of JIT at
run time. It is provided for testing and working
round problems. It should never be needed in nor-
mal use.
-o, --only-matching
Show only the part of the line that matched a pat-
tern instead of the whole line. In this mode, no
context is shown. That is, the -A, -B, and -C
options are ignored. If there is more than one
match in a line, each of them is shown separately.
If -o is combined with -v (invert the sense of the
match to find non-matching lines), no output is
generated, but the return code is set appropri-
ately. If the matched portion of the line is
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empty, nothing is output unless the file name or
line number are being printed, in which case they
are shown on an otherwise empty line. This option
is mutually exclusive with --file-offsets and
--line-offsets.
-onumber, --only-matching=number
Show only the part of the line that matched the
capturing parentheses of the given number. Up to
32 capturing parentheses are supported. Because
these options can be given without an argument
(see above), if an argument is present, it must be
given in the same shell item, for example, -o3 or
--only-matching=2. The comments given for the non-
argument case above also apply to this case. If
the specified capturing parentheses do not exist
in the pattern, or were not set in the match,
nothing is output unless the file name or line
number are being printed.
-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 settings. By default, a
directory is read as a normal file; in some oper-
ating systems this gives an immediate end-of-file.
This option is a shorthand for setting the -d
option to "recurse".
--recursion-limit=number
See --match-limit above.
-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 subject 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
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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 equivalent 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 addi-
tion, 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
Many of the short and long forms of pcregrep's options are
the same as in the GNU grep program (version 2.5.4). Any
long option of the form --xxx-regexp (GNU terminology) is
also available as --xxx-regex (PCRE terminology). However,
the --file-offsets, --include-dir, --line-offsets, --locale,
--match-limit, -M, --multiline, -N, --newline, --recursion-
limit, -u, and --utf-8 options are specific to pcregrep, as
is the use of the --only-matching option with a capturing
parentheses number.
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Although most of the common options work the same way, a few
are different in pcregrep. For example, the --include
option's argument is a glob for GNU grep, but a regular
expression for pcregrep. If both the -c and -l options are
given, GNU grep lists only file names, without counts, but
pcregrep gives the counts.
OPTIONS WITH DATA
There are four different ways in which an option with data
can be specified. If a short form option is used, the data
may follow immediately, or (with one exception) in the next
command line item. For example:
-f/some/file
-f /some/file
The exception is the -o option, which may appear with or
without data. Because of this, if data is present, it must
follow immediately in the same item, for example -o3.
If a long form option is used, the data may appear in the
same command line item, separated by an equals character, or
(with two exceptions) 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 begin-
ning 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 exceptions to the above are the --colour (or --color)
and --only-matching options, for which the data is optional.
If one of these options does have data, it must be given in
the first form, using an equals character. Otherwise pcre-
grep will assume 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.
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The --match-limit option of pcregrep can be used to set the
overall resource limit; there is a second option called
--recursion-limit that sets a limit on the amount of memory
(usually stack) that is used (see the discussion of these
options above).
DIAGNOSTICS
Exit status is 0 if any matches were found, 1 if no matches
were found, and 2 for syntax errors, overlong lines, non-
existent or inaccessible files (even if matches were found
in other files) or too many matching errors. Using the -s
option to suppress error messages about inaccessible files
does not affect the return code.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | library/pcre |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
SEE ALSO
pcrepattern(3), pcretest(1).
AUTHOR
Philip Hazel
University Computing Service
Cambridge CB2 3QH, England.
REVISION
Last updated: 06 September 2011
Copyright (c) 1997-2011 University of Cambridge.
NOTES
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from http://source-
forge.net/projects/pcre/files/pcre/8.21/pcre-8.21.tar.gz
Further information about this software can be found on the
open source community website at http://pcre.org/.
SunOS 5.11 Last change: 14