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pcregrep - a grep with Perl-compatible regular expressions.
pcregrep [options] [long options] [pattern] [path1 path2 ...]
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 for a full description of syntax and semantics 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. 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 argument 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 the 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. However, there are options that can change how pcregrep behaves. In particular, the -M option makes it possible to search for patterns that span line boundaries.
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.
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 filenames that start with hyphens.
Output a brief help message and exit.
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.
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.
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 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.
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.
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.
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Last updated: 23 January 2006
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