diff options
Diffstat (limited to 'plugins/Pcre16/docs/doc/pcregrep.txt')
| -rw-r--r-- | plugins/Pcre16/docs/doc/pcregrep.txt | 741 |
1 files changed, 0 insertions, 741 deletions
diff --git a/plugins/Pcre16/docs/doc/pcregrep.txt b/plugins/Pcre16/docs/doc/pcregrep.txt deleted file mode 100644 index 97d9a7bd37..0000000000 --- a/plugins/Pcre16/docs/doc/pcregrep.txt +++ /dev/null @@ -1,741 +0,0 @@ -PCREGREP(1) General Commands Manual 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 pcresyntax(3) for a quick-reference summary of pattern syn- - tax, or pcrepattern(3) for a full description of the 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 to delimit patterns - on the command line because they are interpreted by the shell, and - indeed quotes 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 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 pcregrep 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 --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 can be no longer than 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 a line, 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 behaviour means that the order in which multiple patterns are - specified can affect the output when one of the above options is used. - This is no longer the same behaviour as GNU grep, which now manages to - display earlier matches for later patterns (as long as there is no - overlap). - - 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, pcregrep 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, respectively. 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. - - -BINARY FILES - - By default, a file that contains a binary zero byte within the first - 1024 bytes is identified as a binary file, and is processed specially. - (GNU grep also identifies binary files in this manner.) See the - --binary-files option for a means of changing the way binary files are - handled. - - -OPTIONS - - 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. Similarly, except where noted below, if an option is - given twice, the later setting is used. 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 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. - - -a, --text - Treat binary files as text. This is equivalent to --binary- - files=text. - - -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. - - --binary-files=word - Specify how binary files are to be processed. If the word is - "binary" (the default), pattern matching is performed on - binary files, but the only output is "Binary file <name> - matches" when a match succeeds. If the word is "text", which - is equivalent to the -a or --text option, binary files are - processed in the same way as any other file. In this case, - when a match succeeds, the output may be binary garbage, - which can have nasty effects if sent to a terminal. If the - word is "without-match", which is equivalent to the -I - option, binary files are not processed at all; they are - assumed not to be of interest. - - --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 other- - wise 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- - 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 standard out- - put 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 setting the envi- - ronment 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 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 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 in - non-Windows environments, for compatibility with GNU grep), - "recurse" (equivalent to the -r option), or "skip" (silently - skip the path, the default in Windows environments). In the - "read" 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; in others it - may provoke an error. - - -e pattern, --regex=pattern, --regexp=pattern - Specify a pattern to be matched. This option can be used mul- - tiple times in order to specify several patterns. It can also - be used as a way of specifying 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 no limit to the number of patterns. They are - applied to each line in the order in which they are defined - until one matches. - - If -f is used with -e, the command line patterns are matched - first, followed by the patterns from the file(s), 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, with X first, 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 matters only if you are using -o or - --colo(u)r to show the part(s) of the line that matched. - - --exclude=pattern - Files (but not directories) whose names match the pattern are - skipped without being processed. This applies to all files, - whether listed on the command line, obtained from --file- - list, or by scanning a directory. The pattern is a PCRE regu- - lar expression, and is matched against the final component of - the file name, not the entire path. The -F, -w, and -x - options do not apply to this pattern. The option may be given - any number of times in order to specify multiple patterns. If - a file name matches both an --include and an --exclude pat- - tern, it is excluded. There is no short form for this option. - - --exclude-from=filename - Treat each non-empty line of the file as the data for an - --exclude option. What constitutes a newline when reading the - file is the operating system's default. The --newline option - has no effect on this option. This option may be given more - than once in order to specify a number of files to read. - - --exclude-dir=pattern - Directories whose names match the pattern are skipped without - being processed, whatever the setting of the --recursive - option. This applies to all directories, whether listed on - the command line, obtained from --file-list, or by scanning a - parent directory. The pattern is a PCRE regular expression, - and is matched against the final component of the directory - name, not the entire path. The -F, -w, and -x options do not - apply to this pattern. The option may be given any number of - times in order to specify more than one pattern. If a direc- - tory matches both --include-dir and --exclude-dir, it is - excluded. There is no short form for this option. - - -F, --fixed-strings - Interpret each data-matching pattern as a list of fixed - strings, separated by newlines, instead of as a regular - expression. What constitutes a newline for this purpose is - controlled by the --newline option. 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). This option applies only to the patterns that are - matched against the contents of files; it does not apply to - patterns specified by any of the --include or --exclude - options. - - -f filename, --file=filename - Read patterns from the file, one per line, and match them - against each line of input. What constitutes a newline when - reading the file is the operating system's default. The - --newline option has no effect on this option. Trailing white - space is removed from each line, and blank lines are ignored. - An empty file contains no patterns and therefore matches - nothing. See also the comments about multiple patterns versus - a single pattern with alternatives in the description of -e - above. - - If this option is given more than once, all the specified - files are read. A data line is output if any of the patterns - match it. A 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 the - names of paths to be searched. - - --file-list=filename - Read a list of files and/or directories that are to be - scanned from the given file, one per line. Trailing white - space is removed from each line, and blank lines are ignored. - These paths are processed before any that are listed on the - command line. The filename can be given as "-" to refer to - the standard input. If --file and --file-list are both spec- - ified as "-", patterns are read first. This is useful only - when the standard input is a terminal, from which further - lines (the list of files) can be read after an end-of-file - indication. If this option is given more than once, all the - specified files are read. - - --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 multiple 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 number is also being output, it follows the file name. - - --help Output a help message, giving brief details of the command - options and file type support, and then exit. Anything else - on the command line is ignored. - - -I Treat binary files as never matching. This is equivalent to - --binary-files=without-match. - - -i, --ignore-case - Ignore upper/lower case distinctions during comparisons. - - --include=pattern - If any --include patterns are specified, the only files that - are processed are those that match one of the patterns (and - do not match an --exclude pattern). This option does not - affect directories, but it applies to all files, whether - listed on the command line, obtained from --file-list, or by - scanning a directory. The pattern is a PCRE regular expres- - sion, and is matched against the final component of the file - name, not the entire path. The -F, -w, and -x options do not - apply to this pattern. The option may be given any number of - times. If a file name matches both an --include and an - --exclude pattern, it is excluded. There is no short form - for this option. - - --include-from=filename - Treat each non-empty line of the file as the data for an - --include option. What constitutes a newline for this purpose - is the operating system's default. The --newline option has - no effect on this option. This option may be given any number - of times; all the files are read. - - --include-dir=pattern - If any --include-dir patterns are specified, the only direc- - tories that are processed are those that match one of the - patterns (and do not match an --exclude-dir pattern). This - applies to all directories, whether listed on the command - line, obtained from --file-list, or by scanning a parent - directory. The pattern is a PCRE regular expression, and is - matched against the final component of the directory name, - not the entire path. The -F, -w, and -x options do not apply - to this pattern. The option may be given any number of times. - If a directory 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 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 normally 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 sup- - pressing the listing of files with no matches. - - --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 processed 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 cur- - rently possible only in Unix-like 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 perfor- - mance, 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 offset 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 sepa- - rately. This option is mutually exclusive with --file-offsets - and --only-matching. - - --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. - - --match-limit=number - Processing some regular expression patterns can require a - very large amount of memory, leading in some cases to a pro- - gram 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 pcregrep - to do the matching has two parameters that can limit the - resources that it uses. - - The --match-limit option provides a means of 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 func- - tion called match() which it calls repeatedly (sometimes - recursively). The limit set by --match-limit is imposed on - the number of times this function 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 recursion - depth is a smaller number than the total number 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 set- - tings 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 contain literal newline char- - acters 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 "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. This option does not work when input - is read line by line (see --line-buffered.) - - -N newline-type, --newline=newline-type - The PCRE library supports five 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, an "anycrlf" convention, which rec- - ognizes any of the preceding three types, and an "any" con- - vention, in which any Unicode line ending sequence is assumed - to end a line. The Unicode sequences are the three just men- - tioned, 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, pcregrep 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 to scan files - that have come from other environments without having to mod- - ify their line endings. If the data that is being scanned - does not agree with the convention set by this option, pcre- - grep may behave in strange ways. Note that this option does - not apply to files specified by the -f, --exclude-from, or - --include-from options, which are expected to use the operat- - ing system's standard newline sequence. - - -n, --line-number - Precede each output line by its line number in the file, fol- - lowed 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 prob- - lems. It should never be needed in normal use. - - -o, --only-matching - Show only the part of the line that matched a pattern 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 appropriately. If the matched portion of - the line is 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 parenthe- - ses are supported, and -o0 is equivalent to -o without a num- - ber. 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. - - If this option is given multiple times, multiple substrings - are output, in the order the options are given. For example, - -o3 -o1 -o3 causes the substrings matched by capturing paren- - theses 3 and 1 and then 3 again to be output. By default, - there is no separator (but see the next option). - - --om-separator=text - Specify a separating string for multiple occurrences of -o. - The default is an empty string. Separating strings are never - coloured. - - -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". - - --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. All patterns (including - those for any --exclude and --include options) and all sub- - ject lines that are scanned must be valid strings of UTF-8 - characters. - - -V, --version - Write the version numbers of pcregrep and the PCRE library to - the standard output and then exit. Anything else on the com- - mand line is ignored. - - -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. This - option applies only to the patterns that are matched against - the contents of files; it does not apply to patterns speci- - fied by any of the --include or --exclude options. - - -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. This option applies only to the patterns that - are matched against the contents of files; it does not apply - to patterns specified by any of the --include or --exclude - options. - - -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. Any parts of the input files that - are written to the standard output are copied identically, with what- - ever newline sequences they have in the input. However, the setting of - this option does not affect the interpretation of files specified by - the -f, --exclude-from, or --include-from options, which are assumed to - use the operating system's standard newline sequence, nor does it - affect the way in which pcregrep writes informational messages to the - standard error and output streams. For these it uses the string "\n" to - indicate newlines, relying on the C I/O library to convert this to an - appropriate sequence. - - -OPTIONS COMPATIBILITY - - Many of the 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). How- - ever, the --file-list, --file-offsets, --include-dir, --line-offsets, - --locale, --match-limit, -M, --multiline, -N, --newline, --om-separa- - tor, --recursion-limit, -u, and --utf-8 options are specific to pcre- - grep, as is the use of the --only-matching option with a capturing - parentheses number. - - Although most of the common options work the same way, a few are dif- - ferent 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 spec- - ified. If a short form option is used, the data may follow immedi- - ately, or (with one exception) in the next command line item. For exam- - ple: - - -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 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 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 pcregrep 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. - - 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 inaccessi- - ble files does not affect the return code. - - -SEE ALSO - - pcrepattern(3), pcresyntax(3), pcretest(1). - - -AUTHOR - - Philip Hazel - University Computing Service - Cambridge CB2 3QH, England. - - -REVISION - - Last updated: 03 April 2014 - Copyright (c) 1997-2014 University of Cambridge. |