diff options
| author | Matthew Vernon <matthew@debian.org> | 2018-02-24 12:07:04 +0000 |
|---|---|---|
| committer | Matthew Vernon <matthew@debian.org> | 2018-02-24 12:07:04 +0000 |
| commit | e98c3314cf9e05aa99f5e192862ec37f29b7dbb5 (patch) | |
| tree | b69bb3feb63a4fd79ad8a6e55865228f6fde04eb /doc/pcre2grep.txt | |
| parent | 92b17f0eb8fddd7117c5344a1e1177daec21995a (diff) | |
New upstream version 10.31
Diffstat (limited to 'doc/pcre2grep.txt')
| -rw-r--r-- | doc/pcre2grep.txt | 889 |
1 files changed, 498 insertions, 391 deletions
diff --git a/doc/pcre2grep.txt b/doc/pcre2grep.txt index 31aa610..30517b4 100644 --- a/doc/pcre2grep.txt +++ b/doc/pcre2grep.txt @@ -51,61 +51,73 @@ DESCRIPTION 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 pcre2grep 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 + controlled by parameters that can be set by the --buffer-size and + --max-buffer-size options. The first of these sets the size of buffer + that is obtained at the start of processing. If an input file contains + very long lines, a larger buffer may be needed; this is handled by + automatically extending the buffer, up to the limit specified by --max- + buffer-size. The default values for these parameters are specified when + pcre2grep is built, with the default defaults being 20K and 1M respec- + tively. An error occurs if a line is too long and the buffer can no + longer be expanded. + + The block of memory that is actually used is three times the "buffer + size", to allow for buffering "before" and "after" lines. If the buffer + size is too small, fewer than requested "before" and "after" lines may + be output. + + 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 + 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 + 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 + 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 + 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 + 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 + 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 + "(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, pcre2grep uses + If the LC_ALL or LC_CTYPE environment variable is set, pcre2grep uses the value to set a locale when calling the PCRE2 library. The --locale option can be used to override this. SUPPORT FOR COMPRESSED FILES - It is possible to compile pcre2grep 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. + It is possible to compile pcre2grep so that it uses libz or libbz2 to + read compressed files whose names end in .gz or .bz2, respectively. You + can find out whether your pcre2grep binary has support for one or both + of these file types by running it with the --help option. If the appro- + priate support is not present, all files are treated as plain text. The + standard input is always so treated. When input is from a compressed + .gz or .bz2 file, the --line-buffered option is ignored. 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 + (GNU grep identifies binary files in this manner.) However, if the new- + line type is specified as "nul", that is, the line terminator is a + binary zero, the test for a binary file is not applied. See the --binary-files option for a means of changing the way binary files are handled. @@ -113,7 +125,7 @@ BINARY FILES 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 + 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 @@ -126,46 +138,50 @@ OPTIONS names that start with hyphens. -A number, --after-context=number - Output number lines of context after each matching line. If - file names 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, - pcre2grep guarantees to have up to 8K of following text - available for context output. + Output up to number lines of context after each matching + line. Fewer lines are output if the next match or the end of + the file is reached, or if the processing buffer size has + been set too small. If file names 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 contigu- + ous in the input file. The value of number is expected to be + relatively small. When -c is used, -A is ignored. -a, --text - Treat binary files as text. This is equivalent to --binary- + 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 - file names 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, - pcre2grep guarantees to have up to 8K of preceding text - available for context output. + Output up to number lines of context before each matching + line. Fewer lines are output if the previous match or the + start of the file is within number lines, or if the process- + ing buffer size has been set too small. If file names 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. When -c is used, -B is + ignored. --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 + 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 and are skipped without causing any output or affecting the return code. --buffer-size=number - Set the parameter that controls how much memory is used for - buffering files that are being scanned. + Set the parameter that controls how much memory is obtained + at the start of processing for buffering files that are being + scanned. See also --max-buffer-size below. -C number, --context=number Output number lines of context both before and after each @@ -174,19 +190,21 @@ OPTIONS -c, --count Do not output lines from the files that are being scanned; - instead output the number of matches (or non-matches if -v is - used) that would otherwise have caused lines to be shown. By - default, this count is the same as the number of suppressed - lines, but if the -M (multiline) option is used (without -v), - there may be more suppressed lines than the number of - matches. - - If no lines are selected, the number zero is output. If sev- - eral 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. + instead output the number of lines that would have been + shown, either because they matched, or, if -v is set, because + they failed to match. By default, this count is exactly the + same as the number of lines that would have been output, but + if the -M (multiline) option is used (without -v), there may + be more suppressed lines than the count (that is, the number + of matches). + + If no lines are selected, the number zero is output. If sev- + eral files are are being scanned, a count is output for each + of them and the -t option can be used to cause a total to be + output at the end. 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 @@ -204,205 +222,225 @@ OPTIONS 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 PCRE2GREP_COLOUR or PCRE2GREP_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 nei- - ther of the environment variables is set, the default is - "1;31", which gives red. + The colour that is used can be specified by setting one of + the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR, + PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that + order. If none of these are set, pcre2grep looks for + GREP_COLORS or GREP_COLOR (in that order). The value of the + variable should be a string of two numbers, separated by a + semicolon, except in the case of GREP_COLORS, which must + start with "ms=" or "mt=" followed by two semicolon-separated + colours, terminated by the end of the string or by a colon. + If GREP_COLORS does not start with "ms=" or "mt=" it is + ignored, and GREP_COLOR is checked. + + If the string obtained from one of the above variables con- + tains any characters other than semicolon or digits, the set- + ting is ignored and the default colour is used. The string is + copied directly into the control string for setting colour on + a terminal, so it is your responsibility to ensure that the + values make sense. If no relevant environment variable 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 + 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 + 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. + --depth-limit=number + See --match-limit below. + -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 + 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 + 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 + 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 + line that is X or Y, whereas if the two patterns are given separately, with X first, pcre2grep 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 + 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- + 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 PCRE2 reg- - ular expression, and is matched against the final component - of the file name, not the entire path. The -F, -w, and -x + ular 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- + 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 + 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 + 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 + 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 PCRE2 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 + parent directory. The pattern is a PCRE2 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 + 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 + 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 file name 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 + 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 pat- + terns 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 file name 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 + 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 file name can be given as "-" to refer to + These paths are processed before any that are listed on the + command line. The file name 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 + 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 + 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. + separately. This option is mutually exclusive with --output, + --line-offsets, and --only-matching. -H, --with-filename - Force the inclusion of the file name at the start of output + Force the inclusion of the file name at the start of output lines when searching a single file. By default, the file name is not shown in this case. For matching lines, the file name 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. When the -M option causes a pattern to match - more than one line, only the first is preceded by the file - name. + is used. If a line number is also being output, it follows + the file name. When the -M option causes a pattern to match + more than one line, only the first is preceded by the file + name. This option overrides any previous -h, -l, or -L + options. -h, --no-filename Suppress the output file names when searching multiple files. By default, file names are shown when multiple files are searched. For matching lines, the file name 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. + line number is also being output, it follows the file name. + This option overrides any previous -H, -L, or -l options. + + --heap-limit=number + See --match-limit below. - --help Output a help message, giving brief details of the command - options and file type support, and then exit. Anything else + --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 Ignore binary files. This is equivalent to --binary- + -I Ignore binary files. 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 PCRE2 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 + 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 PCRE2 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 + 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 + 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 PCRE2 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 + 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 PCRE2 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, + 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. + 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. This option overrides any previous -H, -h, or -l + options. -l, --files-with-matches Instead of outputting lines from the files, just output the @@ -413,7 +451,8 @@ OPTIONS 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. + pressing the listing of files with no matches. This opeion + overrides any previous -H, -h, or -L options. --label=name This option supplies a name to be used for the standard input @@ -421,163 +460,194 @@ OPTIONS 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 pcre2grep 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 pcre2grep to buffer up - large amounts of data. However, its use will affect perfor- - mance, and the -M (multiline) option ceases to work. + When this option is given, non-compressed 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 + pcre2grep can determine that it is reading from a terminal + (which is currently 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 pcre2grep to + buffer up large amounts of data. However, its use will affect + performance, and the -M (multiline) option ceases to work. + When input is from a compressed .gz or .bz2 file, --line- + buffered is ignored. --line-offsets - Instead of showing lines or parts of lines that match, show + 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. + 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 --output, + --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 PCRE2 - library's default (usually the "C" locale) is used. There is + 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 PCRE2 + 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 pcre2_match() function that is called by - pcre2grep 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, PCRE2 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 PCRE2 library is compiled, with - the default default being 10 million. + Processing some regular expression patterns may take a very + long time to search for all possible matching strings. Others + may require a very large amount of memory. There are three + options that set resource limits for matching. + + The --match-limit option provides a means of limiting comput- + ing resource usage when processing patterns that are not + going to match, but which have a very large number of possi- + bilities in their search trees. The classic example is a pat- + tern that uses nested unlimited repeats. Internally, PCRE2 + has a counter that is incremented each time around its main + processing loop. If the value set by --match-limit is + reached, an error occurs. + + The --heap-limit option specifies, as a number of kilobytes, + the amount of heap memory that may be used for matching. Heap + memory is needed only if matching the pattern requires a sig- + nificant number of nested backtracking points to be remem- + bered. This parameter can be set to zero to forbid the use of + heap memory altogether. + + The --depth-limit option limits the depth of nested back- + tracking points, which indirectly limits the amount of memory + that is used. The amount of memory needed for each backtrack- + ing point depends on the number of capturing parentheses in + the pattern, so the amount of memory that is used before this + limit acts varies from pattern to pattern. 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 PCRE2 library is compiled, with + the default defaults being very large and so effectively + unlimited. + + --max-buffer-size=number + This limits the expansion of the processing buffer, whose + initial size can be set by --buffer-size. The maximum buffer + size is silently forced to be no smaller than the starting + buffer size. -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 first is the line in which the match started, and - the last is the line 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 PCRE2 library is called in "mul- - tiline" mode. This allows a matched string to extend past the - end of a line and continue on one or more subsequent lines. - However, pcre2grep still processes the input line by line. - Once a match has been handled, scanning restarts at the - beginning of the next line, just as it does when -M is not - present. This means that it is possible for the second or - subsequent lines in a multiline match to be output again as - part of another match. - - The newline sequence that separates multiple lines must be - matched as part of the pattern. For example, to find the - phrase "regular expression" in a file where "regular" might - be at the end of a line and "expression" at the start of the + Allow patterns to match more than one line. When this option + is set, the PCRE2 library is called in "multiline" mode. This + allows a matched string to extend past the end of a line and + continue on one or more subsequent lines. Patterns used with + -M may usefully contain literal newline characters and inter- + nal occurrences of ^ and $ characters. The output for a suc- + cessful match may consist of more than one line. The first + line is the line in which the match started, and the last + line is the line in which the match ended. If the matched + string ends with a newline sequence, the output ends at the + end of that line. If -v is set, none of the lines in a + multi-line match are output. Once a match has been handled, + scanning restarts at the beginning of the line after the one + in which the match ended. + + The newline sequence that separates multiple lines must be + matched as part of the pattern. For example, to find the + phrase "regular expression" in a file where "regular" might + be at the end of a line and "expression" at the start of the next line, you could use this command: pcre2grep -M 'regular\s+expression' <file> - The \s escape sequence matches any white space character, - including newlines, and is followed by + so as to match - trailing white space on the first line as well as possibly + The \s escape sequence matches any white space character, + including newlines, and is followed by + so as to match + trailing white space on the first line as well as possibly handling a two-character newline sequence. - There is a limit to the number of lines that can be matched, - imposed by the way that pcre2grep buffers the input file as - it scans it. However, pcre2grep ensures that at least 8K - characters or the rest of the file (whichever is the shorter) - are available for forward matching, and similarly the previ- - ous 8K characters (or all the previous characters, if fewer - than 8K) are guaranteed to be available for lookbehind asser- - tions. The -M option does not work when input is read line by - line (see --line-buffered.) + There is a limit to the number of lines that can be matched, + imposed by the way that pcre2grep buffers the input file as + it scans it. With a sufficiently large processing buffer, + this should not be a problem, but the -M option does not work + when input is read line by line (see --line-buffered.) -N newline-type, --newline=newline-type - The PCRE2 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- + The PCRE2 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, + 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 PCRE2 library is built, a default line-ending - sequence is specified. This is normally the standard + When the PCRE2 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, pcre2grep uses the library's default. The + by this option, pcre2grep uses the library's default. The possible values for this option are CR, LF, CRLF, ANYCRLF, or - ANY. This makes it possible to use pcre2grep to scan files + ANY. This makes it possible to use pcre2grep 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, - pcre2grep 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 + ify their line endings. If the data that is being scanned + does not agree with the convention set by this option, + pcre2grep 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 operating 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 + lowed by a colon for matching lines or a hyphen for context lines. If the file name is also being output, it precedes the - line number. When the -M option causes a pattern to match - more than one line, only the first is preceded by its line + line number. When the -M option causes a pattern to match + more than one line, only the first is preceded by its line number. This option is forced if --line-offsets is used. - --no-jit If the PCRE2 library is built with support for just-in-time + --no-jit If the PCRE2 library is built with support for just-in-time compiling (which speeds up matching), pcre2grep 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- + 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 text, --output=text + When there is a match, instead of outputting the whole line + that matched, output just the given text. This option is + mutually exclusive with --only-matching, --file-offsets, and + --line-offsets. Escape sequences starting with a dollar char- + acter may be used to insert the contents of the matched part + of the line and/or captured substrings into the text. + + $<digits> or ${<digits>} is replaced by the captured sub- + string of the given decimal number; zero substitutes the + whole match. If the number is greater than the number of cap- + turing substrings, or if the capture is unset, the replace- + ment is empty. + + $a is replaced by bell; $b by backspace; $e by escape; $f by + form feed; $n by newline; $r by carriage return; $t by tab; + $v by vertical tab. + + $o<digits> is replaced by the character represented by the + given octal number; up to three digits are processed. + + $x<digits> is replaced by the character represented by the + given hexadecimal number; up to two digits are processed. + + Any other character is substituted by itself. In particular, + $$ is replaced by a single dollar. + -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. + 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, + on a separate line of output. 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 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 --output, + --file-offsets and --line-offsets. -onumber, --only-matching=number Show only the part of the line that matched the capturing @@ -587,82 +657,98 @@ OPTIONS (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 + to this option. 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 out- put. 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). + are output for each match, in the order the options are + given, and all on one line. For example, -o3 -o1 -o3 causes + the substrings matched by capturing parentheses 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 + 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 + 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 + 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 + 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. + -t, --total-count + This option is useful when scanning more than one file. If + used on its own, -t suppresses all output except for a grand + total number of matching lines (or non-matching lines if -v + is used) in all the files. If -t is used with -c, a grand + total is output except when the previous output is just one + line. In other words, it is not output when just one file's + count is listed. If file names are being output, the grand + total is preceded by "TOTAL:". Otherwise, it appears as just + another number. The -t option is ignored when used with -L + (list files without matches), because the grand total would + always be zero. + -u, --utf-8 Operate in UTF-8 mode. This option is available only if PCRE2 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 + 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 pcre2grep and the PCRE2 library - to the standard output and then exit. Anything else on the + Write the version numbers of pcre2grep and the PCRE2 library + to the standard output and then exit. Anything else on the command line is ignored. -v, --invert-match - Invert the sense of the match, so that lines which do not + 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. + Force the patterns only to match "words". That is, there must + be a word boundary at the start and end of each matched + string. This is equivalent to having "\b(?:" at the start of + each pattern, and ")\b" at the end. 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. -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 top-level - branch in every pattern. This option applies only to the pat- - terns that are matched against the contents of files; it does - not apply to patterns specified by any of the --include or - --exclude options. + Force the patterns to start matching only at the beginnings + of lines, and in addition, require them to match entire + lines. In multiline mode the match may be more than one line. + This is equivalent to having "^(?:" at the start of each pat- + tern and ")$" at the end. 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 PCRE2 + 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 PCRE2 library's default (usually the "C" locale) is used. @@ -670,82 +756,87 @@ NEWLINES The -N (--newline) option allows pcre2grep 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 + 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 pcre2grep writes informational messages to the + use the operating system's standard newline sequence, nor does it + affect the way in which pcre2grep 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 + 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 pcre2grep's options are the same as - in the GNU grep program. Any long option of the form --xxx-regexp (GNU + in the GNU grep program. Any long option of the form --xxx-regexp (GNU terminology) is also available as --xxx-regex (PCRE2 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 - pcre2grep, 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 pcre2grep. For example, the --include option's argument is a - glob for GNU grep, but a regular expression for pcre2grep. If both the - -c and -l options are given, GNU grep lists only file names, without + ever, the --depth-limit, --file-list, --file-offsets, --heap-limit, + --include-dir, --line-offsets, --locale, --match-limit, -M, --multi- + line, -N, --newline, --om-separator, --output, -u, and --utf-8 options + are specific to pcre2grep, 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 pcre2grep. For example, the --include option's argument is a + glob for GNU grep, but a regular expression for pcre2grep. If both the + -c and -l options are given, GNU grep lists only file names, without counts, but pcre2grep gives the counts as well. 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- + 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 + 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) + 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 + 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 + 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 pcre2grep will assume that it has no data. -CALLING EXTERNAL SCRIPTS +USING PCRE2'S CALLOUT FACILITY + + pcre2grep has, by default, support for calling external programs or + scripts or echoing specific strings during matching by making use of + PCRE2's callout facility. However, this support can be disabled when + pcre2grep is built. You can find out whether your binary has support + for callouts by running it with the --help option. If the support is + not enabled, all callouts in patterns are ignored by pcre2grep. + + A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu- + ment is either a number or a quoted string (see the pcre2callout docu- + mentation for details). Numbered callouts are ignored by pcre2grep; + only callouts with string arguments are useful. - On non-Windows systems, pcre2grep has, by default, support for calling - external programs or scripts during matching by making use of PCRE2's - callout facility. However, this support can be disabled when pcre2grep - is built. You can find out whether your binary has support for call- - outs by running it with the --help option. If the support is not - enabled, all callouts in patterns are ignored by pcre2grep. + Calling external programs or scripts - A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu- - ment is either a number or a quoted string (see the pcre2callout docu- - mentation for details). Numbered callouts are ignored by pcre2grep. - String arguments are parsed as a list of substrings separated by pipe - (vertical bar) characters. The first substring must be an executable - name, with the following substrings specifying arguments: + If the callout string does not start with a pipe (vertical bar) charac- + ter, it is parsed into a list of substrings separated by pipe charac- + ters. The first substring must be an executable name, with the follow- + ing substrings specifying arguments: executable_name|arg1|arg2|... @@ -781,6 +872,18 @@ CALLING EXTERNAL SCRIPTS local matching failure occurs and the matcher backtracks in the normal way. + Echoing a specific string + + If the callout string starts with a pipe (vertical bar) character, the + rest of the string is written to the output, having been passed through + the same escape processing as text from the --output option. This pro- + vides a simple echoing facility that avoids calling an external program + or script. No terminator is added to the string, so if you want a new- + line, you must include it explicitly. Matching continues normally + after the string is output. If you want to see only the callout output + but not any output from an actual match, you should end the relevant + pattern with (*FAIL). + MATCHING ERRORS @@ -794,9 +897,9 @@ MATCHING ERRORS such errors, pcre2grep gives up. The --match-limit option of pcre2grep 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). + resource limit. There are also other limits that affect the amount of + memory used during matching; see the discussion of --heap-limit and + --depth-limit above. DIAGNOSTICS @@ -807,6 +910,10 @@ DIAGNOSTICS errors. Using the -s option to suppress error messages about inaccessi- ble files does not affect the return code. + When run under VMS, the return code is placed in the symbol + PCRE2GREP_RC because VMS does not distinguish between exit(0) and + exit(1). + SEE ALSO @@ -822,5 +929,5 @@ AUTHOR REVISION - Last updated: 19 June 2016 - Copyright (c) 1997-2016 University of Cambridge. + Last updated: 13 November 2017 + Copyright (c) 1997-2017 University of Cambridge. |