1021 lines
57 KiB
Plaintext
1021 lines
57 KiB
Plaintext
PCRE2GREP(1) General Commands Manual PCRE2GREP(1)
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NAME
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pcre2grep - a grep with Perl-compatible regular expressions.
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SYNOPSIS
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pcre2grep [options] [long options] [pattern] [path1 path2 ...]
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DESCRIPTION
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pcre2grep searches files for character patterns, in the same way as
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other grep commands do, but it uses the PCRE2 regular expression li-
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brary to support patterns that are compatible with the regular expres-
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sions of Perl 5. See pcre2syntax(3) for a quick-reference summary of
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pattern syntax, or pcre2pattern(3) for a full description of the syntax
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and semantics of the regular expressions that PCRE2 supports.
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Patterns, whether supplied on the command line or in a separate file,
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are given without delimiters. For example:
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pcre2grep Thursday /etc/motd
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If you attempt to use delimiters (for example, by surrounding a pattern
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with slashes, as is common in Perl scripts), they are interpreted as
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part of the pattern. Quotes can of course be used to delimit patterns
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on the command line because they are interpreted by the shell, and in-
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deed quotes are required if a pattern contains white space or shell
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metacharacters.
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The first argument that follows any option settings is treated as the
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single pattern to be matched when neither -e nor -f is present. Con-
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versely, when one or both of these options are used to specify pat-
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terns, all arguments are treated as path names. At least one of -e, -f,
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or an argument pattern must be provided.
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If no files are specified, pcre2grep reads the standard input. The
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standard input can also be referenced by a name consisting of a single
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hyphen. For example:
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pcre2grep some-pattern file1 - file3
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Input files are searched line by line. By default, each line that
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matches a pattern is copied to the standard output, and if there is
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more than one file, the file name is output at the start of each line,
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followed by a colon. However, there are options that can change how
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pcre2grep behaves. In particular, the -M option makes it possible to
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search for strings that span line boundaries. What defines a line
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boundary is controlled by the -N (--newline) option.
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The amount of memory used for buffering files that are being scanned is
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controlled by parameters that can be set by the --buffer-size and
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--max-buffer-size options. The first of these sets the size of buffer
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that is obtained at the start of processing. If an input file contains
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very long lines, a larger buffer may be needed; this is handled by au-
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tomatically extending the buffer, up to the limit specified by --max-
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buffer-size. The default values for these parameters can be set when
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pcre2grep is built; if nothing is specified, the defaults are set to
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20KiB and 1MiB respectively. An error occurs if a line is too long and
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the buffer can no longer be expanded.
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The block of memory that is actually used is three times the "buffer
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size", to allow for buffering "before" and "after" lines. If the buffer
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size is too small, fewer than requested "before" and "after" lines may
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be output.
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Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the
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greater. BUFSIZ is defined in <stdio.h>. When there is more than one
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pattern (specified by the use of -e and/or -f), each pattern is applied
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to each line in the order in which they are defined, except that all
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the -e patterns are tried before the -f patterns.
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By default, as soon as one pattern matches a line, no further patterns
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are considered. However, if --colour (or --color) is used to colour the
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matching substrings, or if --only-matching, --file-offsets, or --line-
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offsets is used to output only the part of the line that matched (ei-
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ther shown literally, or as an offset), scanning resumes immediately
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following the match, so that further matches on the same line can be
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found. If there are multiple patterns, they are all tried on the re-
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mainder of the line, but patterns that follow the one that matched are
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not tried on the earlier matched part of the line.
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This behaviour means that the order in which multiple patterns are
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specified can affect the output when one of the above options is used.
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This is no longer the same behaviour as GNU grep, which now manages to
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display earlier matches for later patterns (as long as there is no
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overlap).
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Patterns that can match an empty string are accepted, but empty string
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matches are never recognized. An example is the pattern "(su-
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per)?(man)?", in which all components are optional. This pattern finds
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all occurrences of both "super" and "man"; the output differs from
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matching with "super|man" when only the matching substrings are being
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shown.
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If the LC_ALL or LC_CTYPE environment variable is set, pcre2grep uses
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the value to set a locale when calling the PCRE2 library. The --locale
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option can be used to override this.
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SUPPORT FOR COMPRESSED FILES
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It is possible to compile pcre2grep so that it uses libz or libbz2 to
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read compressed files whose names end in .gz or .bz2, respectively. You
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can find out whether your pcre2grep binary has support for one or both
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of these file types by running it with the --help option. If the appro-
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priate support is not present, all files are treated as plain text. The
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standard input is always so treated. When input is from a compressed
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.gz or .bz2 file, the --line-buffered option is ignored.
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BINARY FILES
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By default, a file that contains a binary zero byte within the first
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1024 bytes is identified as a binary file, and is processed specially.
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However, if the newline type is specified as NUL, that is, the line
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terminator is a binary zero, the test for a binary file is not applied.
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See the --binary-files option for a means of changing the way binary
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files are handled.
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BINARY ZEROS IN PATTERNS
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Patterns passed from the command line are strings that are terminated
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by a binary zero, so cannot contain internal zeros. However, patterns
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that are read from a file via the -f option may contain binary zeros.
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OPTIONS
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The order in which some of the options appear can affect the output.
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For example, both the -H and -l options affect the printing of file
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names. Whichever comes later in the command line will be the one that
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takes effect. Similarly, except where noted below, if an option is
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given twice, the later setting is used. Numerical values for options
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may be followed by K or M, to signify multiplication by 1024 or
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1024*1024 respectively.
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-- This terminates the list of options. It is useful if the next
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item on the command line starts with a hyphen but is not an
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option. This allows for the processing of patterns and file
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names that start with hyphens.
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-A number, --after-context=number
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Output up to number lines of context after each matching
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line. Fewer lines are output if the next match or the end of
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the file is reached, or if the processing buffer size has
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been set too small. If file names and/or line numbers are be-
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ing output, a hyphen separator is used instead of a colon for
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the context lines. A line containing "--" is output between
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each group of lines, unless they are in fact contiguous in
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the input file. The value of number is expected to be rela-
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tively small. When -c is used, -A is ignored.
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-a, --text
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Treat binary files as text. This is equivalent to --binary-
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files=text.
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-B number, --before-context=number
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Output up to number lines of context before each matching
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line. Fewer lines are output if the previous match or the
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start of the file is within number lines, or if the process-
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ing buffer size has been set too small. If file names and/or
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line numbers are being output, a hyphen separator is used in-
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stead of a colon for the context lines. A line containing
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"--" is output between each group of lines, unless they are
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in fact contiguous in the input file. The value of number is
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expected to be relatively small. When -c is used, -B is ig-
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nored.
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--binary-files=word
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Specify how binary files are to be processed. If the word is
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"binary" (the default), pattern matching is performed on bi-
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nary files, but the only output is "Binary file <name>
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matches" when a match succeeds. If the word is "text", which
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is equivalent to the -a or --text option, binary files are
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processed in the same way as any other file. In this case,
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when a match succeeds, the output may be binary garbage,
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which can have nasty effects if sent to a terminal. If the
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word is "without-match", which is equivalent to the -I op-
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tion, binary files are not processed at all; they are assumed
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not to be of interest and are skipped without causing any
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output or affecting the return code.
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--buffer-size=number
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Set the parameter that controls how much memory is obtained
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at the start of processing for buffering files that are being
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scanned. See also --max-buffer-size below.
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-C number, --context=number
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Output number lines of context both before and after each
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matching line. This is equivalent to setting both -A and -B
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to the same value.
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-c, --count
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Do not output lines from the files that are being scanned;
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instead output the number of lines that would have been
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shown, either because they matched, or, if -v is set, because
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they failed to match. By default, this count is exactly the
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same as the number of lines that would have been output, but
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if the -M (multiline) option is used (without -v), there may
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be more suppressed lines than the count (that is, the number
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of matches).
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If no lines are selected, the number zero is output. If sev-
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eral files are are being scanned, a count is output for each
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of them and the -t option can be used to cause a total to be
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output at the end. However, if the --files-with-matches op-
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tion is also used, only those files whose counts are greater
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than zero are listed. When -c is used, the -A, -B, and -C op-
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tions are ignored.
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--colour, --color
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If this option is given without any data, it is equivalent to
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"--colour=auto". If data is required, it must be given in
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the same shell item, separated by an equals sign.
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--colour=value, --color=value
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This option specifies under what circumstances the parts of a
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line that matched a pattern should be coloured in the output.
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By default, the output is not coloured. The value (which is
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optional, see above) may be "never", "always", or "auto". In
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the latter case, colouring happens only if the standard out-
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put is connected to a terminal. More resources are used when
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colouring is enabled, because pcre2grep has to search for all
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possible matches in a line, not just one, in order to colour
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them all.
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The colour that is used can be specified by setting one of
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the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR,
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PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that
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order. If none of these are set, pcre2grep looks for
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GREP_COLORS or GREP_COLOR (in that order). The value of the
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variable should be a string of two numbers, separated by a
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semicolon, except in the case of GREP_COLORS, which must
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start with "ms=" or "mt=" followed by two semicolon-separated
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colours, terminated by the end of the string or by a colon.
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If GREP_COLORS does not start with "ms=" or "mt=" it is ig-
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nored, and GREP_COLOR is checked.
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If the string obtained from one of the above variables con-
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tains any characters other than semicolon or digits, the set-
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ting is ignored and the default colour is used. The string is
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copied directly into the control string for setting colour on
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a terminal, so it is your responsibility to ensure that the
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values make sense. If no relevant environment variable is
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set, the default is "1;31", which gives red.
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-D action, --devices=action
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If an input path is not a regular file or a directory, "ac-
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tion" specifies how it is to be processed. Valid values are
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"read" (the default) or "skip" (silently skip the path).
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-d action, --directories=action
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If an input path is a directory, "action" specifies how it is
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to be processed. Valid values are "read" (the default in
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non-Windows environments, for compatibility with GNU grep),
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"recurse" (equivalent to the -r option), or "skip" (silently
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skip the path, the default in Windows environments). In the
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"read" case, directories are read as if they were ordinary
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files. In some operating systems the effect of reading a di-
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rectory like this is an immediate end-of-file; in others it
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may provoke an error.
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--depth-limit=number
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See --match-limit below.
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-e pattern, --regex=pattern, --regexp=pattern
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Specify a pattern to be matched. This option can be used mul-
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tiple times in order to specify several patterns. It can also
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be used as a way of specifying a single pattern that starts
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with a hyphen. When -e is used, no argument pattern is taken
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from the command line; all arguments are treated as file
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names. There is no limit to the number of patterns. They are
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applied to each line in the order in which they are defined
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until one matches.
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If -f is used with -e, the command line patterns are matched
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first, followed by the patterns from the file(s), independent
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of the order in which these options are specified. Note that
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multiple use of -e is not the same as a single pattern with
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alternatives. For example, X|Y finds the first character in a
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line that is X or Y, whereas if the two patterns are given
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separately, with X first, pcre2grep finds X if it is present,
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even if it follows Y in the line. It finds Y only if there is
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no X in the line. This matters only if you are using -o or
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--colo(u)r to show the part(s) of the line that matched.
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--exclude=pattern
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Files (but not directories) whose names match the pattern are
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skipped without being processed. This applies to all files,
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whether listed on the command line, obtained from --file-
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list, or by scanning a directory. The pattern is a PCRE2 reg-
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ular expression, and is matched against the final component
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of the file name, not the entire path. The -F, -w, and -x op-
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tions do not apply to this pattern. The option may be given
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any number of times in order to specify multiple patterns. If
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a file name matches both an --include and an --exclude pat-
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tern, it is excluded. There is no short form for this option.
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--exclude-from=filename
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Treat each non-empty line of the file as the data for an
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--exclude option. What constitutes a newline when reading the
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file is the operating system's default. The --newline option
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has no effect on this option. This option may be given more
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than once in order to specify a number of files to read.
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--exclude-dir=pattern
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Directories whose names match the pattern are skipped without
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being processed, whatever the setting of the --recursive op-
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tion. This applies to all directories, whether listed on the
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command line, obtained from --file-list, or by scanning a
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parent directory. The pattern is a PCRE2 regular expression,
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and is matched against the final component of the directory
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name, not the entire path. The -F, -w, and -x options do not
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apply to this pattern. The option may be given any number of
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times in order to specify more than one pattern. If a direc-
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tory matches both --include-dir and --exclude-dir, it is ex-
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cluded. There is no short form for this option.
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-F, --fixed-strings
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Interpret each data-matching pattern as a list of fixed
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strings, separated by newlines, instead of as a regular ex-
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pression. What constitutes a newline for this purpose is con-
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trolled by the --newline option. The -w (match as a word) and
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-x (match whole line) options can be used with -F. They ap-
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ply to each of the fixed strings. A line is selected if any
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of the fixed strings are found in it (subject to -w or -x, if
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present). This option applies only to the patterns that are
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matched against the contents of files; it does not apply to
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patterns specified by any of the --include or --exclude op-
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tions.
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-f filename, --file=filename
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Read patterns from the file, one per line, and match them
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against each line of input. As is the case with patterns on
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the command line, no delimiters should be used. What consti-
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tutes a newline when reading the file is the operating sys-
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tem's default interpretation of \n. The --newline option has
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no effect on this option. Trailing white space is removed
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from each line, and blank lines are ignored. An empty file
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contains no patterns and therefore matches nothing. Patterns
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read from a file in this way may contain binary zeros, which
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are treated as ordinary data characters. See also the com-
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ments about multiple patterns versus a single pattern with
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alternatives in the description of -e above.
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If this option is given more than once, all the specified
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files are read. A data line is output if any of the patterns
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match it. A file name can be given as "-" to refer to the
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standard input. When -f is used, patterns specified on the
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command line using -e may also be present; they are tested
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before the file's patterns. However, no other pattern is
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taken from the command line; all arguments are treated as the
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names of paths to be searched.
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--file-list=filename
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Read a list of files and/or directories that are to be
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scanned from the given file, one per line. What constitutes a
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newline when reading the file is the operating system's de-
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fault. Trailing white space is removed from each line, and
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blank lines are ignored. These paths are processed before any
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that are listed on the command line. The file name can be
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given as "-" to refer to the standard input. If --file and
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--file-list are both specified as "-", patterns are read
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first. This is useful only when the standard input is a ter-
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minal, from which further lines (the list of files) can be
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read after an end-of-file indication. If this option is given
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more than once, all the specified files are read.
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--file-offsets
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Instead of showing lines or parts of lines that match, show
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each match as an offset from the start of the file and a
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length, separated by a comma. In this mode, no context is
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shown. That is, the -A, -B, and -C options are ignored. If
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there is more than one match in a line, each of them is shown
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separately. This option is mutually exclusive with --output,
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--line-offsets, and --only-matching.
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-H, --with-filename
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Force the inclusion of the file name at the start of output
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lines when searching a single file. By default, the file name
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is not shown in this case. For matching lines, the file name
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is followed by a colon; for context lines, a hyphen separator
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is used. If a line number is also being output, it follows
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the file name. When the -M option causes a pattern to match
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more than one line, only the first is preceded by the file
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name. This option overrides any previous -h, -l, or -L op-
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tions.
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-h, --no-filename
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Suppress the output file names when searching multiple files.
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By default, file names are shown when multiple files are
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searched. For matching lines, the file name is followed by a
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colon; for context lines, a hyphen separator is used. If a
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line number is also being output, it follows the file name.
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This option overrides any previous -H, -L, or -l options.
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--heap-limit=number
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See --match-limit below.
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--help Output a help message, giving brief details of the command
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options and file type support, and then exit. Anything else
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on the command line is ignored.
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-I Ignore binary files. This is equivalent to --binary-
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files=without-match.
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-i, --ignore-case
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Ignore upper/lower case distinctions during comparisons.
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--include=pattern
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If any --include patterns are specified, the only files that
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are processed are those whose names match one of the patterns
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and do not match an --exclude pattern. This option does not
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affect directories, but it applies to all files, whether
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listed on the command line, obtained from --file-list, or by
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scanning a directory. The pattern is a PCRE2 regular expres-
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sion, and is matched against the final component of the file
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name, not the entire path. The -F, -w, and -x options do not
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apply to this pattern. The option may be given any number of
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times. If a file name matches both an --include and an --ex-
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clude pattern, it is excluded. There is no short form for
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this option.
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--include-from=filename
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Treat each non-empty line of the file as the data for an
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--include option. What constitutes a newline for this purpose
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is the operating system's default. The --newline option has
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no effect on this option. This option may be given any number
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of times; all the files are read.
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--include-dir=pattern
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If any --include-dir patterns are specified, the only direc-
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tories that are processed are those whose names match one of
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the patterns and do not match an --exclude-dir pattern. This
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applies to all directories, whether listed on the command
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line, obtained from --file-list, or by scanning a parent di-
|
|
rectory. 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,
|
|
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. This option overrides any previous -H, -h, or -l
|
|
options.
|
|
|
|
-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 that occurs
|
|
with -c on its own. This option overrides any previous -H,
|
|
-h, or -L options.
|
|
|
|
--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, 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 or
|
|
Windows. 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
|
|
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 --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 li-
|
|
brary's default (usually the "C" locale) is used. There is no
|
|
short form for this option.
|
|
|
|
-M, --multiline
|
|
Allow patterns to match more than one line. When this option
|
|
is 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, in-
|
|
cluding newlines, and is followed by + so as to match trail-
|
|
ing white space on the first line as well as possibly han-
|
|
dling 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. 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.)
|
|
|
|
-m number, --max-count=number
|
|
Stop processing after finding number matching lines, or non-
|
|
matching lines if -v is also set. Any trailing context lines
|
|
are output after the final match. In multiline mode, each
|
|
multiline match counts as just one line for this purpose. If
|
|
this limit is reached when reading the standard input from a
|
|
regular file, the file is left positioned just after the last
|
|
matching line. If -c is also set, the count that is output
|
|
is never greater than number. This option has no effect if
|
|
used with -L, -l, or -q, or when just checking for a match in
|
|
a binary file.
|
|
|
|
--match-limit=number
|
|
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 go-
|
|
ing to match, but which have a very large number of possibil-
|
|
ities in their search trees. The classic example is a pattern
|
|
that uses nested unlimited repeats. Internally, PCRE2 has a
|
|
counter that is incremented each time around its main pro-
|
|
cessing loop. If the value set by --match-limit is reached,
|
|
an error occurs.
|
|
|
|
The --heap-limit option specifies, as a number of kibibytes
|
|
(units of 1024 bytes), the amount of heap memory that may be
|
|
used for matching. Heap memory is needed only if matching the
|
|
pattern requires a significant number of nested backtracking
|
|
points to be remembered. 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 lim-
|
|
its can be set when the PCRE2 library is compiled; if they
|
|
are not specified, the defaults are very large and so effec-
|
|
tively 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.
|
|
|
|
-N newline-type, --newline=newline-type
|
|
Six different conventions for indicating the ends of lines in
|
|
scanned files are supported. For example:
|
|
|
|
pcre2grep -N CRLF 'some pattern' <file>
|
|
|
|
The newline type may be specified in upper, lower, or mixed
|
|
case. If the newline type is NUL, lines are separated by bi-
|
|
nary zero characters. The other types are the single-charac-
|
|
ter sequences CR (carriage return) and LF (linefeed), the
|
|
two-character sequence CRLF, an "anycrlf" type, which recog-
|
|
nizes any of the preceding three types, and an "any" type,
|
|
for which any Unicode line ending sequence is assumed to end
|
|
a line. The Unicode sequences are the three just mentioned,
|
|
plus VT (vertical tab, U+000B), FF (form feed, U+000C), NEL
|
|
(next line, U+0085), LS (line separator, U+2028), and PS
|
|
(paragraph separator, U+2029).
|
|
|
|
When the PCRE2 library is built, a default line-ending se-
|
|
quence is specified. This is normally the standard sequence
|
|
for the operating system. Unless otherwise specified by this
|
|
option, pcre2grep uses the library's default.
|
|
|
|
This option 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 op-
|
|
erating 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 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
|
|
number. This option is forced if --line-offsets is used.
|
|
|
|
--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-
|
|
lems. It should never be needed in normal use.
|
|
|
|
-O text, --output=text
|
|
When there is a match, instead of outputting the line that
|
|
matched, output just the text specified in this option, fol-
|
|
lowed by an operating-system standard newline. In this mode,
|
|
no context is shown. That is, the -A, -B, and -C options are
|
|
ignored. The --newline option has no effect on this option,
|
|
which is mutually exclusive with --only-matching, --file-off-
|
|
sets, and --line-offsets. However, like --only-matching, if
|
|
there is more than one match in a line, each of them causes a
|
|
line of output.
|
|
|
|
Escape sequences starting with a dollar character 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> or $o{<digits>} is replaced by the character whose
|
|
code point is the given octal number. In the first form, up
|
|
to three octal digits are processed. When more digits are
|
|
needed in Unicode mode to specify a wide character, the sec-
|
|
ond form must be used.
|
|
|
|
$x<digits> or $x{<digits>} is replaced by the character rep-
|
|
resented by the given hexadecimal number. In the first form,
|
|
up to two hexadecimal digits are processed. When more digits
|
|
are needed in Unicode mode to specify a wide character, the
|
|
second form must be used.
|
|
|
|
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,
|
|
on a separate line of output. If -o is combined with -v (in-
|
|
vert 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
|
|
parentheses of the given number. Up to 50 capturing parenthe-
|
|
ses are supported by default. This limit can be changed via
|
|
the --om-capture option. A pattern may contain any number of
|
|
capturing parentheses, but only those whose number is within
|
|
the limit can be accessed by -o. An error occurs if the num-
|
|
ber specified by -o is greater than the limit.
|
|
|
|
-o0 is the same as -o without a number. 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 ex-
|
|
ample, -o3 or --only-matching=2. The comments given for the
|
|
non-argument case above also apply 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 output.
|
|
|
|
If this option is given multiple times, multiple substrings
|
|
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 but one option).
|
|
|
|
--om-capture=number
|
|
Set the number of capturing parentheses that can be accessed
|
|
by -o. The default is 50.
|
|
|
|
--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 "re-
|
|
curse".
|
|
|
|
--recursion-limit=number
|
|
This is an obsolete synonym for --depth-limit. See --match-
|
|
limit above for details.
|
|
|
|
-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.
|
|
|
|
-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 to-
|
|
tal 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 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 lines
|
|
that are scanned must be valid strings of UTF-8 characters.
|
|
If an invalid UTF-8 string is encountered, an error occurs.
|
|
|
|
-U, --utf-allow-invalid
|
|
As --utf, but in addition subject lines may contain invalid
|
|
UTF-8 code unit sequences. These can never form part of any
|
|
pattern match. Patterns themselves, however, must still be
|
|
valid UTF-8 strings. This facility allows valid UTF-8 strings
|
|
to be sought within arbitrary byte sequences in executable or
|
|
other binary files. For more details about matching in non-
|
|
valid UTF-8 strings, see the pcre2unicode(3) documentation.
|
|
|
|
-V, --version
|
|
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
|
|
match any of the patterns are the ones that are found. When
|
|
this option is set, options such as --only-matching and
|
|
--output, which specify parts of a match that are to be out-
|
|
put, are ignored.
|
|
|
|
-w, --word-regex, --word-regexp
|
|
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 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 or-
|
|
der, for a locale. The first one that is set is used. This can be over-
|
|
ridden by the --locale option. If no locale is set, the PCRE2 library's
|
|
default (usually the "C" locale) is used.
|
|
|
|
|
|
NEWLINES
|
|
|
|
The -N (--newline) option allows pcre2grep to scan files with newline
|
|
conventions that differ from the default. This option affects only the
|
|
way scanned files are processed. It does not affect the interpretation
|
|
of files specified by the -f, --file-list, --exclude-from, or --in-
|
|
clude-from options.
|
|
|
|
Any parts of the scanned input files that are written to the standard
|
|
output are copied with whatever newline sequences they have in the in-
|
|
put. However, if the final line of a file is output, and it does not
|
|
end with a newline sequence, a newline sequence is added. If the new-
|
|
line setting is CR, LF, CRLF or NUL, that line ending is output; for
|
|
the other settings (ANYCRLF or ANY) a single NL is used.
|
|
|
|
The newline setting does not affect the way in which pcre2grep writes
|
|
newlines in informational messages to the standard output and error
|
|
streams. Under Windows, the standard output is set to be binary, so
|
|
that "\r\n" at the ends of output lines that are copied from the input
|
|
is not converted to "\r\r\n" by the C I/O library. This means that any
|
|
messages written to the standard output must end with "\r\n". For all
|
|
other operating systems, and for all messages to the standard error
|
|
stream, "\n" is used.
|
|
|
|
|
|
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
|
|
terminology) is also available as --xxx-regex (PCRE2 terminology). How-
|
|
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, --utf, -U, and
|
|
--utf-allow-invalid 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-
|
|
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 di-
|
|
rectory, 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 op-
|
|
tions does have data, it must be given in the first form, using an
|
|
equals character. Otherwise pcre2grep will assume that it has no data.
|
|
|
|
|
|
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 completely or
|
|
partially disabled when pcre2grep is built. You can find out whether
|
|
your binary has support for callouts by running it with the --help op-
|
|
tion. If callout support is completely disabled, all callouts in pat-
|
|
terns are ignored by pcre2grep. If the facility is partially disabled,
|
|
calling external programs is not supported, and callouts that request
|
|
it are ignored.
|
|
|
|
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.
|
|
|
|
Echoing a specific string
|
|
|
|
Starting the callout string with a pipe character invokes an echoing
|
|
facility that avoids calling an external program or script. This facil-
|
|
ity is always available, provided that callouts were not completely
|
|
disabled when pcre2grep was built. The rest of the callout string is
|
|
processed as a zero-terminated string, which means it should not con-
|
|
tain any internal binary zeros. It is written to the output, having
|
|
first been passed through the same escape processing as text from the
|
|
--output (-O) option (see above). However, $0 cannot be used to insert
|
|
a matched substring because the match is still in progress. Instead,
|
|
the single character '0' is inserted. Any syntax errors in the string
|
|
(for example, a dollar not followed by another character) causes the
|
|
callout to be ignored. No terminator is added to the output string, so
|
|
if you want a newline, you must include it explicitly using the escape
|
|
$n. For example:
|
|
|
|
pcre2grep '(.)(..(.))(?C"|[$1] [$2] [$3]$n")' <some file>
|
|
|
|
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 pattern with (*FAIL).
|
|
|
|
Calling external programs or scripts
|
|
|
|
This facility can be independently disabled when pcre2grep is built. It
|
|
is supported for Windows, where a call to _spawnvp() is used, for VMS,
|
|
where lib$spawn() is used, and for any Unix-like environment where
|
|
fork() and execv() are available.
|
|
|
|
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|...
|
|
|
|
Any substring (including the executable name) may contain escape se-
|
|
quences started by a dollar character. These are the same as for the
|
|
--output (-O) option documented above, except that $0 cannot insert the
|
|
matched string because the match is still in progress. Instead, the
|
|
character '0' is inserted. If you need a literal dollar or pipe charac-
|
|
ter in any substring, use $$ or $| respectively. Here is an example:
|
|
|
|
echo -e "abcde\n12345" | pcre2grep \
|
|
'(?x)(.)(..(.))
|
|
(?C"/bin/echo|Arg1: [$1] [$2] [$3]|Arg2: $|${1}$| ($4)")()' -
|
|
|
|
Output:
|
|
|
|
Arg1: [a] [bcd] [d] Arg2: |a| ()
|
|
abcde
|
|
Arg1: [1] [234] [4] Arg2: |1| ()
|
|
12345
|
|
|
|
The parameters for the system call that is used to run the program or
|
|
script are zero-terminated strings. This means that binary zero charac-
|
|
ters in the callout argument will cause premature termination of their
|
|
substrings, and therefore should not be present. Any syntax errors in
|
|
the string (for example, a dollar not followed by another character)
|
|
causes the callout to be ignored. If running the program fails for any
|
|
reason (including the non-existence of the executable), a local match-
|
|
ing failure occurs and the matcher backtracks in the normal way.
|
|
|
|
|
|
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 PCRE2 matching function has a re-
|
|
source limit that causes it to abort in these circumstances. If this
|
|
happens, pcre2grep outputs an error message and the line that caused
|
|
the problem to the standard error stream. If there are more than 20
|
|
such errors, pcre2grep gives up.
|
|
|
|
The --match-limit option of pcre2grep can be used to set the overall
|
|
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
|
|
|
|
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.
|
|
|
|
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
|
|
|
|
pcre2pattern(3), pcre2syntax(3), pcre2callout(3), pcre2unicode(3).
|
|
|
|
|
|
AUTHOR
|
|
|
|
Philip Hazel
|
|
University Computing Service
|
|
Cambridge, England.
|
|
|
|
|
|
REVISION
|
|
|
|
Last updated: 04 October 2020
|
|
Copyright (c) 1997-2020 University of Cambridge.
|