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GREP(1)                   BSD General Commands Manual                  GREP(1)

NAME
     grep, egrep, fgrep, zgrep, zegrep, zfgrep -- file pattern searcher

SYNOPSIS
     grep [-abcdDEFGHhIiJLlmnOopqRSsUVvwxZ] [-A num] [-B num] [-C[num]] [-e pattern] [-f file]
          [--binary-files=value] [--color[=when]] [--colour[=when]] [--context[=num]] [--label]
          [--line-buffered] [--null] [pattern] [file ...]

DESCRIPTION
     The grep utility searches any given input files, selecting lines that match one or more patterns.  By
     default, a pattern matches an input line if the regular expression (RE) in the pattern matches the
     input line without its trailing newline.  An empty expression matches every line.  Each input line that
     matches at least one of the patterns is written to the standard output.

     grep is used for simple patterns and basic regular expressions (BREs); egrep can handle extended regu-lar regular
     lar expressions (EREs).  See re_format(7) for more information on regular expressions.  fgrep is
     quicker than both grep and egrep, but can only handle fixed patterns (i.e. it does not interpret regu-lar regular
     lar expressions).  Patterns may consist of one or more lines, allowing any of the pattern lines to
     match a portion of the input.

     zgrep, zegrep, and zfgrep act like grep, egrep, and fgrep, respectively, but accept input files com-pressed compressed
     pressed with the compress(1) or gzip(1) compression utilities.

     The following options are available:

     -A num, --after-context=num
             Print num lines of trailing context after each match.  See also the -B and -C options.

     -a, --text
             Treat all files as ASCII text.  Normally grep will simply print ``Binary file ... matches'' if
             files contain binary characters.  Use of this option forces grep to output lines matching the
             specified pattern.

     -B num, --before-context=num
             Print num lines of leading context before each match.  See also the -A and -C options.

     -b, --byte-offset
             The offset in bytes of a matched pattern is displayed in front of the respective matched line.

     -C[num, --context=num]
             Print num lines of leading and trailing context surrounding each match.  The default is 2 and
             is equivalent to -A 2 -B 2.  Note: no whitespace may be given between the option and its argu-ment. argument.
             ment.

     -c, --count
             Only a count of selected lines is written to standard output.

     --colour=[when, --color=[when]]
             Mark up the matching text with the expression stored in GREP_COLOR environment variable.  The
             possible values of when can be `never', `always' or `auto'.

     -D action, --devices=action
             Specify the demanded action for devices, FIFOs and sockets.  The default action is `read',
             which means, that they are read as if they were normal files.  If the action is set to `skip',
             devices will be silently skipped.

     -d action, --directories=action
             Specify the demanded action for directories.  It is `read' by default, which means that the
             directories are read in the same manner as normal files.  Other possible values are `skip' to
             silently ignore the directories, and `recurse' to read them recursively, which has the same
             effect as the -R and -r option.

     -E, --extended-regexp
             Interpret pattern as an extended regular expression (i.e. force grep to behave as egrep).

     -e pattern, --regexp=pattern
             Specify a pattern used during the search of the input: an input line is selected if it matches
             any of the specified patterns.  This option is most useful when multiple -e options are used to
             specify multiple patterns, or when a pattern begins with a dash (`-').

     --exclude
             If specified, it excludes files matching the given filename pattern from the search.  Note that
             --exclude patterns take priority over --include patterns, and if no --include pattern is speci-fied, specified,
             fied, all files are searched that are not excluded.  Patterns are matched to the full path
             specified, not only to the filename component.

     --exclude-dir
             If -R is specified, it excludes directories matching the given filename pattern from the
             search.  Note that --exclude-dir patterns take priority over --include-dir patterns, and if no
             --include-dir pattern is specified, all directories are searched that are not excluded.

     -F, --fixed-strings
             Interpret pattern as a set of fixed strings (i.e. force grep to behave as fgrep).

     -f file, --file=file
             Read one or more newline separated patterns from file.  Empty pattern lines match every input
             line.  Newlines are not considered part of a pattern.  If file is empty, nothing is matched.

     -G, --basic-regexp
             Interpret pattern as a basic regular expression (i.e. force grep to behave as traditional
             grep).

     -H      Always print filename headers with output lines.

     -h, --no-filename
             Never print filename headers (i.e. filenames) with output lines.

     --help  Print a brief help message.

     -I      Ignore binary files.  This option is equivalent to --binary-file=without-match option.

     -i, --ignore-case
             Perform case insensitive matching.  By default, grep is case sensitive.

     --include
             If specified, only files matching the given filename pattern are searched.  Note that --exclude
             patterns take priority over --include patterns.  Patterns are matched to the full path speci-fied, specified,
             fied, not only to the filename component.

     --include-dir
             If -R is specified, only directories matching the given filename pattern are searched.  Note
             that --exclude-dir patterns take priority over --include-dir patterns.

     -J, --bz2decompress
             Decompress the bzip2(1) compressed file before looking for the text.

     -L, --files-without-match
             Only the names of files not containing selected lines are written to standard output.  Path-names Pathnames
             names are listed once per file searched.  If the standard input is searched, the string
             ``(standard input)'' is written.

     -l, --files-with-matches
             Only the names of files containing selected lines are written to standard output.  grep will
             only search a file until a match has been found, making searches potentially less expensive.
             Pathnames are listed once per file searched.  If the standard input is searched, the string
             ``(standard input)'' is written.

     --mmap  Use mmap(2) instead of read(2) to read input, which can result in better performance under some
             circumstances but can cause undefined behaviour.

     -m num, --max-count=num
             Stop reading the file after num matches.

     -n, --line-number
             Each output line is preceded by its relative line number in the file, starting at line 1.  The
             line number counter is reset for each file processed.  This option is ignored if -c, -L, -l, or
             -q is specified.

     --null  Prints a zero-byte after the file name.

     -O      If -R is specified, follow symbolic links only if they were explicitly listed on the command
             line.  The default is not to follow symbolic links.

     -o, --only-matching
             Prints only the matching part of the lines.

     -p      If -R is specified, no symbolic links are followed.  This is the default.

     -q, --quiet, --silent
             Quiet mode: suppress normal output.  grep will only search a file until a match has been found,
             making searches potentially less expensive.

     -R, -r, --recursive
             Recursively search subdirectories listed.

     -S      If -R is specified, all symbolic links are followed.  The default is not to follow symbolic
             links.

     -s, --no-messages
             Silent mode.  Nonexistent and unreadable files are ignored (i.e. their error messages are sup-pressed). suppressed).
             pressed).

     -U, --binary
             Search binary files, but do not attempt to print them.

     -V, --version
             Display version information and exit.

     -v, --invert-match
             Selected lines are those not matching any of the specified patterns.

     -w, --word-regexp
             The expression is searched for as a word (as if surrounded by `[[:<:]]' and `[[:>:]]'; see
             re_format(7)).

     -x, --line-regexp
             Only input lines selected against an entire fixed string or regular expression are considered
             to be matching lines.

     -y      Equivalent to -i.  Obsoleted.

     -Z, -z, --decompress
             Force grep to behave as zgrep.

     --binary-files=value
             Controls searching and printing of binary files.  Options are binary, the default: search
             binary files but do not print them; without-match: do not search binary files; and text: treat
             all files as text.

     --context[=num]
             Print num lines of leading and trailing context.  The default is 2.

     --line-buffered
             Force output to be line buffered.  By default, output is line buffered when standard output is
             a terminal and block buffered otherwise.

     If no file arguments are specified, the standard input is used.

EXIT STATUS
     The grep utility exits with one of the following values:

     0     One or more lines were selected.
     1     No lines were selected.
     >1    An error occurred.

EXAMPLES
     To find all occurrences of the word `patricia' in a file:

           $ grep 'patricia' myfile

     To find all occurrences of the pattern `.Pp' at the beginning of a line:

           $ grep '^\.Pp' myfile

     The apostrophes ensure the entire expression is evaluated by grep instead of by the user's shell.  The
     caret `^' matches the null string at the beginning of a line, and the `\' escapes the `.', which would
     otherwise match any character.

     To find all lines in a file which do not contain the words `foo' or `bar':

           $ grep -v -e 'foo' -e 'bar' myfile

     A simple example of an extended regular expression:

           $ egrep '19|20|25' calendar

     Peruses the file `calendar' looking for either 19, 20, or 25.

SEE ALSO
     ed(1), ex(1), gzip(1), sed(1), re_format(7)

STANDARDS
     The grep utility is compliant with the IEEE Std 1003.1-2008 (``POSIX.1'') specification.

     The flags [-AaBbCDdGHhIJLmoPRSUVwZ] are extensions to that specification, and the behaviour of the -f
     flag when used with an empty pattern file is left undefined.

     All long options are provided for compatibility with GNU versions of this utility.

     Historic versions of the grep utility also supported the flags [-ruy].  This implementation supports
     those options; however, their use is strongly discouraged.

HISTORY
     The grep command first appeared in Version 6 AT&T UNIX.

BSD                              July 28, 2010                             BSD

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