grep-manpage.txt

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 regular 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 regular 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 compressed with the compress(1) or gzip(1) com-
     pression 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 spec-
	     ified 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 argument.

     -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 pat-
	     tern from the search.  Note that --exclude patterns take priority
	     over --include patterns, and if no --include pattern is speci-
	     fied, all files are searched that are not excluded.  Patterns are
	     matched to the full path specified, not only to the filename com-
	     ponent.

     --exclude-dir
	     If -R is specified, it excludes directories matching the given
	     filename pattern from the search.	Note that --exclude-dir pat-
	     terns 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 consid-
	     ered 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 sen-
	     sitive.

     --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, 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 pri-
	     ority 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.  Pathnames 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.  Path-
	     names 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 unde-
	     fined 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 suppressed).

     -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 pat-
	     terns.

     -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 regu-
	     lar 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.

ENVIRONMENT
     GREP_OPTIONS  May be used to specify default options that will be placed
		   at the beginning of the argument list.  Backslash-escaping
		   is not supported, unlike the behavior in GNU grep.

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.

BUGS
     The grep utility does not normalize Unicode input, so a pattern contain-
     ing composed characters will not match decomposed input, and vice versa.

BSD				 July 28, 2010				   BSD