GREP(1) General Commands Manual GREP(1)
grep, egrep, fgrep, rgrep, bzgrep, bzegrep, bzfgrep, zgrep, zegrep, zfgrep
– file pattern searcher
grep [-abcdDEFGHhIiJLlMmnOopqRSsUVvwXxZz] [-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 ...]
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
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)
compression utilities. bzgrep, bzegrep, and bzfgrep act like grep, egrep,
and fgrep, respectively, but accept input files compressed with the
bzip2(1) compression utility.
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.
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
-B num, --before-context=num
Print num lines of leading context before each match. See also the
-A and -C options.
The offset in bytes of a matched pattern is displayed in front of
the respective matched line.
Print num lines of leading and trailing context surrounding each
match. The default value of num is “2” and is equivalent to “-A 2
-B 2”. Note: no whitespace may be given between the option and its
Only a count of selected lines is written to standard output.
Mark up the matching text with the expression stored in the
GREP_COLOR environment variable. The possible values of when are
“never”, “always” and “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
are 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.
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 (‘-’).
If specified, it excludes files matching the given filename pattern
from the search. Note that --exclude and --include patterns are
processed in the order given. If a name matches multiple patterns,
the latest matching rule wins. If no --include pattern is
specified, all files are searched that are not excluded. Patterns
are matched to the full path specified, not only to the filename
If -R is specified, it excludes directories matching the given
filename pattern from the search. Note that --exclude-dir and
--include-dir patterns are processed in the order given. If a name
matches multiple patterns, the latest matching rule wins. If no
--include-dir pattern is specified, all directories are searched
that are not excluded.
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.
Interpret pattern as a basic regular expression (i.e., force grep
to behave as traditional grep).
-H Always print filename headers with output lines.
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 the
Perform case insensitive matching. By default, grep is case
If specified, only files matching the given filename pattern are
searched. Note that --include and --exclude patterns are processed
in the order given. If a name matches multiple patterns, the
latest matching rule wins. Patterns are matched to the full path
specified, not only to the filename component.
If -R is specified, only directories matching the given filename
pattern are searched. Note that --include-dir and --exclude-dir
patterns are processed in the order given. If a name matches
multiple patterns, the latest matching rule wins.
Decompress the bzip2(1) compressed file before looking for the
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 unless a --label is specified.
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 unless a --label
Label to use in place of “(standard input)” for a file name where a
file name would normally be printed. This option applies to -H,
-L, and -l.
--mmap Use mmap(2) instead of read(2) to read input, which can result in
better performance under some circumstances but can cause undefined
Decompress the LZMA compressed file before looking for the text.
-m num, --max-count=num
Stop reading the file after num matches.
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
--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.
Prints only the matching part of the lines.
-p If -R is specified, no symbolic links are followed. This is the
-q, --quiet, --silent
Quiet mode: suppress normal output. grep will only search a file
until a match has been found, making searches potentially less
-R, -r, --recursive
Recursively search subdirectories listed. (i.e., force grep to
behave as rgrep).
-S If -R is specified, all symbolic links are followed. The default
is not to follow symbolic links.
Silent mode. Nonexistent and unreadable files are ignored (i.e.,
their error messages are suppressed).
Search binary files, but do not attempt to print them.
-u This option has no effect and is provided only for compatibility
with GNU grep.
Display version information and exit.
Selected lines are those not matching any of the specified
The expression is searched for as a word (as if surrounded by
‘[[:<:]]’ and ‘[[:>:]]’; see re_format(7)). This option has no
effect if -x is also specified.
Only input lines selected against an entire fixed string or regular
expression are considered to be matching lines.
-y Equivalent to -i. Obsoleted.
Treat input and output data as sequences of lines terminated by a
zero-byte instead of a newline.
Decompress the xz(1) compressed file before looking for the text.
Force grep to behave as zgrep.
Controls searching and printing of binary files. Options are:
binary (default) Search binary files but do not print them.
without-match Do not search binary files.
text Treat all files as text.
Force output to be line buffered. By default, output is line
buffered when standard output is a terminal and block buffered
If no file arguments are specified, the standard input is used.
Additionally, “-” may be used in place of a file name, anywhere that a file
name is accepted, to read from standard input. This includes both -f and
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.
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.
- Find all occurrences of the pattern ‘patricia’ in a file:
$ grep 'patricia' myfile
- Same as above but looking only for complete words:
$ grep -w 'patricia' myfile
- Count occurrences of the exact pattern ‘FOO’ :
$ grep -c FOO myfile
- Same as above but ignoring case:
$ grep -c -i FOO myfile
- 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.
- Find all lines in a file which do not contain the words ‘foo’ or ‘bar’:
$ grep -v -e 'foo' -e 'bar' myfile
- Peruse the file ‘calendar’ looking for either 19, 20, or 25 using
extended regular expressions:
$ egrep '19|20|25' calendar
- Show matching lines and the name of the ‘*.h’ files which contain the
pattern ‘FIXME’. Do the search recursively from the /usr/src/sys/arm
$ grep -H -R FIXME --include=*.h /usr/src/sys/arm/
- Same as above but show only the name of the matching file:
$ grep -l -R FIXME --include=*.h /usr/src/sys/arm/
- Show lines containing the text ‘foo’. The matching part of the output
is colored and every line is prefixed with the line number and the
offset in the file for those lines that matched.
$ grep -b --colour -n foo myfile
- Show lines that match the extended regular expression patterns read
from the standard input:
$ echo -e 'Free\nBSD\nAll.*reserved' | grep -E -f - myfile
- Show lines from the output of the pciconf(8) command matching the
specified extended regular expression along with three lines of leading
context and one line of trailing context:
$ pciconf -lv | grep -B3 -A1 -E 'class.*=.*storage'
- Suppress any output and use the exit status to show an appropriate
$ grep -q foo myfile && echo File matches
bzip2(1), compress(1), ed(1), ex(1), gzip(1), sed(1), xz(1), zgrep(1),
The grep utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”)
The flags [-AaBbCDdGHhILmoPRSUVw] are extensions to that specification, and
the behaviour of the -f flag when used with an empty pattern file is left
All long options are provided for compatibility with GNU versions of this
Historic versions of the grep utility also supported the flags [-ruy].
This implementation supports those options; however, their use is strongly
The grep command first appeared in Version 6 AT&T UNIX.
The grep utility does not normalize Unicode input, so a pattern containing
composed characters will not match decomposed input, and vice versa.
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