— file pattern searcher
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. If no file arguments are specified, the standard input is
is used for simple patterns and basic regular
expressions (BREs); egrep
can handle extended
regular expressions (EREs). See
information on regular expressions. fgrep
quicker than both grep
, 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.
, respectively, but accept input files
compressed with the
The following options are available:
- Print num lines of
trailing context after each match. See also the
-B and -C
- 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
- 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 is 2 and is
equivalent to -A
2. Note: no whitespace may be given
between the option and its argument.
- Only a count of selected lines is written to standard
- Interpret pattern as an
extended regular expression (i.e. force grep
to behave as egrep).
- 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 (‘-’).
- Interpret pattern as a set
of fixed strings (i.e. force grep to behave
- 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).
- Always print filename headers (i.e. filenames) with output
- Never print filename headers (i.e. filenames) with output
- Ignore binary files.
- Perform case insensitive matching. By default,
grep is case sensitive.
- 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.
- 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
- Stop after num
- 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.
- Print each match, but only the match, not the entire
- Quiet mode: suppress normal output.
grep will only search a file until a match
has been found, making searches potentially less expensive.
- Recursively search subdirectories listed.
- 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.
- Display version information. All other options are
- Selected lines are those not
matching any of the specified patterns.
- The expression is searched for as a word (as if surrounded
by ‘[[:<:]]’ and ‘[[:>:]]’; see
- Only input lines selected against an entire fixed string or
regular expression are considered to be matching lines.
- Force grep to behave as
- 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
- Force output to be line buffered. By default, output is
line buffered when standard output is a terminal and block buffered
utility exits with one of the following
- One or more lines were selected.
- No lines were selected.
- An error occurred.
To find all occurrences of the word ‘patricia’ in a file:
$ grep 'patricia' myfile
To find all occurrences of the pattern
’ at the beginning of a line:
$ grep '^\.Pp' myfile
The apostrophes ensure the entire expression is evaluated by
instead of by the user's shell. The caret
’ matches the null string at the
beginning of a line, and the ‘
’, which would otherwise match any
To find all lines in a file which do not contain the words ‘foo’
$ 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.
utility is compliant with the
IEEE Std 1003.1-2008
extensions to that specification, and the behaviour of the
flag when used with an empty pattern file is
All long options are provided for compatibility with GNU versions of this
Historic versions of the grep
supported the flags
implementation supports those options; however, their use is strongly
command first appeared in
Version 4 AT&T UNIX