Previous: Exit Status, Up: Invoking grep
[Contents][Index]
grep
Programsgrep
searches the named input files
for lines containing a match to the given patterns.
By default, grep
prints the matching lines.
A file named - stands for standard input.
If no input is specified, grep
searches the working
directory . if given a command-line option specifying
recursion; otherwise, grep
searches standard input.
There are four major variants of grep
,
controlled by the following options.
Interpret patterns as basic regular expressions (BREs). This is the default.
Interpret patterns as extended regular expressions (EREs). (-E is specified by POSIX.)
Interpret patterns as fixed strings, not regular expressions. (-F is specified by POSIX.)
Interpret patterns as Perl-compatible regular expressions (PCREs). PCRE support is here to stay, but consider this option experimental when combined with the -z (--null-data) option, and note that ‘grep -P’ may warn of unimplemented features. See Other Options.
In addition,
two variant programs egrep
and fgrep
are available.
egrep
is the same as ‘grep -E’.
fgrep
is the same as ‘grep -F’.
Direct invocation as either
egrep
or fgrep
is deprecated,
but is provided to allow historical applications
that rely on them to run unmodified.