Copyright (C) 1992, 1997-2002, 2004-2017 Free Software Foundation, Inc.

  Copying and distribution of this file, with or without modification,
  are permitted in any medium without royalty provided the copyright
  notice and this notice are preserved.

This is GNU grep, the "fastest grep in the west" (we hope).  All
bugs reported in previous releases have been fixed.  Many exciting new
bugs have probably been introduced in this revision.

GNU grep is provided "as is" with no warranty.  The exact terms
under which you may use and (re)distribute this program are detailed
in the GNU General Public License, in the file COPYING.

GNU grep is based on a fast lazy-state deterministic matcher (about
twice as fast as stock Unix egrep) hybridized with a Boyer-Moore-Gosper
search for a fixed string that eliminates impossible text from being
considered by the full regexp matcher without necessarily having to
look at every character.  The result is typically many times faster
than Unix grep or egrep.  (Regular expressions containing backreferencing
will run more slowly, however.)

See the files AUTHORS and THANKS for a list of authors and other contributors.

See the file INSTALL for compilation and installation instructions.
If there is no INSTALL file, this copy of the source code is intended
for expert hackers; please see the file README-hacking.

See the file NEWS for a description of major changes in this release.

See the file TODO for ideas on how you could help us improve grep.

See the file README-alpha for information on grep development and the CVS

Send bug reports to


Several tests in and fail under the cs_CZ.UTF-8 locale
and have been disabled.

The combination of -o and -i options is broken and the known failing cases
are disabled in

The option -i does not work properly in some multibyte locales such as
tr_TR.UTF-8 where the upper case and lower case forms of a character are not
necessarily of the same byte length.

A list of outstanding and resolved bugs can be found at:

You can also browse the bug-grep mailing list archive at:

For any copyright year range specified as YYYY-ZZZZ in this package
note that the range specifies every single year in that closed interval.