Copyright (C) 1992, 1997-2002, 2004-2020 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 back-references 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 repository. Send bug reports to bug-grep@gnu.org. KNOWN BUGS: Several tests in fmbtest.sh and foad1.sh 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 foad1.sh 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: https://debbugs.gnu.org/cgi/pkgreport.cgi?package=grep You can also browse the bug-grep mailing list archive at: https://lists.gnu.org/r/bug-grep/ For any copyright year range specified as YYYY-ZZZZ in this package note that the range specifies every single year in that closed interval.