gzip 1.3.12

gzip (GNU zip) is a very popular data compression program.

gzip (GNU zip) is a compression utility designed to be a replacement for compress. Its main advantages over compress are much better compression and freedom from patented algorithms. The GNU Project uses it as the standard compression program for its system.

gzip currently uses by default the LZ77 algorithm used in zip 1.9 (the portable pkzip compatible archiver). The gzip format was however designed to accommodate several compression algorithms. See below for a comparison of zip and gzip.

gunzip can currently decompress files created by gzip, compress or pack. The detection of the input format is automatic. For the gzip format, gunzip checks a 32 bit CRC. For pack, gunzip checks the uncompressed length. The compress format was not designed to allow consistency checks. However gunzip is sometimes able to detect a bad .Z file because there is some redundancy in the .Z compression format.
If you get an error when uncompressing a .Z file, do not assume that the .Z file is correct simply because the standard uncompress does not complain. This generally means that the standard uncompress does not check its input, and happily generates garbage output.

gzip produces files with a .gz extension. Previous versions of gzip used the .z extension, which was already used by the pack Huffman encoder. gunzip is able to decompress .z files (packed or gziped).

Several planned features are not yet supported (see the file TODO). See the file NEWS for a summary of changes since 0.5. See the file INSTALL for installation instructions. Some answers to frequently asked questions are given in the file INSTALL, please read it. (In particular, please dont ask me once more for an /etc/magic entry.)

WARNING: on several systems, compiler bugs cause gzip to fail, in particular when optimization options are on. See the section "Special targets" at the end of the INSTALL file for a list of known problems. For all machines, use "make check" to check that gzip was compiled correctly. Try compiling gzip without any optimization if you have a problem.

Usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...]
-c --stdout write on standard output, keep original files unchanged
-d --decompress decompress
-f --force force overwrite of output file and compress links
-h --help give this help
-l --list list compressed file contents
-L --license display software license
-n --no-name do not save or restore the original name and time stamp
-N --name save or restore the original name and time stamp
-q --quiet suppress all warnings
-r --recursive operate recursively on directories
-S .suf --suffix .suf use suffix .suf on compressed files
-t --test test compressed file integrity
-v --verbose verbose mode
-V --version display version number
-1 --fast compress faster
-9 --best compress better
--rsyncable Make rsync-friendly archive
file... files to (de)compress. If none given, use standard input.