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(tool, compression)
GNU compression utility. Gzip reduces the size of the named files using Lempel-Ziv LZ77 compression. Whenever possible, each file is replaced by one with the filename extension ".gz". Compressed files can be restored to their original form using gzip -d or gunzip or zcat.

The Unix "compress" utility is patented (by two separate patents, in fact) and is thus shunned by the GNU Project since it is not free software. They have therefore chosen gzip, which is free of any known software patents and which tends to compress better anyway. All compressed files in the GNU anonymous FTP area (gnu.org/pub/gnu) are in gzip format and their names end in ".gz" (as opposed to "compress"-compressed files, which end in ".Z").

Gzip can uncompress "compress"-compressed files and "pack" files (which end in ".z"). The decompression algorithms are not patented, only compression is.

The gzip program is available from any GNU archive site in shar, tar, or gzipped tar format (for those who already have a prior version of gzip and want faster data transmission). It works on virtually every Unix system, MS-DOS, OS/2 and VMS.


(GNU ZIP) A popular compression program in the Unix world that is also available for Windows and Mac. Using the .GZ file extension, gzip compresses only a single file and is therefore often used in combination with the Unix "tar" utility when more than one file must be compressed. Tar combines multiple files into one archive, and gzip compresses that single archive, creating a file with the extension .TAR.GZ.

"Gunzip" is the gzip decompression utility, and it decompresses archives compressed with gzip or the Unix pack and compress commands. Many have lamented the fact that gzip includes the word "zip" because gzip cannot decompress files compressed with PKZIP. It was named that way because gzip uses one of the algorithms in PKZIP. However, in contrast, many PKZIP utilities can decompress gzip files. For more information, visit www.gzip.org. See archive formats.