Manual Pages  — GZIP

gzip, gunzip, zcat – compression/decompression tool using Lempel-Ziv coding (LZ77)

SYNOPSIS DESCRIPTION OPTIONS ENVIRONMENT EXIT STATUS SIGNALS SEE ALSO HISTORY AUTHORS BUGS

gzip [-cdfhkLlNnqrtVv] [-S suffix] file [ file [... ] ]
gunzip [-cfhkLNqrtVv] [-S suffix] file [ file [... ] ]
zcat [-fhV] file [ file [... ] ]

The following options are available:

-1 -, -fast -2 -, -3 -, -4 -, -5 -, -6 -, -7 -, -8 -9 -, -best
	These options change the compression level used, with the -1 option being the fastest, with less compression, and the -9 option being the slowest, with optimal compression. The default compression level is 6.
-c -, -stdout -, -to-stdout
	This option specifies that output will go to the standard output stream, leaving files intact.
-d -, -decompress -, -uncompress
	This option selects decompression rather than compression.
-f -, -force
	This option turns on force mode. This allows files with multiple links, symbolic links to regular files, overwriting of pre-existing files, reading from or writing to a terminal, and when combined with the -c option, allowing non-compressed data to pass through unchanged.
-h -, -help
	This option prints a usage summary and exits.
-k -, -keep
	This option prevents gzip from deleting input files after (de)compression.
-L -, --license
	This option prints gzip license.
-l -, -list
	This option displays information about the file's compressed and uncompressed size, ratio, uncompressed name. With the -v option, it also displays the compression method, CRC, date and time embedded in the file.
-N -, -name
	This option causes the stored filename in the input file to be used as the output file.
-n -, -no-name
	This option stops the filename and timestamp from being stored in the output file.
-q -, -quiet
	With this option, no warnings or errors are printed.
-r -, -recursive
	This option is used to gzip the files in a directory tree individually, using the fts(3) library.
-S suffix , -suffix suffix
	This option changes the default suffix from .gz to suffix.
-t -, -test
	This option will test compressed files for integrity.
-V -, -version
	This option prints the version of the gzip program.
-v -, -verbose
	This option turns on verbose mode, which prints the compression ratio for each file compressed.

If the environment variable GZIP is set, it is parsed as a white-space separated list of options handled before any options on the command line. Options on the command line will override anything in GZIP.

The gzip utility exits 0 on success, 1 on errors, and 2 if a warning occurs.

gzip responds to the following signals:

SIGINFO
	Report progress to standard error.

The gzip program was originally written by Jean-loup Gailly, licensed under the GNU Public Licence. Matthew R. Green wrote a simple front end for NetBSD distribution media, based on the freely re-distributable zlib library. It was enhanced to be mostly feature-compatible with the original GNU gzip program for NetBSD

This implementation of gzip was ported based on the NetBSD gzip version 20181111, and first appeared in FreeBSD 7.0 .

This implementation of gzip was written by Matthew R. Green <Mt mrg@eterna.com.au> with unpack support written by Xin LI <Mt delphij@FreeBSD.org>.

According to RFC 1952, the recorded file size is stored in a 32-bit integer, therefore, it cannot represent files larger than 4GB. This limitation also applies to -l option of gzip utility.