gzip
,
gunzip
,
zcat
—
compression/decompression tool using Lempel-Ziv
coding (LZ77)
gzip |
[ -cdfhkLlNnqrtVv ]
[-S
suffix ]
file
[] |
gunzip |
[ -cfhkLNqrtVv ]
[-S
suffix ]
file
[] |
The
gzip
program compresses and decompresses
files using Lempel-Ziv coding (LZ77). If no
files are specified,
gzip
will compress from standard input, or
decompress to standard output. When in compression mode, each
file will be replaced with another file with
the suffix, set by the
-S
suffix option, added, if possible.
In decompression mode, each
file will be
checked for existence, as will the file with the suffix added. Each
file argument must contain a separate
complete archive; when multiple
files are
indicated, each is decompressed in turn.
In the case of
gzcat
the resulting data is
then concatenated in the manner of
cat(1).
If invoked as
gunzip
then the
-d
option is enabled. If invoked as
zcat
or
gzcat
then both the
-c
and
-d
options are enabled.
This version of
gzip
is also capable of
decompressing files compressed using
compress(1),
bzip2(1),
or
xz(1).
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.
bzip2(1),
compress(1),
xz(1),
fts(3),
zlib(3)
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 1.3 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
2.0.
This implementation of
gzip
was ported based
on the
NetBSD gzip
version 20170803, and first appeared in
FreeBSD 7.0.
This implementation of
gzip
was written by
Matthew R. Green
<
mrg@eterna.com.au>
with unpack support written by
Xin LI
<
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.