NAME
gzip
- compression/decompression tool using Lempel-Ziv coding (LZ77)
SYNOPSIS
gzip
[-cdfhlNnqrtVv]
[-S suffix]
file
]
[[file ...]
gunzip
[-cfhNqrtVv]
[-S suffix]
file
]
[[file ...]
zcat
[-fhV]
file
]
[[file ...]
DESCRIPTION
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.
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)
or
bzip2(1).
OPTIONS
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, 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.
- -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 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.
ENVIRONMENT
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
.
SEE ALSO
bzip2(1),
compress(1),
fts(3),
zlib(3)
HISTORY
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
NetBSD1.3
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
NetBSD2.0.
This manual documents
NetBSD
gzip
version 20040427.
AUTHORS
This implementation of
gzip
was written by
Matthew R. Green <mrg@eterna.com.au>
.