NAME
gzip,
gunzip,
zcat —
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),
bzip2(1), or
xz(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.
-
-
- -k,
--keep
- This option prevents gzip from deleting
input files after (de)compression.
-
-
- -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.
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
.
EXIT STATUS
The
gzip utility exits 0 on success, 1 on errors, and 2 if a
warning occurs.
SIGNALS
gzip responds to the following signals:
-
-
SIGINFO
- Report progress to standard error.
SEE ALSO
bzip2(1),
compress(1),
xz(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
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 manual documents
NetBSD gzip
version 20170803.
AUTHORS
This implementation of
gzip was written by
Matthew R. Green
<
mrg@eterna.com.au>.