The
program compresses and decompresses files using Lempel-Ziv coding
(LZ77).
If no
files
are specified,
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
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.
-k , -keep
Keep (don't delete) input files during compression
or decompression.
-L , -license
This option prints
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 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
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
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
The
program was originally written by Jean-loup Gailly, licensed under
the GNU Public Licence.
Matthew R. Green wrote a simple front end for
Nx 1.3
distribution media, based on the freely re-distributable zlib library.
It was enhanced to be mostly feature-compatible with the original
GNU
program for
Nx 2.0 .
This implementation of
was ported based on the
Nx
20060927, and first appeared in
Fx 7.0 .
AUTHORS
This implementation of
was written by
An Matthew R. Green Aq mrg@eterna.com.au .
BUGS
According to RFC 1952, the recorded file size is stored in a 32-bit
integer and therefore it can not represent files that is bigger than
4GB in size. This limitation also applies to
-l
option of
utility.
