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GZIP(1) |
FreeBSD General Commands Manual |
GZIP(1) |
gzip , gunzip ,
zcat —
compression/decompression tool using Lempel-Ziv coding
(LZ77)
gzip |
[-cdfhkLlNnqrtVv ] [-S
suffix] file
[file [...]] |
gunzip |
[-cfhkLNqrtVv ] [-S
suffix] file
[file [...]] |
zcat |
[-fhV ] file
[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),
lzip,
zstd(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.
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 20181111, and first appeared in FreeBSD
7.0.
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.
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