GZIP(1)

GZIP(1) | General Commands Manual | GZIP(1)

# 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), lzip, 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@eterna23.net>.

January 8, 2017 | NetBSD 10.1