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GZIP(1)                   BSD General Commands Manual                  GZIP(1)

NAME
     gzip -- compression/decompression tool using Lempel-Ziv coding (LZ77)

SYNOPSIS
     gzip [-cdfhkLlNnqrtVv] [-S suffix] file [file [...]]
     gunzip [-cfhkLNqrtVv] [-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 compres-sion compression
     sion 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.  When invoked as zcat, ``.Z'' will be appended to all filenames that do not
     have that suffix.

     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, 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        Keep (don't delete) input files during compression or decompression.

     -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.

ENVIRONMENT
     If the environment variable GZIP is set, it is parsed as a white-space separated list of options han-dled handled
     dled before any options on the command line.  Options on the command line will override anything in
     GZIP.

SEE ALSO
     bzip2(1), compress(1), xz(1), fts(3), zlib(3), compat(5)

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 redistributable
     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, and first appeared in FreeBSD 7.0.

AUTHORS
     This implementation of gzip was written by Matthew R. Green <mrg@eterna.com.au> with unpack support
     written by Xin LI <delphij@FreeBSD.org>.

BUGS
     According to RFC 1952, the recorded file size is stored in a 32-bit integer, therefore, it can not rep-resent represent
     resent files larger than 4GB.  This limitation also applies to -l option of gzip utility.

BSD                             October 9, 2011                            BSD

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