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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 cod-
     ing (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 sepa-
     rate complete archive; when multiple files are indicated, each is decom-
     pressed in turn.

     In the case of gzcat the resulting data is then concatenated in the man-
     ner 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 suf-
     fix.

     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 com-
                       pression.  The default compression level is 6.

     -c, --stdout, --to-stdout
                       This option specifies that output will go to the stan-
                       dard output stream, leaving files intact.

     -d, --decompress, --uncompress
                       This option selects decompression rather than compres-
                       sion.

     -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 com-
                       pressed and uncompressed size, ratio, uncompressed
                       name.  With the -v option, it also displays the com-
                       pression 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.


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
     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 inte-
     ger, therefore, it can not represent files larger than 4GB.  This limita-
     tion also applies to -l option of gzip utility.

BSD                             October 9, 2011                            BSD

Mac OS X 10.9 - Generated Sun Oct 13 18:49:17 CDT 2013