gzip(1) - NetBSD Manual Pages

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GZIP(1)                 NetBSD General Commands Manual                 GZIP(1)


NAME

     gzip -- 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 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.

     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) 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, overwriting of pre-existing files,
                       reading from or writing to a terminal, and when com-
                       bined with the -c option, allowing non-compressed data
                       to pass through unchanged.

     -h, --help        This option prints a usage summary and exits.

     -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 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), 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 20040427.


AUTHORS

     This implementation of gzip was written by Matthew R. Green
     <mrg@eterna.com.au>.

NetBSD 5.2                      April 27, 2004                      NetBSD 5.2