.SH SYNOPSIS
.ll +8
.B gzip
-.RB [ " \-acdfhlLnNrtvV19 " ]
+.RB [ " \-acdfhklLnNrtvV19 " ]
.RB [ \-S\ suffix ]
[
.I "name \&..."
.ll -8
.br
.B gunzip
-.RB [ " \-acfhlLnNrtvV " ]
+.RB [ " \-acfhklLnNrtvV " ]
.RB [ \-S\ suffix ]
[
.I "name \&..."
reduces the size of the named files using Lempel-Ziv coding (LZ77).
Whenever possible,
each file is replaced by one with the extension
-.B "\&.gz,"
+.BR "\&.gz" ,
while keeping the same ownership modes, access and modification times.
(The default extension is
.B "\-gz"
or
.I gunzip
or
-.I zcat.
+.IR zcat .
If the original name saved in the compressed file is not suitable for its
file system, a new name is constructed from the original one to make it
legal.
.PP
.I gunzip
can currently decompress files created by
-.I gzip, zip, compress, compress -H
+.IR gzip ,
+.IR zip ,
+.IR compress ,
+.I "compress -H"
or
-.I pack.
+.IR pack .
The detection of the input format is automatic. When using
the first two formats,
.I gunzip
checks a 32 bit CRC. For
-.I pack, gunzip
+.I pack
+and
+.I gunzip
checks the uncompressed length. The standard
.I compress
format was not designed to allow consistency checks. However
with several members, use
.I unzip
instead of
-.I gunzip.
+.IR gunzip .
.PP
.I zcat
is identical to
.I gunzip
-.B \-c.
+.BR \-c .
(On some systems,
.I zcat
may be installed as
.I gzcat
to preserve the original link to
-.I compress.)
+.IR compress .)
.I zcat
uncompresses either a list of files on the command line or its
standard input and writes the uncompressed data on standard output.
.I gzip
preserves the mode, ownership and timestamps of files when compressing
or decompressing.
-.PP
-The
-.I gzip
-file format is specified in P. Deutsch, \s-1GZIP\s0 file format
-specification version 4.3, <ftp://ftp.isi.edu/in-notes/rfc1952.txt>,
-Internet RFC 1952 (May 1996). The
-.I zip
-deflation format is specified in P. Deutsch, \s-1DEFLATE\s0 Compressed
-Data Format Specification version 1.3,
-<ftp://ftp.isi.edu/in-notes/rfc1951.txt>, Internet RFC 1951 (May 1996).
-
.SH OPTIONS
.TP
.B \-a --ascii
or the corresponding file already exists, or if the compressed data
is read from or written to a terminal. If the input data is not in
a format recognized by
-.I gzip,
+.IR gzip ,
and if the option --stdout is also given, copy the input data without change
to the standard output: let
.I zcat
behave as
-.I cat.
+.IR cat .
If
.B \-f
is not given,
.B \-h --help
Display a help screen and quit.
.TP
+.B \-k --keep
+Keep (don't delete) input files during compression or decompression.
+.TP
.B \-l --list
For each compressed file, list the following fields:
When decompressing, add .suf to the beginning of the list of
suffixes to try, when deriving an output file name from an input file name.
-
-.IR pack "(1)".
.TP
.B \-t --test
Test. Check the compressed file integrity.
The environment variable
.B GZIP
can hold a set of default options for
-.I gzip.
+.IR gzip .
These options are interpreted first and can be overwritten by
explicit command line parameters. For example:
for sh: GZIP="-8v --name"; export GZIP
On Vax/VMS, the name of the environment variable is GZIP_OPT, to
avoid a conflict with the symbol set for invocation of the program.
.SH "SEE ALSO"
-znew(1), zcmp(1), zmore(1), zforce(1), gzexe(1), zip(1), unzip(1), compress(1),
-pack(1), compact(1)
+znew(1), zcmp(1), zmore(1), zforce(1), gzexe(1), zip(1), unzip(1), compress(1)
.PP
The
.I gzip
file format is specified in P. Deutsch, \s-1GZIP\s0 file format
specification version 4.3,
-.BR <ftp://ftp.isi.edu/in-notes/rfc1952.txt> ,
+.BR <http://www.ietf.org/rfc/rfc1952.txt> ,
Internet RFC 1952 (May 1996).
The
.I zip
deflation format is specified in P. Deutsch, \s-1DEFLATE\s0 Compressed
Data Format Specification version 1.3,
-.BR <ftp://ftp.isi.edu/in-notes/rfc1951.txt> ,
+.BR <http://www.ietf.org/rfc/rfc1951.txt> ,
Internet RFC 1951 (May 1996).
.SH "DIAGNOSTICS"
Exit status is normally 0;
if an error occurs, exit status is 1. If a warning occurs, exit status is 2.
.TP
-Usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...]
+Usage: gzip [-cdfhklLnNrtvV19] [-S suffix] [file ...]
Invalid options were specified on the command line.
.TP
\fIfile\fP\^: not in gzip format
the default compression level (-6). On some highly redundant files,
.I compress
compresses better than
-.I gzip.
+.IR gzip .
.SH "COPYRIGHT NOTICE"
-Copyright \(co 1998, 1999, 2001, 2002 Free Software Foundation, Inc.
+Copyright \(co 1998, 1999, 2001, 2002, 2012 Free Software Foundation, Inc.
.br
Copyright \(co 1992, 1993 Jean-loup Gailly
.PP