Compressed files can be restored to their original form using gzip -d
or gunzip or 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.
gunzip takes a list of files on its command line and replaces each file
whose name ends with .gz, -gz, .z, -z, _z or .Z and which begins with
the correct magic number with an uncompressed file without the original
extension. gunzip also recognizes the special extensions .tgz and .taz
as shorthands for .tar.gz and .tar.Z respectively. When compressing,
gzip uses the .tgz extension if necessary instead of truncating a file
with a .tar extension.
gunzip can currently decompress files created by gzip, zip, compress,
compress -H or pack. The detection of the input format is automatic.
When using the first two formats, gunzip checks a 32 bit CRC. For pack,
gunzip checks the uncompressed length. The standard compress format was
not designed to allow consistency checks. However gunzip is sometimes
able to detect a bad .Z file. If you get an error when uncompressing a
.Z file, do not assume that the .Z file is correct simply because the
standard uncompress does not complain. This generally means that the
standard uncompress does not check its input, and happily generates
garbage output. The SCO compress -H format (lzh compression method)
does not include a CRC but also allows some consistency checks.
Files created by zip can be uncompressed by gzip only if they have a
single member compressed with the 'deflation' method. This feature is
only intended to help conversion of tar.zip files to the tar.gz format.
To extract a zip file with a single member, use a command like gunzip
<foo.zip or gunzip -S .zip foo.zip. To extract zip files with several
members, use unzip instead of gunzip.
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