compress.1 (2010 09)

compress(1) compress(1)

file already exists; do you wish to overwrite (y or n)?

Respond y if you want the output to replace the existing ﬁle; otherwise, respond

uncompress: corrupt input

A SIGSEGV violation was detected which usually means that the input ﬁle has been corrupted.

Compression: xx.xx%

Percentage of the input saved by compression. (Relevant only for

-v.)

-- not a regular file: unchanged

When the input ﬁle is not a regular ﬁle (a directory for example), it is left unaltered.

-- has xxother links: unchanged

The input ﬁle has links which are not symbolic links and has been left unchanged. See ln(1) for

more information.

-- has symbolic links: unchanged

The input ﬁle has symbolic links and has been left unchanged. See ln(1) for more information.

-- file unchanged

No savings is achieved by compression. The input remains unaltered.

EXAMPLES

Compress the ﬁle named

zenith and print compression information to the terminal:

compress -v zenith

The terminal display shows either a line resembling

zenith: Compression: 23.55% -- replaced with zenith.Z

indicating that the compressed ﬁle is 23.55% smaller than the original, or a line resembling

zenith: Compression: -12.04% -- file unchanged

indicating that an additional 12.04% space must be used to compress the ﬁle.

Undo the compression by typing either of the following commands:

uncompress zenith.Z

compress -d zenith.Z

This restores ﬁle zenith.Z to its original uncompressed form and name.

uncompress will perform on standard input if no ﬁles are speciﬁed. For example, to list a compressed

tar ﬁle:

uncompress -c arch.tar.Z | tar -tvf -

WARNINGS

Although compressed ﬁles are compatible between machines with large memory, -b12 should be used for

ﬁle transfer to architectures with a small process data space (64K bytes or less).

NFS

Access control lists of networked ﬁles are summarized (as returned in st_mode by stat(), but not

copied to the new ﬁle (see stat (2)).

AUTHOR

compress was developed by Joseph M. Orost, Kenneth E. Turkowski, Spencer W. Thomas, and James A.

Woods.

FILES

*.Z Compressed ﬁle created by compress and removed by uncompress.