PACK(1) PACK(1)
NAME
pack, unpack, pcat, compress, uncompress, zcat - compress
and expand files
SYNOPSIS
pack [ - ] file ...
unpack file ...
pcat [ file ... ]
compress [ option ... ] [ file ... ]
uncompress [ option ... ] [ file ... ]
zcat [ -V ] [ file ... ]
DESCRIPTION
Pack attempts to compress the files and places the results
in corresponding files named file.z with the same access
modes, dates, and owner as the originals. Successfully
packed files are removed.
Unpack reverses the process.
Pcat unpacks files to the standard output.
The .z suffix may be omitted from the name of the input file
for unpack or pcat.
Pack encodes individual characters in a Huffman code.
Option - causes statistics of the encoding to be printed.
The option toggles on and off at each appearance among the
list of files.
Compress, uncompress, and zcat work like pack, unpack, and
pcat, putting each compressed file into file.Z. The options
are
-f (force) Compress even when it doesn't save space.
-c Write to the standard output; change no files. Zcat is
identical to uncompress -c.
-bbits
Compress uses a modified Lempel-Ziv encoding. Common
substrings in the file are replaced by variable-length
codes up to size bits (default 16). Smaller limits
devour less address space.
PACK(1) PACK(1)
-v Print percent reduction for each file.
-V Print program version number.
Compress-uncompress pack better and are faster overall;
pack-unpack work on smaller machines and are much more
widely available.
SEE ALSO
T. A. Welch, `A Technique for High Performance Data Compres-
sion,' IEEE Computer, 17 (1984) 8-19.
DIAGNOSTICS
The exit code of pack, unpack, or pcat is the number of
files it failed to process.
The exit code of compress, uncompress, or zcat is 0 nor-
mally, 1 for error, 2 for ineffective compression (i.e.
expansion).