compress

1. To feed data through any compression algorithm.

2. tool The Unix program "compress", now largely

supplanted by gzip.

Unix compress was written in C by Joseph M. Orost, James

A. Woods et al., and was widely circulated via Usenet. It

uses the Lempel-Ziv Welch algorithm and normally produces

files with the suffix ".Z".

Compress uses variable length codes. Initially, nine-bit

codes are output until they are all used. When this occurs,

ten-bit codes are used and so on, until an

implementation-dependent maximum is reached.

After every 10 kilobytes of input the compression ratio is

checked. If it is decreasing then the entire string table is

discarded and information is collected from scratch.