Reference

Z (Unix compress)

A .Z file is the output of the classic Unix "compress" command, which uses LZW compression to shrink a single file. It is an old format that predates gzip and is now largely replaced by gzip (.gz) and other tools.

Files & formatsGeneral

Z (Unix compress)

Also known as: .Z file, Unix compress, compress LZW, uncompress

Output of the classic Unix compress (LZW)
Predates and was replaced by gzip
Holds one file; combine with tar for many

The original Unix compressor

The Unix compress utility produced .Z files using LZW compression. For years it was the standard way to shrink files on Unix systems before gzip arrived with better compression and no patent concerns.

A .Z file holds one compressed file; bundling multiple files is done with tar first (producing .tar.Z).

Opening .Z files

The `uncompress` and `gunzip` commands, plus archive tools like 7-Zip and The Unarchiver, open .Z files. Today gzip (.gz) and xz have effectively replaced it.

Related terms

Keep reading the reference.

Files & formatsGZIP (.gz)GZIP is a fast, single-file compressor that produces .gz files. It compresses one file at a time, so to pack a whole folder it is combined with TAR into a tar.gz. It is the default compression behind much of the web and Unix tooling.General Files & formatsTARTAR (tape archive) bundles many files and folders into one .tar file but does not compress them on its own. It is almost always paired with a compressor, producing combinations like tar.gz (gzip) or tar.xz.General Storage conceptsCompression (lossy vs lossless)Compression shrinks a file by encoding its data more efficiently. Lossless compression rebuilds the original exactly, while lossy compression permanently discards detail the eye or ear is least likely to notice in exchange for much smaller files.General