xz / unxz / xzcat

Updated

July 31, 2026

Overview

xz provides high-ratio LZMA2 compression (.xz). Slower and more memory-hungry than gzip/zstd at high levels; common for source tarballs and package payloads.

Syntax

xz [options] [file...]
unxz file.xz
xzcat file.xz

Common Options

Option Description
-d Decompress
-k Keep original
-c stdout
-# / -T n Level / threads
-t Test
-e Extreme (slower)
-0…-9 Compression level

Examples with Explanations

xz file.tar
xz -d file.tar.xz
xz -T0 -9 big.img             # all threads, high ratio
xzcat data.xz | jq .
tar -cJf src.tar.xz src/      # tar + xz
tar -xJf src.tar.xz

Notes

  • Peak RAM scales with level and threads — watch small systems.
  • .lzma is legacy raw LZMA; prefer .xz.
  • For interactive backups, zstd -19 often feels snappier.