unxz: Decompress .xz Files in Pipelines

unxz decompresses .xz files and is equivalent to xz -d, restoring the original by stripping the .xz suffix.

unxz is the read side of xz. Many release tarballs ship as .tar.xz, so unxz (or tar -J) shows up wherever you consume them.

What it does

unxz reads a .xz file, decompresses the LZMA2 stream, writes the original name without the suffix, and removes the compressed file unless -k is set. It is the same binary as xz invoked in decompress mode.

Common usage

Terminal

unxz linux.tar.xz              # -> linux.tar
unxz -k firmware.bin.xz       # keep the .xz
unxz -c data.xz | tar -x      # stream into tar
unxz -t release.tar.xz        # test integrity

Options

Flag	What it does
-k / --keep	Keep the .xz file
-c / --stdout	Write to stdout
-t / --test	Test integrity only
-T0 / --threads=0	Use multiple cores where the stream allows
-f / --force	Overwrite existing output

Common errors in CI

"xz: (stdin): File format not recognized" means the file is not xz; a common cause is a .xz name on a gzip or lzma stream. "xz: <file>: Unexpected end of input" is a truncated download. Multi-threaded decompression only works on streams written in multiple blocks (xz -T with a block size); single-block .xz decompresses single-threaded regardless of -T0.

Related guides

xz: Compress with -9 -T0 for Small Artifactsxz compresses to .xz with LZMA2, the smallest of the common formats. Reference for -9, -T0 threads, -d, and t… xzcat: Stream xz Files to stdout in CIxzcat decompresses .xz files to stdout without writing a file, the xz counterpart to zcat. Reference for pipi… unzstd: Decompress .zst Cache Files in CIunzstd decompresses .zst files, the inverse of zstd. Reference for -c stdout, -k keep, --long window, -o outp… lzma: Legacy .lzma Compression and unlzmalzma compresses to the older .lzma format from xz-utils. Reference for -9, -d, -k, unlzma, lzcat, and when to…