lzma: Legacy .lzma Compression and unlzma

lzma compresses files to the older .lzma (LZMA1) format, provided by xz-utils, with a similar interface to xz but without the newer container.

lzma is the predecessor to xz. You mostly meet it when decompressing old .lzma artifacts; for new work, xz (.xz) is the maintained choice.

What it does

lzma compresses input with the LZMA1 algorithm and the legacy .lzma container, provided by the xz-utils package as an alias mode of xz. unlzma or lzma -d decompresses, and lzcat streams to stdout. The .xz format supersedes it with integrity checks and multi-stream support.

Common usage

Terminal

lzma -9 old.tar               # -> old.tar.lzma
lzma -k -6 data.bin           # keep source
unlzma legacy.tar.lzma        # decompress
lzma -d archive.lzma          # same as unlzma

Options

Flag	What it does
-9	Maximum compression
-k / --keep	Keep the input file
-c / --stdout	Write to stdout
-d / --decompress	Decompress (like unlzma)
-t / --test	Test integrity
-F lzma (on xz)	Force the legacy lzma format when calling xz

In CI

Prefer xz for anything new: .xz adds a CRC check and multi-threading (-T0) that .lzma lacks. Keep lzma around only to read legacy .lzma artifacts. It ships with xz-utils, so installing xz-utils gives you both.

Common errors in CI

"xz: (stdin): File format not recognized" on an .lzma file usually means you called xz -d without -F lzma on a raw stream, or the file is not actually lzma. "Cannot allocate memory" at -9 mirrors xz: LZMA1 -9 also needs a large dictionary. "command not found" means xz-utils is not installed.