TAR.md

Using az with tar

.az files are native LZ4 (levels 1–2) or Zstandard (levels 3–5) streams. Both bsdtar (macOS) and GNU tar detect the format from magic bytes, so no compression flag is required on extraction.

Create

# zstd (default level 3)
tar cf - ./dir | az -c > archive.tar.az

# choose a level explicitly
tar cf - ./dir | az -c -1 > archive-lz4.tar.az   # lz4, fastest
tar cf - ./dir | az -c -5 > archive-zstd.tar.az   # zstd, best ratio

Extract (autodetect)

tar xf archive.tar.az -C /path/to/dest/

tar reads the magic bytes and selects the right decompressor automatically — no -J, --zstd, or --lz4 flag needed.

Verify the format

xxd archive.tar.az | head -1
# lz4  (levels 1–2):  04 22 4d 18 ...
# zstd (levels 3–5):  28 b5 2f fd ...

Cross-tool decompression

Because the format is standard, any lz4 or zstd tool can decompress .az files:

# level 1–2
lz4  -d archive.tar.az --stdout | tar xf -

# level 3–5
zstd -d archive.tar.az --stdout | tar xf -