.LZ

Lzip compressed file

Introduction

Lzip compresses a single file with LZMA, the method used by xz and 7-Zip, inside a deliberately small and simple container designed for long-term archiving. Antonio Díaz Díaz released lzip in 2008. Some GNU projects publish their source code as .tar.lz files alongside other formats.

Structure

An lzip file is one or more members one after another. Numbers are little-endian.

  1. 0Magic LZIP4 bytes
  2. 4Version 11 byte
  3. 5Dictionary size coded in one byte1 byte
  4. 6LZMA data ending with an end-of-stream markervaries
  5. …Trailer CRC-32 of the data, its size, and the size of the whole member20 bytes
One lzip member: header, LZMA data and trailer.

The sizes in the trailer let a tool walk a file backwards, member by member, and find damaged parts, which is the point of the design.

Links

Software

  • lzip (Linux, macOS, Windows)
  • GNU tar, with the --lzip option (Linux, macOS)

Developers

  • lzlib, C library for reading and writing lzip files

Reference