zchunk

zchunk is a compressed file format that splits the file into independent chunks. This allows you to only download changed chunks when downloading a new version of the file, and also makes zchunk files efficient over rsync.

zchunk files are protected with strong checksums to verify that the file you downloaded is, in fact, the file you wanted.

As of zchunk-1.0, the ABI and API have been marked stable, and the only changes allowed are backwards-compatible additions

Installation

To build and install zchunk, first install meson and run

meson build
cd build
ninja
ninja test
sudo ninja install

If you're building on an operating system where some libraries are stored in /usr/local, you'll need to replace

meson build

CFLAGS=-I/usr/local/include CXXFLAGS=-I/usr/local/include LDFLAGS=-L/usr/local/lib meson build

Using the utilities

To decompress a zchunk file, simply run:

unzck 

To compress a new zchunk file, run:

zck 

To download a zchunk file, run:

zckdl -s  

To read a zchunk header, run:

zck_read_header 

Documentation

• Format definition
• Initial announcement
• How zchunk works (with pretty pictures)