DEB files are ar archives, which contain three files:
- debian-binary
- control.tar.gz
- data.tar.gz
Unpacking this file is a two step process.
ar vx mypackage.deb
tar -xzvf data.tar.gz
Alternatively, the contents of data.tar.gz can also be extracted in one step.
ar p mypackage.deb data.tar.gz | tar zx
Of late, the file data.tar.gz has been replaced with data.tar.xz
Useful link