Sometimes, as when dependencies get in the way of installation, it is desirable to break the installation into two separate steps. The --unpack option performs the first step of the installation. dpkg extracts files from the package and places them in their correct locations in the file system.
The configuration of the package, including the installation of configuration files, known as conffiles, is postponed until a later time.
Like install, this option will accept the -R | --recursive option. This allows for unpacking all of the packages in the given directory tree. Following up on the example discussed for --install, a large collection of packages gets unpacked by a command like the following:
dpkg --unpack /usr/local/Debian/archive