postinst is in phonon4qt5-backend-null 4:4.8.3-0ubuntu3.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
1 2 3 4 5 | #!/bin/sh
set -e
. /usr/share/debconf/confmodule
|