preinst is in gnome-icon-theme-full 3.4.0-0ubuntu1.
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 6 7 | #!/bin/sh
set -e
if [ "$1" = "upgrade" ] && dpkg --compare-versions "$2" lt-nl "3.0.0-5"; then
update-alternatives --remove start-here.svg /usr/share/icons/gnome/scalable/places/swirl-foot.svg
fi
|