preinst is in qt4-dev-tools 4:4.8.5+git192-g085f851+dfsg-2ubuntu4.
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 8 9 10 11 12 | #!/bin/sh
set -e
case "$1" in
upgrade)
if dpkg --compare-versions $2 "<<" 4:4.8.5
then
update-alternatives --remove assistant "/usr/bin/assistant-qt4"
update-alternatives --remove linguist "/usr/bin/linguist-qt4"
fi ;;
esac
|