prerm is in xscreensaver 5.30-1+deb8u2.
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 | #!/bin/sh
set -e
case "$1" in
remove|purge)
killall -q /usr/bin/xscreensaver || true
;;
esac
|