preinst is in swi-prolog-x 7.2.3-2.
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 | #! /bin/sh
set -e
if test -L /usr/lib/swi-prolog/xpce
then
rm /usr/lib/swi-prolog/xpce
fi
|