prerm is in john 1.7.8-1.
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 13 14 15 16 17 18 | #!/bin/sh
set -e
case $1 in
remove)
	/usr/share/john/cronjob stop
	;;
upgrade|failed-upgrade|deconfigure)
	# These cases need no actions here
	:
	;;
*)
	echo "$0: undocumented call: $@" >&2
	exit 1
	;;
esac
 |