prerm is in xpilot-ng-server 1:4.7.3-2ubuntu2.
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 19 20 | #! /bin/sh
# prerm script for xpilot-ng-server
set -e
echo -n "Stopping XPilot NG server: "
if start-stop-daemon --stop --quiet --user xpilotng \
	--exec /usr/games/xpilot-ng-server --retry 30 >/dev/null 2>&1; then
   echo "xpilot-ng-server."
else
   # Take more draconian measures, as 'xpilotng' user may be
   # removed by this point by an earlier failed --stop.
   # We risk also terminating servers run by users other
   # than xpilotng here, but this is better than the alternative
   # (keeping an earlier, potentially buggy XPilot NG server
   # running).
   if start-stop-daemon --stop --quiet --exec /usr/games/xpilot-ng-server --retry 30; then
      echo "xpilot-ng-server."
   fi
fi
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