post_install() {
  echo
  echo '!!! NOTE !!!'
  echo 'It is *strongly* encouraged to add users to the "users" group (usermod -aG users <username>) if they will be playing ezQuake/nQuake.
  Trust me. If you hit a bug and you are using a user not in the users group, you are testing bad and you should feel bad.'
  echo
  echo "nQuake has been installed. Please copy the retail pak1.pak files (as exactly that filename) to /opt/quake/id1/
  and do (as root):  chmod 0775 /opt/quake/id1/*.pak ; chgrp users /opt/quake/id1/*.pak'
  If you do not have the retail pak, copy /usr/share/nquake/gpl_maps.pk3 to /opt/quake/id1/
  and do (as root): chmod 0775 /opt/quake/id1/{*.pak,*.pk3} ; chgrp users /opt/quake/id1/{*.pak,*.pk3)"
  echo

  if [ -f "/opt/quake/ezquake/pak.lst" ];
  then
    if ! egrep -qE '^nquake_ezquake.pk3' /opt/quake/ezquake/pak.lst;
    then
      sed -i.no_nquake -e '1s/^/nquake_ezquake.pk3\r\n/' /opt/quake/ezquake/pak.lst
      cat -n /opt/quake/ezquake/pak.lst | sort -k2 -k1n  | uniq -f1 | sort -nk1,1 | cut -f2- > /tmp/ezquake.tmp
      cat /tmp/ezquake.tmp > /opt/quake/ezquake/pak.lst
      rm /tmp/ezquake.tmp
    fi
  else
    echo "Whoops. You might be doing something naughty, as I can't inject the nquake-provided ezquake.pk3 into the proper pak.lst."
    echo "Things *might* or *might not* work quite as expected."
  fi
}

post_upgrade() {

  # fix group ownerships...
  find /opt/quake -group games -exec chgrp users '{}' \;

}

post_remove() {
  # Undo our stupid clever little hack.
  if [ -f "/opt/quake/ezquake/pak.lst.no_nquake" ];
  then
    mv /opt/quake/ezquake/pak.lst.no_nquake /opt/quake/ezquake/pak.lst
  else
    echo "Weird; I can't seem to remove our injected entry from the proper pak.lst."
    echo "You weren't doing something naughty like arbitrarily deleting files from your filesystem, were you?"
  fi
}