# Set up backends
	db_get cupsys/backend && SELECTED=$RET
	list=`echo $SELECTED | sed -e 's/, /,/g'`
	save_IFS=$IFS
	IFS=,
	(cd /usr/lib/cups/backend && rm -f http ipp lpd parallel scsi serial socket usb snmp dnssd)
	for module in $list; do
	  ln /usr/lib/cups/backend-available/$module /usr/lib/cups/backend/$module
	  if [ "$module" = "ipp" ]; then
            ln /usr/lib/cups/backend/ipp /usr/lib/cups/backend/http
	  fi
	done
	IFS=$save_IFS

	# activate new backends on upgrades
	db_fset cupsys/backend changed false
	
	if dpkg --compare-versions "$2" lt-nl "1.3.4-2"; then
	    for module in snmp scsi serial dnssd; do
	        [ -e /usr/lib/cups/backend/$module ] || \
	        ln /usr/lib/cups/backend-available/$module /usr/lib/cups/backend/$module
	    done
	fi