while (<FILE>) {
	# set modification flag to 0
	my $do_mod = 0;
	if ($do_mod) {		# if modification flag is true (>0)
		# apply substitution if matches
		s/priority/bandwidth/g;
		# if line is empty, clear modification flag
		$do_mod = 0 if (/^$/);
	} else {
		# Found first priority, mark modification flag true
		$do_mod++ if (/priority/);
	}
	print;
}