sub dbm_save() {
	my($cache_file, $key, $value, $datetime_prefix) = @_;

	use DB_File;
	use Fcntl ':flock';
	use Time::Local;

	my($status) = '';
	my(%database);
	my($db) = tie(%database, 'DB_File', $cache_file, O_CREAT | O_RDWR, 0644);
	unless ($db) {
#		die("couldn't init DB '$cache_file': $!\n");
		$status = "couldn't init DB '$cache_file': $!";
	} else {
		my($fd) = $db->fd();
		unless (open(DATAFILE, "+<&=$fd")) {
#			die("couldn't safety open DB '$cache_file': $!\n");
			$status = "couldn't safety open DB '$cache_file': $!";
		} else {
			unless (flock(DATAFILE, LOCK_EX)) {
#				die("couldn't lock DB '$cache_file': $!\n");
				$status = "couldn't lock DB '$cache_file': $!";
			} else {
				if ($datetime_prefix) {
					my($sec, $min, $hour, $mday, $month, $year) = (localtime)[0,1,2,3,4,5];
					$year += 1900;
					$month++;
					$datetime_prefix = sprintf("%04d%02d%02d%02d%02d%02d\t", $year, $month, $mday, $hour, $min, $sec);
				} else {
					$datetime_prefix = '';
				}
				$key .= chr(0);
				$database{$key} = $datetime_prefix.$value;
			}
			unless ($db->sync()) {
#				$status = "couldn't sync data with DB '$cache_file': $!";
			}
			unless (close(DATAFILE)) {
				$status = "couldn't close DB '$cache_file': $!";
			}
		}
		undef($db);
		untie(%database);
	}
	return($status);
}