use NDBM_File;
use Fcntl;
tie (%mtime, "NDBM_File",'mtime',O_RDWR|O_CREAT|O_EXCL, 0640) or die "error : $!";
# dump the data
for (sort keys %mtime){
    print "$_ $mtime{$_}\n";
}
# add a new key
$date= MakeDate();
$now = scalar localtime;
$mtime{$now} = $date;
untie %mtime;

sub MakeDate {
    my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
    $year = ($year + 1900) ; $mon++ ;
    my $date = sprintf("%04D%02d%02d", $year, $mon, $mday);
    return $date;
}