My own is this:

my $dt   = "2003 % 05 % 1720:55:23";
$dt =~ /^(\d{4}) % (\d{2}) % (\d{2})/;
$date = "$1-$2-$3";
print "$date\n";

You'll need to change this one if the day of month can have one digit instead of two (i.e. 7 instead of 07). Michele.