# Here's the plain jane, use "localtime" version that
# prepends "0" before all numbers that have only one digit
my @time = localtime();
$time[4]++; # convert from 0 based index to 1 based index
$time[5]-=100; # 2digits=subtract 100 or 4digits=add 1900
$time[$_] = $time[$_]<10? "0".$time[$_]:$time[$_] for (0..5);

my $filename = $time[5].$time[4].$time[3].$time[2].$time[1].$time[0];

# If you have POSIX this is a good alternative
use POSIX;
# %Y = 4 digit year and %y = 2 digit year
my $filename = strftime("%Y%m%d%H%M%S", localtime);


# To make sure that the filename is unique even if the fname
# is generated the same second, add the PID
$filename .= ".".$$;