#! usr/bin/perl -w
use strict;

$\ = "\n";

use Date::Manip;
&Date_Init("TZ=GMT","DateFormat=UK"); # or whatever

while (<DATA>) {
	print UnixDate($_,"%y%m%d");
}

__DATA__
Mon,  9 Aug 2004 10:28 AM
9th August 2004 10:28
10:28 9/8/2004 
Aug 9 2004 10:28
10:28 09 August 2004