Howto create a unique identifier in perl

It's probably because I didn't look in the righ places but I just couldn't find a simple way to create a unique identifier in perl. I decided it's not worth the trouble going through the perl man pages (always a thankless task) when it's so easy to create a unique id with a few lines of code.

And here it is

	#!/usr/bin/perl

	$sessionId  ="";
	$length=16;

	for($i=0 ; $i< $length ;)
	{
		$j = chr(int(rand(127)));

		if($j =~ /[a-zA-Z0-9]/)
		{
			$sessionId .=$j;
			$i++;
		}
	}


	print $sessionId;

It's that simple. You can change the combination of letters and number used in the sessionId by changing this regular expression /[a-zA-Z0-9]/. And change it's length with the $length variable. The longer the identifier the more likely that it's unique.