Also just to clarify - that's a "warning" not an "error" - your program will continue running, but you will see the warning. If you don't want to see warnings about that particular issue (sometimes you know it might be uninitialized but don't care) - you can do this:

#!/usr/bin/perl -w

use strict;
use warnings 'all';

...your code...

..and then...
no warnings 'uninitialized';
my ($foo, $bar) = split /\s+/, $some_uninitialized_variable;
[download]