To expand on the answer above, the correct way to test for definedness, or the lack thereof, is with defined, something like 

if (!defined $var) {...

[download]
, not with 
if ($var eq undef) {...

[download]
See also exists

In reply to Re: Uninitialized errors when using 2 hashes. by ssandv
in thread Uninitialized errors when using 2 hashes. by Anonymous Monk

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