perl -we 'print qw/hello/ if qq/0/'

The ShaBANG!!! line in your file probably contained -w. That explains the error not showing up when warnings are off.

 

______crazyinsomniac_____________________________ Of all the things I've lost, I miss my mind the most. perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"