I'm comparing two files and deducing Add/Del/Changes from the comparison. I had been using a hash map to do it, but run out of ram with 1.7G input files!! So now am trying to read each line in a loop... This doesnt appear to be working for me: my($ln) = <CURR>; All examples I see have that in a while loop (and work)... Full Code is here: http://jurgy.net/code/