<> is a file descriptor reading operation and it is already inside the script, so you should run either perl script.pl mytext.txt >output.txt (passing filename as command line argument) or perl script.pl <mytext.txt >output.txt (passing file contents as STDIN).
Sorry if my advice was wrong.

In reply to Re^5: NON Common Elements between two columns by aitap
in thread NON Common Elements between two columns by Giorgio C

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