in reply to Re^2: Using less memory with BIG files
in thread Using less memory with BIG files
The answer to both your questions happen to be in the open link I gave you. Aside from asking for help here, it is worth finding out how to use the Perl documentation that almost certainly was installed with your Perl. Try typing perldoc from your command line.
True laziness is hard work
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Seekers of Perl Wisdom