Please read Markup in the Monastery; in particular, please do not use <pre> tags in your write-ups, as they screw up many people's display and generally make grumpy monks.

If you don't have space to hold the entire file in memory, then don't read in the entire file - process line by line.

open (IN, filename) or die "cann't open file filename : $!\n";
while (defined(my $line = <IN>)) {
    #process $line
}
close (IN);
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