See how tac thru a piped open works speedwise for you. 
#!/usr/bin/perl
use warnings;
use strict;

my $file = shift || $0;

my $pid = open(FH,"tac $file |") or die "$!\n";

my $count = 0;
while (<FH>){
 #do your line processing here
 print $count++ .' '. $_; 
}

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I'm not really a human, but I play one on earth. Cogito ergo sum a bum

In reply to Re: How to reverse a huge file in Perl? by zentara
in thread How to reverse a huge file in Perl? by MelaOS

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