#!/usr/bin/perl { local $/; open F, $ARGV[0] or die $!; $all = ; close F; @ips = $all =~ m/^(?:[^\|]+\|){9}([^\|]+)/gm; undef $all; # try to reclaim the memory } my %h; $h{$_}++ for @ips; print "$h{$_}\t$_\n" for keys %h;