file1
-----
one
two
three
four
five

six
seven
eight

file2
-----
five
five
five

six
seven
eight
nine
ten
eleven
twelve

##</code><code>##

#!/usr/bin/perl -w
use strict;
use warnings;
use List::Compare;

@ARGV == 2 or die 'Error: Two files needed for comparison.';

open my $inA, '<', $ARGV[0] or die qq{Unable to open file "$ARGV[0]": $!};
chomp( my @nomi = <$inA> );
close $inA;

open my $inB, '<', $ARGV[1] or die qq{Unable to open file "$ARGV[1]": $!};
chomp( my @indirizzi = <$inB> );
close $inB;

my $lc = List::Compare->new(\@nomi, \@indirizzi);

my @intersection = $lc->get_intersection;

print "$_\n" for @intersection;

##</code><code>##

eight
five
seven
six