use strict;
use warnings;

@ARGV == 2 or die "usage: $0 file1 file2\n";
my $file1 = shift;
my $file2 = shift;

open my $in1, '<', $file1 or die "unable to open '$file1': $!";
open my $in2, '<', $file2 or die "unable to open '$file2': $!";
chomp( my @nomi      = <$in1> );
chomp( my @indirizzi = <$in2> );
close $in1;
close $in2;

# Remove any blank or empty lines (optional, depends on your data files).
@nomi      = grep { !/^\s*$/ } @nomi;
@indirizzi = grep { !/^\s*$/ } @indirizzi;

# Create a hash of lines in @nomi.
my %in_nomi;
foreach my $item (@nomi) { $in_nomi{$item}++ }

# Check if each line in @indirizzi is in nomi.
# Note: does not check for duplicate lines in @indirizzi.
foreach my $line (@indirizzi) {
   print "$line\n" if $in_nomi{$line};
}