#!/usr/bin/perl

use strict;
use warnings;

die "Usage: $0 <file1> <file2>\n" unless @ARGV==2;

my %orig=map {$_ => 1} do {
    open my $fh, '<', $ARGV[0] or die $!;
    <$fh>;
};

open my $fh, '<', $ARGV[1] or die $!;
$orig{$_} and print while <$fh>;
 
__END__