{
    local( *INFILE, *FQDN, $_);
    open INFILE, '< /path/to/longwood.pix' or die $!;
    open FQDN, '> /path/to/fqdn.pix' or die $!;
    while (<INFILE>) {
        s/$ipre/(exists($hosts{$1})?$hosts{$1}:$1)/eg;
        print FQDN $_ or die $!;
    }
    close FQDN or die $!;
    close INFILE or die $!;
}