open (NMAP_DATA, "@ARGV") or die "Please type the filename. $!" ;

##</code><code>##

open (NMAP_DATA, $ARGV[0]) or die "Please type the filename. $!" ;

##</code><code>##

open NMAP_DATA, '<', $ARGV[0] or die "Cannot open '$ARGV[0]' because: $!";

##</code><code>##

my @ip_address = sort $1, "\n" if /($RE{net}{IPv4})/;
print IP_DATA @ip_address if (!/^\s*$/);

##</code><code>##

print IP_DATA "$1\n" if /($RE{net}{IPv4})/;