Perl regex extracting domain name from URL

use strict;
use warnings;

use URI::Split qw/ uri_split uri_join /;

my $scheme_host = do {
  my (@parts) = uri_split 'http://linux.pacific.net.au/primary.xml.gz';
  uri_join @parts[0,1];
};

print $scheme_host;

use strict;
use warnings;

my $url = 'http://linux.pacific.net.au/primary.xml.gz';

my ($scheme_host) = $url =~ m|^( .*?\. [^/]+ )|x;

print $scheme_host;

#!/usr/bin/perl -w
use strict;

my $url = $ARGV[0];

if($url =~ /([^:]*:\/\/)?([^\/]+\.[^\/]+)/g) {
  print $2;
}

./test.pl 'https://example.com'
example.com

./test.pl 'https://www.example.com/'
<a href="http://www.example.com">www.example.com</a>

./test.pl 'example.org/'
example.org

 ./test.pl 'example.org'
example.org

./test.pl 'example'  -> no output

#!/usr/bin/perl -w
use strict;

my $url = $ARGV[0];
if($url =~ /([^:]*:\/\/)?([^\/]*\.)*([^\/\.]+\.[^\/]+)/g) {
  print $3;
}

$facebook = "www.facebook.com/xxxxxxxxxxx";

$facebook =~ s/www\.(.*\.com).*/$1/; # get what is between www. and .com

print $facebook;

s/www\.(.*\.(?:net|org|com)).*/$1/;