use CGI::Session;
my $session = new CGI::Session();

my $cookie = $query->cookie(  
                            CGISESSID => $session->id,
                           );
print $query->header(-cookie => $cookie);

##</code><code>##

(my $http_host  = $ENV{'HTTP_HOST'}) =~ s/(www.)?([\w\-.]+)/$2/;

my $cookie = $query->cookie(  
                            CGISESSID => $session->id,
                            -domain  =>  ".".$http_host,
                           );
print $query->header(-cookie => $cookie);