$server_software_version = $_SERVER["SERVER_SOFTWARE"];
                          // author: kracker
                          // Examples: Apache/2.0.46 (CentOS) or Apache/1.3.14 (Win32) or Apache/2.0.40 (Red Hat Linux)
                          // echo ( $server_software_version );

                          if( strstr( $server_software_version, "Apache/1" ) != "" )
                          {
                            echo "server: apache1";
                            $url = htmlspecialchars( $url );
                          }
                          else
                          {
                            echo "server: apache2";
                            $url = htmlspecialchars( $url ) . "/";
                          }