漏刻有时环境部署：php安装提示Can‘t use function return value in write context

$m = ucfirst(get_param('m'));
$a = get_param('a');
$mod = empty($m) ? 'Login' : ucfirst(get_param('m'));
$act = empty($a) ? 'index' : get_param('a');

//加载数据可视化页面;
$m = ucfirst(get_param('m'));
$a = get_param('a');
$mod = empty($m) ? 'Index' : ucfirst(get_param('m'));
$act = empty($a) ? 'rooted' : get_param('a');
$files = DASH_BOARD . '/controller/' . $mod . '.php';