js判断当前页面是pc还是移动端手机
if(/Android|webOS|iPhone|iPod|BlackBerry/i.test(navigator.userAgent)) {
    window.location.href = "https://www.baidu.com/";
} else {
    window.location.href = "http://news.baidu.com/";
}

nginx配置：
if ( $http_user_agent ~* "(Android|iPhone|Windows Phone|UC|Kindle)" ){ 
        rewrite  ^/(.*)$  http://m.xxx.com$uri redirect; 
    }