Ubuntu16.0.4切换阿里源

如国内网络使用ubuntu 则会出现apt-get无法安装更新的问题，这时大家需要切换到一些国内第三方更新源。

1. 首先查看自己的ubuntu系统的codename，直接导致你更新的源是否对你的系统起效果，查看方法： lsb_release -a
   
   我的系统显示结果是：Codename: xenial

2. 确认阿里源支持
   登陆以下网页：http://mirrors.aliyun.com/ubuntu/dists/
   该网页显示了阿里云支持的ubuntu系统下各个Codename版本，确保自己的Codename在该网页中存在（一般都会有的）

3. 备份系统源：
   cd /etc/apt
   sudo mv sources.list sources.list_bak

4. 添加新的源文件：sudo vi sources.list
   # deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ xenial main restricted
   deb-src http://archive.ubuntu.com/ubuntu xenial main restricted #Added by software-properties
   deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted
   deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe #Added by software-properties
   deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
   deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties
   deb http://mirrors.aliyun.com/ubuntu/ xenial universe
   deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
   deb http://mirrors.aliyun.com/ubuntu/ xenial multiverse
   deb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
   deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties
   deb http://archive.canonical.com/ubuntu xenial partner
   deb-src http://archive.canonical.com/ubuntu xenial partner
   deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted
   deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties
   deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
   deb http://mirrors.aliyun.com/ubuntu/ xenial-security multiverse

5. 保存并且sudo apt-get update，更新成功