Ubuntu 16.04 如何更换阿里源(在网上一些分享上补充)
①Ctrl+Alt t 进入终端 (跟windows cmd 类似)
②cd /etc/apt
(进入源文件目录)
③sudo cp sources.list sources.list.bak
(备份源文件，就是将sources.list备份为sources.list.bak）
④sudo vi /etc/apt/sources.list
(用vm 打开sources.list 文件）
⑤dd(一直按dd，直到把内容都删除完)
(dd 是vm 指令，意思是删除一行)
⑥i
(i 是vm 指令，意思进入编辑模式)
⑦复制，粘贴阿里源进来
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
##测试版源
deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
# 源码
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
##测试版源
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
# Canonical 合作伙伴和附加
deb http://archive.canonical.com/ubuntu/ xenial partner
deb http://extras.ubuntu.com/ubuntu/ xenial main
⑧保存
步骤是：
按Esc(键盘左上角)，再按：冒号进入末行命令模式，再按wq保存退出。
先按Esc，再输入 ：wq
⑨更新源和软件
sudo apt-get update 更新源
sudo apt-get upgrade 更新软件
（会有提示，按Y就可以了）
