Ubuntu换源

因为Ubuntu默认的太慢了，所以在网上搜寻方法，特此记录一下

换成国内最快的阿里云源
第一步：备份原来的源文件
cd /etc/apt/
然后会显示下面的源文件sources.list
输入命令
sudo cp sources.list sources.list.bak
就是将sources.list备份到sources.list.bak

第二步：替换源
阿里云源的文件
vi sources.list
删除原内容，输入以下内容（输入之前换root权限，输入命令sudo su）

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

替换

第三步：更新源和软件
sudo apt-get update 更新源
sudo apt-get upgrade 更新软件