Ubuntu16.04换源

1.备份原来的源文件

cd /etc/apt/
ls
sudo cp sources.list sources.list.bak

2.替换源

sudo gedit sources

阿里源：

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 

3.更新源和软件

sudo apt-get update
sudo apt-get upgrade