ubuntu 18.04 配置国内阿里源

1. 备份
   sudo cp /ect/apt/sources.list /etc/apt/sources.list.bak

2. 编辑
   sudo gedit /etc/apt/sources.list

3. 将以下内容复制到最开头：
   deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
   deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
   deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
   deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
   deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

4.更新
sudo apt update
sudo apt upgrade

参考：
https://www.cnblogs.com/gentlemanwuyu/p/11621636.html
https://blog.csdn.net/wangyijieonline/article/details/105360138