ubuntu 18.04 apt-get 更新使用中科大镜像源

sudo cp /etc/apt/sources.list /etc/apt/source.list.bk

sudo vim /etc/apt/sources.list

https://lug.ustc.edu.cn/wiki/mirrors/help/ubuntu

https://mirrors.ustc.edu.cn/repogen/

sudo apt-get update

修改完保存，进行更新