备份
/etc/apt$ sudo cp -p sources.list ./sources.list.back
换源
sudo sed -i 's/deb.debian.org/mirrors.ustc.edu.cn/g' /etc/apt/sources.list
更新一下
sudo apt-get update
标签：cn,etc,sudo,list,apt,debian9,国内,sources
来源： https://blog.csdn.net/qq_17802895/article/details/114214680