Ubuntu20.04更换apt清华镜像源

先备份

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

编辑上面的文件，可以用vim工具，这里我有图形界面，所以用gedit

sudo gedit /etc/apt/sources.list

把下面的内容替换文件里内容，保存

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse

sudo apt-get update
sudo apt-get upgrade

                        
转自：https://blog.youkuaiyun.com/m1993zhao/article/details/134544478