Ubuntu20.04配置国内镜像源

Ubuntu 的软件源配置文件是 /etc/apt/sources.list。
将系统自带的该文件做个备份，后新建该文件，再更改内容。

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

sudo rm /etc/apt/sources.list
sudo touch /etc/apt/sources.list
sudo vi /etc/apt/sources.list

编辑配置文件，配置为阿里源，清华源或其他国内源以提高系统速度。

阿里源(实测有效)文件内容：

deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse

保存文件

:wq

软件包更新，升级

sudo apt-get update
sudo apt-get upgrade

附参考链接：