ubuntu20.04如何更换国内源

　　ubuntu20.04如何更换国内源？ubuntu20.04更换国内源的方法。
　　1.打开终端。
　　2.输入以下命令备份原来的源。
　　sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
　　3.再输入以下命令打开sources.list配置文件更换源。

　　sudo vim/etc/apt/sources.list

　　//配置内容如下
　　deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
　　deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
　　deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
　　deb 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 main restricted universe multiverse
　　deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
　　deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
　　deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
　　deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse focal
　　4.再输入命令更新源。
　　sudo apt-get update
　　5.最后输入命令更新一下软件即可。
　　sudo apt-get upgrade