ubuntu更新源是指更新ubuntu系統的軟件源，比你需要安裝某個軟件時是通過apt-get install xxx命令安裝的，而ubuntu系統下載軟件的地方，一般默認為國外的鏈接，因此會比較慢，能夠換成國內的源提升下載速度。
更換源具體操作步驟：
1.打開終端。
2.輸入以下命令備份原來的源。
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
3.再輸入以下命令打開sources.list配置文件更換源。
sudo vim/etc/apt/sources.list
//配置內容如下
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.再輸入命令更新源。
sudo apt-get update
5.最后輸入命令更新一下軟件即可。
sudo apt-get upgrade
