# 备份原文件 sudo cp sources.list sources.list.bk sudo vi sources.list
# 删除原来的文本,将下面的代码复制进去(以Ubuntu20.04阿里源为例) deb https://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse deb-src https://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse deb-src https://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb https://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse deb-src https://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
# deb https://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse # deb-src https://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb https://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse deb-src https://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse