ubuntu20.04版本更新软件源

中科⼤镜像源

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

deb https://mirrors.ustc.edu.cn/ubuntu/ focal main restricted universe multiversedeb-src https://mirrors.ustc.edu.cn/ubuntu/ focal main restricted universe multiverse

deb https://mirrors.ustc.edu.cn/ubuntu/ focal-updates main restricted universe multiversedeb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-updates main restricted universe multiversedeb https://mirrors.ustc.edu.cn/ubuntu/ focal-backports main restricted universe multiversedeb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-backports main restricted universe multiversedeb https://mirrors.ustc.edu.cn/ubuntu/ focal-security main restricted universe multiversedeb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-security main restricted universe multiversedeb https://mirrors.ustc.edu.cn/ubuntu/ focal-proposed main restricted universe multiversedeb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse