所在文件 /etc/apt/sources.list

官方源

deb http://ports.ubuntu.com/ubuntu-ports bionic main restricted universe multiverse

deb-src http://ports.ubuntu.com/ubuntu-ports bionic main restricted universe multiverse

中科大源

deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic main multiverse restricted universe
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-backports main multiverse restricted universe
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-proposed main multiverse restricted universe
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-security main multiverse restricted universe
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-updates main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-backports main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-proposed main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-security main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-updates main multiverse restricted universe