https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/
Ubuntu 的軟件源配置文件是 /etc/apt/sources.list。將系統自帶的該文件做個備份，將該文件替換為下面內容，即可使用 TUNA 的軟件源鏡像。
[code]$ sudo gedit /etc/apt/sources.list
[code]debhttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main multiverse restricted universe
debhttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main multiverse restricted universe
debhttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main multiverse restricted universe
debhttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main multiverse restricted universe
debhttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main multiverse restricted universe
deb-srchttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main multiverse restricted universe
deb-srchttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main multiverse restricted universe
deb-srchttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main multiverse restricted universe
deb-srchttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main multiverse restricted universe
deb-srchttp://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main multiverse restricted universe
