1、首先備份Ubuntu 8.04 的當前更新源列表
sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup （備份下當前的源列表，有備無患嘛）
2、修改更新源
sudo gedit /etc/apt/sources.list （打開Ubuntu 8.04源列表文件）
在最下面加入
deb http://ubuntu.cn99.com/ubuntu/ hardy main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ hardy-security main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ hardy-updates main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ hardy-proposed main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ hardy-backports main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ hardy main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ hardy-security main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ hardy-updates main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ hardy-proposed main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ hardy-backports main restricted universe multiverse
3、通知 Ubuntu 8.40 啟用新的更新源
sudo apt-get update