1.查看ubuntu版本
#cat /etc/issue
2.网络查找对应版本的更新源
Ubuntu7.04更新源：
#首先推荐
deb http://tw.archive.Ubuntu.com/ubuntu hardy main restricted universe multiverse
deb http://tw.archive.Ubuntu.com/ubuntu hardy-security main restricted universe multiverse
deb http://tw.archive.Ubuntu.com/ubuntu hardy-updates main restricted universe multiverse
deb http://tw.archive.Ubuntu.com/ubuntu hardy-backports main restricted universe multiverse
deb http://tw.archive.Ubuntu.com/ubuntu hardy-proposed main restricted universe multiverse
deb-src http://tw.archive.Ubuntu.com/ubuntu hardy main restricted universe multiverse
deb-src http://tw.archive.Ubuntu.com/ubuntu hardy-security main restricted universe multiverse
deb-src http://tw.archive.Ubuntu.com/ubuntu hardy-updates main restricted universe multiverse
deb-src http://tw.archive.Ubuntu.com/ubuntu hardy-backports main restricted universe multiverse
deb-src http://tw.archive.Ubuntu.com/ubuntu hardy-proposed main restricted universe multiverse
3.终端输入：$sudo gedit /etc/apt/sources.list 清空里面的内容并且把搜索到的新的源地址复制到这里面，复制后用下面命令即可更新系统
$sudo apt-get update 第一个update完之后接着，
$sudo apt-get upgrade
