每次升级Ubuntu都有更换更新源（gengxinyuan），其实更新源地址不必上网找，直接自己更改就可以了。更新源的地址基本上是这样的：
deb oneiric main universe restricted multiverse
这个是Ubuntu 11.10的更新源地址，其中 oneiric就是ubuntu 11.10的开发代号，所以我们只需要将电脑中的更新源列表里的开发代号替换为Ubuntu 12.04的开发代号就可以了，用ctrl+F查找出来全部替换就可以了。因此以后再换版本就不用自己上网搜索更新源了。
Ubuntu 12.04的开发代号是Precise Pangolin，译为精确的穿山甲。所以只需将oneiric替换为precise即可
1、首先备份Ubuntu 11.10源列表
sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup （备份下当前的源列表，有备无患嘛）
2、修改更新源
sudo gedit /etc/apt/sources.list （打开Ubuntu 11.10源列表文件）
3、用ctrl+F查找所有的oneiric，然后全部替换为precise
4、通知ubuntu启用新的更新源 sudo apt-get update
//当然如果你比较懒，或者是全新安装的ubuntu，那你可以直接把下面的代码复制到sources.list中
#台湾源
deb precise main universe restricted multiverse
deb-src precise main universe restricted multiverse
deb precise-security universe main multiverse restricted
deb-src precise-security universe main multiverse restricted
deb precise-updates universe main multiverse restricted
deb-src precise-updates universe main multiverse restricted
#网易 Ubuntu 11.10 源（速度很快）
deb precise main universe restricted multiverse
deb-src precise main universe restricted multiverse
deb precise-security universe main multiverse restricted
deb-src precise-security universe main multiverse restricted
deb precise-updates universe main multiverse restricted
deb precise-proposed universe main multiverse restricted
deb-src precise-proposed universe main multiverse restricted
deb precise-backports universe main multiverse restricted
deb-src precise-backports universe main multiverse restricted
deb-src precise-updates universe main multiverse restricted
#骨头源，骨头源是bones7456架设的一个Ubuntu源 ，提供ubuntu,deepin
deb precise main universe restricted multiverse
deb-src precise main universe restricted multiverse
deb precise-security universe main multiverse restricted
deb-src precise-security universe main multiverse restricted
deb precise-updates universe main multiverse restricted
deb precise-proposed universe main multiverse restricted
deb-src precise-proposed universe main multiverse restricted
deb precise-backports universe main multiverse restricted
deb-src precise-backports universe main multiverse restricted
deb-src precise-updates universe main multiverse restricted
#mirror.lupaworld.com的源，速度很快
deb precise main restricted universe multiverse
deb precise-security main restricted universe multiverse
deb precise-updates main restricted universe multiverse
deb precise-backports main restricted universe multiverse
deb precise main restricted universe multiverse
#ubuntu.cn99.com源（推荐）:
deb precise main restricted universe multiverse
deb precise-updates main restricted universe multiverse
deb precise-security main restricted universe multiverse
deb precise-backports main restricted universe multiverse
deb precise main restricted universe multiverse
//教育网源
如果你是在校大学生，可以使用校园网/教育网，就是用教育网的资源吧，中科大，兰大、厦门大学都有很多资源，尤其是支持ipv6的，那更新速度就按兆算了。
中科大：
厦门大学：
#电子科技大学
deb precise main restricted universe multiverse
deb precise-backports main restricted universe multiverse
deb precise-proposed main restricted universe multiverse
deb precise-security main restricted universe multiverse
deb precise-updates main restricted universe multiverse
deb-src precise main restricted universe multiverse
deb-src precise-backports main restricted universe multiverse
deb-src precise-proposed main restricted universe multiverse
deb-src precise-security main restricted universe multiverse
deb-src precise-updates main restricted universe multiverse
#中国科技大学
deb precise main restricted universe multiverse
deb precise-backports restricted universe multiverse
deb precise-proposed main restricted universe multiverse
deb precise-security main restricted universe multiverse
deb precise-updates main restricted universe multiverse
deb-src precise main restricted universe multiverse
deb-src precise-backports main restricted universe multiverse
deb-src precise-proposed main restricted universe multiverse
deb-src precise-security main restricted universe multiverse
deb-src precise-updates main restricted universe multiverse
#北京理工大学
deb precise main multiverse restricted universe
deb precise-backports main multiverse restricted universe
deb precise-proposed main multiverse restricted universe
deb precise-security main multiverse restricted universe
deb precise-updates main multiverse restricted universe
deb-src precise main multiverse restricted universe
deb-src precise-backports main multiverse restricted universe
deb-src precise-proposed main multiverse restricted universe
deb-src precise-security main multiverse restricted universe
deb-src precise-updates main multiverse restricted universe
#兰州大学
deb ftp://mirror.lzu.edu.cn/ubuntu/ precise main multiverse restricted universe
deb ftp://mirror.lzu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe
deb ftp://mirror.lzu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe
deb ftp://mirror.lzu.edu.cn/ubuntu/ precise-security main multiverse restricted universe
deb ftp://mirror.lzu.edu.cn/ubuntu/ precise-updates main multiverse restricted universe
deb ftp://mirror.lzu.edu.cn/ubuntu-cn/ precise main multiverse restricted universe
#上海交通大学
deb precise main multiverse restricted universe
deb precise-backports main multiverse restricted universe
deb precise-proposed main multiverse restricted universe
deb precise-security main multiverse restricted universe
deb precise-updates main multiverse restricted universe
deb precise main multiverse restricted universe
deb-src precise main multiverse restricted universe
deb-src precise-backports main multiverse restricted universe
deb-src precise-proposed main multiverse restricted universe
deb-src precise-security main multiverse restricted universe
deb-src precise-updates main multiverse restricted universe