Reprinted from http://www.linuxidc.com/Linux/2012-06/63068.htm
Every time you upgrade Ubuntu , you have to replace the update source (gengxinyuan). In fact, you don't need to find the update source address online, you can just change it yourself. The address of the update source is basically like this:
deb http://ubuntu.srt.cn/ubuntu/ oneiric main universe restricted multiverse
This is the update source address of Ubuntu 11.10, of which oneiric is the development code name of ubuntu 11.10, so we only need to replace the development code name in the update source list in the computer with the development code name of Ubuntu 12.04, and use ctrl+F to find it Just replace all. Therefore, if you change the version in the future, you do not need to search for the update source on the Internet yourself.
The development code name of Ubuntu 12.04 is Precise Pangolin, which translates to precise pangolin. So just replace oneiric with precise
1. First backup the Ubuntu 11.10 source list sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup (back up the current source list, be prepared)
2. Modify the update source sudo gedit /etc/apt/sources.list (open the Ubuntu 11.10 source list file)
3. Use ctrl+F to find all oneiric, and then replace all with precise 4. Inform ubuntu to enable the new update source sudo apt-get update
//Of course, if you are lazy, or have a freshly installed ubuntu, then you can directly copy the following code to sources.list
#台湾源
deb http://tw.archive.ubuntu.com/ubuntu/ precise main universe restricted multiverse
deb-src http://tw.archive.ubuntu.com/ubuntu/ precise main universe restricted multiverse
deb http://tw.archive.ubuntu.com/ubuntu/ precise-security universe main multiverse restricted
deb-src http://tw.archive.ubuntu.com/ubuntu/ precise-security universe main multiverse restricted
deb http://tw.archive.ubuntu.com/ubuntu/ precise-updates universe main multiverse restricted
deb-src http://tw.archive.ubuntu.com/ubuntu/ precise-updates universe main multiverse restricted
#网易 Ubuntu 11.10 源（速度很快）
deb http://mirrors.163.com/ubuntu/ precise main universe restricted multiverse
deb-src http://mirrors.163.com/ubuntu/ precise main universe restricted multiverse
deb http://mirrors.163.com/ubuntu/ precise-security universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ precise-security universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ precise-updates universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ precise-proposed universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ precise-proposed universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ precise-backports universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ precise-backports universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ 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 http://ubuntu.srt.cn/ubuntu/ precise main universe restricted multiverse
deb-src http://ubuntu.srt.cn/ubuntu/ precise main universe restricted multiverse
deb http://ubuntu.srt.cn/ubuntu/ precise-security universe main multiverse restricted
deb-src http://ubuntu.srt.cn/ubuntu/ precise-security universe main multiverse restricted
deb http://ubuntu.srt.cn/ubuntu/ precise-updates universe main multiverse restricted
deb http://ubuntu.srt.cn/ubuntu/ precise-proposed universe main multiverse restricted
deb-src http://ubuntu.srt.cn/ubuntu/ precise-proposed universe main multiverse restricted
deb http://ubuntu.srt.cn/ubuntu/ precise-backports universe main multiverse restricted
deb-src http://ubuntu.srt.cn/ubuntu/ precise-backports universe main multiverse restricted
deb-src http://ubuntu.srt.cn/ubuntu/ precise-updates universe main multiverse restricted
#mirror.lupaworld.com的源，速度很快
deb http://mirror.lupaworld.com/ubuntu/archive/ precise main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu/archive/ precise-security main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu/archive/ precise-updates main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu/archive/ precise-backports main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu/ubuntu-cn/ precise main restricted universe multiverse
#ubuntu.cn99.com Source (recommended):
deb http://ubuntu.cn99.com/ubuntu/ precise main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ precise-updates main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ precise-security main restricted universe multiverse
deb http://ubuntu.cn99. com/ubuntu/ precise-backports main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu-cn/ precise main restricted universe multiverse
//education net source
If you are a college student, you can use campus net/education net , is to use the resources of the education network, the University of Science and Technology of China, Landa, Xiamen University have many resources, especially those that support ipv6, then the update speed is calculated by megabytes.
University of Science and Technology of China: http://mirrors.ustc.edu.cn/Xiamen
University: http://mirrors.xmu.edu.cn/howto/ #University of
Electronic Science and Technology of China
deb http://ubuntu.uestc.edu.cn/ubuntu/ precise main restricted universe multiverse
deb http://ubuntu.uestc.edu.cn/ubuntu/ precise-backports main restricted universe multiverse
deb http://ubuntu.uestc.edu.cn/ubuntu/ precise-proposed main restricted universe multiverse
deb http://ubuntu.uestc.edu.cn/ubuntu/ precise-security main restricted universe multiverse
deb http://ubuntu.uestc.edu.cn/ubuntu/ precise-updates main restricted universe multiverse
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ precise main restricted universe multiverse
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ precise-proposed main restricted universe multiverse
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ precise-security main restricted universe multiverse
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ precise-updates main restricted universe multiverse
#中国科技大学
deb http://debian.ustc.edu.cn/ubuntu/ precise main restricted universe multiverse
deb http://debian.ustc.edu.cn/ubuntu/ precise-backports restricted universe multiverse
deb http://debian.ustc.edu.cn/ubuntu/ precise-proposed main restricted universe multiverse
deb http://debian.ustc.edu.cn/ubuntu/ precise-security main restricted universe multiverse
deb http://debian.ustc.edu.cn/ubuntu/ precise-updates main restricted universe multiverse
deb-src http://debian.ustc.edu.cn/ubuntu/ precise main restricted universe multiverse
deb-src http://debian.ustc.edu.cn/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://debian.ustc.edu.cn/ubuntu/ precise-proposed main restricted universe multiverse
deb-src http://debian.ustc.edu.cn/ubuntu/ precise-security main restricted universe multiverse
deb-src http://debian.ustc.edu.cn/ubuntu/ precise-updates main restricted universe multiverse
#北京理工大学
deb http://mirror.bjtu.edu.cn/ubuntu/ precise main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ precise-security main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ precise-updates main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-security main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ 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 http://ftp.sjtu.edu.cn/ubuntu/ precise main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ precise-security main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ precise-updates main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu-cn/ precise main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ precise main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ precise-security main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ precise-updates main multiverse restricted universe
同样可以使用更简单的办法
Ubuntu 12.04 中用户更换一个更快的软件源
http://www.linuxidc.com/Linux/2012-05/59616.htm