Ubuntu 12.04 lts update source

Ubuntu 12.04 lts update source method
1. Back up sources. list file: CP/etc/APT/sources. LIST/home/sources-backup.list (you can also copy sources directly. list Files to other folders. Remember that backup is important !)
2. Open the source file: sudo gedit/etc/APT/sources. List
3. Copy the following update source address to it (delete the original file and back up before deletion)
4. Update the source information: sudo apt-Get update
5. Update the system: sudo apt-Get upgrade

Ubuntu 12.04 lts update source address
Campus Network users: E-Science and Technology Department update source
[Code]
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
[/Code]

Non-campus network users: Netease update source:
[Code]
Deb http://mirrors.163.com/ubuntu/ precise main restricted
Deb-Src http://mirrors.163.com/ubuntu/ precise main restricted
Deb http://mirrors.163.com/ubuntu/ precise-Updates main restricted
Deb-Src http://mirrors.163.com/ubuntu/ precise-Updates main restricted
Deb http://mirrors.163.com/ubuntu/ precise universe
Deb-Src http://mirrors.163.com/ubuntu/ precise universe
Deb http://mirrors.163.com/ubuntu/ precise-Updates universe
Deb-Src http://mirrors.163.com/ubuntu/ precise-Updates universe
Deb http://mirrors.163.com/ubuntu/ precise multiverse
Deb-Src http://mirrors.163.com/ubuntu/ precise multiverse
Deb http://mirrors.163.com/ubuntu/ precise-Updates multiverse
Deb-Src http://mirrors.163.com/ubuntu/ precise-Updates multiverse
Deb http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiverse
Deb-Src http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiverse
Deb http://mirrors.163.com/ubuntu/ precise-security main restricted
Deb-Src http://mirrors.163.com/ubuntu/ precise-security main restricted
Deb http://mirrors.163.com/ubuntu/ precise-security universe
Deb-Src http://mirrors.163.com/ubuntu/ precise-security universe
Deb http://mirrors.163.com/ubuntu/ precise-security multiverse
Deb-Src http://mirrors.163.com/ubuntu/ precise-security multiverse
Deb http://extras.ubuntu.com/ubuntu precise main
Deb-Src http://extras.ubuntu.com/ubuntu precise main
[/Code]

Netease's open-source image server provides dual-line access between China Telecom and China Unicom.
China Telecom line (IP: 60.191.81.189): http://tel.mirrors.163.com
China Unicom line (IP 60.12.227.94): http://uni.mirrors.163.com