参考的是http://www.linuxidc.com/Linux/2012-10/73114.htm
安装ubuntu12.10之后，第一件事就是更换源，ubuntu网易163的更新源速度一直很好。
首先备份源，sudo cp /etc/apt/sources.list /etc/apt/sources.list.old
更换源，sudo gedit /etc/apt/sources.list
将下边的源直接覆盖掉：
deb http://mirrors.163.com/ubuntu/ quantal main universe restricted multiverse
deb-src http://mirrors.163.com/ubuntu/ quantal main universe restricted multiverse
deb http://mirrors.163.com/ubuntu/ quantal-security universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ quantal-security universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ quantal-updates universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ quantal-proposed universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ quantal-proposed universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ quantal-backports universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ quantal-backports universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ quantal-updates universe main multiverse restricted
运行apt-get update
ubuntu中常用命令：
apt-get upgrade
apt-get install
apt-get bulid-dep
12.04源
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