Ubuntu 12.04 更换源之后解决安装软件慢及部分包损坏问题

最近经常碰到Ubuntu下安装包出现问题及慢的问题，更换源是最简便快速的解决办法，当然只限于某些问题。
记录备忘。

1、备份原文件

以下操作均需root权限。

cp /etc/apt/sources.list /etc/apt/sources.list.backup

2、修改源文件

 cp /etc/apt/sources.list /etc/apt/sources.list.backup

3、选择合适的源更换原文件里面的内容：

163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
sohu源

deb http://mirrors.sohu.com/ubuntu/ precise main restricted
deb-src http://mirrors.sohu.com/ubuntu/ precise main restricted
deb http://mirrors.sohu.com/ubuntu/ precise-updates main restricted
deb-src http://mirrors.sohu.com/ubuntu/ precise-updates main restricted
deb http://mirrors.sohu.com/ubuntu/ precise universe
deb-src http://mirrors.sohu.com/ubuntu/ precise universe
deb http://mirrors.sohu.com/ubuntu/ precise-updates universe
deb-src http://mirrors.sohu.com/ubuntu/ precise-updates universe
deb http://mirrors.sohu.com/ubuntu/ precise multiverse
deb-src http://mirrors.sohu.com/ubuntu/ precise multiverse
deb http://mirrors.sohu.com/ubuntu/ precise-updates multiverse
deb-src http://mirrors.sohu.com/ubuntu/ precise-updates multiverse
deb http://mirrors.sohu.com/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ precise-backports main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ precise-security main restricted
deb-src http://mirrors.sohu.com/ubuntu/ precise-security main restricted
deb http://mirrors.sohu.com/ubuntu/ precise-security universe
deb-src http://mirrors.sohu.com/ubuntu/ precise-security universe
deb http://mirrors.sohu.com/ubuntu/ precise-security multiverse
deb-src http://mirrors.sohu.com/ubuntu/ precise-security multiverse
deb http://extras.ubuntu.com/ubuntu precise main
deb-src http://extras.ubuntu.com/ubuntu precise main

4、更新源

apt-get update