Ubuntu换源

1：备份原来的源---->cp /etc/apt/sources.list  /etc/apt/sources.list_backup

2：打开/etc/apt/sources.list，添加源 ---->sudo gedit /etc/apt/sources.list,添加想要的源，此处添加的是163的源，直接覆盖原来的源，如下，添加完成保持退出

#add by Crifan Li 2013-08-08, added 163 source
deb http://mirrors.163.com/ubuntu/ precise main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ precise-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ precise-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ precise-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ precise main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ precise-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ precise-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ precise-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiverse

3：sudo apt-get update