1、1，备份系统默认的源（没有root权限的前面加sudo）cp /etc/apt/sources.list /etc/apt/sources.list.bak
2、,2，修改/etc/apt/sources.list>/etc/apt/sources.listcat >>/etc/apt/sources.list<<EOF# deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ xenial main restricteddeb-src http://archive.ubuntu.com/ubuntu xenial main restricted #Added by software-propertiesdeb http://mirrors.aliyun.com/ubuntu/ xenial main restricteddeb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe #Added by software-propertiesdeb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricteddeb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-propertiesdeb http://mirrors.aliyun.com/ubuntu/ xenial universedeb http://mirrors.aliyun.com/ubuntu/ xenial-updates universedeb http://mirrors.aliyun.com/ubuntu/ xenial multiversedeb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiversedeb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiversedeb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-propertiesdeb http://archive.canonical.com/ubuntu xenial partnerdeb-src http://archive.canonical.com/ubuntu xenial partnerdeb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricteddeb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe #Added by software-propertiesdeb http://mirrors.aliyun.com/ubuntu/ xenial-security universedeb http://mirrors.aliyun.com/ubuntu/ xenial-security multiverseEOF
3、3，执行更新源apt-get update ****不执行是不生效的
