cp /etc/apt/sources.list  /etc/apt/sources.list_buckup -> 将/etc/apt目录下的文件进行备份，防止意外

vi /apt/etc/sources.list 删除所有行(命令为ggdG)，并将最后的阿里软件源粘贴，使用其他的也ok

apt-get clean -> 删除包缓存中的所有包
apt-get update -> 更新生效

deb http://mirrors.aliyun.com/ubuntu/ trusty main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main multiverse restricted universe