#備份當前源
cd /etc/apt/
sudo cp sources.list sources.list.bak
#修改爲ali的源
/etc/apt$ cat sources.list
deb http://mirrors.aliyun.com/ubuntu/ utopic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ utopic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ utopic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ utopic-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ utopic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ utopic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ utopic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ utopic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ utopic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ utopic-backports main restricted universe multiverse
#更新
sudo apt-get update