//1.先备份
cp /etc/apt/sources.list /etc/apt/sources.list.bak
//2.清空
echo " " > /etc/apt/sources.list
//3.写阿里源
echo "deb https://mirrors.aliyun.com/debian stable main contrib non-free">>/etc/apt/sources.list
echo "deb https://mirrors.aliyun.com/debian stable-updates main contrib non-free">>/etc/apt/sources.list
//4.清空缓存
apt-get clean
apt-get update