备份/etc/apt/sources.list
#备份
cp /etc/apt/sources.list /etc/apt/sources.list.bak
在/etc/apt/sources.list文件，注释原文件所有内容，前面添加下面的条目。
deb http://mirrors.aliyun.com/debian/ buster main non-free contrib deb-src http://mirrors.aliyun.com/debian/ buster main non-free contrib deb http://mirrors.aliyun.com/debian-security buster/updates main deb-src http://mirrors.aliyun.com/debian-security buster/updates main deb http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib deb-src http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib deb http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib deb-src http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib
#更新
apt-get update
/etc/apt/sources.list 是包管理工具 apt 所用的记录软件包仓库位置的配置文件
其中，deb：档案类型为二进制预编译软件包，一般我们所用的档案类型。
deb-src：档案类型为用于编译二进制软件包的源代码
文章来源：https://blog.csdn.net/jamesdodo/article/details/106073576
