写在前面
我个人最常用的 Linux 发行版是 debian，因为我觉得它比 Ubuntu 更轻量更稳定更高效。因为每次装完系统都需要更换镜像源，还有其他乱七八糟的事情，所以把过程中的一些问题总结在这里。
apt 更换国内源
- 镜像源文件为：
/etc/apt/sources.list - 国内常用镜像源：
deb http://mirrors.163.com/debian/ buster main non-free contrib deb http://mirrors.163.com/debian/ buster-updates main non-free contrib deb http://mirrors.163.com/debian/ buster-backports main non-free contrib deb http://mirrors.163.com/debian-security/ buster/updates main non-free contrib deb-src http://mirrors.163.com/debian/ buster main non-free contrib deb-src http://mirrors.163.com/debian/ buster-updates main non-free contrib deb-src http://mirrors.163.com/debian/ buster-backports main non-free contrib deb-src http://mirrors.163.com/debian-security/ buster/updates main non-free contrib - 更新源：
sudo apt-get update -
public GPG key error (“NO_PUBKEY)解决方法
sudo apt-key adv --keyserver hkp://pool.sks-keyservers.net:80 --recv-keys THE_MISSING_KEY_HERE #THE_MISSING_KEY_HERE 用缺少的公钥替换
