1.设置软件源

cat > /etc/apt/sources.list<<EOF
deb http://archive.debian.org/debian/ stretch main contrib non-free
deb-src http://archive.debian.org/debian/ stretch main contrib non-free
deb http://archive.debian.org/debian-security/ stretch/updates main contrib non-free
deb-src http://archive.debian.org/debian-security/ stretch/updates main contrib non-free
deb http://archive.debian.org/debian/ stretch-backports main contrib non-free
EOF

2.升级Debian 9 现有的软件包

apt update && apt upgrade -y

3.提示GPG证书问题，NO_PUBLICKEY

记录PUBULICKEY

NO_PUBKEY 648ACFD622F3D138 NO_PUBKEY 0E98404D386FA1D9

3.1安装需要的依赖和软件

apt-get install software-properties-common dirmngr -y

3.2添加gpg证书验证

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys <PUBKEY>
<PUBKEY2>
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 648ACFD622F3D138 0E98404D386FA1D9

4.更换debian12的软件源

cat >/etc/apt/sources.list<<EOF
deb https://mirrors.ustc.edu.cn/debian/ bookworm main contrib non-free non-free-firmware
deb-src https://mirrors.ustc.edu.cn/debian/ bookworm main contrib non-free non-free-firmware
deb https://mirrors.ustc.edu.cn/debian/ bookworm-updates main contrib non-free non-free-firmware
deb-src https://mirrors.ustc.edu.cn/debian/ bookworm-updates main contrib non-free non-free-firmware
deb https://mirrors.ustc.edu.cn/debian/ bookworm-backports main contrib non-free non-free-firmware
deb-src https://mirrors.ustc.edu.cn/debian/ bookworm-backports main contrib non-free non-free-firmware
deb https://security.debian.org/debian-security bookworm-security main contrib non-free non-free-firmware
deb-src https://security.debian.org/debian-security bookworm-security main contrib non-free non-free-firmware
EOF

添加公钥

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 54404762BBB6E853 BDE6D2B9216EC7A8

5.更新软件源索引

apt update -y

在开始升级你现有的 Debian 操作系统前，让我们使用下面的命令验证当前版本

cat /etc/*-release

6.从 Debian 9 升级到 Debian 12

apt update && apt upgrade -y

7.查看当前版本信息

lsb_release -a