1：强制安装 oraclelinux-release 和 redhat-release 的包
从 yum.oracle.com 找到对应版本这两个包的最新版，例如 Oracle Linux 8(对应 CentOs 8) x86_64 这两个包最新版是
https://yum.oracle.com/repo/OracleLinux/OL8/baseos/latest/x86_64/getPackage/oraclelinux-release-8.3-1.0.4.el8.x86_64.rpm
https://yum.oracle.com/repo/OracleLinux/OL8/baseos/latest/x86_64/getPackage/redhat-release-8.3-1.0.0.1.el8.x86_64.rpm
用 rpm 强制安装之
rpm -i -force https://yum.oracle.com/repo/OracleLinux/OL8/baseos/latest/x86_64/getPackage/oraclelinux-release-8.3-1.0.4.el8.x86_64.rpm https://yum.oracle.com/repo/OracleLinux/OL8/baseos/latest/x86_64/getPackage/redhat-release-8.3-1.0.0.1.el8.x86_64.rpm
2: 删除原有 centos release 包
rpm -e centos-gpg-keys centos-repos centos-release
如果有安装 epel-release 也一起删除
rpm -e epel-release
3: 安装 oraclelinux-release-el? 的包，比如 centos 8 就用 oracle-release-el8 ，同样从 yum.oracle.com 找到这个包的最新版
https://yum.oracle.com/repo/OracleLinux/OL8/baseos/latest/x86_64/getPackage/oraclelinux-release-el8-1.0-14.el8.x86_64.rpm
rpm -i https://yum.oracle.com/repo/OracleLinux/OL8/baseos/latest/x86_64/getPackage/oraclelinux-release-el8-1.0-14.el8.x86_64.rpm
(剩下的事情都可以用 yum 来搞定了)
4: 如果之前有安装 epel-release 的话，安装 oracle-epel-release-el? (依然要对应版本)
yum install oracle-epel-release-el8 -y
5: yum 升级到最新版本
yum update -y
6: 可选：使用 Oracle 打造的专用内核 UEK(Unbreakable Enterprise Kernel)
yum install kernel-uek