1.輸入該命令按回車鍵：yum -y install epel-release
2.輸入該命令按回車鍵：yum -y install rpmconf yum-utils
3.輸入該命令按回車鍵：rpmconf -a，出現(xiàn)提示輸入Y按回車鍵
4.輸入該命令按回車鍵：yum -y install dnf
5.輸入該命令按回車鍵：dnf -y remove yum yum-metadata-parser
6.輸入該命令按回車鍵：rm -rf /etc/yum
7.輸入該命令按回車鍵：dnf -y upgrade
8.輸入該命令按回車鍵：dnf -y install https://mirrors.aliyun.com/centos/8/BaseOS/x86_64/os/Packages/{centos-linux-repos-8-3.el8.noarch.rpm,centos-linux-release-8.5-1.2111.el8.noarch.rpm,centos-gpg-keys-8-3.el8.noarch.rpm}
9.輸入該命令按回車鍵dnf -y upgrade https://mirrors.bfsu.edu.cn/epel/epel-release-latest-8.noarch.rpm
10.輸入該命令按回車鍵：dnf clean all
11.輸入該命令按回車鍵：rpm -e `rpm -q kernel`
12.輸入該命令按回車鍵：rpm -e --nodeps sysvinit-tools
13.輸入該命令按回車鍵：dnf -y --releasever=8 --allowerasing --setopt=deltarpm=false distro-sync
14.輸入該命令按回車鍵查看版本：cat /etc/redhat-release
