一、centos8自带的源 yum 和 dnff 无法使用，建议切换到centos-vaulti源，方法如下：
sed -i -e "s|mirrorlist=|#mirrorlist=|g" /etc/yum.repos.d/CentOS-* sed -i -e "s|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g" /etc/yum.repos.d/CentOS-*
二、centos8自带的源 yum 和 dnff 无法使用，也可配置成阿里云的源解决，方法如下：
1、修改 CentOS-AppStream.repo
#vi /etc/yum.repos.d/CentOS-AppStream.repo [AppStream] name=CentOS-$releasever - AppStream baseurl=https://mirrors.aliyun.com/centos/$releasever/AppStream/$basearch/os/ gpgcheck=1 enabled=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
2、修改 CentOS-Base.repo
#vi /etc/yum.repos.d/CentOS-Base.repo [BaseOS] name=CentOS-$releasever - Base baseurl=https://mirrors.aliyun.com/centos/$releasever/BaseOS/$basearch/os/ gpgcheck=1 enabled=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
3、清理缓存
dnf clean all # 清除所有的缓存文件
dnf makecache # 制作元数据缓存