一、进入到yum源相应的目录
cd /etc/yum.repos.d/
二、建立备份目录，把相应的文件进行备份
mkdir bak
mv * bak/
三、编辑配置CentOS-Base.repo文件centos
[root@localhost yum.repos.d]# cat CentOS-Base.repo # file: /etc/yum.repos.d/CentOS-AppStream.repo [aliyun-AppStream] name=CentOS-$releasever - AppStream baseurl=http://mirrors.aliyun.com/centos/$releasever/AppStream/$basearch/os/ gpgcheck=1 enabled=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial # file: /etc/yum.repos.d/CentOS-Base.repo [aliyun-BaseOS] name=CentOS-$releasever - Base baseurl=http://mirrors.aliyun.com/centos/$releasever/BaseOS/$basearch/os/ gpgcheck=1 enabled=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial [aliyun-extras] name=CentOS-$releasever - Extras baseurl=https://mirrors.aliyun.com/centos/8.0.1905/extras/x86_64/os/ enabled=1 gpgcheck=1
四、安装epel-release源dnf -y install epel-release
五、清yum缓存，从新加载缓存
dnf clear all dnf makecache dnf repolist