Yum source file into the first cd /etc/yum.repo.d/
1, repo_bak create a directory for saving the system in the original yum repo file.
sudo mkdir repo_bak
2, backup yum source file to repo_bak
sudo mv * .repo repo_bak /
3, Netease and Ali mirror site to download the open source version of the system corresponding to the repo file
wget http://mirrors.aliyun.com/repo/Centos-7.repo
4, clear the system cache yum yum and generate a new cache
yum yum clean all clear the system cache
yum yum makecache generate cache
5, the installation source epel
yum list | grip epel- release
yum install -y epel-release
6, the use of open source Ali mirroring provides a source of epel
wget -O /etc/yum.repos.d/epel-7.repo http://mirrors.aliyun.com/repo/epel-7.repo
7, once again clear the system cache yum, yum and regenerate new cache
yum yum clean all Clear Cache
yum yum makecache generate cache
8, view system available yum yum source and all sources
yum repolist enabled