#導入gpg key
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
#在/etc/yum.repos.d/下安裝elrepo.repo 文件 yum install https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm
編輯 /etc/yum.repos.d/elrepo.repo 文件，在 mirrorlist= 開頭的行前面加 # 注釋掉；並將 elrepo.org/linux 替換為 mirrors.tuna.tsinghua.edu.cn/elrepo
最后，更新軟件包緩存
yum makecache
EPEL(Extra Packages for Enterprise Linux)是由Fedora Special Interest Group維護的Enterprise Linux（RHEL、CentOS）中經 常用到的包。
touch /etc/yum.repos.d/epel.repo
編輯文件/etc/yum.repos.d/epel.repo，內容如下：
[epel] name=Extra Packages for Enterprise Linux 7 - $basearch baseurl=https://mirrors.tuna.tsinghua.edu.cn/epel/7/$basearch #mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch failovermethod=priority enabled=1 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 [epel-debuginfo] name=Extra Packages for Enterprise Linux 7 - $basearch - Debug baseurl=https://mirrors.tuna.tsinghua.edu.cn/epel/7/$basearch/debug #mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-debug-7&arch=$basearch failovermethod=priority enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 gpgcheck=1 [epel-source] name=Extra Packages for Enterprise Linux 7 - $basearch - Source baseurl=https://mirrors.tuna.tsinghua.edu.cn/epel/7/SRPMS #mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-source-7&arch=$basearch failovermethod=priority enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 gpgcheck=1
保存，退出。
最后，yum makecache