sudo sed -e 's!^metalink=!#metalink=!g' \
    -e 's!^#baseurl=!baseurl=!g' \
    -e 's!https\?://download\.fedoraproject\.org/pub/epel!http://mirrors.tuna.tsinghua.edu.cn/epel!g' \
    -e 's!https\?://download\.example/pub/epel!http://mirrors.tuna.tsinghua.edu.cn/epel!g' \
    -i /etc/yum.repos.d/epel*.repo