Centos7 installs dnf tools to manage rpm packages

dnf is a new rpm package management tool with more powerful functions than yum

    第一步：
         wget http://springdale.math.ias.edu/data/puias/unsupported/7/x86_64/dnf-conf-0.6.4-2.sdl7.noarch.rpm 

    第二步：
         wget http://springdale.math.ias.edu/data/puias/unsupported/7/x86_64//dnf-0.6.4-2.sdl7.noarch.rpm 

    第三步：
         wget http://springdale.math.ias.edu/data/puias/unsupported/7/x86_64/python-dnf-0.6.4-2.sdl7.noarch.rpm 

    安装：
        sudo  yum install python-dnf-0.6.4-2.sdl7.noarch.rpm dnf-0.6.4-2.sdl7.noarch.rpm dnf-conf-0.6.4-2.sdl7.noarch.rpm

    输入dnf --version查看结果
    这个网页可以学习dnf的使用方法：https://my.oschina.net/liuyuantao/blog/756133