在给客户配置一台CentOS 7.8系统的本地yum源后，执行
# yum clean all && yum makecache
# yum list
均报错：
-bash: /usr/bin/yum: /usr/bin/python: bad interpreter: No such file or directory
赶紧whereis python，没有路径，rpm -qa| grep python也没有输出，怀疑客户自己删掉了python。
进入相同版本的iso挂载pkg目录，执行rpm -ivh *python*提示报错，无法正常安装，有很多依赖关系。
只能选择忽略依赖安装，执行：
# rpm -ivh *python* --nodeps
顺利安装了相关python包，再执行yum list看看，结果又报错了：
# yum list
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
No module named yum
Please install a package which provides this module, or
verify that the module is installed correctly.
It's possible that the above module doesn't match the
current version of Python, which is:
2.7.5 (default, Apr 2 2020, 13:16:51)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)]
If you cannot solve this problem yourself, please go to
the yum faq at:
从报错中可以看出是python版本和yum不兼容，感觉没道理呀，相同的源怎么会这样？
只好重新安装yum试试：
# rpm -Uvh --replacepkgs *yum* --nodeps
再次执行yum list可以看到本地yum源，测试下软件包的安装：
# yum -y install ntp
也能顺利安装。
