当你不是root用户时，安装模块时报错：
$ pip install Cmake ... ERROR: Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: '/usr/lib64/python2.7/site-packages/cmake-3.14.4.dist-info' Consider using the `--user` option or check the permissions.
因为代表进行全局安装，安装后全局可用
解决办法就是：
$ pip install --user Cmake DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7. Collecting Cmake Using cached https://files.pythonhosted.org/packages/09/bb/0121c0ae40144b99420a1a0ea081d48ac4d77332600896d7e04bf23aa957/cmake-3.14.4-py2-none-manylinux2010_x86_64.whl Installing collected packages: Cmake Successfully installed Cmake-3.14.4
添加一个--user,代表仅该用户的安装，安装后仅该用户可用。处于安全考虑，尽量使用该命令进行安装。
记得卸载的时候也要添加 --user