pip问题解决方案

错误信息:usr/bin/pip: No such file or directory

解决办法(一共四步，按照下面的步骤来从1到4，最后你会发现问题都解决了):

1.which pip 
/usr/local/bin/pip

2.pip 
-su: /usr/bin/pip: No such file or directory

3.type pip 
pip is hashed (/usr/bin/pip) 
So pip is definintely in /usr/local/bin/pip but it is been cached as in /usr/bin/pip, thanks to the Stackoverflow question, the solution is very simple:

4.hash -r 
When the cache is clear, pip is working again.