解决windows下python2和python3共存时，pip失效

使用pip安装时报错，

pip install SendKeys
Fatal error in launcher: Unable to create process using '"c:\lib\python36\python.exe" "C:\Program Files\Python37\Scripts\pip.exe" install SendKeys'

解决方法：

1.切换到D:\Program Files\Python36\Scripts

2.执行python pip.exe install SomePackage进行安装

3.安装成功后执行pip仍报错

4.查看安装成功后，提示pip要升级

5.执行python -m pip install --upgrade pip

6.升级成功后，再次执行pip，OK了

参考

https://blog.csdn.net/mdzzname/article/details/78239973

http://www.bubuko.com/infodetail-2593817.html