Mac下将Python2.7改为Python3

python -v 小写v:这是版本信息，包括库版本

python -V 大写v：只看python的版本

which python3    查看安装路径

# Setting PATH for Python 3.8

# The orginal version is saved in .bash_profile.pysave

PATH="/Library/Frameworks/Python.framework/Versions/3.8/bin:${PATH}"

export PATH 
 ### //增加这几行内容（如有则无需添加）

 alias python2=‘/System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7‘

 alias python3=‘/Library/Frameworks/Python.framework/Versions/3.8/bin/python3‘

 alias python=python3