查看python版本
python --version修改前默认是指向2.x版本
python2 --version
python3 --version
查看本机python安装目录
which python
which python2
which python3
移除2.x版本的软链接
sudo mv /usr/local/bin/python /usr/local/bin/python2.7
建立3.x版本的软链接
sudo ln -s /Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/bin/python3 /usr/local/bin/python
修改后检查软链接是否生效
python --version指向3.x版本即代表已修改成功