jupyter notebook将python2升级为python3

• 查看python版本：python --version
• 查看pip版本：pip -V
• 官网下载、安装python3
• 查看python安装路径：which python3
• 查看pip安装路径：which pip3
• 将python3、pip3路径添加到系统配置.bashrc ：

$ echo "alias python=/Library/Frameworks/Python.framework/Versions/3.9/bin/python3" >> ~/.bashrc
$ echo "alias pip=/Library/Frameworks/Python.framework/Versions/3.9/bin/pip3" >> ~/.bashrc

• 用pip3重新安装jupyter notebook：

$ pip install jupyterlab 
$ pip install notebook 

• 在终端启动notebook：

$ jupyter notebook