已通过pip安装iPython，如何让系统区分iPython与iPython3并使其运行Python2？

Got it, let's work through this step by step so you can have ipython launch Python 2 by default, while keeping ipython3 tied to Python 3.

Step 1: Install IPython for Python 2 #

First, you need a dedicated IPython instance for Python 2. Depending on your system setup, use one of these commands:

• If your system has pip2 (the Python 2-specific pip):

  pip2 install ipython
  

• If pip2 isn't available, use Python 2's interpreter to call pip directly:

  python2 -m pip install ipython
  

This installs the Python 2-compatible IPython, and in most cases, it will automatically set ipython to point to this version, leaving ipython3 linked to your Python 3 installation.

Step 2: Verify and Fix Command Associations #

Next, check which Python version each ipython command uses:

# Check ipython's Python version
ipython -c "import sys; print('IPython is using Python:', sys.version.split()[0])"
# Check ipython3's Python version
ipython3 -c "import sys; print('IPython3 is using Python:', sys.version.split()[0])"

If ipython still launches Python 3, your system's PATH is prioritizing the Python 3 version. Fix this with an alias:

1. Open your shell config file (e.g., ~/.bashrc for Bash, ~/.zshrc for Zsh) in a text editor.
2. Add this line at the end:

   alias ipython='python2 -m ipython'
   

3. Save the file and reload the config to apply changes right away:

   source ~/.bashrc  # Use ~/.zshrc if you're using Zsh
   

Now ipython will default to Python 2, and ipython3 will keep using Python 3.

Quick Alternative (No Global Changes) #

If you don't want to modify your shell config, you can always launch Python 2's IPython directly with:

python2 -m ipython

This bypasses any PATH priorities and launches the correct version every time.

内容的提问来源于stack exchange，提问作者Daniel W.