切换 Homebrew 安装的 Python 版本

Question

I have Python 3.8 and 3.9 installed via Homebrew:

~ brew list | grep python
python@3.8
python@3.9

I want to use Python 3.9 as my default one with python3 command. I tried the following:

~ brew switch python 3.9
Error: python does not have a version "3.9" in the Cellar.
python's installed versions: 3.8.6

I tried to uninstall Python and reinstall it, but it's used by other packages:

~ brew uninstall python
Error: Refusing to uninstall /usr/local/Cellar/python@3.8/3.8.6
because it is required by glib and php, which are currently installed.
You can override this and force removal with:
  brew uninstall --ignore-dependencies python

How can I use Python 3.9?

Answer 1

There is an Homebrew known issue related to side by side install of Python 3.8 / 3.9 . To workaround, following commands should work for you:

brew unlink python@3.9
brew unlink python@3.8
brew link --force python@3.9

Re-opening your terminal or execute command rehash can be required to take account the change.

Answer 2

Use pyenv . It's a software that lets you switch between any and all Python versions installed on your system. To install pyenv , use the following code in the command-line:

curl https://pyenv.run | bash
exec $SHELL

Then find the name of the python version you want to switch to with this:

pyenv versions

And select it with this:

pyenv global <version-name>

In your case, it's most likely named 3.9.0 .

Answer 3

Updated MacOs Monterrey

For who are facing this problem add the pyenv path to your ~/.zshrc shell file.

export PATH="/Users/username/.pyenv/shims:${PATH}
eval "$(pyenv init --path)

Run in the terminal:

source ~/.zshrc

Check it out:

python3 --version

Font from the issue on GitHub .