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I have a separate installation of Python 3.*, but the first python path in my $PATH variable is the path to system-installed Python. Is this how it should be?

I have added the path to user-installed Python using https://www.architectryan.com/2012/10/02/add-to-the-path-on-mac-os-x-mountain-lion/#.Uydjga1dXDg, and it was popped at the end of $PATH.

Do I understand correctly that, in the current situation, when I run pip, brew etc. on python3 from bash, the changes will be applied to system-installed Python?

The fix I have got so far is to run export PATH=/usr/local/bin:/usr/local/sbin:$PATH every time I want to install or update python, but it is not ideal.

NB: I went with pyenv solution as suggested by @bermudalocket. This pyenv tutorial was very useful.

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2 Answers 2

Reset to default
7

You can accomplish this by adding 

export PATH="/path/to/python:"$PATH

to your ~/.zshrc (or ~/.bash_profile if you're not on Catalina).

I'd like to propose an alternative and suggest pyenv, available via Homebrew. You can set a specific Python version to be "global" (i.e. default everywhere) and/or "local" (i.e. using that version in a specific directory only).

E.g.:

brew install pyenv
pyenv global 2.7.16
cd ~/myProjects/MyProject
pyenv local 3.7.6

If you were to use Python in ~/myProjects/MyProject it will default to 3.7.6, and anywhere else 2.7.16:

cd ~/some/other/directory
python --version
>> Python 2.7.16

cd ~/myProjects/MyProject
python --version
>> Python 3.7.6

https://github.com/pyenv/pyenv#homebrew-on-macos

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  • Thank you! Would you know if setting it global or local (in some directories?) would affect the functioning of system's Python?
    – Yulia V
    Feb 9, 2020 at 3:29
  • 1
    That's the beauty of it. If you run pyenv versions to see a list of available versions, one is system. This means you can run <pyenv global/local> system. Then if you're in a directory that uses the system version, any interactions you have with python will be with the system python.
    – bermudalocket
    Feb 9, 2020 at 4:15
  • Please add user manuals to answers in cases where one shouldn't be putting complete set of instructions. @bermudalocket
    – anki
    Feb 9, 2020 at 20:15
  • @ankii could you please direct me to the section of the Help Center where this requirement is stated? I do not see anything about it here. Thanks.
    – bermudalocket
    Feb 9, 2020 at 20:31
  • Yes there isn't a hard definition of the best answer, but put yourself in the shoes of OP and see if the answer is complete in itself? would it be able to counter any future problems that they might encounter? No. They asked another question, which has answers in the docs. meta.stackoverflow.com/questions/393571 meta.stackoverflow.com/a/260744/10063119 In case you're wondering why SO's things be applicable here, apple.meta.stackexchange.com/a/2509/313842 this is very apt too. Note my usage of ".. putting complete set of instructions.."
    – anki
    Feb 9, 2020 at 21:10
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I installed Python 3.8 for macOS using the installer from python.org, not homebrew which is also installed on my Mac but rarely used. I think the first three lines below to my ~/.bash_profile was automatically added by the installer from python.org.

With those, any changes I make using pip3 seem to affect only the 3.8 whereas those made via pip seem to affect only the 2.7 (which I believe comes installed with macOS). Because I did not use homebrew in installing Python 3.8 (or 2.7), I assume it is not relevant for either version of Python in my case. Hope these help.

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

# Setting PATH for Python 2.7
# I believe the two lines below were already in the file before the above were added
PATH="/Library/Frameworks/Python.framework/Versions/2.7/bin:${PATH}"
export PATH
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