brew install doesn't link python3

Question

I’m having trouble linking python3 and making python3 the default python.

MacOS 10.13.6

Here’s what I did:

$ python --version
Python 2.7.15
$ python3 --version
Python 3.7.0
$ xcode-select --version
xcode-select version 2349.
$ brew install python
...

Python has been installed as
  /usr/local/bin/python3

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /usr/local/opt/python/libexec/bin
...

It doesn’t work. python is still 2.*

$ python --version
Python 2.7.15
$ python3 --version
Python 3.7.0
$ pip --version
pip 10.0.1 from /usr/local/lib/python2.7/site-packages/pip (python 2.7)
$ pip3 --version
pip 18.0 from /usr/local/lib/python3.7/site-packages/pip (python 3.7)

So I did:

$ brew link python3
Warning: Already linked: /usr/local/Cellar/python/3.7.0
To relink: brew unlink python && brew link python
$ python --version
Python 2.7.15
$ brew install python3
...

Warning: python 3.7.0 is already installed and up-to-date
To reinstall 3.7.0, run `brew reinstall python`
$ brew reinstall python

Also doesn’t work

$ brew link python3
Warning: Already linked: /usr/local/Cellar/python/3.7.0
To relink: brew unlink python && brew link python
$ python --version
Python 2.7.15
$ python3 --version
Python 3.7.0

Asked By: Viet

||

Source

Answer 1

I presume you mean that you want the command python to start the Python3 interpreter, and pip to start pip3.

The clue is in the message:

Unversioned symlinks python, python-config, pip etc. pointing to
python3, python3-config, pip3 etc., respectively, have been installed into
/usr/local/opt/python/libexec/bin

That means… “if you want the command python to start python3 and pip to start pip3, you need to put /usr/local/opt/python/libexec/bin at the start of your PATH.”

So, in your login script ($HOME/.profile or similar), you need to put:

export PATH=/usr/local/opt/python/libexec/bin:$PATH

Then log out and log back in for it to take effect.

As an aside, brew link python3 only means… “create a symbolic link in /usr/local/bin/python3 that points to /usr/local/Cellar/python/3.7.0/python3“.

You can see that link, and where it points to, with:

ls -l /usr/local/bin/python3

Answered By: Mark Setchell

Answer 2

At least for python 3.6 the selected answer appears to be incorrect.
It may depend on whether you have multiple python versions brew installed.
In my case i have 3.6, 3.7, 3.8, and 3.9.
so, you

brew unlink [email protected]
brew link [email protected]

after which:

there is no entry /usr/local/opt/python
there is no entry /usr/local/bin/python3

brew link python3 links the most recent python install (3.9 in my case) regardless of the brew link [email protected] issued earlier so it is not useful.

There is an entry /usr/local/bin/python3.6 and there is a symbolic link
/usr/local/bin/python -> python3 but NO /usr/local/bin/python3 entry.

so if you

ln -s /usr/local/bin/python3.6 python3

you will be good to go.

Answered By: Jay

Answer 3

I had installed python via brew and had to follow different steps:

brew install python

Later, I needed the path to add to my $PATH as export PATH=/usr/local/opt/python/libexec/bin:$PATH wasn’t working for me.

I ran:

brew info python

Got this:

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /opt/homebrew/opt/[email protected]/libexec/bin

And then added this to my .zshrc file

export PATH="/opt/homebrew/opt/[email protected]/libexec/bin:$PATH"

With these steps, you have made Python 3.11 the default version on your Mac. You can now use python to refer to Python 3.11 in your terminal.

For more details, I shared the entire process in Python not found on MacOS. I hope this helps.

Make sure to reload your terminal, a fancy way to do that is by running:

exec $SHELL -l

Answered By: Ahmad Awais

brew install doesn't link python3

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