在 MAC OS 上安装了 Python 3.9.1 但仍然说 Python 版本是 2.7

Question

I installed Python 3.9.1 onto my MacBook however when I use the command python --version it says its python 2.7. Here's what going on in my terminal for reference:

$ python -V
Python 2.7.16
$ brew install pyenv
Updating Homebrew...
==> Auto-updated Homebrew!
Updated Homebrew from 565becc90 to e41981a5c.
Updated 1 tap (homebrew/core).
==> New Formulae
htmltest                   mpdecimal                  vitess
==> Updated Formulae
Updated 158 formulae.

==> Homebrew was updated to version 2.7.7
The changelog can be found at:
  https://github.com/Homebrew/brew/releases/tag/2.7.7
Warning: pyenv 1.2.22 is already installed and up-to-date.
To reinstall 1.2.22, run:
  brew reinstall pyenv
$ pyenv install 3.9.1
python-build: use openssl@1.1 from homebrew
python-build: use readline from homebrew
Downloading Python-3.9.1.tar.xz...
-> https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tar.xz
Installing Python-3.9.1...
python-build: use readline from homebrew
python-build: use zlib from xcode sdk
       
Installed Python-3.9.1 to /Users/myname/.pyenv/versions/3.9.1

$ 
$ python --version
Python 2.7.16

Thanks in advance for your help!

Answer 1

I installed Python 3.9.1 onto my MacBook however when I use the command python --version it says its python 2.7. Here's what going on in my terminal for reference:

$ python -V
Python 2.7.16
$ brew install pyenv
Updating Homebrew...
==> Auto-updated Homebrew!
Updated Homebrew from 565becc90 to e41981a5c.
Updated 1 tap (homebrew/core).
==> New Formulae
htmltest                   mpdecimal                  vitess
==> Updated Formulae
Updated 158 formulae.

==> Homebrew was updated to version 2.7.7
The changelog can be found at:
  https://github.com/Homebrew/brew/releases/tag/2.7.7
Warning: pyenv 1.2.22 is already installed and up-to-date.
To reinstall 1.2.22, run:
  brew reinstall pyenv
$ pyenv install 3.9.1
python-build: use openssl@1.1 from homebrew
python-build: use readline from homebrew
Downloading Python-3.9.1.tar.xz...
-> https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tar.xz
Installing Python-3.9.1...
python-build: use readline from homebrew
python-build: use zlib from xcode sdk
       
Installed Python-3.9.1 to /Users/myname/.pyenv/versions/3.9.1

$ 
$ python --version
Python 2.7.16

Thanks in advance for your help!

Answer 2

If you have install python they brew then edit your.zprofile

add this line export PATH=/usr/local/opt/brew/opt/python@3.9/libexec/bin:$PATH

Answer 3

list all python under bin

ls -l /usr/local/bin/python*

something like this will be listed

lrwxr-xr-x  1 ali  admin  24 Dec 28 22:27 /usr/local/bin/python3 -> /usr/local/bin/python3.9
lrwxr-xr-x  1 ali  admin  39 Mar 31  2022 /usr/local/bin/python3 -> ../Cellar/python@3.9/3.9.12/bin/python3
lrwxr-xr-x  1 ali  admin  46 Mar 31  2022 /usr/local/bin/python3-config -> ../Cellar/python@3.9/3.9.12/bin/python3-config
lrwxr-xr-x  1 ali  admin  41 Mar 31  2022 /usr/local/bin/python3.9 -> ../Cellar/python@3.9/3.9.12/bin/python3.9
lrwxr-xr-x  1 ali  admin  48 Mar 31  2022 /usr/local/bin/python3.9-config -> ../Cellar/python@3.9/3.9.12/bin/python3.9-config

then change the symlink to the 3.9 or what's new one for you

ln -s -f /usr/local/bin/python3.9 /usr/local/bin/python

Quit the terminal and start it again, it should work now, usually you have to change the symlink for pip too, cause it's under python3 directory.