[python] How to switch Python versions in Terminal?

My Mac came with Python 2.7 installed by default, but I'd like to use Python 3.6.1 instead.

How can I change the Python version used in Terminal (on Mac OS)?

Please explain clearly and offer no third party version manager suggestions.

Here is a nice and simple way to do it (but on CENTOS), without braking the operating system.

yum install scl-utils

next

yum install centos-release-scl-rh

And lastly you install the version that you want, lets say python3.5

yum install rh-python35

And lastly:

scl enable rh-python35 bash

Since MAC-OS is a unix operating system, the way to do it it should be quite similar.

If you have python various versions of python installed,you can launch any of them using pythonx.x.x where x.x.x represents your versions.

As Inian suggested, you should alias python to point to python 3. It is very easy to do, and very easy to switchback, personally i have an alias setup for p2=python2 and p3=python3 as well to save on keystrokes. Read here for more information: How do I create a Bash alias?

Here is an example of doing so for python:

alias python=python3

Like so:

$ python --version
Python 2.7.6
$ python3 --version
Python 3.4.3
$ alias python=python3
$ python --version
Python 3.4.3

See here for the original: https://askubuntu.com/questions/320996/how-to-make-python-program-command-execute-python-3

pyenv is a 3rd party version manager which is super commonly used (18k stars, 1.6k forks) and exactly what I looked for when I came to this question.

Install pyenv.

Usage

$ pyenv install --list
Available versions:
  2.1.3
  [...]
  3.8.1
  3.9-dev
  activepython-2.7.14
  activepython-3.5.4
  activepython-3.6.0
  anaconda-1.4.0
  [... a lot more; including anaconda, miniconda, activepython, ironpython, pypy, stackless, ....]

$ pyenv install 3.8.1
Downloading Python-3.8.1.tar.xz...
-> https://www.python.org/ftp/python/3.8.1/Python-3.8.1.tar.xz
Installing Python-3.8.1...
Installed Python-3.8.1 to /home/moose/.pyenv/versions/3.8.1

$ pyenv versions
* system (set by /home/moose/.pyenv/version)
  2.7.16
  3.5.7
  3.6.9
  3.7.4
  3.8-dev

$ python --version
Python 2.7.17
$ pip --version
pip 19.3.1 from /home/moose/.local/lib/python3.6/site-packages/pip (python 3.6)

$ mkdir pyenv-experiment && echo "3.8.1" > "pyenv-experiment/.python-version"
$ cd pyenv-experiment

$ python --version
Python 3.8.1
$ pip --version
pip 19.2.3 from /home/moose/.pyenv/versions/3.8.1/lib/python3.8/site-packages/pip (python 3.8)

I have followed the below steps in Macbook.

1. Open terminal
2. type nano ~/.bash_profile and enter
3. Now add the line alias python=python3
4. Press CTRL + o to save it.
5. It will prompt for file name Just hit enter and then press CTRL + x.
6. Now check python version by using the command : python --version

You can just specify the python version when running a program:

for python 2:

python filename.py

for python 3:

python3 filename.py