Install Python

Python is a very popular scripting language, according to StackOverflow 2023 survey it is the third most commonly used language and the fourth in the ranking for professional developers. All in all, it is a very simple language to learn and thus is one of the first languages new developers incorporate in their projects. In this post we will see how to install Python in your system.

TLDR

Tutorial to install python from installable in MacOS.

• Download python-3.12.3-macos11.pkg (or choose your version, as of today latest is 3.12).
• Install using the installer helper that will place all the python files in /Library/Frameworks/Python.framework/Versions/3.12/.
• Create an alias, execute

  echo alias pytyon=/Library/Frameworks/Python.framework/Versions/3.12/bin/python3 >> ~/.zshrc
  

• Run python by executing python in termial.

Install Python with installable

There are many ways to install python in your computer, the most simple one is from python.org. Go to downloads and choose your operating system / architecture and version from the stable releases options.

As an example we will install Python 3.12.3 which is the most recent stable one at the time of writing this post. These version numbers are called major, minor and revision, in the example major is 3, minor is 12 and revision is 3. It is important to choose the right version of python as some software projects may have old functionality and may only work in an older python version.

For MacOS, first download the installer python-3.12.3-macos11.pkg (choose the appropiate installer for your OS) and proceed with the installation. Then, open a terminal and type python3 or python3.12 to start the python command prompt:

Python 3.12.3 (v3.12.3:f6650f9ad7, Apr  9 2024, 08:18:48) [Clang 13.0.0 (clang-1300.0.29.30)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>

That’s it, you are in python!. See that in the prompt it is specified the version 3.12.3 , the date it was released and the compiler (Clang in my case). Just to test type

Python 3.12.3 (v3.12.3:f6650f9ad7, Apr  9 2024, 08:18:48) [Clang 13.0.0 (clang-1300.0.29.30)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> print("Hi there")
Hi there

That’s it, you have successfully installed Python!.

Install location

In MacOS python is installed in /Library/Frameworks/Python.framework/Versions/3.12/ (for Windows it would be C:\Users\<Username>\AppData\Local\Programs\Python\Python3.12). If you installed any other python version, say 3.11.2, just change the path to the corresponding major and minor versions. Let’s explore what is in there, the main directories are:

Directory	Usage
bin	Where the binaries (executables) are stored, this is python and pip among others.
include/python3.12	All header files for the compiled libraries. For instance, the file floatobject.h contains the C++ definition of the float object in Python. The headers in this directory are needed if we want to compile a C++ extension to be used in Python (a Python wrapper for a C++ library).
lib	contains compiled libraries. Concretely it contains libpython3.12.a or libpython3.12.so wich is the (static or dynamic) compiled standard library for python. This directory is added automatically to sys.path. Also custom compiled packages are copied here.
share	Includes miscellaneous files such as documentation, configuration files, and examples. It might also contain man pages, sample scripts, and other shared assets that don’t fit into the binary, header, or library categories.

The python executable you run when typing python3 in your terminal is /Library/Frameworks/Python.framework/Versions/3.12/bin/python3 (just type which python3.12 or which python3).

The commands python3.12 and python3 are recognized because they are executables found in a directory from your PATH variable. To find these directories just tr ':' '\n' <<< "$PATH", for MacOS you will see the path /Library/Frameworks/Python.framework/Versions/3.12/bin, in this directory is where python3.12 executable lives, and also a simulated link to it python3.

Install another python version

Let’s say you need to use Python 3.11.7 for another project but you arleady have 3.12.3, what do you do?. Uninstall and reinstall?. Luckily you don’t need to do that. As we did previously, just download the installable python-3.11.7-macos11.pkg and execute it. Open a new terminal and type python3 --version, you will see that now instead of having 3.12.2 (as installed previously), it will show 3.11.7. What just happend?. Run tr ':' '\n' <<< "$PATH" | grep Python, you will see two paths, first /Library/Frameworks/Python.framework/Versions/3.11/bin and second /Library/Frameworks/Python.framework/Versions/3.12/bin. So by installing a second version we get the new path first. When bash looks for an executable it goes sequentially from the first path to the last, if there are two python3 executables in the PATH, bash will just pick the first, in this case 3.11. But no panic, you can still run any python version installed, check it doing

python3.11 --version
python3.12 --version

so to run a python script script.py in python 3.12 just do python3.12 script.py.

We can still do another “hack” if you want to change pythhon3 be either of the two installed versions, just add the python exec path as the first entry of your PATH:

# to run python3 and execute python3.12
export PATH="/Library/Frameworks/Python.framework/Versions/3.12/bin:${PATH}"

# the following will run script.py using python3.12
python3 script.py 


# to run python3 and execute python3.11
export PATH="/Library/Frameworks/Python.framework/Versions/3.11/bin:${PATH}"

# the following will run script.py using python3.11
python3 script.py 

Make an alias to python executable

To pin a specific python version and run that whenever you type python just create an alias. For that open .bashrc or .zshrc depending if you use bash or zsh shell (look for the equivalent if you have another shell) and append alias pytyon=/Library/Frameworks/Python.framework/Versions/3.12/bin/python3. To append just open a terminal and do the following (assuming you use zsh):

# append the command to the file ~/.zshrc
echo alias pytyon=/Library/Frameworks/Python.framework/Versions/3.12/bin/python3 >> ~/.zshrc

# source ~/.zshrc to make the changes effective
source ~/.zshrc

Uninstall

Get the list of your python installed

ls -lhat /Library/Frameworks/Python.framework/Versions/  

Remove specific versions, in this case we will remove 3.11 and 3.12

sudo rm -rf /Library/Frameworks/Python.framework/Versions/3.11
sudo rm -rf /Library/Frameworks/Python.framework/Versions/3.12

or remove entire python

sudo rm -rf /Library/Frameworks/Python.framework/

Then remove the linked binaries

sudo rm /usr/local/bin/python3 /usr/local/bin/pip3

Then since you have probably modified the $PATH, just go and remove the specific exports and aliases in ~/.zshrc or ~/.bashrc. Also probably the installation has modified ~/.zprofile or ~/.bash_profile adding the paths /Library/Frameworks/Python.framework.... Comment or remove those lines.

Finally remove the alias we created before in ~/.zshrc (or ~/.bashrc). The line alias python=/Library/Frameworks/Python.framework/Versions/3.12/bin/python3.

and restart the terminal by typing

reset

You are all set. Python is deleted from your system