Configuring Python Version on macOS

As a developer working with Python, it’s essential to manage different versions of the language on your system. On macOS, the default version of Python is usually an older version, such as 2.7. In this tutorial, we’ll explore how to set the default Python version to the latest available, which is typically Python 3.x.

Understanding the Problem

When you install a new version of Python on your system, it doesn’t automatically become the default version. Instead, the system continues to use the older version. For example, if you’ve installed Python 3.9 but your system still uses Python 2.7 by default, running python in the terminal will launch the 2.7 interpreter.

Method 1: Using Aliases

One way to set the default Python version is by using aliases. An alias is a shortcut that tells your shell to use an alternative command instead of the default one. To create an alias for Python, follow these steps:

1. Open your shell configuration file in a text editor. The location of this file varies depending on your shell:
   • For Bash (default on older macOS versions): ~/.bash_profile
   • For Zsh (default on newer macOS versions): ~/.zshrc
2. Add the following line to the file: alias python='python3'
3. Save and close the file.
4. Reload your shell configuration by running source ~/.bash_profile or source ~/.zshrc

With this alias in place, whenever you type python in your terminal, it will launch Python 3.x instead of the default version.

Method 2: Creating Symbolic Links

Another approach is to create a symbolic link (symlink) that points to the desired Python executable. A symlink is a file that references another file or directory. To set up a symlink for Python:

1. Open your terminal and navigate to the /usr/local/bin directory.
2. Run the following commands:

unlink /usr/local/bin/python
ln -s /usr/local/bin/python3 /usr/local/bin/python

The first command removes any existing symlink, and the second command creates a new symlink that points to the Python 3.x executable.

Method 3: Using Homebrew

If you have Homebrew installed on your system, you can use it to manage your Python versions. Here’s how:

1. Install Python using Homebrew: brew install python
2. After installation, run ls -l /usr/local/bin/python* to verify the symlinks created by Homebrew.
3. To set the default Python version, create a symlink: ln -s -f /usr/local/bin/python3 /usr/local/bin/python

Tips and Best Practices

When working with multiple Python versions, it’s essential to keep in mind:

• Use the correct shebang line (#!/usr/bin/env python3) when writing scripts to ensure they run with the intended version.
• Be cautious when changing the default Python version, as some applications might rely on older versions.
• Consider using virtual environments (e.g., virtualenv or conda) to manage different projects and their dependencies.

By following these methods and tips, you can easily configure your Python version on macOS and ensure a smooth development experience.