Как изменить версию python по умолчанию в windows

Последнее обновление: 16.12.2022

На одной рабочей машине одновременно может быть установлено несколько версий Python. Это бывает полезно, когда идет работа с некоторыми внешними библиотеками, которые поддерживают разные версии python, либо в силу каких-то
других причин нам надо использовать несколько разных версий. Например, на момент написания статьи последней и актуальной является версия Python 3.11.
Но, допустим, необходимо также установить версию 3.10, как в этом случае управлять отдельными версиями Python?

Windows

На странице загрузок https://www.python.org/downloads/ мы можем найти ссылку на нужную версию:

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И также загрузить ее и установить:

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Чтобы при использовании интерпретатора Python не прописывать к нему весь путь, добавим при установке его в переменные среды. Но здесь надо учитывать, что в переменных среды
может содержаться несколько путей к разным интерпретаторам Python:

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Та версия Python, которая находится выше, будет версией по умолчанию. С помощью кнопки «Вверх» можно нужную нам версию переместить в начало, сделав версией по умолчанию.
Например, в моем случае это версия 3.11. Соответственно, если я введу в терминале команду

или

то консоль отобразит версию 3.11:

C:\python>python --version
Python 3.11.0

Для обращения к версии 3.10 (и всем другим версиям) необходимо использовать указывать номер версии:

C:\python>py -3.10 --version
Python 3.10.9

например, выполнение скрипта hello.py с помощью версии 3.10:

Подобным образом можно вызывать и другие версии Python.

MacOS

На MacOS можно установить разные версии, например, загрузив с официального сайта пакет установщика для определенной версии.

Для обращения к определенной версии Python на MacOS указываем явным образом подверсию в формате python3.[номер_подверсии]. Например, у меня установлена версия
Python 3.10. Проверим ее версию:

Аналогично обращении к версии python3.9 (при условии если она установлена)

К примеру выполнение скрипта hello.py с помощью версии python 3.10:

Linux

На Linux также можно установить одновременно несколько версий Python. Например, установка версий 3.10 и 3.11:

sudo apt-get install python3.10
sudo apt-get install python3.11

Одна из версий является версий по умолчанию. И для обращения к ней достаточно прописать python3, например, проверим версию по умолчанию:

Для обращения к другим версиям надо указывать подверсию:

python3.10 --version
python3.11 --version

Например, выполнение скрипта hello с помощью версии Python 3.10:

Но может сложиться ситуация, когда нам надо изменить версию по умолчанию. В этом случае применяется команда update-alternatives для связывания
определенной версии Python с командой python3. Например, мы хотим установить в качестве версии по умолчанию Python 3.11. В этом случае последовательно выполним следующие команды:

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.10 1
sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.11 2

Числа справа указывают на приоритет/состояние. Так, для версии 3.11 указан больший приоритет, поэтому при обращении к python3 будет использоваться именно версия 3.11 (в моем случае это Python 3.11.0rc1)

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С помощью команды

sudo update-alternatives --config python3

можно изменить версию по умолчанию

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Python is a versatile and powerful programming language widely used for various applications including web development, data analysis, artificial intelligence, and scientific computing. As Python continues to evolve, different versions coexist, and developers often need to switch between them based on project requirements. In this guide, we will explore how to change your global Python version on Windows 11.

Understanding Python Versions

Python versions are categorized mainly into two major branches: Python 2 and Python 3. Python 2 has reached the end of its life and is no longer receiving updates or support from the Python Software Foundation (PSF). Python 3, on the other hand, is actively maintained and updated with new features and enhancements.

When you install Python on your Windows machine, it typically registers itself in the path variable making it accessible from the command line. If multiple versions of Python are installed, you may need to change which version is used when executing Python commands.

Prerequisites

Before you begin, ensure you have the following:

1. Administrator Access: You need admin privileges on your Windows 11 machine to make changes to system paths.
2. Multiple Python Versions: Ensure you have more than one version of Python installed on your machine.
3. Python/installers: If you need to install additional Python versions, download them from the official Python website.

Checking Installed Python Versions

Before changing the global Python version, check your currently installed Python versions. Open PowerShell or Command Prompt and run:

python --version

Or, to check for all installed versions, use:

py -0

The py -0 command will display a list of all the Python installations currently registered with the Python launcher.

Changing Python Versions in Windows 11

There are multiple methods to change the global Python version on Windows 11. Here, we will outline the most common techniques:

1. Using the Python Launcher
2. Modifying the System Environment Variables
3. Using Virtual Environments
4. Updating the PATH variable

1. Using the Python Launcher

The most convenient way to manage multiple Python versions is through the Python launcher (py.exe), which is installed by default with Python.

• To use a specific version of Python, use the following command:

py -3.x

Where 3.x is the desired minor version (for example, py -3.9).

• If you want to create an alias to always use a specific version, you can add a shebang line at the top of your scripts:

#! python3.x

2. Modifying the System Environment Variables

If you wish to change the global Python version and affect all command-line operations, you can modify the system’s environment variables. Here’s how:

1. Open System Properties:

   • Right-click the Start button and select System.
   • Click on Advanced system settings on the left sidebar.
   • In the System Properties window, click the Environment Variables button.

2. Edit the User Variables:

   • Under User variables, look for a variable named Path. Select it and click Edit.
   • In the Edit Environment Variable window, you will see a list of paths. Here, each entry corresponds to a directory that contains executables.

3. Add or Rearrange Python Paths:

   • If you have multiple versions of Python, you may have entries like C:Python39 and C:Python310.
   • To change the global version, rearrange the order of these paths. Move the path of the version you want to use first in the list.
   • To add a new version, click New and paste in the directory path where the desired Python version is installed.

4. Apply Changes:

   • After editing, click OK to close the dialogs.
   • You may need to restart any open command prompts for the changes to take effect.

3. Using Virtual Environments

While changing the global Python version affects the command line for all projects, virtual environments allow for project-specific Python versions. Here’s how to set it up:

1. Install the Required Python Version: Ensure that the desired version of Python is installed.

2. Create a Virtual Environment:

   • Open Command Prompt or PowerShell.
   • Navigate to your project directory and run:

python -m venv myenv

Replace myenv with your desired environment name.

1. Activate the Virtual Environment:
   • For Command Prompt, use:

myenvScriptsactivate

• For PowerShell, use:

.myenvScriptsActivate.ps1

1. Select the Desired Python Version:
   Now, you can install packages and run scripts using the version of Python that’s installed in that virtual environment.

4. Updating the PATH variable

If you’ve installed Python in a custom directory, you may need to add its path to the PATH environment variable. This includes ensuring that the Scripts directory is also included.

1. Open System Properties and go to Environment Variables as described above.
2. In the Path variable, ensure the path to the desired Python directory (like C:Python39) and its Scripts directory (like C:Python39Scripts) are included.

Example of Changing Python Global Version

For instance, if your Python 3.9 is installed in C:Python39 and Python 3.10 is installed in C:Python310, and you want to set Python 3.10 as the global version, follow these steps:

1. Go to Environment Variables as detailed.

2. In the Path editor, locate the entries:

   • C:Python39
   • C:Python310

3. Move C:Python310 to the top of the list.

4. Make sure both paths are included in the list. Then, click OK to apply.

Verifying the Change

After making changes to the environment variables, you should verify whether the correct version of Python is being used. Open a new Command Prompt or PowerShell window and run:

python --version

This should now reflect the newly set global Python version.

Using the Python Executable Directly

In some cases, you might want to run a specific version by invoking its executable directly. You might navigate to the Python installation directory and run:

C:Python310python.exe your_script.py

This method ensures you are using Python from a specific installation, which is particularly useful in scenarios where you want to avoid relying on the global settings.

Common Issues and Troubleshooting

Python Not Recognized

If you receive an error stating that Python is not recognized, ensure that:

• The path to the Python executable is correctly set in the PATH variable.
• You opened a new command prompt after modifying the environment variables.

Conflicting Versions

If you have scripts that require different Python versions, consider using virtual environments. This allows each project to use the specific Python version it needs without affecting others.

Import Errors

When you switch versions, some installed packages may not be compatible. Use pip to reinstall or upgrade essential packages after switching versions:

pip install --upgrade package_name

Conclusion

Changing the global Python version in Windows 11 is a straightforward process, whether you choose to use the Python launcher, modify environment variables, or leverage virtual environments. Each method has its advantages, depending on the complexity of your projects and the number of Python versions you manage.

By skillfully managing your Python installations and versions, you can ensure compatibility across your projects and make the most out of what Python has to offer. As new versions are released, you now have the basic understanding to smoothly transition between them and maintain productivity in your coding endeavors.

Python is a versatile programming language used for various purposes such as data analysis, machine learning, web development, and much more. It can be installed and run on different platforms including Windows, Linux, and macOS.

One common requirement for Python developers is changing the default Python interpreter in the terminal.

This change can be necessary in cases such as the need to work with different Python versions for different projects. In this tutorial, we will guide you through the steps of changing the default Python in your terminal.

Step 1: Check Your Current Python Version

Before proceeding with the changes, it’s important to check your system’s current Python version. This can be done by executing the following command in the terminal:

This command will display the currently installed Python version.

Step 2: Install The Required Python Version

If the Python version that you want to set as default is not already installed on your system, you will need to install it. Please visit the official Python downloads page for installation files and instructions.

Step 3: Change The Default Python Version

Once the desired Python version is installed, you can change the default Python version. In Unix-based systems like Linux and macOS, the command for this would be:

Replace ‘3.8’ with your Python version. Please note that the exact path to the Python binary could vary based on your operating system and Python distribution.

In Windows, changing the PATH system variable would be necessary which is described in the following step:

Step 4: Update The System PATH (For Windows Users)

In Windows, we need to add the path of the desired Python version to the beginning of the system PATH variable. This can be done through the environment variables in the system settings. More details about this process are available in this Microsoft support documentation.

Conclusion

After successfully following these steps, your terminal should now point to the desired Python interpreter by default.

Remember that these settings are session-specific in Unix-based systems, and the terminal will revert back to the original settings at the end of the session.

To keep the changes across sessions, you may need to update your shell configuration files.