# Managing Multiple Python Versions with Pyenv

`pyenv` is a tool that lets you easily switch between multiple versions of Python. It is simple, unobtrusive, and follows the UNIX tradition of single-purpose tools that do one thing well.

## Windows Users (pyenv-win)

Standard `pyenv` does not support Windows natively. Windows users should use the fork **pyenv-win**.

### Installation (PowerShell)

Run the following in PowerShell to install:

```powershell
Invoke-WebRequest -UseBasicParsing -Uri "https://raw.githubusercontent.com/pyenv-win/pyenv-win/master/pyenv-win/install-pyenv-win.ps1" -OutFile "./install-pyenv-win.ps1"; &"./install-pyenv-win.ps1"
```

*Note: You may need to restart your terminal or add environment variables manually if the script fails to do so.*

## macOS / Linux Users

### Installation

```bash
curl https://pyenv.run | bash
```

Follow the instructions output by the script to add `pyenv` to your shell configuration (e.g., `.bashrc` or `.zshrc`).

## Basic Usage

### 1. List Available Versions

To see what versions of Python are available for installation (this list is fetched from python.org):

```bash
pyenv install --list
```

### 2. Install a Python Version

To install a specific version (e.g., 3.10.11):

```bash
pyenv install 3.10.11
```

### 3. Set Global Version

To set the default Python version for your entire system (user profile):

```bash
pyenv global 3.10.11
```

### 4. Set Local Version (Per Project)

To set a specific Python version for a specific project folder. Navigate to your project folder and run:

```bash
pyenv local 3.9.7
```

This creates a `.python-version` file in the directory. Whenever you enter this directory, `pyenv` will automatically switch the `python` command to use version 3.9.7.

## Using with Virtual Environments

`pyenv` manages Python *installations*. You still use `venv` to manage *dependencies*.

1.  Set the local python version: `pyenv local 3.11.0`
2.  Create the virtual environment: `python -m venv .venv`

The virtual environment will be created using the Python version currently active via pyenv.

[[programming/python/python]]