# Installing Python

If Python is already installed, uv will [detect and use](#using-an-existing-python-installation) it without configuration. However, uv can also install and manage Python versions.

To install Python:

```console
$ uv python install
```

This will install a uv-managed Python version even if there is already a Python installation on the system.

<!-- TODO(zanieb): Restore when Python shim management is added
Note that when an automatic Python installation occurs, the `python` command will not be added to the shell. Use `uv python install-shim` to ensure the `python` shim is installed.

Once Python is installed, it can be invoked via `python`:

```console
$ python --version
```

To prevent uv from managing Python system-wide, provide the `--no-shim` option during installation.
-->

Once Python is installed, it will be used by `uv` commands.

## Installing a specific version

To install a specific Python version:

```console
$ uv python install 3.12
```

See the [Python versions](../python-versions.md) documentation for more details.

## Viewing Python installations

To view available and installed Python versions:

```console
$ uv python list
```

See the [`python list`](../python-versions.md#viewing-available-python-versions) documentation for more details.

<!--TODO(zanieb): The above should probably link to a CLI reference and that content should be moved out of that file -->

## Automatic Python downloads

Note that Python does not need to be explicitly installed to use uv. By default, uv will automatically download Python versions when they are required. For example, the following would download Python 3.12 if it was not installed:

```console
$ uv run --python 3.12 python -c 'print("hello world")'
```

Even if a specific Python version is not requested, uv will download the latest version on demand. For example, the following will create a new virtual environment and download a managed Python version if one hasn't been installed yet:

```console
$ uv venv --python-preference only-managed
```

<!-- TODO(zanieb): Restore when Python shim management is added
Note that when an automatic Python installation occurs, the `python` command will not be added to the shell. Use `uv python install-shim` to ensure the `python` shim is installed.
-->

## Using an existing Python installation

uv will also use an existing Python installation if already present on the system. There's no configuration necessary for this behavior: uv will use the system Python if it satisfies the requirements of the command invocation. See the [Python discovery](../python-versions.md#discovery-order) documentation for details.

To force uv to use the system Python, provide the `--python-preference only-system` option. See the [Python version preference](../python-versions.md#adjusting-python-version-preferences) documentation for more details.