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<!-- Thank you for contributing to uv! To help us out with reviewing, please consider the following: - Does this pull request include a summary of the change? (See below.) - Does this pull request include a descriptive title? - Does this pull request include references to any relevant issues? --> ## Summary When going through the docs at https://docs.astral.sh/uv/guides/install-python/#automatic-python-downloads, when you try to copy and paste the example on Windows, in either PowerShell or cmd.exe the example won't work. Inverting the quotes fixes it, and still works on other shells (I only tried bash under wsl) ## Test Plan On any windows system, from powershell, running the example yields the following error: ``` > uv run --python 3.12 python -c 'print("hello world")' File "<string>", line 1 print(hello world) ^^^^^^^^^^^ SyntaxError: invalid syntax. Perhaps you forgot a comma? ``` on cmd.exe ``` > uv run --python 3.12 python -c 'print("hello world")' ``` (there is no output) Inverting the quotes on powershell ``` > uv run --python 3.12 python -c "print('hello world')" hello world ``` on cmd.exe ``` > uv run --python 3.12 python -c "print('hello world')" hello world ``` <!-- How was it tested? -->
128 lines
4.7 KiB
Markdown
128 lines
4.7 KiB
Markdown
# Installing Python
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If Python is already installed on your system, uv will
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[detect and use](#using-an-existing-python-installation) it without configuration. However, uv can
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also install and manage Python versions for you.
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!!! tip
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uv will [automatically fetch Python versions](#automatic-python-downloads) as needed — you don't need to install Python to get started.
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<!-- TODO(zanieb): I don't love this heading. -->
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## Getting started
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To install the latest Python version:
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```console
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$ uv python install
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```
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This will install a uv-managed Python version even if there is already a Python installation on your
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system. If you've previously installed Python with uv, a new version will not be installed.
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!!! note
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Python does not publish official distributable binaries. As such, uv uses third-party distributions from the [`python-build-standalone`](https://github.com/indygreg/python-build-standalone) project. The project is partially maintained by the uv maintainers and is used by other prominent Python projects (e.g., [Rye](https://github.com/astral-sh/rye), [Bazel](https://github.com/bazelbuild/rules_python)). See the [Python distributions](../concepts/python-versions.md#managed-python-distributions) documentation for more details.
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<!-- TODO(zanieb): Restore when Python shim management is added
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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.
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Once Python is installed, it can be invoked via `python`:
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```console
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$ python --version
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```
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To prevent uv from managing Python system-wide, provide the `--no-shim` option during installation.
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-->
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Once Python is installed, it will be used by `uv` commands automatically.
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!!! important
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When Python is installed by uv, it will not be available globally (i.e. via the `python` command).
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Support for this feature is planned for a future release. In the meantime, use
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[`uv run`](../guides/scripts.md#using-different-python-versions) or
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[create and activate a virtual environment](../pip/environments.md) to use `python` directly.
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## Installing a specific version
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To install a specific Python version:
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```console
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$ uv python install 3.12
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```
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To install multiple Python versions:
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```console
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$ uv python install 3.11 3.12
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```
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To install an alternative Python implementation, e.g. PyPy:
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```console
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$ uv python install pypy@3.10
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```
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See the [`python install`](../concepts/python-versions.md#installing-a-python-version) documentation
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for more details.
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## Viewing Python installations
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To view available and installed Python versions:
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```console
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$ uv python list
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```
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See the [`python list`](../concepts/python-versions.md#viewing-available-python-versions)
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documentation for more details.
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<!--TODO(zanieb): The above should probably link to a CLI reference and that content should be moved out of that file -->
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## Automatic Python downloads
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Note that Python does not need to be explicitly installed to use uv. By default, uv will
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automatically download Python versions when they are required. For example, the following would
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download Python 3.12 if it was not installed:
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```console
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$ uv run --python 3.12 python -c "print('hello world')"
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```
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Even if a specific Python version is not requested, uv will download the latest version on demand.
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For example, the following will create a new virtual environment and download a managed Python
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version if Python is not found:
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```console
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$ uv venv
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```
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!!! tip
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Automatic Python downloads can be [easily disabled](../concepts/python-versions.md#disabling-automatic-python-downloads) if you want more control over when Python is downloaded.
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<!-- TODO(zanieb): Restore when Python shim management is added
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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.
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-->
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## Using an existing Python installation
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uv will use existing Python installations if present on your system. There is no configuration
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necessary for this behavior: uv will use the system Python if it satisfies the requirements of the
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command invocation. See the
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[Python discovery](../concepts/python-versions.md#discovery-of-python-versions) documentation for
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details.
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To force uv to use the system Python, provide the `--python-preference only-system` option. See the
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[Python version preference](../concepts/python-versions.md#adjusting-python-version-preferences)
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documentation for more details.
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## Next steps
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To learn more about `uv python`, see the [Python version concept](../concepts/python-versions.md)
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page and the [command reference](../reference/cli.md#uv-python).
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Or, read on to learn how to [run scripts](./scripts.md) and invoke Python with uv.
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