tfsingh
6e9ecde9c2
This PR adds support for ```uv init --script```, as defined in issue #7402 (started working on this before I saw jbvsmo's PR). Wanted to highlight a few decisions I made that differ from the existing PR: 1. ```--script``` takes a path, instead of a path/name. This potentially leads to a little ambiguity (I can certainly elaborate in the docs, lmk!), but strictly allowing ```uv init --script path/to/script.py``` felt a little more natural than allowing for ```uv init --script path/to --name script.py``` (which I also thought would prompt more questions for users, such as should the name include the .py extension?) 2. The request is processed immediately in the ```init``` method, sharing logic in resolving which python version to use with ```uv add --script```. This made more sense to me — since scripts are meant to operate in isolation, they shouldn't consider the context of an encompassing package should one exist (I also think this decision makes the relative codepaths for scripts/packages easier to follow). 3. No readme — readme felt a little excessive for a script, but I can of course add it in! --------- Co-authored-by: João Bernardo Oliveira <jbvsmo@gmail.com>
314 lines
8.5 KiB
Markdown
314 lines
8.5 KiB
Markdown
# Running scripts
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A Python script is a file intended for standalone execution, e.g., with `python <script>.py`. Using
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uv to execute scripts ensures that script dependencies are managed without manually managing
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environments.
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!!! note
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If you are not familiar with Python environments: every Python installation has an environment
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that packages can be installed in. Typically, creating [_virtual_ environments](https://docs.python.org/3/library/venv.html) is recommended to
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isolate packages required by each script. uv automatically manages virtual environments for you
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and prefers a [declarative](#declaring-script-dependencies) approach to dependencies.
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## Running a script without dependencies
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If your script has no dependencies, you can execute it with `uv run`:
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```python title="example.py"
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print("Hello world")
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```
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```console
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$ uv run example.py
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Hello world
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```
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<!-- TODO(zanieb): Once we have a `python` shim, note you can execute it with `python` here -->
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Similarly, if your script depends on a module in the standard library, there's nothing more to do:
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```python title="example.py"
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import os
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print(os.path.expanduser("~"))
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```
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```console
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$ uv run example.py
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/Users/astral
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```
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Arguments may be provided to the script:
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```python title="example.py"
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import sys
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print(" ".join(sys.argv[1:]))
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```
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```console
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$ uv run example.py test
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test
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$ uv run example.py hello world!
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hello world!
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```
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Additionally, your script can be read directly from stdin:
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```console
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$ echo 'print("hello world!")' | uv run -
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```
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Or, if your shell supports [here-documents](https://en.wikipedia.org/wiki/Here_document):
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```bash
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uv run - <<EOF
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print("hello world!")
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EOF
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```
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Note that if you use `uv run` in a _project_, i.e. a directory with a `pyproject.toml`, it will
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install the current project before running the script. If your script does not depend on the
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project, use the `--no-project` flag to skip this:
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```console
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$ # Note, it is important that the flag comes _before_ the script
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$ uv run --no-project example.py
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```
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See the [projects guide](./projects.md) for more details on working in projects.
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## Running a script with dependencies
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When your script requires other packages, they must be installed into the environment that the
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script runs in. uv prefers to create these environments on-demand instead of using a long-lived
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virtual environment with manually managed dependencies. This requires explicit declaration of
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dependencies that are required for the script. Generally, it's recommended to use a
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[project](./projects.md) or [inline metadata](#declaring-script-dependencies) to declare
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dependencies, but uv supports requesting dependencies per invocation as well.
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For example, the following script requires `rich`.
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```python title="example.py"
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import time
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from rich.progress import track
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for i in track(range(20), description="For example:"):
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time.sleep(0.05)
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```
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If executed without specifying a dependency, this script will fail:
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```console
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$ uv run --no-project example.py
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Traceback (most recent call last):
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File "/Users/astral/example.py", line 2, in <module>
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from rich.progress import track
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ModuleNotFoundError: No module named 'rich'
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```
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Request the dependency using the `--with` option:
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```console
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$ uv run --with rich example.py
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For example: ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 100% 0:00:01
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```
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Constraints can be added to the requested dependency if specific versions are needed:
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```console
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$ uv run --with 'rich>12,<13' example.py
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```
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Multiple dependencies can be requested by repeating with `--with` option.
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Note that if `uv run` is used in a _project_, these dependencies will be included _in addition_ to
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the project's dependencies. To opt-out of this behavior, use the `--no-project` flag.
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## Creating a Python script
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Python recently added a standard format for
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[inline script metadata](https://packaging.python.org/en/latest/specifications/inline-script-metadata/#inline-script-metadata).
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It allows for selecting Python versions and defining dependencies. Use `uv init --script` to
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initialize scripts with the inline metadata:
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```console
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$ uv init --script example.py --python 3.12
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```
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## Declaring script dependencies
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The inline metadata format allows the dependencies for a script to be declared in the script itself.
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uv supports adding and updating inline script metadata for you. Use `uv add --script` to declare the
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dependencies for the script:
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```console
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$ uv add --script example.py 'requests<3' 'rich'
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```
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This will add a `script` section at the top of the script declaring the dependencies using TOML:
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```python title="example.py"
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# /// script
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# dependencies = [
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# "requests<3",
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# "rich",
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# ]
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# ///
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import requests
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from rich.pretty import pprint
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resp = requests.get("https://peps.python.org/api/peps.json")
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data = resp.json()
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pprint([(k, v["title"]) for k, v in data.items()][:10])
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```
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uv will automatically create an environment with the dependencies necessary to run the script, e.g.:
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```console
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$ uv run example.py
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[
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│ ('1', 'PEP Purpose and Guidelines'),
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│ ('2', 'Procedure for Adding New Modules'),
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│ ('3', 'Guidelines for Handling Bug Reports'),
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│ ('4', 'Deprecation of Standard Modules'),
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│ ('5', 'Guidelines for Language Evolution'),
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│ ('6', 'Bug Fix Releases'),
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│ ('7', 'Style Guide for C Code'),
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│ ('8', 'Style Guide for Python Code'),
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│ ('9', 'Sample Plaintext PEP Template'),
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│ ('10', 'Voting Guidelines')
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]
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```
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!!! important
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When using inline script metadata, even if `uv run` is [used in a _project_](../concepts/projects.md#running-scripts), the project's dependencies will be ignored. The `--no-project` flag is not required.
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uv also respects Python version requirements:
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```python title="example.py"
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# /// script
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# requires-python = ">=3.12"
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# dependencies = []
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# ///
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# Use some syntax added in Python 3.12
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type Point = tuple[float, float]
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print(Point)
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```
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!!! note
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The `dependencies` field must be provided even if empty.
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`uv run` will search for and use the required Python version. The Python version will download if it
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is not installed — see the documentation on [Python versions](../concepts/python-versions.md) for
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more details.
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## Improving reproducibility
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uv supports an `exclude-newer` field in the `tool.uv` section of inline script metadata to limit uv
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to only considering distributions released before a specific date. This is useful for improving the
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reproducibility of your script when run at a later point in time.
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The date must be specified as an [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamp
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(e.g., `2006-12-02T02:07:43Z`).
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```python title="example.py"
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# /// script
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# dependencies = [
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# "requests",
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# ]
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# [tool.uv]
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# exclude-newer = "2023-10-16T00:00:00Z"
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# ///
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import requests
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print(requests.__version__)
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```
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## Using different Python versions
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uv allows arbitrary Python versions to be requested on each script invocation, for example:
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```python title="example.py"
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import sys
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print(".".join(map(str, sys.version_info[:3])))
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```
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```console
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$ # Use the default Python version, may differ on your machine
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$ uv run example.py
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3.12.1
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```
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```console
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$ # Use a specific Python version
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$ uv run --python 3.10 example.py
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3.10.13
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```
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See the [Python version request](../concepts/python-versions.md#requesting-a-version) documentation
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for more details on requesting Python versions.
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## Using GUI scripts
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On Windows `uv` will run your script ending with `.pyw` extension using `pythonw`:
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```python title="example.pyw"
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from tkinter import Tk, ttk
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root = Tk()
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root.title("uv")
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frm = ttk.Frame(root, padding=10)
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frm.grid()
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ttk.Label(frm, text="Hello World").grid(column=0, row=0)
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root.mainloop()
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```
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```console
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PS> uv run example.pyw
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```
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{: style="height:50px;width:150px"}
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Similarly, it works with dependencies as well:
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```python title="example_pyqt.pyw"
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import sys
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from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QGridLayout
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app = QApplication(sys.argv)
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widget = QWidget()
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grid = QGridLayout()
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text_label = QLabel()
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text_label.setText("Hello World!")
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grid.addWidget(text_label)
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widget.setLayout(grid)
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widget.setGeometry(100, 100, 200, 50)
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widget.setWindowTitle("uv")
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widget.show()
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sys.exit(app.exec_())
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```
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```console
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PS> uv run --with PyQt5 example_pyqt.pyw
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```
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{: style="height:50px;width:150px"}
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## Next steps
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To learn more about `uv run`, see the [command reference](../reference/cli.md#uv-run).
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Or, read on to learn how to [run and install tools](./tools.md) with uv.
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