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Comment by chillaranand | Hacker News Reader

You can specify requirements at the top of file and uv can run the script after automatically installing the dependencies.

https://avilpage.com/2025/04/learn-python-uv-in-100-seconds....

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This works really well in my experience, but it does mean you need to have a working internet connection the first time you run the script.

  # /// script
  # dependencies = [
  #     "cowsay",
  # ]
  # ///
  import cowsay
  cowsay.cow("Hello World")

Then:

  uv run cowscript.py

It manages a disposable hidden virtual environment automatically, via a very fast symlink-based caching mechanism.

You can also add a shebang line so you can execute it directly:

  #!/usr/bin/env -S uv run --script
  #
  # /// script
  # dependencies = ["cowsay"]
  # ///
  import cowsay
  cowsay.cow("Hello World")

Then:

  chmod 755 cowscript
  ./cowscript

If not having a working internet connection is a concern, I would package your script into a shiv zipapp - https://shiv.readthedocs.io/en/latest/

I wish env -S was more portable. It's a newer feature of the coreutils env implementation and isn't supported elsewhere afaik.

You can use so-called "exec magic" instead of `env -S`. Here is an explanation with Python examples: https://dbohdan.com/scripts-with-dependencies#exec-magic (disclosure: my site). In short:

  #! /bin/sh
  "exec" "/usr/bin/env" "uv" "run" "--quiet" "--script" "$0" "$@"
  # /// script
  # dependencies = [
  #   "cowsay",
  # ]
  # ///
  import cowsay
  cowsay.cow("Hello, world!")

On systems that can't run uv, like NetBSD and OpenBSD, switch to pipx:

  #! /bin/sh
  "exec" "/usr/bin/env" "pipx" "run" "$0" "$@"
  # ...

FreeBSD 6.0 added 'env -S'. They have adopted a few different GNU inspired options recently, which I am happy about.

As someone who writes a lot of python, I love uv, but isn't on nearly every system like python is, which is one of the arguments for using python here in the first place

The catch is that there could be a version mismatch between the version of Python installed on the end user's computer and the version on which the script was developed. This problem can be solved with uv, and there aren't really Python-native ways available.

Sure but the sub question here was about packages.

If you are installing packages, then starting with installing uv should be fine.

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