After `uv init`, adding script to `[project.scripts]` does not work

Question

I created a new project with uv 0.5.7:

uv init myproject
cd myproject
uv sync

And my project looks like this:

├── hello.py
├── pyproject.toml
├── README.md
└── uv.lock

At this point, the following works:

uv run python hello.py
uv run python -m hello

I would like to make a script name um by adding the following to pyproject.toml:

[project.scripts]
um = "hello:main"

However, that script is not found when I run it:

$ uv run um                                                                                                                                                                      [umbala:main:]
error: Failed to spawn: `um`
  Caused by: No such file or directory (os error 2)

I need help to create this script, um. What did I miss?

Answer 1

[project.scripts] is not uv-specific; as documented:

In this example, after installing your project, a spam-cli command will be available.

You'd need to uv pip install -e . your package, so the wrapper scripts are generated and placed in your (virtual)env's bin/ directory.

Answer 2

You might be missing a build system. uv requires a defined build system to determine whether to install the current project in the virtualenv. Something like this should work:

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

Using the entry point tables requires a build system to be defined. https://docs.astral.sh/uv/concepts/projects/config/#entry-points