Getting started¶

This tutorial walks through a first resolve with nab against PyPI.

Install¶

uv tool install nab
nab --version

For other install paths (extras, pipx, a checkout) see Install nab.

[project]
name = "example"
version = "0.1.0"
dependencies = [
    "starlette<=0.36.0",
    "fastapi<=0.115.2",
]

nab lock pyproject.toml

Writes pylock.toml next to your project. To see the resolved versions on stdout instead, use the requirements formats:

nab lock --format requirements-without-hashes --output - pyproject.toml

anyio==4.6.2.post1
fastapi==0.115.2
idna==3.10
sniffio==1.3.1
starlette==0.36.0
typing_extensions==4.12.2

The resolver pins one version per package for the host’s marker environment. For multi-platform / multi-Python locks see universal resolution.

Configuration: every key under [tool.nab], what it does, and what the default is.
CLI: every subcommand, flag, exit code, and environment variable.
Lockfile: what is in pylock.toml, the requirements.txt --hash shape, and how nab download consumes them.