Command Cheat Sheet

Command Cheat Sheet

Commands this book actually uses. Run them from the directory that holds the file or the pyproject.toml.

Python

Command	What it does
uv run python file.py	Run a program with the project’s Python 3.14
uv run python -c "print('desk')"	Run a one-liner
uv run python -m cProfile -s tottime file.py	Profile a program

Inside a program, spawn that same interpreter with sys.executable, not a bare python on PATH.

uv

Command	What it does
uv lock	Write/update the lockfile
uv sync	Install the locked environment
uv add pkg	Add a dependency
uv build	Build sdist + wheel into dist/
uv audit	Scan locked deps for known issues
uv pip install dist/*.whl	Install a wheel you just built

ruff

Command	What it does
uv run ruff check .	Lint
uv run ruff check --fix file.py	Lint and apply safe fixes
uv run ruff format .	Format

Silence is success for ruff check.

pytest

Command	What it does
uv run pytest	Run tests
uv run pytest -q	Quieter
uv run pytest path/to/test_file.py	One file

Tiny reminders

Run a complete program:

uv run python hello.py

# hello.py
def main() -> None:
    print("desk is open")


if __name__ == "__main__":
    main()

desk is open

Child process (list of args, no shell):

# run_child.py
import subprocess
import sys


def main() -> None:
    result = subprocess.run(
        [sys.executable, "-c", "print('ticket 7')"],
        capture_output=True,
        text=True,
        check=True,
    )
    print(result.stdout, end="")


if __name__ == "__main__":
    main()

uv run python run_child.py

ticket 7

Secrets stay in the environment (DESK_API_KEY), never in the file you commit.

Times you store are UTC (datetime.now(timezone.utc)), not naive local clocks.

Text files: Path.read_text(encoding="utf-8") and write_text(..., encoding="utf-8").