Python CLI with Typer

Overview

Use Typer for ergonomic CLI construction. Core principle: keep CLI entry points explicit and testable.

Install

bash
1uv add typer

Quick Reference

Workflow

• Define a typer.Typer() app in cli.py.
• Keep command functions small; move logic into separate modules.
• Run CLI via uv run python -m <module> or uv run python cli.py.

Example

python
1import typer
2
3app = typer.Typer()
4
5@app.command()
6def greet(name: str, count: int = 1) -> None:
7    for _ in range(count):
8        typer.echo(f"Hello, {name}!")
9
10if __name__ == "__main__":
11    app()

Usage:

bash
1uv run python cli.py --help
2uv run python cli.py Alice
3uv run python cli.py Alice --count 3

Multiple commands:

python
1import typer
2
3app = typer.Typer()
4
5
6@app.command()
7def create(name: str) -> None:
8    """Create a new item."""
9    typer.echo(f"Creating {name}...")
10
11
12@app.command()
13def delete(name: str, force: bool = False) -> None:
14    """Delete an item."""
15    if not force:
16        if not typer.confirm(f"Delete {name}?"):
17            raise typer.Abort()
18    typer.echo(f"Deleted {name}")
19
20
21if __name__ == "__main__":
22    app()

Common Mistakes

• Putting heavy business logic inside CLI functions.
• Forgetting to wire if __name__ == "__main__" for script entry.

Red Flags

• CLI guidance that ignores Typer when Typer is the chosen framework.