---
title: Command-line options
description: How to start the playground, open a project, and the flags you can pass.
sidebar:
  order: 1
---

Start the playground with no arguments and it opens a fresh, automatically
named temporary project so you can begin straight away:

```sh
rdbms-playground
```

To open an existing project, give its path:

```sh
rdbms-playground path/to/project
```

## Options

| Option | Effect |
|---|---|
| `--resume` | Reopen the most recently used project. Errors if there is none; cannot be combined with a project path. |
| `--data-dir <PATH>` | Use `PATH` as the data root instead of the OS-standard location for this run. |
| `--mode <simple\|advanced>` | Start in this input mode, overriding the project's stored mode (precedence: `--mode` > stored > simple). |
| `--theme <light\|dark>` | Force a theme instead of auto-detecting from the terminal. |
| `--no-undo` | Disable the undo machinery for this run — no snapshot is taken before each change (see [Undo, redo & history](/using-the-playground/undo-and-history/)). |
| `--demo` | Turn on demonstration mode — a teaching aid that briefly shows an on-screen badge for keys that otherwise leave no visible mark (Tab, Enter, the arrows, and the like). Useful for screencasts and for demonstrating the playground to a class. Off by default. |
| `--log-file <PATH>` | Write diagnostic logging to `PATH`. |
| `-h`, `--help` | Print the usage banner and exit. |

## Examples

```sh
# Reopen wherever you left off, in advanced mode
rdbms-playground --resume --mode advanced

# Keep a course's projects in one folder
rdbms-playground --data-dir ~/db-course
```

Where projects are stored, and what a project contains, is covered in
[Projects and storage](/concepts/projects-and-storage/).
