The "help" command:

Usage: fossil help [OPTIONS] [TOPIC]

Display information on how to use TOPIC, which may be a command, webpage, or setting. Webpage names begin with "/". If TOPIC is omitted, a list of topics is returned.

The following options can be used when TOPIC is omitted:

List both common and auxiliary commands
List command-line options common to all commands
List setting names
List unsupported "test" commands
List only auxiliary commands
List all web pages

These options can be used when TOPIC is present:

Format output as HTML rather than plain text