help [subcommand] [topic]
The help subcommand displays a synopsis of common dbx subcommands.
The help subcommand can be run only while the dbx debug program is running.
help
help subcommand
help topic
The help subcommand with no arguments lists
available dbx subcommands and topics.help subcommand, where subcommand is one of the dbx subcommands, displays a synopsis and brief description of the subcommand. help topic (where topic is execution, expression, files, machine, scope, usage, or variables) displays a synopsis and brief description of the topic.