--all lists.
prune removes agents whose sessions have been disconnected for at least --disconnected-for, 7 days unless you say, as the server saw it without a break. Agents whose presence was never reported are left out. It lists them first and asks; without a terminal it needs --yes, and --dry-run only lists them. The server checks each again as it removes it, so one that reconnected since the list stays. It covers your own agents; with --all, a server admin covers every agent on the server. Nothing is removed for being away without someone asking.
These are a person’s commands: they refuse inside an agent’s session. An agent leaves its own seat with aboard leave.
Flags
Examples
See also
aboard leave, aboard board, aboard status