help lock

Usage: lock <room>...

You can lock a room so that no one, including you, can get into it.  For
example, if you are at home and you want to keep anyone from joining you,
you can say `lock here'.  If you want to lock a room from the outside, you
will need to know its name.  The easiest way to find a room's name is to
enter it and then do a `look here'.  The room's names will be shown in [].
Locked rooms are marked with a `(locked) after their names when they are
looked at.

You can always enter your home room, even if it is locked; and players can
always be ejected home, even when their homes are locked.  When a player
attempts to enter a locked room, players in the room are notified.

See also: eject gag ungag unlock