+.It config Oo set Oc Ar variable Ar value
+Set configuration variable
+.Ar variable
+to the given
+.Ar value .
+All previously existing configuration variables with the same name are removed.
+To set a variable for a specific host, use the notation
+.Ar host Ns Li . Ns Ar variable .
+.It config add Ar variable Ar value
+As above, but without removing any previously existing configuration variables.
+.It config del Ar variable Op Ar value
+Remove configuration variables with the same name and
+.Ar value .
+If no
+.Ar value
+is given, all configuration variables with the same name will be removed.