From MorphOS Library
RXCmd - Executes an ARexx command on a given ARexx port directly
PORT - Name of the ARexx port (case sensitive) COMMAND - ARexx command to be executed
RXCmd can be used to send single ARexx commands to a program. It even works with the dummy rexxsyslib.library file provided with the standard MorphOS installation, while the traditional RX command requires installation of a 3rd party rexxsyslib.library file.
RXCmd OWB.1 FULLSCREEN