AMOSi:Arexx Exist

an example can be found on AMOSPro_Examples:Examples/H-8/Help_84.AMOS

Checks for the presence of a named communication port in the Amiga's memory. You'll get a value of TRUE(-1) if it's available, and a FALSE (0) if there's some sort of problem.

test=Arexx Exist("PORT_NAME")