Hello, I have done a serious mistake. If you try to use RPL/2 on a system that doesn't understand what is anonymous semaphores (like MacOS X) or POSIX semaphores (like NetBSD...), you should use 4.1.18 daily snapshot, not 4.1.17 stable release. Next daily snapshot will be available at 8:00 CEST (26th of april 2014). Regards, JKB