Hi, I am trying to do a sem_get on a semaphore that has already been created by a c++ program. But I'm getting this warning: PHP Warning: sem_get(): failed for key 0x31006dc2: Invalid argument in /home/jgreene/views/latest/lcast/apps/webapp/webApp.php on line 11 Here is the line 11: sem_get($key, 1, 0666); And here is ipcs -s before and after the php script runs: ------ Semaphore Arrays -------- key semid owner perms nsems 0x31006dc2 1245191 jgreene 666 1 0x31006e01 1277960 jgreene 666 1 I have another c++ program that can get the existing sem with no problem. I can get the php script to create a new sem with no problem. It does not seem to like to get a sem that's already created... although I haven't tried getting a sem that's been created by another php script... But the entire point is that php is an ephemeral client and a C++ app server creates and responds/locks a resource (in this case shared memory - which does work fine). Btw, in the archives, way back in 2001, there was a pretty much exact same post... unfortunately there was no conclusion posted... I really hope I have better luck!! Jeremy