I'm glad to see you got it working. I was going to mention, that in testing your first version with ShareLite, that it left shared memory segments intact after the program exited. These could be security holes.

It's important in your testing to do an "ipcs" before and after you run your script; and remove any segments you created. You can remove them with ipcrm.

The problem of "leftover" shared memory segments is probably one of the reasons people shy away from using shared memory. It certainly makes me leary of them.