From the service manager point of view, a daemonizing program is a headache. The program that the service manager thinks is starting immediately quits, and it'

From the service manager point of view, a daemonizing program is a headache. The program that the service manager thinks is starting immediately quits, and it's the grandchild (or even great grandchild) that's actually the payload service. Because the parent quit, the grandchild becomes reparented to the init daemon; it is not a child of the service manager. The service manager has no idea what the process ID of the service is. If the self-daemonizing program writes its PID to a pidfile, and the service manaager is configured to know what that is and look for it, it can be obtained that way. Not being the parent of the process, the service manager doesn't get notified when that process terminates. It has to use hacks to poll for it; like kill the PID with signal 0 to check liveness, and pray that the PID isn't recycled. If you're writing a deamon program, make sure daemonization is optional, favoring opt-in over opt-out.