Complex sentence: The daemon serves as the root of the user space's process tree; the first process (pid 1) has a special role on Unix systems, as it receives a SIGCHLD signal when a daemon process (which has detached from its parent) terminates.
Split into simpler sentences: The daemon serves as the root of the user space's process tree. The first process (pid 1) has a special role on Unix systems, as it receives a SIGCHLD signal when a daemon process (which has detached from its parent) terminates.