The setsid function creates a new session if the calling process
    is not a process group leader. Upon return, the calling process
    is the session leader of this new session and the process
    group leader of a new process group, and it has no controlling
    terminal. The process group ID of the calling process is set
    equal to the process ID of the calling process. The calling
    process is the only process in the new process group and the
    only process in the new session.

    This function requires that long (32-bit) UID/GID support be
    enabled. See 32-Bit UID and GID Macro (Integrity servers, Alpha)
    for more information.