Description

   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.