The origin of orphan Process Groups

 

The origin of orphan Process Groups:

When a terminal controls the process (that is, the first process of a session) to terminate, the terminal can be used to establish a new session. This may cause a problem where any process in the old Session (A collection of one or more Process Groups) accesses the terminal again. To prevent such problems, the concept of orphan Process Groups is introduced. When a process is composed of an orphan process group, posix.1 requires that the sighup (suspended) signal be sent to the process in the stopped state in the orphan process group. By default, the system processes this signal by terminating the process, however, if this signal is ignored or processed separately, the pending process can continue to be executed.