Some systems do not allow a child to exist if its parent has terminated. In
such systems, if a process terminates (either normally or abnormally), then
all its children must also be terminated. This phenomenon, referred to as
cascading termination, is normally initiated by the operating system.
To illustrate process execution and termination, consider that, in Linux
and UNIX systems, we can terminate a process by using the exit() system
call, providing an exit status as a parameter: