_exit - terminate a process
_exit() terminates a process with the following consequences:
All of the descriptors open in the calling process are closed. This
may entail delays, for example, waiting for output to drain; a process
in this state may not be killed, as it is already dying.
If the parent process of the calling process is executing a wait() or
waitpid(), or is interested in the SIGCHLD signal, then it is notified
of the calling process's termination and the low-order eight bits of
status are made available to it (see wait(2V)).
If the parent process of the calling process is not executing a wait()
or waitpid(), status is saved for return to the parent process whenever
the parent process executes an appropriate subsequent wait() or wait-
The parent process ID of all of the calling process's existing child
processes are also set to 1. This means that the initialization
process (see intro(2)) inherits each of these processes as well. Any
stopped children are restarted with a hangup signal (SIGHUP).
If the process is a controlling process, SIGHUP is sent to each process
in the foreground process group of the controlling terminal belonging
to the calling process, and the controlling terminal associated with
the session is disassociated from the session, allowing it to be
acquired by a new controlling process (see setsid(2V)).
If _exit() causes a process group to become orphaned, and if any member
of the newly-orphaned process group is stopped, then SIGHUP followed by
SIGCONT is sent to each process in the newly-orphaned process group
Each attached shared memory segment is detached and the value of
shm_nattach in the data structure associated with its shared memory
identifier is decremented by 1.
For each semaphore for which the calling process has set a semadj value
(see semop(2)), that semadj value is added to the semval of the speci-
If process accounting is enabled (see acct(2V)), an accounting record
is written to the accounting file.
Most C programs will call the library routine exit(3) which performs
cleanup actions in the standard I/O library before calling _exit().
_exit() never returns.
intro(2), acct(2V), fork(2V), semop(2), wait(2V), exit(3)
21 January 1990 EXIT(2V)