The
_exit()
system call
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 has an outstanding
wait(2)
call
or catches the
SIGCHLD
signal,
it is notified of the calling process's termination and
the
status
is set as defined by
wait(2).
- The parent process-ID of all of the calling process's existing child
processes are set to the process-ID of the calling process's reaper;
the reaper (normally the initialization process)
inherits each of these processes
(see
procctl(2),
init(8)
and the
DEFINITIONS
section of
intro(2)).
- If the termination of the process causes any process group
to become orphaned (usually because the parents of all members
of the group have now exited; see
"orphaned process group"
in
intro(2)),
and if any member of the orphaned group is stopped,
the
SIGHUP
signal and the
SIGCONT
signal are sent to all members of the newly-orphaned process group.
- If the process is a controlling process (see
intro(2)),
the
SIGHUP
signal is sent to the foreground process group of the controlling terminal,
and all current access to the controlling terminal is revoked.
Most C programs call the library routine
exit(3),
which flushes buffers, closes streams, unlinks temporary files, etc.,
before
calling
_exit().
