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exit(2)				 System	Calls			       exit(2)

NAME
       exit, _exit - terminate process

SYNOPSIS
       #include	<stdlib.h>

       void exit(int status);

       #include	<unistd.h>

       void _exit(int status);

DESCRIPTION
       The exit() function first calls all functions registered	by atexit(3C),
       in the reverse order of their registration. Each	function is called  as
       many times as it	was registered.

       If  a  function registered by a call to atexit(3C) fails	to return, the
       remaining registered functions are not  called  and  the	 rest  of  the
       exit() processing is not	completed. If exit() is	called more than once,
       the effects are undefined.

       The exit() function then	flushes	all output streams,  closes  all  open
       streams,	and removes all	files created by tmpfile(3C).

       The _exit() and exit() functions	terminate the calling process with the
       following consequences:

	  o  All of the	file descriptors, directory  streams,  conversion  de-
	     scriptors	and  message catalogue descriptors open	in the calling
	     process are closed.

	  o  If	the parent process of  the  calling  process  is  executing  a
	     wait(2),  wait3(3C), waitid(2) or waitpid(2), and has neither set
	     its SA_NOCLDWAIT flag nor set SIGCHLD to SIG_IGN, it is  notified
	     of	the calling process's termination and the low-order eight bits
	     (that is, bits 0377) of status are	made available to it.  If  the
	     parent  is	not waiting, the child's status	will be	made available
	     to	it when	the parent subsequently	executes  wait(2),  wait3(3C),
	     waitid(2) or waitpid(2).

	  o  If	 the  parent process of	the calling process is not executing a
	     wait(2), wait3(3C), waitid(2) or waitpid(2), and has not set  its
	     SA_NOCLDWAIT flag,	or set SIGCHLD to SIG_IGN, the calling process
	     is	transformed into a zombie process. A zombie process is an  in-
	     active process and	it will	be deleted at some later time when its
	     parent process executes wait(2), wait3(3C),  waitid(2)  or	 wait-
	     pid(2).  A	zombie process only occupies a slot in the process ta-
	     ble; it has no other space	allocated either  in  user  or	kernel
	     space. The	process	table slot that	it occupies is partially over-
	     laid with time accounting information (see	 <sys/proc.h>)	to  be
	     used by the times(2) function.

	  o  Termination  of  a	 process does not directly terminate its chil-
	     dren. The sending of a SIGHUP signal  as  described  below	 indi-
	     rectly terminates children	in some	circumstances.

	  o  A SIGCHLD will be sent to the parent process.

	  o  The  parent  process  ID of all of	the calling process's existing
	     child processes and zombie	processes is set to 1. That is,	 these
	     processes	are  inherited	by the initialization process (see in-
	     tro(2)).

	  o  Each mapped memory	object is unmapped.

	  o  Each attached shared-memory segment is detached and the value  of
	     shm_nattch	 (see shmget(2)) in the	data structure associated with
	     its shared	memory ID is decremented by 1.

	  o  For each semaphore	for which the calling process has set a	semadj
	     value  (see  semop(2)),  that value is added to the semval	of the
	     specified semaphore.

	  o  If	the process is a controlling process, the SIGHUP  signal  will
	     be	 sent  to  each	process	in the foreground process group	of the
	     controlling terminal belonging to the calling process.

	  o  If	the process is a controlling process, the controlling terminal
	     associated	 with  the  session is disassociated from the session,
	     allowing it to be acquired	by a new controlling process.

	  o  If	the exit of the	process	causes a process group to  become  or-
	     phaned,  and if any member	of the newly-orphaned process group is
	     stopped, then a SIGHUP signal followed by a SIGCONT  signal  will
	     be	sent to	each process in	the newly-orphaned process group.

	  o  If	 the  parent  process  has  set	 its SA_NOCLDWAIT flag,	or set
	     SIGCHLD to	SIG_IGN, the status will be discarded, and  the	 life-
	     time of the calling process will end immediately.

	  o  If	the process has	process, text or data locks, an	UNLOCK is per-
	     formed (see plock(3C) and memcntl(2)).

	  o  All open named semaphores in the process are closed as if by  ap-
	     propriate calls to	sem_close(3RT).	All open message queues	in the
	     process are closed	as if by appropriate calls  to	mq_close(3RT).
	     Any outstanding asynchronous I/O operations may be	cancelled.

	  o  An	 accounting  record  is	 written on the	accounting file	if the
	     system's accounting routine is enabled (see acct(2)).

	  o  An	extended accounting record is written to the extended  process
	     accounting	 file  if the system's extended	process	accounting fa-
	     cility is enabled (see acctadm(1M)).

	  o  If	the current process is the last	process	within its task	and if
	     the  system's  extended  task accounting facility is enabled (see
	     acctadm(1M)), an extended accounting record is written to the ex-
	     tended task accounting file.

RETURN VALUES
       These functions do not return.

ERRORS
       No errors are defined.

USAGE
       Normally	applications should use	exit() rather than _exit().

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE	TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |_exit() is Async-Signal Safe |
       +-----------------------------+-----------------------------+

SEE ALSO
       acctadm(1M),   intro(2),	  acct(2),   close(2),	memcntl(2),  semop(2),
       shmget(2), sigaction (2),  times(2),  wait(2),  waitid(2),  waitpid(2),
       atexit(3C),  fclose(3C),	 mq_close(3RT),	plock(3C), signal(3HEAD), tmp-
       file(3C), wait3(3C), attributes(5)

SunOS 5.9			  10 Dec 1999			       exit(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | USAGE | ATTRIBUTES | SEE ALSO

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