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exit(2)

exit(2)                          System Calls                          exit(2)



NAME
       exit, quick_exit, _Exit, _exit - terminate process

SYNOPSIS
       #include <stdlib.h>


       void exit(int status);


       void quick_exit(int status);


       void _Exit(int status);


       #include <unistd.h>


       void _exit(int status);

DESCRIPTION
       A  call  to  exit()  results  in normal program termination. The exit()
       function first calls all functions registered  by  atexit(3C),  in  the
       reverse  order  of their registration, except that a function is called
       after any previously registered functions that had already been  called
       at the time it was registered. Each function is called as many times as
       it was registered. If, during the call to any such function, a call  to
       the  longjmp(3C)  function is made that would terminate the call to the
       registered function, the behavior is undefined.


       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  open  streams with unwritten
       buffered data, closes all open streams, and removes all  files  created
       by tmpfile(3C).


       Finally,  control  is  returned to the host environment by means of the
       function call _Exit(status).


       The quick_exit() function, and the related  at_quick_exit(3C)  function
       are specified in the C11 standard. The quick_exit() function is similar
       to the exit() function except that  no  open  streams  are  flushed  or
       closed   when   control  is  returned  to  the  host  environment.  See
       INCITS/ISO/IEC 9899:2011.


       The _Exit() and _exit() functions are functionally equivalent. They  do
       not  call functions registered with atexit(3C) or at_quick_exit(3C), do
       not call any registered signal handlers, and do not flush open streams.


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

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


           o      If  the parent process of the calling process is executing a
                  wait(3C), wait3(3C), waitid(2), or waitpid(3C), and has nei‐
                  ther  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 subse‐
                  quently executes wait(), wait3(), waitid(), or waitpid().


           o      If the parent process of the calling process is not  execut‐
                  ing  a  wait(), wait3(), waitid(), or waitpid(), and has not
                  set its SA_NOCLDWAIT flag, or set SIGCHLD  to  SIG_IGN,  the
                  calling process is transformed into a zombie process. A zom‐
                  bie process is an inactive process and it will be deleted at
                  some  later  time  when  its parent process executes wait(),
                  wait3(), waitid(), or waitpid(). A zombie process only occu‐
                  pies  a  slot  in  the  process table; it has no other space
                  allocated either in user or kernel space. The process  table
                  slot  that  it  occupies  is  partially  overlaid  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
                  children. The sending of a SIGHUP signal as described  below
                  indirectly 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 exist‐
                  ing child processes and zombie processes is set to  1.  That
                  is,  these  processes  are  inherited  by the initialization
                  process (see Intro(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 sem‐
                  val 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
                  orphaned,  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
                  lifetime of the calling process will end immediately.


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


           o      All open named semaphores in the process are closed as if by
                  appropriate calls to sem_close(3C). All open message  queues
                  in  the  process  are  closed  as if by appropriate calls to
                  mq_close(3C). 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 facility is enabled (see acctadm(8)).


           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(8)), an extended accounting  record  is
                  written to the extended 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(7) for descriptions of the following attributes:


       tab()  box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
       TRIBUTE VALUE _ Interface StabilityCommitted _  MT-LevelSee  below.   _
       StandardSee standards(7).



       The _exit() and _Exit() functions are Async-Signal-Safe.

SEE ALSO
       acct(2),  close(2),  Intro(2),  memcntl(2), semop(2), shmget(2), sigac‐
       tion(2),   times(2),    waitid(2),    at_quick_exit(3C),    atexit(3C),
       fclose(3C),  mq_close(3C), plock(3C), tmpfile(3C), wait(3C), wait3(3C),
       waitpid(3C), signal.h(3HEAD), attributes(7), standards(7), acctadm(8)



Oracle Solaris 11.4               13 Jun 2018                          exit(2)
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