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NAME

       exit - cause normal process termination

SYNOPSIS

       #include <stdlib.h>

       void exit(int status);

DESCRIPTION

       The  exit() function causes normal process termination and the value of
       status & 0377 is returned to the parent (see wait(2)).

       All functions registered with atexit(3) and on_exit(3) are  called,  in
       the  reverse  order  of their registration.  (It is possible for one of
       these  functions  to  use  atexit(3)  or  on_exit(3)  to  register   an
       additional  function  to  be  executed  during exit processing; the new
       registration is added to the front of the list of functions that remain
       to  be  called.)   If  one of these functions does not return (e.g., it
       calls _exit(2), or kills itself  with  a  signal),  then  none  of  the
       remaining   functions  is  called,  and  further  exit  processing  (in
       particular, flushing of stdio(3) streams) is abandoned.  If a  function
       has  been registered multiple times using atexit(3) or on_exit(3), then
       it is called as many times as it was registered.

       All open stdio(3) streams are flushed and  closed.   Files  created  by
       tmpfile(3) are removed.

       The  C standard specifies two constants, EXIT_SUCCESS and EXIT_FAILURE,
       that may be passed to exit() to  indicate  successful  or  unsuccessful
       termination, respectively.

RETURN VALUE

       The exit() function does not return.

CONFORMING TO

       SVr4, 4.3BSD, POSIX.1-2001, C89, C99.

NOTES

       It  is  undefined what happens if one of the functions registered using
       atexit(3) and on_exit(3) calls either exit() or longjmp(3).

       The use of EXIT_SUCCESS and EXIT_FAILURE is slightly more portable  (to
       non-Unix  environments) than the use of 0 and some nonzero value like 1
       or -1.  In particular, VMS uses a different convention.

       BSD has attempted to standardize exit codes; see the file <sysexits.h>.

       After exit(), the  exit  status  must  be  transmitted  to  the  parent
       process.   There  are three cases.  If the parent has set SA_NOCLDWAIT,
       or has set the SIGCHLD handler to SIG_IGN, the status is discarded.  If
       the  parent was waiting on the child it is notified of the exit status.
       In both cases the exiting process dies immediately.  If the parent  has
       not  indicated that it is not interested in the exit status, but is not
       waiting, the exiting process turns into a "zombie"  process  (which  is
       nothing  but  a  container  for  the  single byte representing the exit
       status) so that the parent can learn the  exit  status  when  it  later
       calls one of the wait(2) functions.

       If  the implementation supports the SIGCHLD signal, this signal is sent
       to the parent.  If the parent has set  SA_NOCLDWAIT,  it  is  undefined
       whether a SIGCHLD signal is sent.

       If  the process is a session leader and its controlling terminal is the
       controlling  terminal  of  the  session,  then  each  process  in   the
       foreground  process group of this controlling terminal is sent a SIGHUP
       signal, and the terminal is disassociated from this  session,  allowing
       it to be acquired by a new controlling process.

       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 this process group.  See setpgid(2) for  an  explanation  of
       orphaned process groups.

SEE ALSO

       _exit(2), setpgid(2), wait(2), atexit(3), on_exit(3), tmpfile(3)

COLOPHON

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