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       exit - cause normal process termination


       #include <stdlib.h>

       void exit(int status);


       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

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

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


       The exit() function does not return.


       For an explanation of the terms used in this section, see attributes(7).

       │InterfaceAttributeValue               │
       │exit()    │ Thread safety │ MT-Unsafe race:exit │
       The exit() function uses a global variable that is not protected, so  it  is  not  thread-


       POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.


       It  is  undefined  what  happens  if  one  of the functions registered using atexit(3) and
       on_exit(3) calls either exit() or longjmp(3).  Note  that  a  call  to  execve(2)  removes
       registrations created using atexit(3) and on_exit(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.


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


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