exit (3)

NAME

       exit - cause normal program termination

SYNOPSIS

       #include <stdlib.h>

       void exit(int status);

DESCRIPTION

       The exit() function causes normal program termination and the the value
       of status & 0377 is returned to the parent (see  wait(2)).   All  func-
       tions  registered with atexit() and on_exit() are called in the reverse
       order of their registration, and  all  open  streams  are  flushed  and
       closed.  Files created by tmpfile() are removed.

       The C standard specifies two defines EXIT_SUCCESS and EXIT_FAILURE that
       may be passed to exit() to indicate successful or unsuccessful termina-
       tion, respectively.

RETURN VALUE

       The exit() function does not return.

CONFORMING TO

       SVID 3, POSIX, BSD 4.3, ISO 9899 (``ANSI C'')

NOTES

       During the exit processing, it is possible to register additional func-
       tions with atexit() and on_exit().  Always the last-registered function
       is  removed from the chain of registered functions, and invoked.  It is
       undefined what happens if  during  this  processing  either  exit()  or
       longjmp() is called.

       The  use of EXIT_SUCCESS and EXIT_FAILURE is slightly more portable (to
       non-Unix environments) than that 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 <sysex-
       its.h>.

       After exit(), the exit status must be transmitted to  the  parent  pro-
       cess. 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 sta-
       tus) so that the parent can learn the exit status when it  later  calls
       one of the wait() 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 the

SEE ALSO

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

                                  2001-11-17                           exit(3)