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EXIT(3)                    Linux Programmer's Manual                   EXIT(3)



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 non-zero 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 ALSO
       _exit(2), wait(2), atexit(3), on_exit(3), tmpfile(3)

COLOPHON
       This  page  is part of release 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                             2007-06-12                           EXIT(3)