ATEXIT(3P)                                          POSIX Programmer's Manual                                         ATEXIT(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       atexit - register a function to run at process termination

SYNOPSIS
       #include <stdlib.h>

       int atexit(void (*func)(void));


DESCRIPTION
       The  atexit()  function  shall register the function pointed to by func, to be called without arguments at normal program
       termination. At normal program termination, all functions registered by the atexit() function shall  be  called,  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. Normal termination occurs either by a call to exit() or a return  from
       main().

       At least 32 functions can be registered with atexit().

       After  a successful call to any of the exec functions, any functions previously registered by atexit() shall no longer be
       registered.

RETURN VALUE
       Upon successful completion, atexit() shall return 0; otherwise, it shall return a non-zero value.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The functions registered by a call to atexit() must return to ensure that all registered functions are called.

       The application should call sysconf() to obtain the value of {ATEXIT_MAX}, the number of functions  that  can  be  regis-
       tered. There is no way for an application to tell how many functions have already been registered with atexit().

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       exit(), sysconf(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>

COPYRIGHT
       Portions  of  this  text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for
       Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6,  Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open  Group
       Standard   is   the   referee   document.   The   original   Standard   can   be   obtained  online  at  http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                    ATEXIT(3P)