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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 registered. 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, Copyright (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.opengroup.org/unix/online.html .