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NAME

       atexit - register a function to be called at normal process termination

SYNOPSIS

       #include <stdlib.h>

       int atexit(void (*function)(void));

DESCRIPTION

       The atexit() function registers the given  function  to  be  called  at
       normal  process  termination, either via exit(3) or via return from the
       program’s main().  Functions so registered are called  in  the  reverse
       order of their registration; no arguments are passed.

       POSIX.1-2001  requires that an implementation allow at least ATEXIT_MAX
       (32) such functions to be registered.  The actual limit supported by an
       implementation can be obtained using sysconf(3).

       When  a child process is created via fork(2), it inherits copies of its
       parent’s registrations.  Upon a successful call to one of  the  exec(3)
       functions, all registrations are removed.

RETURN VALUE

       The  atexit()  function returns the value 0 if successful; otherwise it
       returns a nonzero value.

CONFORMING TO

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

NOTES

       Functions registered using atexit() (and on_exit(3)) are not called  if
       a process terminates abnormally because of the delivery of a signal.

   Linux Notes
       Since  glibc  2.2.3,  atexit()  (and  on_exit(3))  can be used within a
       shared library to establish functions that are called when  the  shared
       library is unloaded.

EXAMPLE

       #include <stdio.h>
       #include <stdlib.h>
       #include <unistd.h>

       void
       bye(void)
       {
           printf("That was all, folks\n");
       }

       int
       main(void)
       {
           long a;
           int i;

           a = sysconf(_SC_ATEXIT_MAX);
           printf("ATEXIT_MAX = %ld\n", a);

           i = atexit(bye);
           if (i != 0) {
               fprintf(stderr, "cannot set exit function\n");
               exit(EXIT_FAILURE);
           }

           exit(EXIT_SUCCESS);
       }

SEE ALSO

       _exit(2), exit(3), on_exit(3)

COLOPHON

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       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.