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



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

SYNOPSIS
       #include <&lt;stdlib.h>&gt;

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

DESCRIPTION
       The atexit() function registers the given function to be called at nor-
       mal process termination, either via exit(3) or via return from the pro-
       gram'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 non-zero 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
       This page is part of release 3.05 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



Linux                             2003-11-01                         ATEXIT(3)