atexit(3)

1ATEXIT(3)                  Linux Programmer's Manual                 ATEXIT(3)
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NAME

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

9       #include <stdlib.h>
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11       int atexit(void (*function)(void));
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DESCRIPTION

14       The atexit() function registers the given function to be called at nor‐
15       mal process termination, either via exit(3) or via return from the pro‐
16       gram's main().  Functions so registered are called in the reverse order
17       of their registration; no arguments are passed.
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19       POSIX.1-2001 requires that an implementation allow at least  ATEXIT_MAX
20       (32) such functions to be registered.  The actual limit supported by an
21       implementation can be obtained using sysconf(3).
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23       When a child process is created via fork(), it inherits copies  of  its
24       parents  registrations.   Upon  a  successful call to one of the exec()
25       functions, all registrations are removed.
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RETURN VALUE

28       The atexit() function returns the value 0 if successful;  otherwise  it
29       returns a non-zero value.
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EXAMPLE

32       #include <stdio.h>
33       #include <stdlib.h>
34       #include <unistd.h>
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36       void bye(void) {
37               printf("That was all, folks\n");
38       }
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40       int main(){
41               long a;
42               int i;
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44               a = sysconf(_SC_ATEXIT_MAX);
45               printf("ATEXIT_MAX = %ld\n", a);
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47               i = atexit(bye);
48               if (i != 0) {
49                       fprintf(stderr, "cannot set exit function\n");
50                       return EXIT_FAILURE;
51               }
52               return EXIT_SUCCESS;
53       }
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NOTES

56       Since  glibc  2.2.3,  atexit()  (and on_exit()) can be used to within a
57       shared library to establish functions that are called when  the  shared
58       library is unloaded.
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60       Functions registered using atexit() (and on_exit()) are not called if a
61       process terminates abnormally because of the delivery of a signal.
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CONFORMING TO

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