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ATEXIT(3) Linux Programmer's Manual ATEXIT(3)
atexit - register a function to be called at normal process termination
#include <stdlib.h>
int atexit(void (*function)(void));
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.
The same function may be registered multiple times: it is called once for each
registration.
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.
The atexit() function returns the value 0 if successful; otherwise it returns
a nonzero value.
SVr4, 4.3BSD, C89, C99, POSIX.1-2001.
Functions registered using atexit() (and on_exit(3)) are not called if a
process terminates abnormally because of the delivery of a signal.
If one of the functions registered functions calls _exit(2), then any
remaining functions are not invoked, and the other process termination steps
performed by exit(3) are not performed.
POSIX.1-2001 says that the result of calling exit(3) more than once (i.e.,
calling exit(3) within a function registered using atexit()) is undefined. On
some systems (but not Linux), this can result in an infinite recursion;
portable programs should not invoke exit(3) inside a function registered using
atexit().
The atexit() and on_exit(3) functions register functions on the same list: at
normal process termination, the registered functions are invoked in reverse
order of their registration by these two functions.
POSIX.1-2001 says that the result is undefined if longjmp(3) is used to
terminate execution of one of the functions registered atexit().
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.
#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);
}
_exit(2), exit(3), on_exit(3)
This page is part of release 3.32 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 2008-12-05 ATEXIT(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface