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

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 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(), it inherits copies of the its parents registrations. Upon a successful call to one of the exec() functions, all registrations are removed.

RETURN VALUE The atexit() function returns the value 0 if successful; otherwise it returns a non-zero value.

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

void bye(void) { printf("That was all, folks0); }

int main(){ long a; int i;

a = sysconf(_SC_ATEXIT_MAX); printf("ATEXIT_MAX = %ld0, a);

i = atexit(bye); if (i != 0) { fprintf(stderr, "cannot set exit function0); return EXIT_FAILURE; } return EXIT_SUCCESS; }

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

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

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

SEE ALSO _exit(3), exit(3), on_exit(3)

2003-11-01 ATEXIT(3)