atexit - register a function to be called on exit
atexit "void (*function)(void)"
The atexit function registers the given function to be called at
program exit, whether via exit(3) or via return from the program’s
main. Functions so registered are called in reverse order; no
arguments are passed. At least 32 functions can always be
registered, and more are allowed as long as sufficient memory can
atexit returns the value 0 if successful; otherwise the value -1 is
returned and the global variable errno is set to indicate the
No memory was available to add the function to the list. The
existing list of functions is unmodified.
The atexit function conforms to ANSI X3.159-1989.