atexit - register a function to be called at normal program termination.
The atexit() function registers the given
function to be called at normal program termination,
whether 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
The atexit() function returns the value 0 if
successful; otherwise it returns a nonzero value;
errno is not set.
SVID 3, BSD 4.3, ISO 9899