An exit callback function is a function that
gawk calls before it exits.
Such functions are useful if you have general “cleanup” tasks
that should be performed in your extension (such as closing database
connections or other resource deallocations).
You can register such
a function with
gawk using the following function:
void awk_atexit(void (*funcp)(void *data, int exit_status),
dataparameter will be the original value of
exit_statusparameter is the exit status value that
gawkintends to pass to the
gawksaves in order to pass to the function pointed to by
Exit callback functions are called in last-in, first-out (LIFO)
order—that is, in the reverse order in which they are registered with