The GNU C Library also provides the wait3 function for compatibility
with BSD. This function is declared in sys/wait.h. It is the
predecessor to wait4, which is more flexible. wait3 is
now obsolete.
pid_t wait3 (int *status-ptr, int options, struct rusage *usage) ¶Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.
If usage is a null pointer, wait3 is equivalent to
waitpid (-1, status-ptr, options).
If usage is not null, wait3 stores usage figures for the
child process in *rusage (but only if the child has
terminated, not if it has stopped). See Resource Usage.