Introductory concepts

poll() IO
Pass a set of FDs to check for various IO states
read, write, error, HUP, OOB

struct pollfds pfds[3];
int readyfds;
int timeout = 3; /* milliseconds */

bzero(&pfds, sizeof(pfds));
pfds[0].events = POLLRDNORM;
pfds[1].events = POLLWRNORM;
pfds[2].events = POLLWRNORM;

readyfds = poll(&pfds, 3, timeout);

if (pfds[0].revents | POLLRDNORM) {
    /* Handle STDIN ready */
}
if (pfds[1].revents | POLLWRNORM) {
    /* Handle STDOUT ready */
}
if (pfds[2].revents | POLLWRNORM) {
    /* Handle STDERR read */
}