A simple test to determine if your OS allows polling devices, e.g. /dev/null

poll_dev.c

#include <stdio.h>
#include <poll.h>

#include <fcntl.h>

int main() {
    int fd = open("/dev/null", O_WRONLY);
    struct pollfd pollfds = { fd, POLLOUT, 0 };
    if (fd < 0) {
        perror("open");
        return 1;
    }
    if (poll(&pollfds, 1, -1) < 0) {
        perror("poll");
        return 2;
    }
    if (pollfds.revents == POLLNVAL) {
        puts("huh? why poll({/dev/null, POLLOUT, 0}, 1) returns POLLNVAL?");
    }
    if (pollfds.revents == POLLOUT) {
        puts("working as expected");
    }
    return 0;
}