Linux poll 機制

語法
#須引入這個header
#include <poll.h>

#poll用法
int poll(struct pollfd *fds, nfds_t nfds, int timeout);

#define _GNU_SOURCE /* See feature_test_macros(7) */
#include  <signal.h>
#include  <poll.h>

int ppoll(struct pollfd *fds, nfds_t nfds,
const struct timespec *tmo_p, const sigset_t *sigmask);