int main(void){struct pollfd fds[2];int ret;int i = 0;fds[0].fd = STDIN_FILENO;fds[0].events = POLLIN;fds[1].fd = STDOUT_FILENO;fds[1].events = POLLOUT;while(i<5){ret = poll(fds,2,TIMEOUT*1000);if(ret == -1){perror("poll");return 1;}if(!ret){printf("%d seconds elapsed. \n",TIMEOUT);}if(fds[0].revents & POLLIN){printf("stdin is readable\n");}if(fds[1].revents & POLLOUT){printf("stdout is writeable\n");}i++;}return 0;}運(yùn)行./poll 的時(shí)候我也沒(méi)有輸出啊，為什么直接就打印了stdout is writable 。是不是stdout就一直被用著呢 。還有當(dāng)我運(yùn)行 ./poll < lala.txt 的時(shí)候，由于用了stdin ，它打印出了 stdin isreadable ，但是為什么一打就是5條啊。