select 함수

write set 인 wfds를 출력으로하는 select 문 예제

#include <stdio.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/select.h>

#define BUF_SIZE 30

int main(int argc, char *argv[])
{
	fd_set reads, temps, wset; //fd선언
	int result, str_len;
	char buf[BUF_SIZE];
	struct timeval timeout;

	FD_ZERO(&wset); // fd배열을모두 0값으로 초기화
	//FD_SET(0, &reads); // 0 is standard input(console)
  FD_SET(1, &wset);

  
	/*
	timeout.tv_sec=5;
	timeout.tv_usec=5000;
	*/

	while(1)
	{
		temps=wset;
		timeout.tv_sec=5;
		timeout.tv_usec=0;
    //printf("select 직전 \n");
		result=select(9, 0, &wset, 0, &timeout);
		if(result==-1)
		{
			puts("select() error!");
			break;
		}
		else if(result==0)
		{
			puts("Time-out!");
		}
		else 
		{
			if(FD_ISSET(1, &wset)) 
			{
				//str_len=read(0, buf, BUF_SIZE);
				//buf[str_len]=0;
				//printf("message from console:");
        sleep(5);
			}
		}
    printf("끝\n");
	}
  //printf("끝\n");
	return 0;
}