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

int main() {
    fd_set rfds;
    struct timeval tv;
    int retval,n;
    char buffer[256];

   /* Watch stdin (fd 0) to see when it has input. */
   FD_ZERO(&rfds);
   FD_SET(0, &rfds);
   /* Wait up to five seconds. */
   tv.tv_sec = 5;
   tv.tv_usec = 0;

   retval = select(1, &rfds, NULL, NULL, &tv);

   if (retval) {
      /* FD_ISSET(0, &rfds) will be true. */
       n = read(0,buffer,255);
       if (n > 0) {
	 buffer[n]='\0';
         printf("Data is available: %s\n",buffer);
       }
       else printf("error on read\n");
   }
   else
       printf("No data within five seconds.\n");
   exit(0);
}