有名管道的非阻塞设置

#include<sys/types.h>
#include<sys/stat.h>
#include<errno.h>
#include<string.h>
#include<stdio.h>
#include<unistd.h>
#include<fcntl.h>
int
main (void)
{
  char buf[1024];
  char fn[] = "myfifo";
  int ret = mkfifo (fn, S_IRUSR | S_IWUSR);
  if (ret == -1)
    {
      printf ("mkfifo error:%s
", strerror (errno));
      return 1;
    }
  int rd = open (fn, O_RDONLY | O_NONBLOCK);
  int fd = open (fn, O_WRONLY | O_NONBLOCK, S_IRWXU);//此处注意，必须先打开读，否则会打不开fifo,根据论坛提到的如果设置非阻塞，必须先open一个fifo读。
  if (fd == -1)
    {
      printf ("open error:%s
", strerror (errno));
      return 1;
    }
  write (fd, "hello", 5);
  read (rd, buf, 5);
  write (1, buf, 5);//向设备1写入，即显示屏
  close (fd);
  unlink (fn);
  return 0;
}