#include <unistd.h>
#include <stdio.h>

main()
{
    char *s, buf[1024];
    int fds[2];       
     s = "hello world\n";
     pipe(fds);          
     if (fork() == 0) {
         printf("11111 \n");     /* how to make 111111 before 444444 */
         read(fds[0], s, 6);
         printf("22222\n");
     } else {
       printf("33333\n");
       write(fds[1], buf, 6);
       printf("44444\n");
    }
} /* example3.c */