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

/* to test how pipe '|' works. */

int main(void)
{
    int pid;
    int exam;
    char buf[BUFSIZ];
    int fd[2];   /* used for pipe */

    /* this message actually goes to the screen */
    printf("hello before we are in pipe \n");  
    
    /* now create a pipe */
    if (pipe(fd) == -1)
    {
	perror(" pipe failed\n");
	exit(1);
    }
    
    if ((pid = fork()) == -1)
    {
	perror(" fork failed \n");
	exit(2);
    }

    if (pid == 0)  /* child process */
    {
	close(0);                        /* close the stdin */
	dup(fd[0]);                      /* dup() uses fd[0] (stdin) */
    					 /* because the close(0) call was */
					 /* right before it. At this point, */
					 /* '1' becomes the lowest un-used */
					 /* file id number. Thus, it (1) */
					 /* will be used to 'dup' fid. This */
					 /* is exactly what we want Now all */
					 /* the output to stdout will be */
					 /* redirected to the file that */
					 /* 'fid' was associated with. */
	execlp("./dummy",NULL);
	perror("error in execvp\n");
/*
	scanf("%s",buf);
	printf("%s\n",buf);
*/
    }
    else          /* parent process */
    {
	close(1); /* close stdout */
	dup(fd[1]);
	printf("message-from-parent\n");
	wait(NULL);   /* waiting for child to terminate */
    }
    return 0;
}