#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int pd[2], n, i;
char line[256];

int main()
{
    pipe(pd);               // create a pipe
    printf("pd=[%d, %d]\n", pd[0], pd[1]);
    if(fork()){             // fork a child to share the pipe
        printf("parent %d close pd[0]\n", getpid());
        close(pd[0]);       // parent as pipe WRITER
        while(i++ < 10){    // parent writes to pipe 10 times
            printf("parent %d writing to pipe\n", getpid());
            n = write(pd[1], "I AM YOUR PAPA", 16);
            printf("parent %d wrote %d bytes to pipe\n", getpid(), n);
        }
        printf("parent %d exit\n", getpid());
    }
    else{
        printf("child %d close pd[1]\n", getpid());
        close(pd[1]);       // child as pipe READER
        while(1){           // child read from pipe
            printf("child %d reading from pipe\n", getpid());
            if((n = read(pd[0], line, 128))){       //try to read 128 bytes
                line[n]=0;
                printf("child read %d bytes from pipe: %s\n", n, line);
            }
            else            // pipe has no data and no writer
                exit(0);
        }
    }
}