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

int main() {
   int pipes[2];
   int messagelen = 22;
   char data[50];
   int childPID;
 
   
   pipe(pipes);
   childPID = fork();
   if(childPID != 0) {
// remember - if fork returns a non-zero value, this is the parent
      close(pipes[0]);  // the parent doesn't read - just writes.
      strcpy(data, "Go clean your room! (from Parent)");
      messagelen = strlen(data);
      write(pipes[1], &messagelen, sizeof(int));
      write(pipes[1], data, messagelen * sizeof(char) + 1); //Add 1 for \0
                                                            //at end of string
      printf("Message Sent, length= %d\n", messagelen);
   }
   else {
      close(pipes[1]);  // and the child just reads, with no writing
      read(pipes[0], &messagelen, sizeof(int));
      read(pipes[0], data, messagelen * sizeof(char) + 1);
      printf("Uh oh - I've (child %d) been told: \"%s\" \n(len=%d)\n", 
                    getpid(), data, messagelen);
   }
}

/*

gcc -o fork2 fork2.c

./fork2
Message Sent, length= 33
Uh oh - I've (child 18985) been told: "Go clean your room! (from Parent)" 
(len=33)

*/