Keeping pids

As I fork() 2 childs from the same parent, I would like to keep my first child's pid and pass it to the 2nd child. Question is how do I do it? I've tried global variables or maybe I did it incorrectly.

From the start, I was told by my lecturer that global variables are bad so I didn't read much about it. Here's a piece of the code...

Code:

---

#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <signal.h>
#include <errno.h>

int firstID;

int main(){

  int id;

  if(fork() == 0){
    id = (int)getpid();
    printf("I am child : %d\n", id);
    firstID = id;
  }
  else{
    if(fork() == 0){
      printf("My First child's ID : %d\n", firstID);
    }
  }

  return 0;
}

---

When I print the pid on the 2nd fork, it shows me '0'.

Global variables are initialized to zero by default.


Quzah.

But if you see the code there, in the first fork, I've set the variable with the pid but it didn't appear on the second fork.

Is there any solution on how I can keep the value of the first child's pid so it can be printed in the second child?

Code:

---

int main(){
  int id;

  id = fork();
  if(id == 0){
    id = (int)getpid();
    printf("I am child : %d\n", id);
  }
  else{
    if(fork() == 0){
      printf("My First child's ID : %d\n", id);
    }
  }

  return 0;
}

---

Quote:

---

Originally Posted by quzah

Global variables are initialized to zero by default.


Quzah.

---

I thought that was only if the 'static' keyword was present.

Nope.

Thanks Salem, I got it to work this time