#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string.h>

/* Global variable to manipulate */
int globalVariable = 2;

int main(int argc, char *argv[]){

  /* One to see where we are, one to wait for the child in our parent */
  pid_t ws, pid;
  /* Needed for waitpid() */
  int  childExitStatus;

  /* We'll manipulate these too */
  int localVariable = 20;
  char identifier[20];

  pid = fork();
  
  /* Child process */
  if(pid == 0){
    strcpy(identifier,"Child Process: ");
    globalVariable++;
    localVariable++;
    sleep(5);
  }

  /* Error condition */
  else if(pid < 0){
    printf("Failed to fork \n");
    return -1;   
  }

  /* Parent process, pid > 0 */
  else{
    strcpy(identifier,"Parent Process: ");
    ws = waitpid(pid,&childExitStatus,WUNTRACED);
    printf("Child process ended. pid was: %d\n",ws);
  }

  /* Code executed by both parent and child. */
  printf("%s \n",identifier);
  printf(" Global variable: %d (address: %p)\n",globalVariable, &globalVariable);
  printf(" Local variable: %d (address: %p)\n",localVariable, &localVariable);

  return 0;
}