#include <unistd.h>     /* Symbolic Constants */
#include <sys/types.h>  /* Primitive System Data Types */ 
#include <errno.h>      /* Errors */
#include <stdio.h>      /* Input/Output */
#include <sys/wait.h>   /* Wait for Process Termination */
#include <stdlib.h>     /* General Utilities */

int global; 
pid_t childpid; /* variable to store the child's pid */
int status;     /* parent process: child's exit status */
void childfoo()
{
	  
  global = 100;
  printf("CHILD: I am the child process! PID: %d\n", getpid());
  printf("CHILD: My Value of global : %d\n", global); 
  exit(0);

}
 
int main()
{

  /* only 1 int variable is needed because each process would have its
       own instance of the variable
       here, 2 int variables are used for clarity */
        
  /* now create new process */
  childpid = fork();
    
  if (childpid >= 0) /* fork succeeded */
    {
      if (childpid == 0) /* fork() returns 0 to the child process */
        {
	  childfoo();
        }
      else /* fork() returns new pid to the parent process */
        {
	  wait(&status); /* wait for child to exit, and store its status */
	  printf("PARENT: I am the parent process  %d\n", getpid());
	  printf("PARENT: My Value of global : %d\n", global); 
	  exit(0);  /* parent exits */       
        }
    }
  else /* fork returns -1 on failure */
    {
      perror("fork"); /* display error message */
      exit(0); 
    }
}