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

int var_glb; /* A global variable*/

int main(void)
{
  pid_t childPID;
  int var_lcl = 0;
  printf("\n################# parent: start ###################################\n");  
  setvbuf (stdout, NULL, _IONBF, BUFSIZ);
  
  childPID = fork();
  
  if(childPID >= 0) // fork was successful
    {
      if(childPID == 0) // child process
        {
	  printf("\n----------------- child: start ----------------------------------\n");	  
	  var_lcl++;
	  var_glb++;
	  printf("\n Child Process (before calling system) :: ls -al /etc/mc\n");
	  system("/usr/bin/ls -a -l /etc/mc/");
	  printf("\n Child Process (after calling system)  :: var_lcl = [%d], var_glb[%d]\n", var_lcl, var_glb);
	  printf("\n----------------- child: stop ------------------------------------\n");	  	  
        }
      else //Parent process
        {
	  var_lcl = 10;
          var_glb = 20;
	  printf("\n Parent process :: var_lcl = [%d], var_glb[%d]\n", var_lcl, var_glb);
        }
    }
  else // fork failed
    {
      printf("\n Fork failed, quitting!!!!!!\n");
      return 1;
    }
  
  printf("\n################# parent: stop ####################################\n");
  return 0;
}