/* fork2.c - Create 2 child processes.
 */
#include <stdio.h>
#include <unistd.h>

main(int argc, char **argv)
{
  char *catarg[3], *factorarg[3];
  int i, return_value;

  /* Here are the arguments to pass to child process.
  */
  catarg[0] = "cat";
  catarg[1] = "f1.txt";
  catarg[2] = NULL;

  factorarg[0] = "factor";
  factorarg[1] = "5040";
  factorarg[2] = NULL;

  /* Print out Process ID.  Used to prove which process is talking.
   */
  printf("I am process %d.\n", getpid());


  /* Try to fork and create a new process address space, then
   * in the child:  attempt to exec the 'cat' program/command.
   */
  if (fork() == 0)
  {
    printf ("      Cat process %d\n", getpid());
    execv("/bin/cat", catarg);
  }
  else
  {
    /* The parent:  if we successfully called cat, we are going to "wait"
     * until it finishes and then only move on from there.
     */
    printf ("   (parent) pid = %d\n", getpid(), i);

    // Experiment:  Take out this call to wait to see funny behavior.
    wait(&i);
  }

  if (fork() == 0)
  {
    printf("      Factor process %d\n", getpid());
    execv("/usr/bin/factor", factorarg);
  }
  else
  {
    printf("   (parent) pid = %d\n", getpid());
    wait(&i);
  }
}