/**
 * This program forks a separate process using the fork()/exec() system calls.
 *
 * Figure 3.10
 *
 * @author Gagne, Galvin, Silberschatz
 * Operating System Concepts  - Seventh Edition
 * Copyright John Wiley & Sons - 2005.
 */

#define _GNU_SOURCE

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


int
main (int argc, char **argv)
{
  char *my_command = NULL;
  size_t n, t;
  int m;
  pid_t pid;
  char *comm_copy;

  my_command = (char *) malloc (80 * sizeof (char));

  fprintf (stdout, " Enter a command:> ");
  fgets (my_command, 79, stdin);
  n = strlen (my_command) - 1;	/* Remove the EOL character */
  my_command[n] = '\0';		/* Set last char to NULL character */

/*  fprintf(stdout," %s %d\n", my_command, n);*/

  /* fork a child process */
  pid = fork ();

  if (pid < 0)
    {				/* error occurred */
      fprintf (stderr, "Fork Failed\n");
      exit (-1);		/* Get out. */
    }
  else if (pid == 0)
    {				/* child process */
      printf ("** I am the child %d **\n", pid);

      comm_copy = (char *) malloc (80 * sizeof (char));
      strcpy (comm_copy, strrchr (my_command, '/') + 1);
      /* Copy the last part of the filename, past final '/' char. */

      fprintf (stdout, " IN CHILD: Pointer value: %s %s\n", my_command,
	       comm_copy);

      if (execlp (my_command, comm_copy, NULL) < 0)
	{
	  perror ("Child");	/* Print a meaningful error statement */
	  exit (-1);		/* This should not be reached if execlp succeeds. */
	}
    }
  else
    {				/* parent process */
      /* parent will wait for the child to complete */
      printf ("I am the parent %d\n", pid);
/*    fprintf(stdout," IN PARENT: Pointer value: %x\n %s\n", my_command,
    my_command); */
/*      wait (NULL);
      printf ("Child Complete\n"); */
      exit (0);
    }
}