#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

main(int argc, char *argv[])
{ int pid;
  printf("Single\n");
  pid = fork();

  if (pid < 0)
  { perror("fork failed");
    exit(-1);
  }

  /* child */
  else if (pid == 0)
  { printf("  Child Process\n");
    printf("  Executing %s using execvp ...\n",argv[1]);

    execvp(argv[1], &argv[1]);     /* see man execvp */

    /* If execvp returns, the call has failed */
    perror("execvp failed to run");
    exit(-1);
  }

  /* parent */
  else
  { wait( (int *)0 );   /* wait to avoid child zombie  */
    printf("Parent Process\n");
    printf("--my child has completed the %s\n",argv[1]);
    exit(0);
  }
}