#include <stdio.h>
main()
{
  char buf[1024];
  char *args[64];
  for (;;)
  {
    /* Prompt for and read a command */
    printf("Command: ");
    if (gets(buf) == NULL)
    {
      printf("\n");
      exit(0);
    }
    /* Split the string into arguments */
    parse(buf, args);
    /* Execute the command */
    execute(args);
  }
}

parse(char *buf, char **args)
{
  while(*buf != NULL)
  {
    /* Strip whitespaces. Use nulls, so that the
      previous argument is terminated automaticaly. */
    while((*buf == ' ') || (*buf == '\t'))
      *buf++ = NULL;
    /* Save the argument */
    *args++ = buf;
    /* Skip over the argument */
    while((*buf != NULL) && (*buf != ' ') && (*buf != '\t'))
      buf++;
  }
  *args = NULL;
}

execute(char **args)
{
  int pid, status;
  /* Get a child process */
  if((pid = fork()) < 0)
  {
    perror("fork");
    exit(1);
  }
  /* The child executes the code inside the if */
  if(pid == 0)
  {
    execvp(*args, args);
    perror(*args);
    exit(1);
  }
  /* The parrent executes the wait */
  while(wait(&status) != pid)
    /* empty */;
}