A bash builtin command named “enable” to enable or disable a bash builtin command

$command
$echo $?
0
$enable -n command
$command
bash: command: command not found
$echo $?
127
$enable command
$command
$enable -n enable
$enable
bash: enable: command not found
$

RELATED SOURCE CODE EXPOSURE

/* Enable/disable shell commands present in LIST.  If list is not specified,
   then print out a list of shell commands showing which are enabled and
   which are disabled. */
int
enable_builtin (list)
     WORD_LIST *list;
{
  int result, flags;
  int opt, filter;
#if defined (HAVE_DLOPEN) && defined (HAVE_DLSYM)
  char *filename;
#endif

  result = EXECUTION_SUCCESS;
  flags = 0;

  reset_internal_getopt ();
  while ((opt = internal_getopt (list, "adnpsf:")) != -1)
    {
      switch (opt)
	{
	case 'a':
	  flags |= AFLAG;
	  break;
	case 'n':
	  flags |= NFLAG;
	  break;
	case 'p':
	  flags |= PFLAG;
	  break;
	case 's':
	  flags |= SFLAG;
	  break;
	case 'f':
#if defined (HAVE_DLOPEN) && defined (HAVE_DLSYM)
	  flags |= FFLAG;
	  filename = list_optarg;
	  break;
#else
	  builtin_error (_("dynamic loading not available"));
	  return (EX_USAGE);
#endif
#if defined (HAVE_DLCLOSE)
	case 'd':
	  flags |= DFLAG;
	  break;
#else
	  builtin_error (_("dynamic loading not available"));
	  return (EX_USAGE);
#endif /* HAVE_DLCLOSE */
	CASE_HELPOPT;
	default:
	  builtin_usage ();
	  return (EX_USAGE);
	}
    }

  list = loptend;

#if defined (RESTRICTED_SHELL)
  /* Restricted shells cannot load new builtins. */
  if (restricted && (flags & (FFLAG|DFLAG)))
    {
      sh_restricted ((char *)NULL);
      return (EXECUTION_FAILURE);
    }
#endif

  if (list == 0 || (flags & PFLAG))
    {
      filter = (flags & AFLAG) ? (ENABLED | DISABLED)
			       : (flags & NFLAG) ? DISABLED : ENABLED;

      if (flags & SFLAG)
	filter |= SPECIAL;

      list_some_builtins (filter);
    }
#if defined (HAVE_DLOPEN) && defined (HAVE_DLSYM)
  else if (flags & FFLAG)
    {
      filter = (flags & NFLAG) ? DISABLED : ENABLED;
      if (flags & SFLAG)
	filter |= SPECIAL;

      result = dyn_load_builtin (list, filter, filename);
#if defined (PROGRAMMABLE_COMPLETION)
      set_itemlist_dirty (&it_builtins);
#endif
    }
#endif
#if defined (HAVE_DLCLOSE)
  else if (flags & DFLAG)
    {
      while (list)
	{
	  opt = dyn_unload_builtin (list->word->word);
	  if (opt == EXECUTION_FAILURE)
	    result = EXECUTION_FAILURE;
	  list = list->next;
	}
#if defined (PROGRAMMABLE_COMPLETION)
      set_itemlist_dirty (&it_builtins);
#endif
    }
#endif
  else
    {
      while (list)
	{
	  opt = enable_shell_command (list->word->word, flags & NFLAG);

	  if (opt == EXECUTION_FAILURE)
	    {
	      sh_notbuiltin (list->word->word);
	      result = EXECUTION_FAILURE;
	    }
	  list = list->next;
	}
    }
  return (result);
}

SOURCE CODE TAKEN FROM DEBIAN Bash SOURCE