What causes "%s: unrecognized option `%c%s'\n" in NationalSecurityAgency/ghidra?

Add the missing option character to the optstring (append ':' if it takes an argument).

%s: unrecognized option `%c%s'\n

Error message

%s: unrecognized option `%c%s'\n

What it means

GNU getopt reports an unrecognized option. The `%c%s` form fires for a short-style token (`-x` or `+x`) whose first character is not present in the optstring passed to getopt/getopt_long. The message goes to stderr and getopt returns '?' to the caller; it does not abort. Suppressible by setting opterr = 0.

Source

Thrown at GPL/DemanglerGnu/src/demangler_gnu_v2_41/c/getopt.c:767

	  return pfound->val;
	}

      /* Can't find it as a long option.  If this is not getopt_long_only,
	 or the option starts with '--' or is not a valid short
	 option, then it's an error.
	 Otherwise interpret it as a short option.  */
      if (!long_only || argv[optind][1] == '-'
	  || my_index (optstring, *nextchar) == NULL)
	{
	  if (opterr)
	    {
	      if (argv[optind][1] == '-')
		/* --option */
		fprintf (stderr, _("%s: unrecognized option `--%s'\n"),
			 argv[0], nextchar);
	      else
		/* +option or -option */
		fprintf (stderr, _("%s: unrecognized option `%c%s'\n"),
			 argv[0], argv[optind][0], nextchar);
	    }
	  nextchar = (char *) "";
	  optind++;
	  optopt = 0;
	  return '?';
	}
    }

  /* Look at and handle the next short option-character.  */

  {
    char c = *nextchar++;
    char *temp = my_index (optstring, c);

    /* Increment `optind' when we start to process its last character.  */
    if (*nextchar == '\0')
      ++optind;

View on GitHub (pinned to d5f144c24d)

Solutions

Add the missing option character to the optstring (append ':' if it takes an argument).
Check the offending letter via optopt and correct the typo in the invocation or the optstring.
If the token is intentionally unsupported, set opterr = 0 and handle the returned '?' with a custom message.
With getopt_long_only, rename single-character long options that collide with short-option letters.

Example fix

// before
while ((c = getopt_long(argc, argv, "ab:c", lo, &i)) != -1) { ... }
// invocation: prog -z  ->  unrecognized option `-z'

// after (add 'z', or suppress + handle)
while ((c = getopt_long(argc, argv, "ab:cz", lo, &i)) != -1) { ... }

Defensive patterns

Strategy: validation

Validate before calling

// before getopt, confirm option letters you accept are all in optstring
const char *expected = "ab:cz";
if (strchr(expected, userChar) == NULL) { fprintf(stderr, "bad -%c\n", userChar); }
opterr = 0; // silence builtin; handle '?' yourself

Prevention

Generate usage text and optstring from one source to prevent drift.
Always branch on getopt's '?' return and inspect optopt.
Avoid single-char long-option names when using getopt_long_only.

When it happens

Trigger: getopt/getopt_long is invoked with an optstring that does not contain the option letter the user typed (e.g. prog run as `-z` while optstring is "ab:c"). Also reached under getopt_long_only when a single-dash token's leading char is neither in optstring nor a unique long-option prefix.

Common situations: A flag was added to the usage/help text but never added to the optstring; a typo in the option letter; getopt_long_only ambiguity between a short cluster and a long name.

Related errors

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/a79d10eca61ac0e4. Report an issue: GitHub.