What causes "%s: option `%s' requires an argument" in NationalSecurityAgency/ghidra?

Provide the required argument: --style=gnu or --style gnu.

%s: option `%s' requires an argument

Error message

%s: option `%s' requires an argument

What it means

GNU getopt long-option path: the matched option has has_arg == 1 (required_argument) but no argument is available (optind >= argc, i.e. the option was last on the command line with no following token and no attached =value). With opterr set, getopt prints this and returns optstring[0]==':' ? ':' : '?'. It is a missing-required-argument usage error.

Source

Thrown at GPL/DemanglerGnu/src/demangler_gnu_v2_24/c/getopt.c:734

			fprintf (stderr,
				 _("%s: option `%c%s' doesn't allow an argument\n"),
				 argv[0], argv[optind - 1][0], pfound->name);

		      nextchar += strlen (nextchar);

		      optopt = pfound->val;
		      return '?';
		    }
		}
	    }
	  else if (pfound->has_arg == 1)
	    {
	      if (optind < argc)
		optarg = argv[optind++];
	      else
		{
		  if (opterr)
		    fprintf (stderr,
			   _("%s: option `%s' requires an argument\n"),
			   argv[0], argv[optind - 1]);
		  nextchar += strlen (nextchar);
		  optopt = pfound->val;
		  return optstring[0] == ':' ? ':' : '?';
		}
	    }
	  nextchar += strlen (nextchar);
	  if (longind != NULL)
	    *longind = option_index;
	  if (pfound->flag)
	    {
	      *(pfound->flag) = pfound->val;
	      return 0;
	    }
	  return pfound->val;
	}

View on GitHub (pinned to d5f144c24d)

Solutions

Provide the required argument: --style=gnu or --style gnu.
Check --help to confirm which options require arguments and their expected values.
Quote/escape the argument so the shell passes it as one token that getopt can consume.
Review the script's conditional flag-building to ensure value and flag are appended together.

Example fix

# before
$ tool --style
... option `--style' requires an argument

# after
$ tool --style gnu   # or --style=gnu

Defensive patterns

Strategy: validation

Validate before calling

// Ensure required-argument options always receive a value
if (optionRequiresArg(name) && value == null) {
    throw new IllegalArgumentException("Option " + name + " requires an argument");
}

Type guard

boolean isCompleteInvocation(String name, String value, Set<String> requiredArgFlags) {
    return !requiredArgFlags.contains(name) || value != null;
}

Try / catch

int rc = run_child({"tool", "--" + name});
if (rc != 0 && stderr_contains("requires an argument")) {
    // prompt for or supply the missing value, then re-run
}

Prevention

Consult --help to learn which options require arguments.
When conditionally appending a flag, always append its value in the same branch.
Quote the argument so the shell delivers it as one token for getopt to consume.
Validate assembled argument lists against the option spec before invoking the tool.

When it happens

Trigger: Specifying a long option that requires an argument but providing none - e.g. '--style' as the last token with no following value and no '=value'. getopt looks for the next argv element, finds none, and reports the requirement.

Common situations: Forgetting the value for an option that needs one (-o/--output with no filename); the value being swallowed by shell quoting/word-splitting so getopt sees the option as last; a script conditionally appending the flag but not its value; trailing-option positioned where the value is parsed as another flag.

Related errors

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/e340f622ab47b0ff. Report an issue: GitHub.