Show usage and exit non-zero for unsupported option in nop

Towards https://gitlab.com/graphviz/graphviz/-/issues/1843.

diff --git a/cmd/tools/nop.c b/cmd/tools/nop.c
index a80536fa7c5435d192d16f56cc141a3ba46613ad..008a5fc8a071a0a1a20349674b841459dcbad08f 100644 (file)
--- a/cmd/tools/nop.c
+++ b/cmd/tools/nop.c
@@ -50,9 +50,11 @@ static void init(int argc, char *argv[])
        case '?':
            if (optopt == '?')
                usage(0);
-           else
-               fprintf(stderr, "nop: option -%c unrecognized - ignored\n",
+           else {
+               fprintf(stderr, "nop: option -%c unrecognized\n",
                        optopt);
+               usage(1);
+           }
            break;
        }
     }