better error message for missing option argument.

1 files changed, 3 insertions, 2 deletions

diff --git a/marsond.c b/marsond.c
index a2ba67d..309d62c 100644
--- a/marsond.c
+++ b/marsond.c
@@ -108,7 +108,7 @@ void parse_args(int argc, char **argv) {
       }
    }
 
-	while( (opt = getopt(argc, argv, "d:hfk:p:vV")) != -1) {
+	while( (opt = getopt(argc, argv, ":d:hfk:p:vV")) != -1) {
 		switch(opt) {
 			case 'd': delay_ms = atoi(optarg); break;
 			case 'f': foreground++;            break;
@@ -117,7 +117,8 @@ void parse_args(int argc, char **argv) {
 			case 'p': pause_ms = atoi(optarg); break;
 			case 'v': debugging++;             break;
 			case 'V': version(); exit(0);      break;
-			default:  die("invalid option (try --help)"); break;
+			case ':': die("option -%c requires an argument (try --help)", optopt); break;
+			default:  die("invalid option -%c (try --help)", optopt); break;
 		}
 	}