fprintf(stderr, dohalt ?
-		    "usage: halt [-clNnpq] [-k kernel]\n" :
-		    "usage: reboot [-cdlNnpqr] [-k kernel]\n");
+		fprintf(stderr, "usage: %s%s [-%sflNnpq%s] "
+		    "[-e name=value] [-k kernel] [-o options]\n",
+		    dofast ? "fast" : "",
+		    dohalt ? "halt" : dofast ? "boot" : "reboot",
+		    dohalt ? "D" : "cDd",
+		    dohalt || dofast ? "" : "r");
 	}
 	exit(1);
 }