Refactor clear(1)

Adopting best practices(tm) we developed with sbase.

clear.1

@@ -8,4 +8,4 @@
 .Nm
 .Sh DESCRIPTION
 .Nm
-clears the screen
+clears the screen.

clear.c

@@ -2,9 +2,23 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-int
-main(void)
+#include "util.h"
+
+static void
+usage(void)
 {
+	eprintf("usage: %s\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	argv0 = argv[0], argc--, argv++;
+
+	if (argc)
+		usage();
+
 	printf("\x1b[2J\x1b[H");
+
 	return 0;
 }