- added a usage-screen and a system-type check

examples/passwd-wrapper.scm

@@ -321,9 +321,20 @@ Please choose a password with at least 2 character classes.")
 	     (else
 	      (lp pw))))))))
 
+(define (display-usage)
+  (display "Usage: passwd-wrapper.scm\n")
+  (display "Change NIS, Kerberos IV and Kerberos V passwords at once.\n")
+  (display "Written by David Frese.\n"))
+
 (define (main args)
+  (if (null? (cdr args))
+      (case system-type
+	((freebsd solaris)
 	 (let ((old-pw (ask/check-old-password))
 	       (new-pw (ask-new-password)))
 	   (if (change-all-passwords old-pw new-pw)
 	       (display "Password changed.\n")
 	       (display "Password could not be changed.\n"))))
+	(else
+	 (raise-unsupported-machine)))
+      (display-usage)))