your basic rc.shutdown file

src/etc/Makefile

@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.97 1999/04/30 00:46:25 art Exp $
+#	$OpenBSD: Makefile,v 1.98 1999/07/06 07:55:03 deraadt Exp $
 
 TZDIR=		/usr/share/zoneinfo
 LOCALTIME=	US/Pacific
@@ -18,8 +18,8 @@ BIN1=	aliases bootptab changelist ccd.conf csh.cshrc csh.login csh.logout \
 	ipf.rules ksh.kshrc locate.rc man.conf monthly motd mrouted.conf \
 	myname ipnat.rules netstart networks newsyslog.conf passwd.conf \
 	phones printcap protocols rbootd.conf rc rc.conf rc.local \
-	rc.securelevel remote rpc security services shells syslog.conf weekly \
-	etc.${MACHINE}/disktab dhclient.conf
+	rc.securelevel rc.shutdown remote rpc security services shells \
+	syslog.conf weekly etc.${MACHINE}/disktab dhclient.conf
 
 # -rw-rw-r--
 BIN2=	motd

src/etc/rc.shutdown

@@ -0,0 +1,17 @@
+#	$OpenBSD: rc.shutdown,v 1.1 1999/07/06 07:55:03 deraadt Exp $
+#
+# If it exists, this script is run at system-shutdown by reboot(8),
+# halt(8).
+# If the architecture supports keyboard requested halting, it is also
+# run by init(8) when such an event happens.
+#
+
+echo -n /etc/rc.shutdown in progress...
+
+#
+# Your shell code goes here
+#
+
+
+echo done.
+exit 0		# An exit code of 2 will cause init(8) to attempt powerdown.