Use ${rcexec} in rc_pre to do the config testing. This allows to specify

macros with spaces in them. With and OK ajacoutot

src/etc/rc.d/bgpd

@@ -1,6 +1,6 @@
 #!/bin/ksh
 #
-# $OpenBSD: bgpd,v 1.4 2018/01/11 19:52:12 rpe Exp $
+# $OpenBSD: bgpd,v 1.5 2019/01/21 01:41:16 claudio Exp $
 
 daemon="/usr/sbin/bgpd"
 
@@ -8,7 +8,8 @@ daemon="/usr/sbin/bgpd"
 
 # child will not return a config parsing error to the parent
 rc_pre() {
-	${daemon} -n ${daemon_flags}
+	# use rcexec here since daemon_flags may contain arguments with spaces
+	${rcexec} "${daemon} -n ${daemon_flags}"
 }
 
 rc_cmd $1

src/etc/rc.d/httpd

@@ -1,6 +1,6 @@
 #!/bin/ksh
 #
-# $OpenBSD: httpd,v 1.6 2018/01/11 19:52:12 rpe Exp $
+# $OpenBSD: httpd,v 1.7 2019/01/21 01:41:16 claudio Exp $
 
 daemon="/usr/sbin/httpd"
 
@@ -8,7 +8,8 @@ daemon="/usr/sbin/httpd"
 
 # child will not return a config parsing error to the parent
 rc_pre() {
-	${daemon} -n ${daemon_flags}
+	# use rcexec here since daemon_flags may contain arguments with spaces
+	${rcexec} "${daemon} -n ${daemon_flags}"
 }
 
 rc_cmd $1

src/etc/rc.d/iked

@@ -1,6 +1,6 @@
 #!/bin/ksh
 #
-# $OpenBSD: iked,v 1.6 2018/01/11 22:44:44 rpe Exp $
+# $OpenBSD: iked,v 1.7 2019/01/21 01:41:16 claudio Exp $
 
 daemon="/sbin/iked"
 
@@ -13,7 +13,8 @@ rc_pre() {
 	[[ ${sasyncd_flags} != NO ]] &&
 		daemon_flags="-S ${daemon_flags}"
 
-	${daemon} -n ${daemon_flags}
+	# use rcexec here since daemon_flags may contain arguments with spaces
+	${rcexec} "${daemon} -n ${daemon_flags}"
 }
 
 rc_cmd $1

src/etc/rc.d/relayd

@@ -1,6 +1,6 @@
 #!/bin/ksh
 #
-# $OpenBSD: relayd,v 1.5 2018/01/11 22:44:44 rpe Exp $
+# $OpenBSD: relayd,v 1.6 2019/01/21 01:41:16 claudio Exp $
 
 daemon="/usr/sbin/relayd"
 
@@ -8,7 +8,8 @@ daemon="/usr/sbin/relayd"
 
 # Child will not return a config parsing error to the parent.
 rc_pre() {
-	${daemon} -n ${daemon_flags}
+	# use rcexec here since daemon_flags may contain arguments with spaces
+	${rcexec} "${daemon} -n ${daemon_flags}"
 }
 
 rc_cmd $1

src/etc/rc.d/switchd

@@ -1,6 +1,6 @@
 #!/bin/ksh
 #
-# $OpenBSD: switchd,v 1.3 2018/01/11 22:44:44 rpe Exp $
+# $OpenBSD: switchd,v 1.4 2019/01/21 01:41:16 claudio Exp $
 
 daemon="/usr/sbin/switchd"
 
@@ -8,7 +8,8 @@ daemon="/usr/sbin/switchd"
 
 # Child will not return a config loading error to the parent.
 rc_pre() {
-	${daemon} -n ${daemon_flags}
+	# use rcexec here since daemon_flags may contain arguments with spaces
+	${rcexec} "${daemon} -n ${daemon_flags}"
 }
 
 rc_cmd $1

src/etc/rc.d/vmd

@@ -1,6 +1,6 @@
 #!/bin/ksh
 #
-# $OpenBSD: vmd,v 1.9 2018/09/27 17:15:36 reyk Exp $
+# $OpenBSD: vmd,v 1.10 2019/01/21 01:41:16 claudio Exp $
 
 daemon="/usr/sbin/vmd"
 
@@ -8,7 +8,8 @@ daemon="/usr/sbin/vmd"
 
 # Child will not return a config parsing error to the parent.
 rc_pre() {
-	${daemon} -n ${daemon_flags}
+	# use rcexec here since daemon_flags may contain arguments with spaces
+	${rcexec} "${daemon} -n ${daemon_flags}"
 }
 
 rc_stop() {