rc.d/ddb: Really silently exit

The comment says “silently exit if ddb is not enabled”, but we'd exit
with an error message.

Note that I switched the sysctl variable used to test for the presence
of ddb from debug.ddb.scripting.scripts to d.d.s.script, which has a
smaller value if set.

While here, drop a pointless fork-exec, and use ${SYSCTL_N} for
consistency.

PR:		177217
MFC after:	1 week
Reviewed by:	kevans
Differential Revision:	https://reviews.freebsd.org/D57686

1 files changed, 2 insertions, 2 deletions

diff --git a/libexec/rc/rc.d/ddb b/libexec/rc/rc.d/ddb
index 08a7d345c326..a30df2dc1c5e 100755
--- a/libexec/rc/rc.d/ddb
+++ b/libexec/rc/rc.d/ddb
@@ -20,8 +20,8 @@ stop_cmd=":"
 ddb_prestart()
 {
 	# Silently exit if ddb is not enabled
-	if [ -z "`sysctl -Nq debug.ddb.scripting.scripts`" ]; then
-		return 1
+	if ! ${SYSCTL_N} -q debug.ddb.scripting.script >/dev/null; then
+		exit 1
 	fi
 }