Don't protect savecore(8) from being run with a bad dumpdir

argument. Don't fail silently, but let savecore(8) make noise. It
won't behave badly, it doesn't need protection.

At the same time, allow the administrator to have dumpdev enabled
while dumpdir (savecore(8)) is disabled and document how to do it.

PR:		conf/35725

2 files changed, 15 insertions, 3 deletions

diff --git a/etc/rc b/etc/rc
index 345959b..40a26d8 100644
--- a/etc/rc
+++ b/etc/rc
@@ -552,12 +552,17 @@ case ${dumpdev} in
 	'')
 		dumpdir='/var/crash'
 		;;
+	[Nn][Oo])
+		dumpdir='NO'
+		;;
 	esac
 
-	if [ -e "${dumpdev}" -a -d "${dumpdir}" ]; then
+	if [ -e "${dumpdev}" ]; then
 		/sbin/dumpon -v ${dumpdev}
-		echo -n 'Checking for core dump: '
-		/sbin/savecore ${savecore_flags} "${dumpdir}"
+		if [ "$dumpdir" != 'NO' ]; then
+			echo -n 'Checking for core dump: '
+			/sbin/savecore ${savecore_flags} "${dumpdir}"
+		fi
 	fi
 	;;
 esac
diff --git a/share/man/man5/rc.conf.5 b/share/man/man5/rc.conf.5
index 91d7c41..4b463d3 100644
--- a/share/man/man5/rc.conf.5
+++ b/share/man/man5/rc.conf.5
@@ -1727,6 +1727,13 @@ specified by the
 variable.
 The default value is
 .Dq /var/crash .
+Set to
+.Dq NO
+to not run
+.Xr savecore 8
+at boot time when
+.Va dumpdir
+is set.
 .It Va enable_quotas
 .Pq Vt bool
 Set to