diff --git a/ctdb/config/events/legacy/11.routing.script b/ctdb/config/events/legacy/11.routing.script
index 018ee5732a6..3a526e1ed47 100755
--- a/ctdb/config/events/legacy/11.routing.script
+++ b/ctdb/config/events/legacy/11.routing.script
@@ -39,7 +39,7 @@ updateip)
 	oiface=$2
 	niface=$3
 	while read iface dest gw; do
-	    if [ "$niface" = "$iface" -o "$oiface" = "$iface" ] ; then
+	    if [ "$niface" = "$iface" ] || [ "$oiface" = "$iface" ] ; then
 		ip route add "$dest" via "$gw" dev "$iface" >/dev/null 2>&1
 	    fi
 	done <"${CTDB_BASE}/static-routes"
diff --git a/ctdb/config/events/legacy/13.per_ip_routing.script b/ctdb/config/events/legacy/13.per_ip_routing.script
index 269829483ab..ed5677327a1 100755
--- a/ctdb/config/events/legacy/13.per_ip_routing.script
+++ b/ctdb/config/events/legacy/13.per_ip_routing.script
@@ -20,8 +20,8 @@ table_id_prefix="ctdb."
 [ "$CTDB_PER_IP_ROUTING_TABLE_ID_LOW" -lt "$CTDB_PER_IP_ROUTING_TABLE_ID_HIGH" ] 2>/dev/null || \
     die "error: CTDB_PER_IP_ROUTING_TABLE_ID_LOW[$CTDB_PER_IP_ROUTING_TABLE_ID_LOW] and/or CTDB_PER_IP_ROUTING_TABLE_ID_HIGH[$CTDB_PER_IP_ROUTING_TABLE_ID_HIGH] improperly configured"
 
-if [ "$CTDB_PER_IP_ROUTING_TABLE_ID_LOW" -le 253 -a \
-    255 -le "$CTDB_PER_IP_ROUTING_TABLE_ID_HIGH" ] ; then
+if [ "$CTDB_PER_IP_ROUTING_TABLE_ID_LOW" -le 253 ] &&  \
+	   [ 255 -le "$CTDB_PER_IP_ROUTING_TABLE_ID_HIGH" ] ; then
     die "error: range CTDB_PER_IP_ROUTING_TABLE_ID_LOW[$CTDB_PER_IP_ROUTING_TABLE_ID_LOW]..CTDB_PER_IP_ROUTING_TABLE_ID_HIGH[$CTDB_PER_IP_ROUTING_TABLE_ID_HIGH] must not include 253-255"
 fi
 
@@ -49,7 +49,7 @@ ipv4_is_valid_addr()
     for _o in $(export IFS="." ; echo $_ip) ; do
 	# The 2>/dev/null stops output from failures where an "octet"
 	# is not numeric.  The test will still fail.
-	if ! [ 0 -le $_o -a $_o -le 255 ] 2>/dev/null ; then
+	if ! [ 0 -le $_o ] && [ $_o -le 255 ] 2>/dev/null ; then
 	    return 1
 	fi
 	_count=$((_count + 1))
@@ -149,8 +149,9 @@ ensure_table_id_for_ip ()
 	    fi
 	    # Potentially update the new table id to be used.  The
 	    # redirect stops error spam for a non-numeric value.
-	    if [ "$_new" -le "$_t" -a \
-		"$_t" -le "$CTDB_PER_IP_ROUTING_TABLE_ID_HIGH" ] 2>/dev/null ; then
+	    if [ "$_new" -le "$_t" ] && \
+		       [ "$_t" -le "$CTDB_PER_IP_ROUTING_TABLE_ID_HIGH" ] \
+			       2>/dev/null ; then
 		_new=$((_t + 1))
 	    fi
 	done <"$rt_tables"
@@ -317,8 +318,8 @@ add_missing_routes ()
 	    [ -n "$_iface" ] || continue
 
 	    _table_id="${table_id_prefix}${_ip}"
-	    if [ -z "$(ip route show table "$_table_id" 2>/dev/null)" -o \
-		"$1" = "force" ]  ; then
+	    if [ -z "$(ip route show table "$_table_id" 2>/dev/null)" ] || \
+		       [ "$1" = "force" ]  ; then
 		add_routing_for_ip "$_iface" "$_ip"
 	    fi
 	done
diff --git a/ctdb/config/events/legacy/60.nfs.script b/ctdb/config/events/legacy/60.nfs.script
index 2eb90b421c8..1b87b3d27e3 100755
--- a/ctdb/config/events/legacy/60.nfs.script
+++ b/ctdb/config/events/legacy/60.nfs.script
@@ -139,7 +139,7 @@ nfs_check_service ()
 	fi
 
 	if $_ok ; then
-	    if [ $unhealthy_after -ne 1 -o $restart_every -ne 0 ] ; then
+	    if [ $unhealthy_after -ne 1 ] || [ $restart_every -ne 0 ] ; then
 		ctdb_counter_init "$_progname"
 	    fi
 	    exit 0
@@ -179,7 +179,7 @@ nfs_check_service ()
 # shellcheck disable=SC2031
 nfs_restart_service ()
 {
-    if [ -z "$service_stop_cmd" -o -z "$service_start_cmd" ] ; then
+    if [ -z "$service_stop_cmd" ] || [ -z "$service_start_cmd" ] ; then
 	die "ERROR: Can not restart service \"${_progname}\" without corresponding service_start_cmd/service_stop_cmd settings"
     fi
 
diff --git a/ctdb/tests/shellcheck/scripts/local.sh b/ctdb/tests/shellcheck/scripts/local.sh
index ab92aaa5575..84019144009 100644
--- a/ctdb/tests/shellcheck/scripts/local.sh
+++ b/ctdb/tests/shellcheck/scripts/local.sh
@@ -28,14 +28,7 @@ shellcheck_test ()
 		# SC2164: Use cd ... || exit in case cd fails.
 		#         - Most hits are on known directories.  Too
 		#           much churn, maybe later.
-		# SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not
-		#         well defined.
-		# SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not
-		#         well defined.
-		#         - This can cause issues but the number of
-		#           true positives will be very low.  Too much
-		#           churn, maybe later.
-		_excludes="SC1090,SC1091,SC2162,SC2164,SC2166"
+		_excludes="SC1090,SC1091,SC2162,SC2164"
 		unit_test shellcheck --exclude="$_excludes" "$@"
 	else
 		echo "WARNING: shellcheck not installed, skipping test"
diff --git a/ctdb/tools/ctdb_diagnostics b/ctdb/tools/ctdb_diagnostics
index ccaf85963cb..f86d14d389e 100755
--- a/ctdb/tools/ctdb_diagnostics
+++ b/ctdb/tools/ctdb_diagnostics
@@ -217,7 +217,7 @@ t=$(date +%s)
 for i in $nodes; do
     t2=$(onnode "$i" date +%s)
     d=$((t2 - t))
-    if [ "$d" -gt 30 -o "$d" -lt -30 ]; then
+    if [ "$d" -gt 30 ] || [ "$d" -lt -30 ]; then
 	error "time on node $i differs by $d seconds"
     fi
 done
diff --git a/ctdb/tools/onnode b/ctdb/tools/onnode
index d6595fff4aa..35c46c3c779 100755
--- a/ctdb/tools/onnode
+++ b/ctdb/tools/onnode
@@ -106,7 +106,7 @@ echo_nth ()
 	    node="$1"
     fi
 
-    if [ -n "$node" -a "$node" != "#DEAD" ] ; then
+    if [ -n "$node" ] && [ "$node" != "#DEAD" ] ; then
 	echo "$node"
     else
 	echo "${prog}: \"node ${n}\" does not exist" >&2
@@ -213,7 +213,7 @@ get_nodes ()
 	local f="${CTDB_BASE}/nodes"
 	if [ -n "$ctdb_nodes_file" ] ; then
 		f="$ctdb_nodes_file"
-		if [ ! -e "$f" -a "${f#/}" = "$f" ] ; then
+		if [ ! -e "$f" ] && [ "${f#/}" = "$f" ] ; then
 			# $f is relative, try in $CTDB_BASE
 			f="${CTDB_BASE}/${f}"
 		fi