[net-next,09/12] selftests: netfilter: conntrack_ipip_mtu.sh: shellcheck cleanups

diff --git a/tools/testing/selftests/net/netfilter/conntrack_ipip_mtu.sh b/tools/testing/selftests/net/netfilter/conntrack_ipip_mtu.sh
index ac0dff0f80d7..9832a5d0198a 100755
--- a/tools/testing/selftests/net/netfilter/conntrack_ipip_mtu.sh
+++ b/tools/testing/selftests/net/netfilter/conntrack_ipip_mtu.sh
@@ -31,7 +31,7 @@  setup_ns r_a r_b r_w c_a c_b
 
 cleanup() {
 	cleanup_all_ns
-	rm -f ${rx}
+	rm -f "$rx"
 }
 
 trap cleanup EXIT
@@ -46,20 +46,20 @@  listener_ready()
 test_path() {
 	msg="$1"
 
-	ip netns exec ${c_b} socat -t 3 - udp4-listen:5000,reuseaddr > ${rx} < /dev/null &
+	ip netns exec "$c_b" socat -t 3 - udp4-listen:5000,reuseaddr > "$rx" < /dev/null &
 
 	busywait $BUSYWAIT_TIMEOUT listener_ready "$c_b" 5000
 
 	for i in 1 2 3; do
 		head -c1400 /dev/zero | tr "\000" "a" | \
-			ip netns exec ${c_a} socat -t 1 -u STDIN UDP:192.168.20.2:5000
+			ip netns exec "$c_a" socat -t 1 -u STDIN UDP:192.168.20.2:5000
 	done
 
 	wait
 
-	bytes=$(wc -c < ${rx})
+	bytes=$(wc -c < "$rx")
 
-	if [ $bytes -eq 1400 ];then
+	if [ "$bytes" -eq 1400 ];then
 		echo "OK: PMTU $msg connection tracking"
 	else
 		echo "FAIL: PMTU $msg connection tracking: got $bytes, expected 1400"
@@ -78,24 +78,24 @@  test_path() {
 # 10.4.4.1 via 10.2.2.254      (Router B via Wanrouter)
 # No iptables rules at all.
 
-ip link add veth0 netns ${r_a} type veth peer name veth0 netns ${r_w}
-ip link add veth1 netns ${r_a} type veth peer name veth0 netns ${c_a}
+ip link add veth0 netns "$r_a" type veth peer name veth0 netns "$r_w"
+ip link add veth1 netns "$r_a" type veth peer name veth0 netns "$c_a"
 
 l_addr="10.2.2.1"
 r_addr="10.4.4.1"
-ip netns exec ${r_a} ip link add ipip0 type ipip local ${l_addr} remote ${r_addr} mode ipip || exit $ksft_skip
+ip netns exec "$r_a" ip link add ipip0 type ipip local "$l_addr" remote "$r_addr" mode ipip || exit $ksft_skip
 
 for dev in lo veth0 veth1 ipip0; do
-    ip -net ${r_a} link set $dev up
+    ip -net "$r_a" link set "$dev" up
 done
 
-ip -net ${r_a} addr add 10.2.2.1/24 dev veth0
-ip -net ${r_a} addr add 192.168.10.1/24 dev veth1
+ip -net "$r_a" addr add 10.2.2.1/24 dev veth0
+ip -net "$r_a" addr add 192.168.10.1/24 dev veth1
 
-ip -net ${r_a} route add 192.168.20.0/24 dev ipip0
-ip -net ${r_a} route add 10.4.4.0/24 via 10.2.2.254
+ip -net "$r_a" route add 192.168.20.0/24 dev ipip0
+ip -net "$r_a" route add 10.4.4.0/24 via 10.2.2.254
 
-ip netns exec ${r_a} sysctl -q net.ipv4.conf.all.forwarding=1 > /dev/null
+ip netns exec "$r_a" sysctl -q net.ipv4.conf.all.forwarding=1 > /dev/null
 
 # Detailed setup for Router B
 # ---------------------------
@@ -108,46 +108,46 @@  ip netns exec ${r_a} sysctl -q net.ipv4.conf.all.forwarding=1 > /dev/null
 # 10.2.2.1 via 10.4.4.254      (Router A via Wanrouter)
 # No iptables rules at all.
 
-ip link add veth0 netns ${r_b} type veth peer name veth1 netns ${r_w}
-ip link add veth1 netns ${r_b} type veth peer name veth0 netns ${c_b}
+ip link add veth0 netns "$r_b" type veth peer name veth1 netns "$r_w"
+ip link add veth1 netns "$r_b" type veth peer name veth0 netns "$c_b"
 
 l_addr="10.4.4.1"
 r_addr="10.2.2.1"
 
-ip netns exec ${r_b} ip link add ipip0 type ipip local ${l_addr} remote ${r_addr} mode ipip || exit $ksft_skip
+ip netns exec "$r_b" ip link add ipip0 type ipip local "${l_addr}" remote "${r_addr}" mode ipip || exit $ksft_skip
 
 for dev in veth0 veth1 ipip0; do
-	ip -net ${r_b} link set $dev up
+	ip -net "$r_b" link set $dev up
 done
 
-ip -net ${r_b} addr add 10.4.4.1/24 dev veth0
-ip -net ${r_b} addr add 192.168.20.1/24 dev veth1
+ip -net "$r_b" addr add 10.4.4.1/24 dev veth0
+ip -net "$r_b" addr add 192.168.20.1/24 dev veth1
 
-ip -net ${r_b} route add 192.168.10.0/24 dev ipip0
-ip -net ${r_b} route add 10.2.2.0/24 via 10.4.4.254
-ip netns exec ${r_b} sysctl -q net.ipv4.conf.all.forwarding=1 > /dev/null
+ip -net "$r_b" route add 192.168.10.0/24 dev ipip0
+ip -net "$r_b" route add 10.2.2.0/24 via 10.4.4.254
+ip netns exec "$r_b" sysctl -q net.ipv4.conf.all.forwarding=1 > /dev/null
 
 # Client A
-ip -net ${c_a} addr add 192.168.10.2/24 dev veth0
-ip -net ${c_a} link set dev veth0 up
-ip -net ${c_a} route add default via 192.168.10.1
+ip -net "$c_a" addr add 192.168.10.2/24 dev veth0
+ip -net "$c_a" link set dev veth0 up
+ip -net "$c_a" route add default via 192.168.10.1
 
 # Client A
-ip -net ${c_b} addr add 192.168.20.2/24 dev veth0
-ip -net ${c_b} link set dev veth0 up
-ip -net ${c_b} route add default via 192.168.20.1
+ip -net "$c_b" addr add 192.168.20.2/24 dev veth0
+ip -net "$c_b" link set dev veth0 up
+ip -net "$c_b" route add default via 192.168.20.1
 
 # Wan
-ip -net ${r_w} addr add 10.2.2.254/24 dev veth0
-ip -net ${r_w} addr add 10.4.4.254/24 dev veth1
+ip -net "$r_w" addr add 10.2.2.254/24 dev veth0
+ip -net "$r_w" addr add 10.4.4.254/24 dev veth1
 
-ip -net ${r_w} link set dev veth0 up mtu 1400
-ip -net ${r_w} link set dev veth1 up mtu 1400
+ip -net "$r_w" link set dev veth0 up mtu 1400
+ip -net "$r_w" link set dev veth1 up mtu 1400
 
-ip -net ${r_a} link set dev veth0 mtu 1400
-ip -net ${r_b} link set dev veth0 mtu 1400
+ip -net "$r_a" link set dev veth0 mtu 1400
+ip -net "$r_b" link set dev veth0 mtu 1400
 
-ip netns exec ${r_w} sysctl -q net.ipv4.conf.all.forwarding=1 > /dev/null
+ip netns exec "$r_w" sysctl -q net.ipv4.conf.all.forwarding=1 > /dev/null
 
 # Path MTU discovery
 # ------------------
@@ -187,5 +187,5 @@  test_path "without"
 #packet is too big (1400) for the tunnel PMTU (1380) to Router B, it is
 #dropped on Router A before sending.
 
-ip netns exec ${r_a} iptables -A FORWARD -m conntrack --ctstate NEW
+ip netns exec "$r_a" iptables -A FORWARD -m conntrack --ctstate NEW
 test_path "with"