add

check-open.sh

@@ -0,0 +1,15 @@
+function EPHEMERAL_PORT() {
+    LOW_BOUND=49152
+    RANGE=16384
+    while true; do
+        CANDIDATE=$[$LOW_BOUND + ($RANDOM % $RANGE)]
+        (echo "" >/dev/tcp/127.0.0.1/${CANDIDATE}) >/dev/null 2>&1
+        if [ $? -ne 0 ]; then
+            echo $CANDIDATE
+            break
+        fi
+    done
+}
+
+port=$(EPHEMERAL_PORT)
+echo $port