get local IP for substitution

setup.sh

@@ -30,6 +30,28 @@ echo "pressing ENTER (i.e. no answer)."
 echo -e "You may exit this script at any prompt by typing 'X'${norm}\n"
 
 
-
+### get local IP address
+while true; do
+    read -p "What is this NGINX machine's primary local IP4 address? (${detectedIP}) " inputIP
+    case "${inputIP}" in
+        '')
+            IP4="${detectedIP}"
+            break
+            ;;
+        [Xx]*)
+            echo -e "\n${cyan}---exiting---\n${norm}"
+            exit 1
+            ;;
+        *)
+            # check IP for validity
+            if [[ "${inputIP}" =~ ^${regexIP4}$ ]]; then
+                IP4="${inputIP}"
+                break
+            else
+                echo -e "\n${err}Invalid IP4 format (xxx.xxx.xxx.xxx)${norm}"
+            fi
+            ;;
+    esac
+done
 
 exit 0