only try to install prerequisites when missing, only offer node packages, if node installed

4-public-ip.sh

@@ -4,40 +4,40 @@
 # keep trying until we get a result
 
 # dig
-if [[ -n $(command -v "dig") ]]; then
+if [[ -n $(command -v 'dig') ]]; then
     # via opendns
-    address=$(dig "@resolver1.opendns.com" -4 "myip.opendns.com" "A" "+short")
-    if [[ "$?" -ne "0" ]]; then
+    address=$(dig '@resolver1.opendns.com' -4 'myip.opendns.com' A '+short')
+    if [[ "$?" -ne '0' ]]; then
         # dig was unsuccessful
-        echo "$address" 1>&2
-        address=""
+        echo "${address}" 1>&2
+        address=''
     fi
 fi
 
 # curl
-if [[ -z "$address" ]] && [[ -n $(command -v "curl") ]]; then
+if [[ -z "${address}" ]] && [[ -n $(command -v 'curl') ]]; then
     # via ipinfo.io
-    address=$(curl -4 --fail --silent --show-error "https://ipinfo.io/ip")
+    address=$(curl -4 --fail --silent --show-error 'https://ipinfo.io/ip')
 
-    if [[ -z "$address" ]]; then
+    if [[ -z "${address}" ]]; then
         # via google
-        address=$(curl -4 --fail --silent --show-error "https://domains.google.com/checkip")
+        address=$(curl -4 --fail --silent --show-error 'https://domains.google.com/checkip')
     fi
 fi
 
 # wget
-if [[ -z "$address" ]] && [[ -n $(command -v "wget") ]]; then
+if [[ -z "${address}" ]] && [[ -n $(command -v 'wget') ]]; then
     # via ipinfo.io
-    address=$(wget -4 --quiet --output-document - "https://ipinfo.io/ip")
+    address=$(wget -4 --quiet --output-document - 'https://ipinfo.io/ip')
 
-    if [[ -z "$address" ]]; then
+    if [[ -z "${address}" ]]; then
         # via google
-        address=$(wget -4 --quiet --output-document - "https://domains.google.com/checkip")
+        address=$(wget -4 --quiet --output-document - 'https://domains.google.com/checkip')
     fi
 fi
 
-if [[ -n "$address" ]]; then
-    echo "$address"
+if [[ -n "${address}" ]]; then
+    echo "${address}"
 else
     echo 'Tried everything, unable to resolve IP address.' 1>&2
 fi