Track your public IP and cache the updated IP locally

updateIP.sh

#/bin/bash

# https://theawesomegarage.com/blog/godaddy-terminated-my-free-dns-management-api-now-what

# This script is used to check the current IP-address, and update a cache file if needed
# The cache file is used by other scripts to check if their IP needs to be updated
# The reason for using a current IP-cache, is to reduce load on calling ipinfo.io
# which has a rate limit of 50.000 calls a month. With 5 domains, checking every 5
# minutes, that is almost 50.000 calls. With a common check, we reduce the number to

# Define the cache file
CACHE_FILE="/tmp/.myPublicIP"

# Make the API call and get the response and HTTP status code
response=$(curl -s -w "%{http_code}" http://ipinfo.io/json)
http_code=$(echo "$response" | tail -c 4)
new_ip=$(echo $response | grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b")

# Check if the HTTP status code is 200 (OK)
if [ "$http_code" -eq 200 ]; then
    # Check if the cache file exists
    if [ -f "$CACHE_FILE" ]; then
        # Read the old IP from the cache file
        old_ip=$(cat "$CACHE_FILE")
    else
        old_ip=""
    fi

    # Compare the old IP with the new IP
    if [ "$new_ip" != "$old_ip" ]; then
        # Update the cache file with the new IP
        echo "$new_ip" > "$CACHE_FILE"
        [ -e $CACHE_FILE ] && currentIP=`cat $CACHE_FILE`
        echo "New IP: $currentIP"
    fi
else
    echo "Error getting IP. HTTP Status Code: $http_code"
fi