script

#!/bin/bash

CUR_DATE=$(date "+%y-%m-%d %H:%M:%S")

n=0
y=0

USERNAME="1"
PASSWORD="2"
DOMAIN="kathy.tk"

IP_WAN=$(dig +short myip.opendns.com @resolver1.opendns.com)
IP_DNS=$(dig "$DOMAIN" | grep IN | awk '{match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/); ip = substr($0,RSTART,RLENGTH); print ip}')

LOG="/var/log/DNS_update.log"
TMP="/tmp/DNS_update.tmp"

THE_COMMAND=$(curl -s http://"$USERNAME":"$PASSWORD"@freedns.afraid.org/nic/update?hostname="$DOMAIN"&myip="$IP_WAN")

MAKE_FILE() {

FILE="$1"

    if
        [[ ! -f "$FILE" ]]; then
        touch "$FILE"
        echo "$CUR_DATE - Created $FILE" >> "$LOG"
    fi
}

CLEANUP_GOOD() {

    rm "$TMP"
    echo "$CUR_DATE - WAN update SUCCESS" >> "$LOG"
}

CLEANUP_BAD() {

    rm "$TMP"
    echo "$CUR_DATE - WAN update FAILED: Maximum loops allowed reached" >> "$LOG"
}

THE_LOOP() {

MAKE_FILE "$LOG"
MAKE_FILE "$TMP"

    until [[ "$y" -eq 10 ]] || [[ "$n" -eq 1 ]]; do

        if
            "$THE_COMMAND"; then
            echo "$CUR_DATE - Running script" >> "$LOG"
        else
            echo "$CUR_DATE - Script was not run: $THE_COMMAND failed" >> "$LOG"
        fi

        if
            [[ "$IP_WAN" == "$IP_DNS" ]]; then
            echo "$CUR_DATE - $IP_WAN matches $IP_DNS" >> "$LOG"
            let n++
            trap CLEANUP_GOOD exit 0
        else
            echo "$CUR_DATE - IP addresses do not match. Retrying.." >> "$LOG"
            let y++
            sleep 60
        fi

    done

if
    [[ "$y" -eq 10 ]]; then
        trap CLEANUP_BAD exit 0
fi
}

THE_LOOP