afraiddns.sh

#!/usr/bin/env bash

set -e

# Updates the freedns.afraid.org DNS record for a domain, if the domain's
# resolved IP does not match the external IP of the machine running this program.
usage() {
    echo "usage: afraiddns.sh <domain>"
    exit 1
}

DOMAIN=$1
[ -z $DOMAIN ] && usage

EXISTING=$(nslookup $DOMAIN | grep "Address" | tail -n 1 | sed 's/[^0-9.]//g')
NEW=$(dig +short myip.opendns.com @resolver1.opendns.com)
[ $NEW != $EXISTING ] && curl "http://freedns.afraid.org/dynamic/update.php?"$AFRAID_DNS_API_KEY
echo date=$(date) existing=$EXISTING new=$NEW