There are a number of ways to figure out your public IP address automatically, which can be extremely useful for Dynamic DNS (DDNS) situations or other automation ventures, these are some of them:
dig +short @resolver1.opendns.com ANY myip.opendns.com
curl https://ifconfig.co
curl http://whatismyip.akamai.com/
It would be nice if the Cloudflare DNS service (1.1.1.1) supported this too!