dig +short myip.opendns.com @resolver1.opendns.com
or
dig TXT +short o-o.myaddr.l.google.com @ns1.google.com
Windows
nslookup myip.opendns.com. resolver1.opendns.com
dig +short myip.opendns.com @resolver1.opendns.com
or
dig TXT +short o-o.myaddr.l.google.com @ns1.google.com
Windows
nslookup myip.opendns.com. resolver1.opendns.com