Source: How can I get my external IP address in a shell script?
A safer and more reliable way than using curl to get your public IP is to use dig as below:
# OpenDNS:
dig @resolver1.opendns.com ANY myip.opendns.com +short
# Google:
dig @ns1.google.com TXT o-o.myaddr.l.google.com +short
# Akamai:
dig @ns1-1.akamaitech.net ANY whoami.akamai.net +short
Just make sure dnsutils is installed if dig isn’t installed.