I’ve deployed a Centos server and wanted to make sure I was going out through the correct IP address. With a windows machine I would just use something like www.whatismyip.com. However, with only the CLI this isnt possible. Having a POP3 server external to this device I just popped the mail server to get the IP address from the logs.
An alternative is to use wget:
wget -q -O – checkip.dyndns.org
The output will show something like this:
<html><head><title>Current IP Check</title></head><body>Current IP Address: XXX.XXX.XXX.XXX</body></html>
You can use (eg) sed to trim the output but this was good enough for my purposes