Finding out your PC’s IP in Linux is a simple matter of typing ifconfig in a Terminal shell. But what if you’re behind a router? Thanks to a simple shell script, you can display your IP in the command line by simply invoking the whatismyip command.
sudo nano whatismyip
In the new file paste this:
curl -s myip.dk |grep ‘”Box”‘ | egrep -o ‘[0-9.]+’
Close and save the file then make it executable:
sudo chmod +x /usr/bin/whatismyip
Now every thime you type whatismyip the IP assigned to you by your ISP will be printed in the Terminal window.
Original idea here.