If you want to know what your IP address is while on your Android phone, and you have terminal, then you might try as I did tonight. I opened up a terminal application and tried:
Nothing again! Searching I found that I needed to specify the name of the network interface, or else it would not work. I also discovered that I could find all the names of interfaces by doing:
So, for most phones the name to use from this list is eth0. To find out my IP address on my phone, I finally ran in my terminal application:
I even tried this without root access, and it works!