There are a few terminal emulators around, but one of the best is this free one: https:// market.android.com/details?id=jackpal. androidterm&feature=search_result. Once installed, typing ‘su’ will then grant the app root privileges and allow you to change all the interesting files in the root directory.
To navigate around your cell phone within the terminal, type ‘ls’; this will show you all the files in the directory. To enter the root directory, type ‘cd root’. For more information on terminal commands, head to http://ss64.com/bash/.-
This How to Hack a Cell Phone article taken from :
Android Tips, Tricks, Apps & Hacks 2