If you want to root your Motorola Droid Razr xt910, but can’t find proper Linux docs, here is a small howto. Do it on your own responsibility, you may brick your device!
This method should work on any Linux distribution, be it Ubuntu, Debian, Fedora and so on. My Razr was running Android 4.0.4 when I was rooting it.
The first thing you have to do, is to make sure you have adb command working, available from http://developer.android.com/sdk/index.html – we won’t cover adb installation in detail (it may well be available in your distribution repositories, i.e. via apt-get install adb)
Next one – connecting your phone via USB to your laptop or PC and enabling USB debugging mode in your phone: menu -> System settings -> Developer options -> USB debugging.
You will also need su, busybox and superuser app. For convenience, you can download them all from here (1.5 MB tar.bz archive):
The last step is running these commands (they are also included in the tar.bz2 archive, above). Note that you have to modify the PATH variable, if your adb binary is not in your standard path: