I'm running Kubuntu 12.04 and connecting it via USB to an LG P705 Android device. A short time ago the adb devices command listed it -- but something happened and now that command now gives only an empty list. Yet mtp-detect finds and lists the device correctly. What might have happened?
For adb you have to install android-tools package.
sudo apt-get update sudo apt-get install android-tools-adb
and if you wants the fastboot:
sudo apt-get install android-tools-fastboot