I installed bitcoin-qt (v 0.12.1) on Kubuntu 15.10. When starting it the first time the GUI asked me for the datadir. I set it to an external disk.

Where are this settings stored? There is no bitcoin.conf file in my /home/<user>/.bitcoin/ directory.

I know, that I can manually create the bitcoin.conf file. But I'm just curious, where the settings are stored, if no such file is present?