I have installed on my laptop Ubuntu 15.10. From the software center, I installed the Arduino IDE (arduino 2:1.0.5+dfsg2-4). I was working through the examples with my Uno clone. It all works great. Only time I have trouble is if the baud rate on the Serial Monitor is mismatched with the sketch, it freezes up.
My real trouble is trying to work with Digispark. From their instructions digispark:tutorials:connecting I am supposed to go to Files>Preferences and in the Additional boards manager URLs, enter http://digistump.com/package_digistump_index.json There is no Additional boards manager in the preferences window. Then in Tools>Board>Boards Manager... There is no Boards Manager, just the list of Arduino Boards.
It seems that there is either a new way of adding boards to the IDE or I need to install an older version. Either way, I'm not quite smart enough to figure out how to do either. Help me please!