dsyleixa:
after having updated Arduino 1.8.5. to 1.8.8 on my PC, I now have to do that also on my Raspi.
In /home/pi/ can find a folder
arduino-1.8.5
feat also a subfolder "portable",
but IIRC there are supposed to be 1 or 2 to additional Arduino program folders (I read something about that in another topic), but I can't see them though (show hidden files is activated in the filemanager).Which is the correct upgrade procedure to 1.8.8 on the Pi, not leaving any file orphans behind?
If you have never used the Arduino IDE without the "portable" subfolder present, then the only other folder used by the Arduino IDE is the sketchbook folder. You can find the location of that folder in the Arduino IDE at File > Preferences > Sketchbook location. If you have run the Arduino IDE without the "portable" folder, then there will also be a folder at /home/{username}/.arduino15. That is a hidden folder.