Ok, finally got this thing to work. All the installation craziness and bash/dash was in vain. Here is my recipe for ANSYS APDL in Ubuntu:
The installation will hang at the installation of arcnode at ca. 92 % completion. Simply close the installation window, ANSYS is now installed.
Now you need to change the ownership of the following folders:
sudo chown -R $USER:$USER ~/.ansys
sudo chown -R $USER:$USER ~/.config/Ansys
As I want "only" ANSYS APDL, this can be tested then with starting the ANSYS Launcher from folder belonging to the user:
(Replace $USER with your Linux user name.)
I could not figure out what was causing the arcnode to hang during the installation. As I will not be using this (and chose not to install this...), I also do not care.