I want to find a way to synchronize the default application preferences for Ubuntu between multiple installations. For example, if I choose Geany as the default text editor for .js files, I want it to become the default text editor for all of my Ubuntu installations. Is there any software that makes this possible, or software libraries that I could use to implement such a feature?
I don't know about any automated way but you can always go ahead and copy the
mimeapps.list
file located at~/.local/share/applications
between your installations. That way all your custom file type associations should be transferred safely.