Current Darktable version on my machine is 2.3.0+805~g1e1cf11. It’s fine. As a backup I want extract and save my custom presets - basecurves for my cameras, custom lens profiles, + a thing or two. Maybe I’d like to have clean installation of Darktable and then import certain presets or even share them with a friend. Is there a way to save certain presets without copying entire database?
Do these instructions still work entirely? Which entries should I run then?
Those instructions won’t work any more. Presets, styles and tags are now in their own database data.db.
Thank you, glad to hear straight from DT devs. Is this file version independent? how do I make sure that my presets that were formerly stored in library.db are now in data.db ?
It contains a version number and will be compatible with future dt releases. Opening it with an older release won’t be possible (in general). Just like the library.db.
how do I make sure that my presets that were formerly stored in library.db are now in data.db ?
The first time darktable sees a library.db with the old format that still included presets, … it will first check if there is a data.db already. If it’s missing it will be created. Then the relevant parts of the library will be copied over to data.db.
If there are clashes, for example two styles with the same name but different settings, the new one will be renamed.
Afterwards the library.db will be updated to its new version and the data now in data.db will be removed.
You will no longer be able to use that library.db with older versions of dt. But that was the case for every database format update in the past years. We are currently at version 15 for library.db and version 1 for data.db. Chances are you never noticed any of the past updates, so this one should be smooth, too. 
The big benefit of this system is that you can
:memory:) and still have access to styles, presets and tags. This is especially useful when using darktable as an editor from some external application like GIMP or digikam.Can’t agree with you more on the benefits of such approach. Thank you very much @houz, I will plan installing DT updates accordingly!