Linux preferences

[Sarah Reichelt]

Sorry, I feel I've asked this before, but I can't find the answer in
the archives.

Where do Linux users expect preferences to be saved?

In Macs I use the specialFolderPath("Preferences").
In Windows I use specialFolderPath(26).

What is the Linux equivalent? specialFolderPath doesn't seem to be a
function that works under Linux.

On a related topic, what is the path for the user's documents folder
in Linux and how do to find it? Or is it considered OK just to store
data in the application's folder (doesn't sound Linux-ish).

TIA,
Sarah