[bigfishrunning]

To be fair, desktop linux doesn't really have built-in anything (except what's appropriate for a kernel, like filesystems and a TCP stack...). Many linux distributions package epub readers (calibre, okular, fbreader, bookworm), and they tend to be really easy to install.

[carlosjobim]

If it has built in a text editor, image viewer, web browser, then ebook reader should be next in the list. I assume even non-graphic Linux distros have the aforementioned built in.

Linux with only kernel, filesystem and TCP stack isn't really what I would call "desktop Linux". I don't know what I'd call it.

Also, Bookworm looks like a lovely ebook reader!