[CentOS] reading -- and editing -- ebooks

Last week I bought a couple books, not ebooks.  I considered buying the
ebook, but don't want to need a special device/appliance to read it.
I'd much prefer to read ebooks on the Linux (CentOS) machine I'm already
using.

Also, I'd like to be able to programmatically convert the ebook into a
format I can edit myself, e.g., HTML.

I have no experience owning or purchasing ebooks.  Could people who have
clue me in on how they work and if the above is possible.


Thanks much.


-- 
Without music, life would be a mistake.
	--Friedrich Nietzsche