Converting epubs to Plain-Text?

[Linux for blind general discussion]

We interrupt these Fedora discussions to bring you a separate subject.
I have several, maybe 18 ebooks in an epub format, from BookShare-and-Usenet. 
In looking around, an only tool I can find is "ebook-convert" part of a Calibre 
package to convert these. However, following cryptic instructions in its 
man-page, as well as what I see in duckduckgo, I am getting no where. Are their 
other better tools I need to grab in a Debian SID console? In addition, I 
really would like to convert all of these at once, in a batch. Thanks so much 
in advance for any-and-all guidance. We now resume our regularly scheduled 
programming
Chime