Calibre has CLI as well, if the GUI is really offensive. On Artix, part of pacman -Ql calibre
:
calibre /usr/bin/calibre
calibre /usr/bin/calibre-complete
calibre /usr/bin/calibre-customize
calibre /usr/bin/calibre-debug
calibre /usr/bin/calibre-parallel
calibre /usr/bin/calibre-server
calibre /usr/bin/calibre-smtp
calibre /usr/bin/calibredb
calibre /usr/bin/ebook-convert
calibre /usr/bin/ebook-device
calibre /usr/bin/ebook-edit
calibre /usr/bin/ebook-meta
calibre /usr/bin/ebook-polish
calibre /usr/bin/ebook-viewer
calibre /usr/bin/fetch-ebook-metadata
calibre /usr/bin/lrf2lrs
calibre /usr/bin/lrfviewer
calibre /usr/bin/lrs2lrf
calibre /usr/bin/markdown-calibre
calibre /usr/bin/web2disk
calibre /usr/lib/
calibre /usr/lib/calibre/
calibre /usr/lib/calibre/calibre/
...
Although ebook-convert
shows on its man page as converting from one epub format to another, it can as well convert to pdf. I don't know if it's possible to convert from pdf to epub, but if the calibre GUI's does it, perhaps some of calibre's CLIs can do it as well.
Pandoc can also convert from epub to pdf, though my experience with pandoc as a very basic user is that the results, are not of the quality I'd expect, but again, that is without using special arguments, css, and stuff, perhaps advanced users can get the best out of pandoc...