title_body: Is there a way to convert an ePub page flip direction to rtl automatically? In other words, can you update the spine tag with a script instead of converting to zip, opening, and replacing?
  Thanks.
upvoted_answer: Create an epub3 book or convert your existing epub2 book to an epub3 book and add a page-progression-direction="rtl" attribute to the &lt;spine&gt; tag in the content.opf file.
  
  You can convert epub2 books to epub3 books with Calibre. (Polish books ▶ Upgrade book internals.)