Tex4ebook tidy command missing

Question

I'm converting a Latex document with Tex4ebook (built on tex4ht) and I get the following warning: exec_epub: tidy command seems missing, you should install it in order to make a valid epub file. But where do I install it and what does it do?

Thanks in advance.

Answer 1

tex4ebook uses HTML Tidy for clean-up of the generated XML files that can contain some issues resulting from the conversion process. If tex4ebook cannot find Tidy, it will use regular expressions for the clean-up. It is usually enough for production of the valid Epub file, so you don't really need to worry about the warning, as long as the generated file is valid.