Hi, file -i *.epub returns 'application/x-not-regular-file' or 'application/zip' and it should return 'application/epub+zip' (at least this is on Fedora).
I was not able to hack source to make it return valid type but here is magic for epub: https://github.com/file/file/blob/master/magic/Magdir/archive#L866 An example epub is here (in Czech): https://knihy.nic.cz/files/nic/edice/pavel_satrapa_ipv6_2012.epub j.
