Lightweight PDF to mobi and epub converter for Ubuntu

By lightweight I mean NOT Calibre. Please. I do not need a cataloging/library management software- which would not only consume unnecessary disk space but also ignore my current cataloging which I have maintained for years. I just need a quick and dirty batch convert to epub or mobi without having to deal with the myriad issues of using calibre. **Are there any simple PDF epub and PDFmobi conversion tools for Ubuntu?** There seems to be several for Windows based machines but strictly only calibre for Ubuntu.