Is there any way to convert odt documents to doc or rtf on linux without openoffice or any library that relies on having openoffice installed ?
OpenOffice.org and its derivatives (LibreOffice, Symphony, etc) currently have one of the best converters between ODF and the Microsoft formats (besides the ODF support built into MS Office).
If those converters are not an option for you, you can choose between some alternatives: Foremost you might want to check out the KOffice project which also offers command line tools for file conversion:
Then there is another open source project with a free BSD license available on SourceForge:
This project offers not only add-ins for Microsoft Office, but also a stand-alone command line version which also runs on Linux.
Then there would also be a different approach: You can automate Google Docs using command line tools:
Google Docs file conversion have internally been based on the OpenOffice.org file filters, but as far as I know they have been replaced by Aspose, a library for document formats.
Aspose is available in several versions, and as you have a Linux dependency you might want to check out their Java version.
The library has its price, but you won't find another library that is not a full office suite with that quality.