there are no plenty viruses presently on linux platform
Yes, and aiding people in creating linux viruses won't keep it that way.
(or we can say virus free OS)
Actually there are linux viruses, though they are usually rare. So no linux isn't really virus free.
is there any tool for generation of viruses like Bliss, Diesel, Gildo,Satyr...
Aiding people in the creation of viruses (no matter the platform) for potentially malicious purposes is against the rules of the site. Please refer to them if you're unsure of why that is:
http://www.linuxquestions.org/rules.php
Please email me if you have a legitimate reason for wanting these tools and I'll re-open this thread, but until that point it's closed.
Thanks,
-CC