Hi Friends,
Can anybody please send me the best links for reading online unix tutorials. I knew the unix little bit, but I don't know properly 
Regards,
Nag
Unix is a bit general - here are some general links to pdf files you might find useful:
Linux: The Linux Documentation Project: Guides
Oracle documentation, especially Solaris: Oracle Documentation
If it is for reading online, I guess you do not need pdfs as there are plenty of sites explaining things about Unix/Linux, like
http://www.linux-tutorial.info/modules.php?name=MContent&obj=topics
There should be also threads about this in the forums here. Please use the search function.