Question: I want to learn C , UNIX and LINUX, and more about embedded systems. Very much interested in them. Are there any online courses or websites which can guide me. And please suggest books to read in learning them.

Thanks for your time.

Ya please lets your answers and comments come in , they are invaluable to me..!!

Answer: 
There are many amazing resources online. My favorite is from MIT.

<http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/>

Free courses. They can be pretty in depth, and cover many more subjects than just computer science and mathematics.
Other than the resources suggested above, you need to understand why you need these languages. Programming language or an OS alone will only take you as far -- for e.g. if you are programming on embedded platforms usually memory is not in abundance. So you need to code for memory optimization. If you are working on real time, you would need to understand interrupt handling well etc. I'd suggest definitely spend time on the architecture (ARM Cortex-M1 etc) for which you are planning to code. Always helps.

For more quirks look into <http://en.wikibooks.org/wiki/Embedded_Systems/C_Programming>

Orielly's Programming Embedded Systems in C and C++ is a good place to start once you have the basics of C/C++ clear.