Hiring process started with a phone asked all your details. Then in one week got a call for face-to-face. The interview is completely on C. Until they feel you are really good in C, then dont ask about other skills, like linux etc. Their main focus is on C.
There are many pdf's available online like "crack the interview" etc. Make sure you have prepared or recalled the thingsin C. They are very good that they will ask you to come for one more interview on C if they feel you are nervous and couldnt answer the questions. Company is good. Saw ppl going here and there with laptops and boards, discussing only about work while sitting there for the interview to start.