Programming

Generally shell/perl scripting knowledge is required for senior linux/unix administrator positions not software engineer.

Need for C/C++ is not that great nowadays and if there are positions, a great deal of experience is required with these languages (at least a couple of years of work experience with big C/C++ projects).

Its different situation with Objective-C, its need and usage is on a rise. If I'd have to learn a new interesting language I'd definitely start with Objective-C in your case, its also more .NET'ish than basic C/C++ since libstdc and libstdc++ cover very basic functionality and are mainly targeted to 'do it yourself' programmers while Objective-C comes packed with libraries that cover stuff from A to Z. Also Objective-C+Gnustep/cocoa is a direct competitor to C#+.NET to relation what they can do and how they do it.

If you are looking for bright future and stability, I'd recommend you sticking with what you can do best and improving on it, since .NET is not going away any time soon and finding a job that requires .NET skills is relatively easy.

Its quite difficult to get into this field. openings are less. but unix is used for maintenance jobs as well like server maintenance and all. But system programming is done mainly on linux. But as I told u openings are less and they ask for experience on this field. But it has a great future in india specially in abroad. But mind it one thing u must must have the interest to work on this field else its quite difficult to work here. First make ur mind set and come for it. Brush up all your operating system knowledge from Silverthz-Galvin book.