kasm, on Aug 15 2005, 06:04 AM, said:
Linux is operating system as dos unix and windows. It is not a language. So the question may be formulated as: how to install or how to use or which Linux system is available?

Erm, since this is the C/C++ programming section, it is presumed that the question is in regards to programming for *NIX using C/C++.
I've actually answered this question elsewhere (a thing about good programming books, with a description, estimated difficulty level, etc.). So, to answer your question here are two I would specifically recommend for programming in a *NIX environment. The second book is more specialised, but does involve a little more than just network programming. The first is an absolute MUST.
UNIX system programming : a programmer's guide to software development / 1999 / Keith Haviland, Dina Gray, Ben Salama. / Advanced+
This is a more complicated book, based in C, that starts with the basic system calls, fork(), exec(), etc, and moves onto more advanced topics such as IPC, network calls, shared memory, and a whole lot more that I haven't even had a chance to touch on yet. Very, very good book for *NIX programmers.
UNIX network programming / 1990 / W. Richard Stevens. / Advanced+
An older book about network programming. Some parts are not as commonly used today, but others are still as pertinent to network programming today as it was then. A good read.
In addition to those books, man pages are extremely useful. Use them a lot.
Web pages:
Ju Rao's Computer Books -- This page has incredible amounts of books about everything. There's quite a few links to books about *NIX programming here.
Here are a few links to some of the books on the page above. I'm sure there's a lot more, but these stood out.
Advance Linux Programming
UNIX System Calls and Subroutines using C
As I said, there's a heck of a lot more around than that, but that's enough to get you started. Google is also invaluable.
Anyway, good luck with your coding, and be sure to start up some convos here if anything stumps you.