Ah ok, good to know, thanks. It's only version 3.
it was just example good, not sure if I need it. I will try other code which works with version 3 then first.
e.g. this one:
(glClear no reference, if i add -lGL it can compile (g++ ./test.cpp -lglfw -lGL)
ok. compiled without error
but if I start the program nothing happens. I instantly get back to console.
Edit: with apt-get I can only get version 3. Thanks for links but I would like to start with apt-get version. If I install something new other things can go wrong :). And program should also work on computer which have only version 3.
EDIT2: IT IS WORKING NOW
(for some reason I need to restart my PC first)
thanks all for your help