Ebook: POSIX.4--programming for the real world

I would have to second the other reviews of this truly exceptional text, I will rather merely add one more observation:

Apparently now in 2009 the book is out of print, it is dated by standards of the fast moving software industry and Unix development, surely the hardware is dramatically faster now, and yet while other books of that age cannot be sold for even symbolic $0.01, here the price soars to astonishing heights. Well deserved, get yourself a copy, the content is timeless and unique. We have yet to wait for an updated version of this or similar book with some more current description of real time, timers and sophisticated IO with Posix. Or is there? Sometimes some of the industry common API's endure generations unchanged, because their very stability is the benefit, and their generality does not enforce extensions.