Linux - Unleashing the Workstation in Your PC (3rd ed.)

NIX achieved its widespread propagation, its penetration of UNIX history U the university domain, and its reach into research and industry due to its early dissemination by AT&T to all interested parties at almost no cost and as source code. UNIX's present functionality emanated not just from AT&T developers but also from many external developers who used the product and contributed their own further developments, which they then put at AT&T's disposal. (Consider the contributions of