Advanced Programming in the Unix Environment is a computer programming book by W. Richard Stevens describing the application programming interface of the UNIX family of operating systems. The book illustrates UNIX application programming in the C programming language. The book has been widely lauded as well written, well crafted, and comprehensive. It received a "hearty recommendation" in a Linux Journal review. OSNews describes it as "one of the best tech books ever published" in a review of the second edition.