This is a book about UNIX programming. It starts with basic concepts and ends with coverage of advanced topics. It is a self-teaching guide, and yet it functions as a UNIX reference book. The examples provided are written in the C and C++ languages. The examples are short programs, each intended to demonstrate use of a particular programming facility. The C++ programs are written as simple programs and should be well understood by those that do not program in C++. This book attempts to be UNIX platform neutral. Throughout the book, differences in functionality are noted for your convenience. This will save you time when you must write projects that must be UNIX portable. FreeBSD 3.4 release is used throughout this book for demonstration purposes. This guarantees that the example programs will compile and run without any additional effort on that platform. This also grants a specific level of functionality, since some functions are lacking or vary on other platforms. You can obtain FreeBSD from the Internet or purchase it on a CD-ROM at a nominal cost. This allows you to work through the book on a platform that is on a par with other professional UNIX platforms.