This book effectively combines the way of development of Linux and the principles of Unix and sums up the design principles in Linux and Unix software development. The first 8 chapters respectively introduce nine basic philosophical guidelines and 10 minor criteria of Linux and Unix. Chapter 9 and Chapter 10 compare the design ideas with those of other systems. Finally, the application of Unix philosophical criteria is introduced. The book is suitable for all developers of Linux and Unix operating systems. It can also benefit other developers.