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Reviewer: Robert Edward Van Cleef

Advertised as the “ first ever to document the sophisticated workings of the UNIX kernel,” this book provides a readable introduction to UNIX system internals. In the Preface, the author states that the book originated in a course that he taught at AT&T Bell Laboratories; it is, therefore, no surprise that the book is ideally structured for use in a classroom environment. Chapters 1 and 2 present an overview of the UNIX operating system and a short discussion of the internal structure. The rest of the book divides into three parts: Chapters 3–5—The File System; Chapters 6–9—Process Control; and Chapters 10–13—Advanced Topics. Each part is broken down into discussions on the logical flow of the various algorithms used in the system, with a description of how they interact with each other. The algorithms are presented in a C-like pseudocode that I found easy to read and understand. Small C programs are also provided as examples of how various system calls are used. Finally, each chapter ends with a collection of exercises, including some that are “exploratory in nature, designed for investigation as a research problem.” It is the discussion of interactions between different parts of the operating system that I found to be the most interesting. Without getting into hardware-specific issues, or “exposing” AT&Ts copyrighted source to the non-licensed public, the author shows how different algorithms have been used and modified to support context switching, scheduling of priorities, interrupt handling, etc., and warns of potentially wrong assumptions about these interactions. Because of its structured format, large bibliography, and complete index, this book will also be a valuable addition to any reference library. Below is a chapter-by-chapter outline of the contents. :9N(1) General Overview of the System—History, System Structure, User Perspective, Operating System Services, Assumptions about Hardware, Summary. (2) Introduction to the Kernel—Architecture of the UNIX Operating System, Introduction to System Concepts, Kernel Data Structures, System Administration, Summary and Preview, Exercises. (3) The Buffer Cache—Buffer Headers, Structure of the Buffer Pool, Scenarios for Retrieval of a Buffer, Reading and Writing Disk Blocks, Advantages and Disadvantages of the Buffer Cache, Summary, Exercises. (4) Internal Representation of Files—Inodes, Structure of a Regular File, Directories, Conversion of a Path Name to an Inode, Super Block, Inode Assignment to a New File, Allocation of Disk Blocks, Other File Types, Summary, Exercises. (5) System Calls for the File System—Open, Read, Write, File and Record Locking, Adjusting the Position of File IO—LSEEK, Close, File Creation, Creation of Special Files, Change Directory and Change Root, Change Owner and Change Mode, Stat and Fstat, Pipes, DUP, Mounting and Unmounting File Systems, Link, Unlink, File System Abstractions, File System Maintenance, Summary, Exercises. (6) The Structure of Processes—Process States and Transitions, Layout of System Memory, The Context of a Process, Saving the Context of a Process, Manipulation of the Process Address Space, Sleep, Summary, Exercises. (7) Process Control—Process Creation, Signals, Process Termination, Awaiting Process Termination, Invoking Other Programs, The User ID of a Process, The Shell, System Boot and the Init Process, Summary, Exercises. (8) Process Scheduling and Time—Process Scheduling, Systems Calls for Time, Clock, Summary, Exercises. (9) Memory Management Policies—Swapping, Demand Paging, A Hybrid System with Swapping and Demand Paging, Summary, Exercises. (10) The IO System—Driver Interfaces, Disk Drivers, Terminal Drivers, Streams, Summary, Exercises. (11) Interprocess Communication—Process Tracing, System V IPC, Network Communications, Sockets, Summary, Exercises. (12) Multiprocessor Systems—Problem of Multiprocessor Systems, Solution with Master and Slave Processors, Solution with Semaphores, The Tunis System, Performance Limitations, Exercises. (13) Distributed UNIX Systems—Satellite Processors, The Newcastle Connection, Transparent Distributed File Systems, A Transparent Distributed Model without Stub Processes, Summary, Exercises. Also included is an appendix on System Calls, a Bibliography, and an Index.