Unlock the secrets of Linux system programming and take your coding skills to the next level Do you use Linux, but not really understand it? Have you ever wondered how ls -l knows everything it does? Could you explain to a coworker why ls and find can be external commands but cd and umask must be built into the shell? The answers to these questions, and more, are in Linux Application Development by Example, Second Edition! This book tells you exactly what you need to know--no more and no less--about the fundamental Linux system programming APIs. Following the latest POSIX standard, author Arnold Robbins explains how the basic file, process, IPC and networking APIs work. When possible, he demonstrates the use of the APIs with code drawn from real programs (V7 Unix, BSD Unix, and GNU), and when that's not possible, he provides small, clearly documented and annotated, standalone example programs of his own. All code presented in the book is available for download, so you can compile, run, and modify the programs yourself. Robbins focuses on both high-level principles and "under the hood" techniques. Along the way, he carefully addresses real-world issues like performance, portability, and robustness. Each chapter closes with exercises, ranging from coding problems to thought experiments, to help you cement your understanding of the material covered, and all chapters have been thoroughly revised and updated for this edition, along with two chapters new in this edition. Memory management File I/O File metadata Processes, Users and groups Sorting and searching Argument parsing Extended interfaces Signals Internationalization Basic Networking Debugging And more! Just learning to program? Switching from Windows or macOS? Already developing with Linux but interested in exploring the system call interface further? No matter which, quickly and directly, this book will help you master the fundamentals needed to build serious Linux software. "It's rare that I read a programming book and find myself enjoying it. I enjoyed going through this manuscript, to the point where I would be surprised that a couple hours would go by while I was absorbed in the topics.... It deserves to sit on my shelf alongside other classics." --Matthew Helmke, Linux author and consultant With a Foreword by Chet Ramey, maintainer of the Bash shell Register your book for convenient access to downloads, updates, and/or corrections as they become available. See inside book for details.

Table of Contents:
Foreword xv Preface xvii Part I: Files and Users 1 Chapter 1: Introduction 3 1.1 The Linux/Unix File Model 3 1.2 The Linux/Unix Process Model 7 1.3 Standard C versus Original C 9 1.4 Why GNU Programs Are Better 13 1.5 Portability Revisited 17 1.6 Some Words about Coding Style 18 1.7 Artificial Intelligence Isn't Intelligent 19 1.8 Suggested Reading 19 1.9 Summary 20 Exercises 21 Chapter 2: Arguments, Options, and the Environment 23 2.1 Option and Argument Conventions 23 2.2 Basic Command-Line Processing 26 2.3 Option Parsing: getopt() and getopt_long() 28 2.4 The Environment 37 2.5 Summary 49 Exercises 49 Chapter 3: User-Level Memory Management 51 3.1 Linux/Unix Address Space 51 3.2 Memory Allocation 55 3.3 Summary 76 Exercises 77 Chapter 4: Files and File I/O 79 4.1 Introducing the Linux/Unix I/O Model 79 4.2 Presenting a Basic Program Structure 79 4.3 Determining What Went Wrong 81 4.4 Doing Input and Output 87 4.5 Random Access: Moving Around within a File 96 4.6 Creating Files 101 4.7 Forcing Data to Disk 106 4.8 Setting File Length 107 4.9 Summary 108 Exercises 109 Chapter 5: Directories and File Metadata 111 5.1 Considering Directory Contents 111 5.2 Creating and Removing Directories 121 5.3 Reading Directories 123 5.4 Obtaining Information about Files 130 5.5 Avoiding Race Conditions: openat() and Friends 144 5.6 Changing Ownership, Permission, and Modification Times 145 5.7 Summary 151 Exercises 153 Chapter 6: General Library Interfaces--Part 1 155 6.1 Times and Dates 155 6.2 Sorting and Searching Functions 171 6.3 User and Group Names 190 6.4 Terminals: isatty() 196 6.5 Suggested Reading 196 6.6 Summary 197 Exercises 198 Chapter 7: Putting It All Together: ls 201 7.1 V7 ls Options 201 7.2 V7 ls Code 202 7.3 Summary 218 Exercises 218 Chapter 8: Filesystems and Directory Walks 221 8.1 Mounting and Unmounting Filesystems 221 8.2 Files for Filesystem Administration 228 8.3 Retrieving Per-Filesystem Information 234 8.4 Moving Around in the File Hierarchy 247 8.5 Processing a File Hierarchy: GNU du 261 8.6 Changing the Root Directory: chroot() 269 8.7 Summary 270 Exercises 271 Part II: Processes, Networking, and Internationalization 273 Chapter 9: Process Management and Pipes 275 9.1 Process Creation and Management 275 9.2 Process Groups 300 9.3 Basic Interprocess Communication: Pipes and FIFOs 302 9.4 File Descriptor Management 307 9.5 Example: Two-Way Pipes in gawk 323 9.6 Suggested Reading 327 9.7 Summary 328 Exercises 330 Chapter 10: Signals 333 10.1 Introduction 333 10.2 Signal Actions 333 10.3 Standard C Signals: signal() and raise() 334 10.4 Signal Handlers in Action 337 10.5 The System V Release 3 Signal APIs: sigset() et al. 349 10.6 POSIX Signals 350 10.7 Signals for Interprocess Communication 360 10.8 Important Special-Purpose Signals 363 10.9 Signals across fork() and exec() 378 10.10 Summary 379 Exercises 381 Chapter 11: Permissions and User and Group ID Numbers 383 11.1 Checking Permissions 383 11.2 Retrieving User and Group IDs 385 11.3 Checking as the Real User: access() 388 11.4 Setting Extra Permission Bits for Directories 391 11.5 Setting Real and Effective IDs 393 11.6 Working with All Three IDs: getresuid() and setresuid() (Linux) 398 11.7 Crossing a Security Minefield: Setuid root 399 11.8 Suggested Reading 400 11.9 Summary 401 Exercises 403 Chapter 12: Resource Limits 405 12.1 Introduction 405 12.2 System Limits: sysconf(), pathconf(), and fpathconf() 405 12.3 Getting Configuration String Variables: confstr() 411 12.4 Basic Process Limits: ulimit() 413 12.5 Hard and Soft Limits: getrlimit() and setrlimit() 414 12.6 Summary 417 Exercises 418 Chapter 13: General Library Interfaces--Part 2 419 13.1 Assertion Statements: assert() 419 13.2 Low-Level Memory: The memXXX() Functions 423 13.3 Temporary Files 426 13.4 Committing Suicide: abort() 434 13.5 Nonlocal Gotos 435 13.6 Pseudorandom Numbers 442 13.7 Metacharacter Expansions 450 13.8 Regular Expressions 459 13.9 Suggested Reading 467 13.10 Summary 468 Exercises 469 Chapter 14: Sockets and Basic Networking 473 14.1 Introduction, with a Little Bit of History 473 14.2 Networking Technologies 474 14.3 Internet Building Blocks 474 14.4 Networking and Client/Server 477 14.5 Basic Structure of a Server Program 478 14.6 Basic Structure of a Client Program 488 14.7 Specialized Send and Receive Functions 492 14.8 Handling Multiple Open Connections: select() 494 14.9 pselect(): A Smarter Version of select() 501 14.10 Unix-Domain Sockets 502 14.11 Suggested Reading 502 14.12 Summary 503 Exercises 504 Chapter 15: Internationalization and Localization 507 15.1 Introduction 507 15.2 Locales and the C Library 508 15.3 Dynamic Translation of Program Messages 526 15.4 Can You Spell That for Me, Please? 540 15.5 Suggested Reading 553 15.6 Summary 553 Exercises 555 Chapter 16: Extended Interfaces 557 16.1 Allocating Aligned Memory: posix_memalign() and memalign() 557 16.2 Locking Files 558 16.3 More Precise Times 567 16.4 Advanced Searching with Binary Trees 575 16.5 Summary 586 Exercises 587 Part III: Debugging and Final Project 589 Chapter 17: Debugging 591 17.1 First Things First 591 17.2 Compilation for Debugging 592 17.3 GDB Basics 593 17.4 Programming for Debugging 606 17.5 Debugging Tools I: A Modern lint 632 17.6 Debugging Tools II: Memory Allocation Debuggers 633 17.7 Asking for Help 650 17.8 Software Testing 651 17.9 Debugging Rules 653 17.10 Suggested Reading 655 17.11 Summary 656 Exercises 657 Chapter 18: A Project That Ties Everything Together 659 18.1 Project Description 659 18.2 Suggested Reading 661 Part IV: Appendices 663 Appendix A: Teach Yourself Programming in Ten Years 665 Appendix B: Caldera Ancient UNIX License 671 Appendix C: GNU General Public License 673 Appendix D: License for the One True Awk 685 Appendix E: License for 4.4 BSD Code 687 Index 689