Linux Application Development by Example
Description
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.
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Arnold Robbins is a professional software engineer and technical author. He has been working with Unix systems of various sorts, GNU/Linux systems, C, C++, and all the other major Unix tools since 1980. As a long-time volunteer for the GNU project, he has been the maintainer of gawk (GNU Awk) for many years. In 2024, he was awarded the USENIX Lifetime Achievement Award ("The Flame") for his work on GNU Awk and for his numerous books on topics related to Unix and Linux.
Content
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
