A comprehensive, entertaining, and technically accurate guide to POSIX shell scripting that takes you from complete beginner to writing production-ready scripts.
This book teaches portable shell scripting using POSIX-compliant syntax, ensuring your scripts work across Linux, macOS, BSD, and other Unix-like systems. Written with humor and practical examples, it makes learning shell scripting engaging while maintaining technical accuracy.
- Chapter 1: Introduction - Why Shell Scripting? - The power of automation and why POSIX matters
- Chapter 2: The Shell Universe - Understanding shells, terminals, and your environment
- Chapter 3: The Shebang Bang Theory - Starting your scripts correctly with
#!/bin/sh
- Chapter 4: Variables - Your Script's Memory Bank - Variables, parameter expansion, and special parameters
- Chapter 5: Conditionals - Teaching Your Script to Think - if statements, test commands, and case statements
- Chapter 6: Loops - Making Your Script Do the Heavy Lifting - for, while, and until loops
- Chapter 7: Functions - Don't Repeat Yourself - Creating reusable code blocks
- Chapter 8: Input/Output - Talking to the World - Reading input, redirecting output, and here documents
- Chapter 9: Command Substitution and Pipelines - The Unix philosophy in action
- Chapter 10: Pattern Matching and Text Processing - grep, sed, awk, and regular expressions
- Chapter 11: Error Handling - When Things Go Wrong - Graceful failure and recovery strategies
- Chapter 12: Portability - Write Once, Run Anywhere - Ensuring your scripts work everywhere
- Chapter 13: Debugging - Finding the Gremlins - Tools and techniques for troubleshooting
- Chapter 14: Best Practices and Common Pitfalls - Professional patterns and what to avoid
- Chapter 15: Real-World Scripts - Putting It All Together - Complete production-ready examples
- Write portable POSIX-compliant shell scripts
- Understand the difference between POSIX features and shell-specific extensions
- Handle errors gracefully and debug effectively
- Process text using Unix tools (grep, sed, awk)
- Build real-world automation solutions
- Follow industry best practices for maintainable scripts
- Create production-ready backup systems, deployment pipelines, and monitoring tools
- Beginners with no shell scripting experience
- System administrators wanting to automate tasks
- DevOps engineers building deployment and automation tools
- Developers needing to understand shell scripting
- Anyone wanting to master the command line
- Start with Chapter 1 if you're new to shell scripting
- Set up your environment as described in Chapter 1
- Try the examples and complete the exercises in each chapter
- Build your own scripts using the patterns you learn
- A Unix-like operating system (Linux, macOS, BSD, WSL on Windows)
- A POSIX-compliant shell (usually
/bin/sh) - A text editor
- Enthusiasm to learn!
- Comprehensive Coverage: From basics to advanced topics
- Humor Throughout: Learning doesn't have to be dry
- Practical Examples: Real code you can use
- Exercises: Reinforce your learning with hands-on practice
- POSIX Focus: Write scripts that work everywhere
- Best Practices: Learn the right way from the start
- Production-Ready Code: Complete scripts for real-world use
- System backup manager with rotation and compression
- Service health monitor with alerting
- Zero-downtime deployment pipeline
- Log analyzer and reporter
- Configuration management tools
- And many more!
Read chapters 1-7 in order to build a solid foundation, then explore advanced topics as needed.
Jump to specific chapters that interest you, or start with Chapter 15 for complete real-world examples.
Use the table of contents to find specific topics when you need them.
This book has been technically reviewed for:
- POSIX compliance
- Correct shell behavior
- Security best practices
- Portable code patterns
Where bash-specific or non-POSIX features are shown, they are clearly marked with alternatives provided.
Found an error or have a suggestion? Please open an issue or submit a pull request.
This book is provided as educational material. Code examples are free to use in your projects.
Thanks to the Unix pioneers who created the shell, the POSIX committee for standardization, and the countless system administrators who've kept these traditions alive.
"The shell is not just a tool, it's a philosophy. Master it, and you master the art of making computers do your bidding while you focus on more interesting problems."
Happy Scripting! 🚀