Effective awk Programming (2015)
Part I. The awk Language
Chapter 1. Getting Started with awk
Chapter 2. Running awk and gawk
Chapter 3. Regular Expressions
Chapter 4. Reading Input Files
Chapter 7. Patterns, Actions, and Variables
Part II. Problem Solving with awk
Chapter 10. A Library of awk Functions
Chapter 11. Practical awk Programs
Part III. Moving Beyond Standard awk with gawk
Chapter 12. Advanced Features of gawk
Chapter 13. Internationalization with gawk
Chapter 14. Debugging awk Programs
Chapter 15. Arithmetic and Arbitrary-Precision Arithmetic with gawk
Chapter 16. Writing Extensions for gawk
Part IV. Appendices
Appendix A. The Evolution of the awk Language
Appendix C. GNU General Public License