Arnold Robbins 
Effective awk Programming [EPUB ebook] 
Universal Text Processing and Pattern Matching

When processing text files, the awk language is ideal for handling data extraction, reporting, and data-reformatting jobs. This practical guide serves as both a reference and tutorial for POSIX-standard awk and for the GNU implementation, called gawk. This book is useful for novices and awk experts alike.In this thoroughly revised edition, author and gawk lead developer Arnold Robbins describes the awk language and gawk program in detail, shows you how to use awk and gawk for problem solving, and then dives into specific features of gawk. System administrators, programmers, webmasters, and other power users will find everything they need to know about awk and gawk. You will learn how to:Format text and use regular expressions in awk and gawk Process data using awk’s operators and built-in functions Manage data relationships using associative arrays Define your own functions"Think in awk" with two full chapters of sample functions and programs Take advantage of gawk’s many advanced features Debug awk programs with the gawk built-in debugger Extend gawk by writing new functions in C or C++This book is published under the terms of the GNU Free Documentation License. You have the freedom to copy and modify this GNU manual.Royalties from the sales of this book go to the Free Software Foundation and to the author.