AWK is an interpreted programming language that is included in most versions of Unix. The name is derived from the initials of its creators--Alfred Aho, Peter Weinberger, and Brian Kernighan--who developed the language in 1977. The language is particularly designed for filtering and manipulating textual data. In this respect, it is similar to Perl, though Perl is more powerful. There are many variants of AWK, including gawk, which is the GNU version.
Effective AWK Programming was published by the Free Software Foundation (FSF) and distributed in electronic form with the GNU AWK source code. It was also published by SSC to help make it more widely available in book form, and is now offered by O'Reilly & Associates.
Effective AWK Programming covers every aspect of the AWK 3.0.3 and 3.0.4 language. It offers the most up-to-date coverage of the POSIX standard for AWK available anywhere, and clearly distinguishes standard AWK features from GNU AWK-specific features. The author sheds light on many of the "dark corners" of the language (areas to watch out for when programming), devotes two full chapters to example programs, and includes a summary of how the AWK language evolved.
For anyone who writes scripts in the awk family of languages, the third edition of
Effective awk Programming provides an in-depth guide to processing text files with plenty of working sample code. Whether you are starting out with awk or are an experienced developer, this book will help you extend the reach of your awk scripts.
This tutorial covers the entire spectrum of awk script development: From the basics of opening, searching, and transforming text files, to a comprehensive tutorial for regular expressions, to more advanced features like internetworking. The focus is on the practical side of creating and running awk scripts, and there's plenty of hands-on advice for installing and running today's awk (and gawk).
The book begins with the fundamentals of awk for opening and transforming text flat files. The coverage of regular expressions, from simple rules for matching text to more advanced options, is particularly solid. You learn how to add variables and expressions for more intelligent awk scripts, plus how to parse data into records and fields. You'll also find out how to redirect output from awk scripts to other programs, a useful technique that can cause awk to get a lot more done in real applications.
Later, you learn several valuable sample awk scripts that mimic existing Unix utilities (like grep, id, and split), plus samples for counting words in documents and printing mailing labels, and even a stream editor. This grab bag of sample code lets you try out the techniques presented earlier in the book. Other sections look at support for networking in today's gawk; for example, how gawk can read and write to URLs on the network almost just as easily as local files. Full sample code will teach the beginner or expert how to get productive with networks and awk. Final appendices trace the evolution of the awk language and show you how to download and install gawk.
Suitable for beginner and experienced awk developers, Effective awk Programming, Third Edition, is an extremely worthwhile source of information on a wide range of programming techniques for today's awk. --Richard Dragan
Topics covered:
- Introduction to the awk programming language
- Running awk scripts
- Basic file processing
- Tutorial for regular expressions
- Strategies for matching text
- Dynamic regular expressions
- Parsing data into records and lines (including separating fields and handling multiple-line records)
- Using print and printf for printed output with awk (including format specifiers)
- Redirecting awk scripts output to other processes
- Basic and advanced awk expressions (constants, variables, and function calls)
- Patterns
- Shell variables and actions
- Arrays (including multidimensional arrays and sorting)
- Built-in and custom awk functions
- Internationalizing and localizing awk scripts
- Advanced gawk (communicating with other processes and networking programming)
- Running awk and gawk
- Sample awk scripts
- Internetworking with awk
- History and evolution of awk
- Downloading and installing gawk
