Effective awk Programming, 4th Edition

Chapter 12. Advanced Features of gawk

Write documentation as if whoever reads it is a violent psychopath who knows where you live.

—Steve English, as quoted by Peter Langston

This chapter discusses advanced features in gawk. It’s a bit of a “grab bag” of items that are otherwise unrelated to each other. First, we look at a command-line option that allows gawk to recognize nondecimal numbers in input data, not just in awk programs. Then, gawk’s special features for sorting arrays are presented. Next, two-way I/O, discussed briefly in earlier parts of this book, is described in full detail, along with the basics of TCP/IP networking. Finally, we see how gawk can profile an awk program, making it possible to tune it for performance.

Additional advanced features are discussed in separate chapters of their own:

• Chapter 13, Internationalization with gawk, discusses how to internationalize your awk programs, so that they can speak multiple national languages.

• Chapter 14, Debugging awk Programs, describes gawk’s built-in command-line debugger for debugging awk programs.

• Chapter 15, Arithmetic and Arbitrary-Precision Arithmetic with gawk, describes how you can use gawk to perform arbitrary-precision arithmetic.

• Chapter 16, Writing Extensions for gawk, discusses the ability to dynamically add new built-in functions to gawk.

Allowing Nondecimal Input Data

If you run gawk with the --non-decimal-data option, you can have nondecimal values in your input data:

$ echo 0123 123 0x123 |
> gawk --non-decimal-data ...