The Section 8.2 in Chapter 8 describes how to write your own awk functions. Writing functions is important, because it allows you to encapsulate algorithms and program tasks in a single place. It simplifies programming, making program development more manageable, and making programs more readable.
One valuable way to learn a new programming language is to read programs in that language. To that end, this chapter and Chapter 13 provide a good-sized body of code for you to read, and hopefully, to learn from.
This chapter presents a library of useful awk functions. Many of the sample programs presented later in this book use these functions. The functions are presented here in a progression from simple to complex.
The Section 13.3.7 in Chapter 13 presents a program that you can use to extract the source code for these example library functions and programs from the Texinfo source for this book. (This has already been done as part of the gawk distribution.)
If you have written one or more useful, general-purpose awk functions and would like to contribute them to the author’s collection of awk programs, see the Section P.6 in the preface for more information.
The programs in this chapter and in Chapter 13 freely use features that are gawk-specific. Rewriting these programs for different implementations of awk is pretty straightforward.
Diagnostic error messages are sent to /dev/stderr.
| "cat 1>&2", instead of
"/dev/stderr" if your ...