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, a command-line option allows gawk to recognize nondecimal numbers in input data, not just in awk programs. Next, two-way I/O, discussed briefly in earlier parts of this Web page, is described in full detail, along with the basics of TCP/IP networking and BSD portal files. Finally, gawk can profile an awk program, making it possible to tune it for performance.
Dynamic Extensions, discusses the ability to dynamically add new built-in functions to gawk. As this feature is still immature and likely to change, its description is relegated to an appendix.