Advanced AWK Sources

I have recently discovered the PHENOMENAL power of AWK and its uses to
programmers converting data formats.

I have a reference:

Dale Dougherty, "sed & awk", pub. O'Reilly & Associates, (date not known),
ISBN 0-937175-59-5

I might add a counter question:

Does anyone know if there is a good readable book on the advantages and
methods of using UNIX tools - C, sed, grep, awk etc in GIS?? This area currently
occupies much of my time. Also can anyone advise me on any sources - book, internet news boards, etc who can help me understand pointers and array uses in C?

Jeremy Stocks.

University of Wales at Bangor, U.K.