Advanced Bash-Scripting Guide
An in-depth exploration of the art of shell scripting
by Mendel Cooper
here.
-- Tom
P.S. At the end is a C program to generate an ASCII table. Which reminds me of a story. I remember once programming such a table in IBM Macro Assembler language - gave it to my intructor. He used to tell his subsequent classes that it was possible (which is what got me hooked on doing it in the first place), and when a student who tried but failed to implement it as a macro like I did, stated in class that it couldn't be done, the instructor pulled it out of his briefcase to show him the proof - the expression on the student's face I was told was precious!