The egrep program is used to scan files for character strings (e.g. words). Its basic function is to go through a text file line for line, and print all lines matching a search pattern or regular expression to `standard out(put)'.
DadaDodo is a program that analyses texts for word probabilities, and then generates random sentences based on that. Sometimes these sentences are nonsense; but sometimes they cut right through to the heart of the matter, and reveal hidden meanings.
Here is an outline of the key issues, mostly in Becker's own words, hoping it would motivate you to read the original. The main points have been highlighted in bold. The complete citation of the book is given below.