All the material has been rechecked for accuracy, errata have been incorporated and the text re-edited. The result is a 230 page book covering everything from basics of GNU Make to advanced topics like eliminating recursive make, doing arithmetic in GNU Make or dealing with spaces in file names.
The book contains 43 separate articles about GNU Make, plus a complete reference to the GNU Make Standard Library.
You can buy a copy in either form here.
A big thank you to everyone who's commented, emailed, or made suggestions on my GNU Make articles over the years.