Working With Unix Processes (workingwithunixprocesses.com)

I'm intrigued, but would appreciate a free first chapter or two.

$27 ebook on unix processes, signals, and all that jazz. Examples and sample code in Ruby. Written by Jesse Storimer (jstorimer at HN) of Shopify.

I read the first six chapters and I really, really like it so far, great writing style and very informative!