Signals are asynchronous notifications (like Ctrl+C). Molay teaches you how to catch them, ignore them, and why signal() is now obsolete in favor of sigaction(). You will build a simple alarm clock program.
If you work through the PDF systematically, you will gain a deep, practical understanding of: understanding unix linux programming molay pdf
The "fork/exec" model is uniquely Unix. The book dedicates significant space to: Signals are asynchronous notifications (like Ctrl+C )