Understanding the shell, both memorizing its syntax and appreciating how it and the GUI are an abstraction of something deeper (though I find it helpful to think of the GUI as the abstraction for he command line), is under appreciated when it comes to learning to code, so a guide like this is really helpful to point to.

What do people think of the shortness of the chapters? That is, having hem cover one command each? I would lean toward combining similar concepts, such as cp and mv, so that the higher-level capabilities, the ones that make the shell uniquely more powerful than the GUI (such as piping), stand out more...but maybe it's better to have things one at a time?