Manuals are good once you already know something or if you want to become an expert. I don't think either of these are the buyer of the one-liner book. The one-liner buyer is a person who has the occasional need to script and doesn't want to have to become an expert again every time they need to do something.

I learned enough awk once-upon-a-time that I think the book could be very useful. I tend to do python three-liners like somebody else here mentioned, but if I had a very quick way to find the awk, I'd use it more. The problem I have is that I'm not sure an ebook makes it fast enough.