By the way, while not exactly necessary for learning scripting, a lot of scripting generally involves grabbing filenames and manipulating text. So you'll certainly find yourself using the commands find, sed, and awk a lot, which come with their own complex syntax and scripting systems. The Unix grymoire has pages dealing with all three of these commands.
(Note though that the grymoire is written for older unix-based versions of these commands, and there are some differences between them and the gnu versions that Linux uses, but it's good for getting the basics down.)
Finally, you'll also eventually want to learn regular expressions. All of the above commands, as well the shell itself, use regex in one form or another, so it's well worth learning. I don't have any specific page to suggest here, but there are tons of tutorials out there, so look around.