This is by far the most open objective for any of the two exams. Frankly, I think this objective should be better defined. Yes, RHCEs should be expected to know a significant amount of shell scripting but by leaving this objective defined in such a open fashion it risks people spending too much time on time, probably not a bad thing in itself, or none at all.
At any rate, if you have never done any shell scripting, I recommend this tutorial, continued here. If you are familiar with the basics or even if you are not, you can follow this guide. I've also been looking at this book. I don't endorse it or not endorse it, it just came up on a search of books24x7.com.
