Here is my favourite book about Korn Shell scripting: "The Korn Shell Programming Tutorial" by Barry J. Rosenberg. It will teach you everything you need to know from the beginning up to a medium advanced level of scripting.

But, again: what you need is not a tool, what you really need is to clarify WHAT you want to monitor. Before you find out WHAT to do every discussion about HOW to do it is moot. I for my part will be glad to help you with this and i am sure the experts here will too, but until after there is a clear picture what you want to do i won't suggest any tools. There might be good or bad tools for your purpose but before we have to establish what this purpose is.

Furthermore: you have heard "topas" and "nmon" and some other tools here a lot. These are very good if you want to get a quick and thorough overview of a system. Often this view is already plotted in graphs without having to bother with plotting tools.

I prefer to use system tools instead ("vmstat", "iostat", "ps", ...) because these offer a lot more flexibility first and because they do not aggregate data second. Aggregation of data is good to get overviews, but when you have to analyse a problem you might need the underlying data to get meaningful results. In such a case it is good to have the source, not some arbitrary summation thereof.

I hope this helps.

bakunin