I wrote a tutorial on how to write statefull scripts in Lua on my blog. ''Stateful scripts are a simple yet powerfully way to enhance your monitoring which I think is used far to little. Using stateful script you can easily add simple predictions and change management. This is very easy to accomplished using NSClient++ as its built-in scripting modules by default provides stateful scripts (in contrast to Nagios and Icinga which tends to be stateless). This tutorial will walk you through writing a simple stateful script in Lua. If you are still confused about stateful scripts the main benefit is that they remember things. Thus you can alert when something changes as well as predict the future. A good example of this is disk growth prediction but there are a lot of other scenarios where they are useful.'' You can find it here: [http://blog.medin.name/2012/11/26/enhance-your-monitoring-with-stateful-scripts/] // Michael Medin