extract container's data (not the filename!)

Hello.

I thought this would be simple, but I can't find any other posts on this.

I have a script that inserts files into containers.

In some cases they will be plain text files. And in some of those cases, I want to be able to use scripts on the text data stored in the container.

So, is there a function or method to just grab the ascii data somehow?

Some limitations: everything is pretty much script-driven, and this is for a cross-platform runtime, so using a plugin or apple-script is pretty much out of the question.