If you are slurping your data from a file, then you will not have any problem with variable interpolation, and the $ sign will not give you any trouble. It is only if you are creating the string yourself in your code with double quotes that this "problem" arises. If you read data from a file, no variable interpolation occurs, so that it is as if you had used single quotes.

And this is also basically what Corion said in the first place, but maybe you did not understand fully how it applied to your question.