It's definitely an omission in the OP's post.... but perhaps s/he omitted reading On asking for help and How do I post a question effectively?.

kar_thik82: If the gentle hints fail to move you, here's the compressed version: We're not code-a-matic. We're here to try to help you learn, but NOT to simply satisfy your 'gimme's.

Then there's another: I know what I mean. Why don't you?. How do you determine which blank lines to retain and which to elide? The pattern for moving File1's content to output isn't the same, as far as I can see, as the pattern for moving 2's content.

So, please consider UPDATING (with a note that you've done so) your OP to provide a tighter spec and the code you've tried along with explicit warnings and/or error message and a clear explanation of how the output fails to match your intent.