What you're asking is:

1. How do I parse a file in a given format into Perl data structures?
2. How do I transform one Perl data structure into another?
3. How do I write a Perl data structure out to a file?

How far have you gone in handling this? I would suggest writing your program in terms of those three questions.

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.