Problem Statement

Rename:

This should be done twice:   once "here", i.e. in the current working directory and once in the filesystem root. It can be assumed that the user has the rights to do so. (In unix-type systems, only the user root would have sufficient permissions in the filesystem root.)

Let's start with the solution:

RenameFile("input.txt", "output.txt")
RenameFile("docs\", "mydocs\")

RenameFile("/input.txt","/output.txt")
RenameFile("/docs\","/mydocs\")