For the last several months I have copied several data folders to zip files at weekly intervals. Now I'd like to combine those zip files into one zip file, because most of the contents of the existing zip files are just different versions of the same data files.
So if a file appears in more than one of the existing zip files, I'd like the newest version to be in the new zip file being created. Of course if a file appears in only one existing zip file, then I want it in the final zip file also.
I'm trying to avoid having to unzip them one by one to a working folder, overwriting data from older zip files with data from newer zip files, and then rezipping everything into a new zip file.
From what I understand pkzip would combine the zip files themselves, but is there a dependable and fast free method anyone can tell me about?