a little tool to join CSVs
Use it like this: joincsv labels.csv content1.csv content2.csv
Labels from the first CSV are applied as headers for the successive CSVs. The first row of the first CSV should be your desired new headers in order. The subsequent rows of the first CSV should be those same headers in the columns where those values appear in your content CSVs.
If that doesn't make any sense, see the examples folder.