Flip a PDF on Ubuntu using the Terminal and PDFTK

I was looking for a quick way to flip PDF files for the sake of adding e-signatures. I ran across a CLI utility called PDFTK.

sudo apt install  pdftk

You can rotate using direction, north and south = 180 degrees, east, and west = 90 degrees. In my case, the documents were upside down so I flipped them 180 degrees south.

pdftk 'some pdf file.pdf' cat 1-endsouth output SomePDF.pdf