I had problems using pdftk with the cat parameter had a better success with output. The following command worked for me: pdftk file_1.pdf file_1.pdf file_1.pdf file_1.pdf cat output.pdf Using cat produced the following error: Error: Unexpected text in page range end, here: output.pdf Exiting. Acceptable keywords, for example: 'even' or 'odd'.
To rotate pages, use: 'north' 'south' 'east' 'west' 'left' 'right' or 'down' Errors encountered. No output created.
Input errors, so no output created.. I created a 172mb PDF is no time at all.