#!/bin/sh
output=$(basename "$1" | sed 's/\.pdf$/_2pp.pdf/')
nbpages=$(pdfinfo "$1" | grep Pages | sed 's/Pages:[ ]*//')

if [ $nbpages = 1 ]; then
  pdftk A="$1" cat A A output "$output";
else
  cp "$1" "$output";
fi

if [ $(pdfinfo "$1" | grep "Page size" | sed 's/Page size:[ ]*//' | sed 's/\(\..*\)\? x/ -ge/' | sed 's/\(\..*\)\? pts.*//') ]; then
  cat "$output" | pdftk - cat -W output "$output";
fi

pdftops "$output" -paper A4 - | psnup -2 -pa4 -q | ps2pdf14 - > dummy_.pdf;
pdftk dummy_.pdf rotate 1-endeast output "$output";
evince "$output";
rm "$output" dummy_.pdf;