#!/usr/bin/sh

file=original54.pdf;

newfile=$(basename $file .pdf)-2.pdf;

tmpfile=$(mktemp --suffix=.pdf);

blankfile=$(mktemp --suffix=.pdf);

cp -f $file $newfile;

numberofpages=`pdftk $file dump_data | grep "NumberOfPages" | sed 's:.*\([0-9][0-9*]\).*:\1:'`;

echo "" | ps2pdf -sPAPERSIZE=a4 - $blankfile;

while (( $numberofpages % 4 != 0 ));

do 

  ((numberofpages++));

  pdftk A=$newfile B=$blankfile cat A B output $tmpfile;

  cp -f $tmpfile $newfile;

done;

neworder=`

for ((  a=1, b=3, c=4, d=2 ;

        a <=numberofpages ;

        ((a+=4)), ((b+=4)), ((c+=4)), ((d+=4))

    ));

do

echo -n "$a $b $c $d ";

done`;

pdftk $tmpfile cat $neworder output $newfile;