doitall.sh

gistfile1.txt

    #!/bin/bash
    # https://unix.stackexchange.com/a/407146

    if [ ! -f "${1}" ];then
        echo "filename must be first argument"
        exit 99
    fi

    pdftk "${1}" burst

    rotate=$(cat doc_data.txt | grep PageMediaRotation | head -1 | awk '{print $2}')
    if [ "$rotate" == "90" ]; then 
        pw=`cat doc_data.txt  | grep PageMediaDimensions | head -1 | awk '{print $3}'`
        ph=`cat doc_data.txt  | grep PageMediaDimensions | head -1 | awk '{print $2}'`
    else
        pw=`cat doc_data.txt  | grep PageMediaDimensions | head -1 | awk '{print $2}'`
        ph=`cat doc_data.txt  | grep PageMediaDimensions | head -1 | awk '{print $3}'`
    fi
        w2=$(echo "scale=0; $pw / 2" | bc )
        echo "$w2"
        w2px=$( echo "scale=0;$w2*10" | bc)
        hpx=$(echo "scale=0;$ph*10" | bc)
        for f in  pg_[0-9]*.pdf ; do
            lf=left_$f
            rf=right_$f
            gs -o ${lf} -sDEVICE=pdfwrite -g${w2px}x${hpx} -c "<</PageOffset [0 0]>> setpagedevice" -f ${f}
            gs -o ${rf} -sDEVICE=pdfwrite -g${w2px}x${hpx} -c "<</PageOffset [-${w2} 0]>> setpagedevice" -f ${f}
        done
        ls -1 [lr]*_[0-9]*pdf | sort -n -k3 -t_ > fl
        pdftk `cat fl`  cat output newfile.pdf