Crop and rotate pdf

#!/bin/bash
if [ ! $1 ]; then
    exit 1;
fi
mkdir /tmp/pdfconv-$1
convert -density 300 $1 /tmp/pdfconv-$1/part.jpg
for img in /tmp/pdfconv-$1/*.jpg ; do
    convert -rotate 90 -crop 100%x50% $img $img-crop.jpg
done
convert -adjoin /tmp/pdfconv-$1/*-crop-*.jpg $1-cropped.pdf