PDF to Jpeg convertor script. Instructions in comments.

pdfcon.sh

#!/bin/sh
# Need 2 directories:
# 1 ./toprocess
# 2 ./processed
#
# PHP dumps PDFs into "toprocess" dir.
# This script then converts and dump jpgs into "processed"
# Then deletes pdf contents of current directory.
#
# Run this script via crontab as so:
#
# 10,20,30,40,50 * * * * cd /full/path/to/this/scriptdir/ && ./pdfcon.sh

count=`ls -1 *.pdf 2>/dev/null | wc -l`
if [ $count != 0 ]; then
        for i in *.pdf;
        do
            convert -density 300 $i -antialias -resize 2160x4462 ./processed/$i.jpg;
        done

        rm -f *.pdf;
fi