Shell script for printer cron (w/ lock)

printer.sh

#!/bin/bash 
# Romain Bochet
# Use as a cron
# Print all the files included in a folder with lp, and move them in another folder. 
# Use absolute path (mandatory for crons)

SOURCE="/home/dropbox/print/"
DONE="/home/romain/printed/"
LOCK="/tmp/printerlock"

# Test if another thread is running this script
if [ -f $LOCK ] 
then
exit
fi

touch $LOCK

for FILE in `ls $SOURCE`
do
  /usr/bin/lp $FILE
  /bin/mv "$SOURCE$FILE" $DONE 
done

rm $LOCK