Spin down usb hard drive

spinDownHd

# activate the script via crontab as root user 
# */5 * * * * /home/roberto/script/spinDownHd2 > /home/roberto/logspindown

DISK=sda
echo "start"
SGSTART=/usr/bin/sg_start
if [ ! -x $SGSTART ]
then
  echo "$SGSTART missing. aborting."
  exit 1
fi

PREVIOUS=/run/.spindown-$DISK

#to prevent errors from the first run, create the file
if [ ! -f $PREVIOUS ]
then
  touch $PREVIOUS
fi

# Then see if there's activity in between this run and the previous run.
# If not, spin down.

line1=`cat $PREVIOUS`
line2=`grep " $DISK " /proc/diskstats`
echo "$line2" > $PREVIOUS

if [ "x$line1" = "x$line2" ]
then
  echo "spin down"
  $SGSTART -r -S /dev/$DISK
fi

exit 0