temp.sh

# Loop forever - Ctrl-C to stop.
while(true);do 

  # Cat the device - assuming only one 28-XXXX (temp sensor) device
  # pipe that to grep for the data line (there are two lines, only 
  # one is interesting). Use awk to split out the rubbish, leaving
  # just the temp value
  temp_raw=$(cat /sys/bus/w1/devices/28-*/w1_slave | \
             grep t= | \
            awk -F= '{print $2}')
  # Use bc (apt-get install bc) to divide the raw number by 1000
  # Bash variable arithmetic would also work, but you would be 
  # limited to just an INT, and I wanted the 3 decimal places that
  # the sensor provides.
  temp_C=$(echo "scale=3; $temp_raw/1000" | bc)

  # simply echo out the temp in degrees C
  echo $temp_C

done