pi@raspberrypi2 ~ $ git clone https://github.com/adafruit/Adafruit_Python_DHT.git
pi@raspberrypi2 ~ $ cd Adafruit_Python_DHT/
pi@raspberrypi2 ~ $ sudo apt-get install build-essential python-dev
pi@raspberrypi2 ~ $ python setup.py build
pi@raspberrypi2 ~ $ sudo python setup.py install

pi@raspberrypi2 ~ $ cat /usr/local/bin/ADHT_metern.py
#!/usr/bin/python
# Copyright (c) 2014 Adafruit Industries
# Author: Tony DiCola

# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
import sys

import Adafruit_DHT

# Parse command line parameters.
sensor_args = { '11': Adafruit_DHT.DHT11,
                '22': Adafruit_DHT.DHT22,
                '2302': Adafruit_DHT.AM2302 }
if len(sys.argv) == 4 and sys.argv[1] in sensor_args:
        sensor = sensor_args[sys.argv[1]]
        pin = sys.argv[2]
        id = sys.argv[3]
else:
        print 'usage: sudo ./Adafruit_DHT.py [11|22|2302] GPIOpin# metern_id'
        print 'example: sudo ./Adafruit_DHT.py 2302 4 8 - Read from an AM2302 connected to GPIO #4 and metern id 8'
        sys.exit(1)

# Try to grab a sensor reading.  Use the read_retry method which will retry up
# to 15 times to get a sensor reading (waiting 2 seconds between each retry).
humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)

# Note that sometimes you won't get a reading and
# the results will be null (because Linux can't
# guarantee the timing of calls to read the sensor).
# If this happens try again!
if humidity is not None and temperature is not None:
        print '{0}({1:0.1f}*C)'.format(id, temperature)
        print '{0}({1:0.1f}*%)'.format(id, humidity)
else:
        print 'ERROR'

pi@raspberrypi2 ~ $ sudo chmod +x /usr/local/bin/ADHT_metern.py

pi@raspberrypi2 ~ $ sudo ADHT_metern.py 22 24 8
8(24.2*C)
8(74.7*%)

ADHT_metern.py 22 24 8 > /run/shm/metern8.txt

pi@raspberrypi2 ~ $ cat /etc/cron.d/dht22
#!/bin/bash

SHELL=/bin/bash
PATH=/usr/local/bin:/usr/local/sbin:/sbin:/bin:/usr/sbin:/usr/bin

# Minute  Hour    Day of Month   Month              Day of Week        User   Command
# (0-59)  (0-23)  (1-31)         (1-12 or Jan-Dec)  (0-6 or Sun-Sat)
*/15      *       *              *                  *                  root   ADHT_metern.py 22 24 8 > /run/shm/metern8.txt

pi@raspberrypi2 ~ $ sudo chmod +x /etc/cron.d/dht22

cat /run/shm/metern8.txt | grep C

cat /run/shm/metern8.txt | grep %