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Running Python Script Inside Bash Not Working When In Crontab

Hi guys I would like to ask for some help with my bash script.
I am running 2 python script inside my bash script and it is working when I'm running it manually but when I'm using cron only the commands in the .sh file is working not on .py
Please take note that I already install necessary utils and packages for python3.
This is the script:
#!/usr/bin/env bash
# list.tmp path directory
fileLoc="/home/ec2-user/PushNotification/Incoming34days/list34days.tmp"
# URL to POST request
refLink='http link'
# Title of Push Notification
title='34th day: Grace Period is about to end'
# curl type
type='Notification'
# curl action_type
actionType='NotificationActivity'
# Get the current date and time
now=$(date '+%b %d %Y %H:%M:%S')
# Message to the user
body="Subscribe to the Philippine Mobile Number plan now to continue receiving calls and texts and sending text messages to the Philippines."
# Logs location
logsLoc="/home/ec2-user/PushNotification/Incoming34days/logs.tmp"
# current number
currentNumLoc="/home/ec2-user/PushNotification/Incoming34days/currentNum.tmp"
echo "[$now] Sending notifications to mobile numbers advising today is the last day of grace period..." > $logsLoc
# Python file to SELECT all id who has 34 days counter
python3 select34days.py
# psql -d $database -t -c "SELECT id FROM svn WHERE current_date - expiry_date::DATE = 4" psql must be setup using .pgpass for postgresql authentication, please indicated database
# name and query list directory. Deleting the last line from list.txt
# This is to read the textfile list.txt line per line
while IFS='' read -r list;
# for list in `cat list.txt`;
do
# curl POST request
response=$(curl --location --request POST $refLink \
--header 'Authorization: Basic YXBwdm5vdXNlcjphcHB2bm9wYXNz' \
--header 'Content-Type: application/json' \
--data-raw '{
"title":"'"$title"'",
"body":"'"$body"'",
"min" :[{"mobileNumber" : "'"$list"'"}],
"type" : "'"$type"'",
"action_type" : "'"$actionType"'"}')
# Echo mobile number
echo "[$now] Mobile Number: $list" >> $logsLoc
# Echo response from curl
echo "Response: '$response'"
echo "[$now] Result: '$response'" >> $logsLoc
# Update the current number of the list
echo $list > $currentNumLoc
echo "[$now] Updating $list status into EXPIRED" >> $logsLoc
# Updating status into EXPIRED
python3 updateQuery34.py
done < "$fileLoc"
# end of script
The select34days.py and updateQuery34.py is not running.
I have a log.tmp to check regarding this situation and only displaying commands inside my .sh file
Inside my cron are
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/bin:/usr/bin
MAILTO=root

Your PATH looks wrong:
PATH=/sbin:/bin:/usr/bin:/usr/bin
This includes /usr/bin twice which isn't necessary, but hints that something else should have been there.
Depending on how you've installed it, python might be in /usr/bin/ or /usr/local/bin or even somewhere in /opt.
At the commandline you can find python's directory using:
dirname $(which python3)
This directory needs to be added to your path in your crontab.

Just declare the specific directory with script name (eg. /etc/test.sh)every time you are using bash scripts and adding it to a cron job since the cron doesn't know where is the specific script within the the server.

Python startup script using STDOUT for outputs, using init.d method

My environment is Debian Jesse on a embedded arm display.
I am using a bash script to automatically launch my app using the init.d method. It launches a second python script as a daemon that handles my application on startup and reboot.
Because it is run this way to the best of my knowledge this is now a daemon background process, and it disconnects STDOUT and STDIN from my python script.
The system and application is for a single purpose, so spamming the console with outputs from a background process is not only not a problem, but it is desired. With the outputs I can easily ssh or serial console into the display and see all the live debug outputs or exceptions.
I have looked into possible ways to force the process to the foreground, or redirect the outputs to STDOUT but have not found any definite answer when the script is run at startup.
My logging to a file is working perfect and otherwise the app works well in the state it is in. Currently when I need to debug I stop the application and run it manually to get all the outputs.
I have considered using sockets to redirect the outputs from the app, and then running a separate script that is listening will print to console... but that seems less than ideal and that a better solution might exist.
Is there methods to achieve this or should I just accept this.
EDIT 1 (additional details)
Because I am using multiple logs for multiple processes I have created a logger class. The stream handler uses the default which should be sys.stderr.
import logging
import logging.handlers
class LoggerSetup(object):
def __init__(self, logName, logFileNameAndPath, logSizeBytes, logFileCount):
log = logging.getLogger(logName)
log.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s - %(levelname)s - ' + logName + ' - %(message)s',datefmt="%m-%d %H:%M:%S")
# Add the log message handler to the logger
if(logFileCount > 0):
fileHandler = logging.handlers.RotatingFileHandler(logFileNameAndPath, maxBytes=logSizeBytes, backupCount=logFileCount)
log.addHandler(fileHandler)
fileHandler.setFormatter(formatter)
consoleHandler = logging.StreamHandler()
log.addHandler(consoleHandler)
consoleHandler.setFormatter(formatter)
log.info(logName + ' initialized')
For more reference here is the startup script launch on boot. It then runs my python run.py which handles the rest of the startup process.
#!/bin/sh
### BEGIN INIT INFO
# Provides: ArcimotoStart
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Startup script
# Description: startip script that points to run.py
### END INIT INFO
# Change the next 3 lines to suit where you install your script and what you want to call it
DAEMON=/app/run.py
DAEMON_NAME=app
# Add any command line options for your daemon here
DAEMON_OPTS=""
# This next line determines what user the script runs as.
# Root generally not recommended but necessary if you are using certain features in Python.
DAEMON_USER=root
# The process ID of the script when it runs is stored here:
PIDFILE=/var/run/$DAEMON_NAME.pid
. /lib/lsb/init-functions
do_start () {
log_daemon_msg "Starting system $DAEMON_NAME daemon"
start-stop-daemon --start --background --pidfile $PIDFILE --make-pidfile --user $DAEMON_USER --chuid $DAEMON_USER --startas $DAEMON -- $DAEMON_OPTS
log_end_msg $?
}
do_stop () {
log_daemon_msg "Stopping system $DAEMON_NAME daemon"
start-stop-daemon --stop --pidfile $PIDFILE --retry 10
log_end_msg $?
}
case "$1" in
start|stop)
do_${1}
;;
restart|reload|force-reload)
do_stop
do_start
;;
status)
status_of_proc "$DAEMON_NAME" "$DAEMON" && exit 0 || exit $?
;;
*)
echo "Usage: /etc/init.d/$DAEMON_NAME {start|stop|restart|status}"
exit 1
;;
esac
exit 0

Permission Denied when trying to run Shell Script (containing Python sub-script)

I'm currently creating a Raspberry Pi (Model B) based temperature sensor with a display. I am trying to run a shell start up script in the LX Terminal but keep getting a "Permission Denied" error next to a Python sub-script as follows:
pi#raspberrypi ~ $ sudo /home/pi/tempsense/etc/init.d/envmon start
Starting envmon
pi#raspberrypi ~ $ /home/pi/tempsense/etc/init.d/envmon: 15:/home/pi/tempsense/etc/init.d/envmon: home/pi/tempsense/opt/envmon/displayenvmon.py: Permission denied
The shell script is:
#!/bin/sh
### BEGIN INIT INFO
# Provides: envmon
# Required-Start: $local_fs
# Required-Stop: $local_fs
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start/stop envmon
### END INIT INFO
case "$1" in
start)
/home/pi/tempsense/opt/envmon/dht11 &
echo "Starting envmon"
/home/pi/tempsense/opt/envmon/displayenvmon.py &
;;
stop)
pkill dht11
pkill displayenvmon
echo "envmon stopped"
;;
*)
echo "Usage: /home/pi/tempsense/etc/init.d/envmon {start|stop}"
exit 1
;;
esac
exit 0
The Python script causing the Permission denied errors is:
#!/usr/local/lib/python2.7/dist-packages
from RPLCD import CharLCD
import RPi.GPIO as GPIO
import subprocess, re
import time
# Data file - current reading
datfile = "/var/envmon.data"
# Rate at which the LCD is updated
UPDATE_RATE = 5
lcd = CharLCD(cols=16, rows=2,
pin_rw=None,
pin_rs=7,
pin_e=8,
pins_data=[25,24,23,18],
numbering_mode=GPIO.BCM)
lcd.cursor_pos = (0, 0)
lcd.write_string('Visit #UWS_Pi')
lcd.cursor_pos = (1, 0)
lcd.write_string('TEMP & HUMID')
time.sleep(5);
# Get IP address - looks for first IP address which is not 127.0.0.1
address_string = subprocess.getoutput("ip addr")
ipaddr = "Unknown"
# Reg exp to extract IP addresss
search_inet = re.compile('inet (\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})')
for line in address_string.split('\n') :
match = search_inet.search(line)
if (match != None) :
if (match.group(1) != '127.0.0.1') :
ipaddr = match.group(1)
break
# Print the IP address to the LCD
lcd.cursor_pos = (1,0)
lcd.write_string (ipaddr)
# Sleep to give chance to read IP address
time.sleep(5)
# Loop get most recent reading and display on screen
while (True):
fh = open (datfile, "r")
entry = fh.read()
# split into separate entries
[currtime, currtemp, currhumid] = entry.split()
# Change currtime to a formatted time ready for displaying
formattime = time.strftime ("%d/%m/%Y %H:%M", time.localtime(int(currtime)))
# print time to display
lcd.cursor_pos = (0,0)
lcd.write_string (formattime)
# Print temp and humidity values
lcd.cursor_pos = (1,0)
lcd.write_string ("T " + currtemp + "C RH " + currhumid + "% ")
time.sleep(UPDATE_RATE)
I am new to this and any helpful advice is appreciated.

To use the GPIO pins, the Python script needs to be run with administrator privileges. Either execute the shell script as root or call your Python script using sudo from within the shell script.

Either log in as root, or run the program with sudo, because usually permission denied means you need root permissions, sudo runs that specific program with root permissions if you don't want to log in as root.

python-notify module & cron: gio.Error

I'm asking some help to show notifications using python-crontab, because everything I've tried do not work. The display is not initilised when the script is launched by cron. When I start it manually, that's work.
The codes I've tried:
#!/usr/bin/env python
# coding: utf8
import subprocess
import os
#os.environ.setdefault("XAUTHORITY", "/home/guillaume" + "/.Xauthority")
#os.environ.setdefault('DISPLAY', ':0.0') # do not work
#os.environ['DISPLAY'] = ':0.0' # do not work
print = os.environ
cmd2 = 'notify-send test'
subprocess.call(cmd2, shell=True)
# more code, which is working (using VLC)
cmd3 = "cvlc rtp://232.0.2.183:8200 --sout file/mkv:/path/save/file.mkv" # to download TV's flow
with open("/path/debug_cvlc.log", 'w') as out:
proc = subprocess.Popen(cmd3, stderr=out, shell=True, preexec_fn=os.setsid)
pid = proc.pid # to get the pid
with open("/path/pid.log", "w") as f:
f.write(str(pid)) # to write the pid in a file
# I'm using the pid to stop the download with another cron's task, and to display another notify message.
# Download and stop is working very well, and zenity too. But not notify-send
Thanks
Edit: here are the environment variables I have for this cron's script:
{'LANG': 'fr_FR.UTF-8', 'SHELL': '/bin/sh', 'PWD': '/home/guillaume', 'LOGNAME': 'guillaume', 'PATH': '/usr/bin:/bin', 'HOME': '/home/guillaume', 'DISPLAY': ':0.0'}
Edit2: I'm calling my script in cron like this:
45 9 30 6 * export DISPLAY=:0.0 && python /home/path/script.py > /home/path/debug_cron_on.log 2>&1
I precise I have two screens, so I think DISPLAY:0.0 is the way to display this notify..
But I don't see it.
Edit3: It appears that I've a problem with notify-send, because it's working using zenity:
subprocess.call("zenity --warning --timeout 5 --text='this test is working'", shell=True)
I have notify-send version 0.7.3, and I precise that notify-send is working with the terminal.
Edit4: Next try with python-notify.
import pynotify
pynotify.init("Basic")
n = pynotify.Notification("Title", "TEST")
n.show()
The log file show this: (in french)
Traceback (most recent call last):
File "/home/path/script.py", line 22, in <module>
n.show()
gio.Error: Impossible de se connecter : Connexion refusée
#Translating: Unable to connect : Connection refused
So, I have problem with dbus? what is this?
Solution: Get the DBUS_SESSION_BUS_ADDRESS before creating the cron order:
cron = CronTab()
dbus = os.getenv("DBUS_SESSION_BUS_ADDRESS") # get the dbus
# creating cron
cmd_start = "export DBUS_SESSION_BUS_ADDRESS=" + str(dbus) + " && export DISPLAY=:0.0 && cd /path && python /path/script.py > path/debug_cron.log 2>&1"
job = cron.new(cmd_start)
job = job_start.day.on(self.day_on) # and all the lines to set cron, with hours etc..
cron.write() # write the cron's file
Finally, the cron's line is like that:
20 15 1 7 * export DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-M0JCXXbuhC && export DISPLAY=:0.0 && python script.py
Then the notification is displaying. Problem resolved !! :)

You are calling the cron like
45 9 30 6 * DISPLAY=:0.0 python /home/path/script.py > /home/path/debug_cron_on.log 2>&1
which is incorrect, since you are not exporting the DISPLAY variable, and the subsequent command does not run.
Try this instead
45 9 30 6 * export DISPLAY=:0.0 && cd /home/path/ && python script.py >> debug_cron.log 2>&1
Also, you are setting the DISPLAY variable within your cron job as well, so try if the cron job works without exporting it in the job line
45 9 30 6 * cd /home/path/ && python script.py >> debug_cron.log 2>&1
EDIT
While debugging, run the cron job every minute. Following worked for me:
Cron entry
* * * * * cd /home/user/Desktop/test/send-notify && python script.py
script.py
#!/usr/bin/env python
import subprocess
import os
os.environ.setdefault('DISPLAY', ':0.0')
print os.environ
cmd2 = 'notify-send test'
subprocess.call(cmd2, shell=True)
EDIT 2
Using pynotify, script.py becomes
#!/usr/bin/env python
import pynotify
import os
os.environ.setdefault('DISPLAY', ':0.0')
pynotify.init("Basic")
n = pynotify.Notification("Title", "TEST123")
n.show()
and cron entry becomes
* * * * * cd /home/user/Desktop/test/send-notify && python script.py
EDIT 3
One environment variable DBUS_SESSION_BUS_ADDRESS is missing from the cron environment.
It can be set in this and this fashion

crontab is considered an external host -- it doesn't have permission to write to your display.
Workaround: allow anyone to write to your display. Type this in your shell when you're logged in:
xhost +

Daemonizing a python script in debian

I have a python script that i want to run in the background on startup. This is the script:
#!/usr/bin/python
from Adafruit_CharLCD import Adafruit_CharLCD
from subprocess import *
from time import sleep, strftime
from datetime import datetime
from datetime import timedelta
from os import system
from os import getloadavg
from glob import glob
#Variables
lcd = Adafruit_CharLCD() #Stores LCD object
cmdIP = "ip addr show eth0 | grep inet | awk '{print $2}' | cut -d/ -f1" #Current IP
cmdHD = "df -h / | awk '{print $5}'" # Available hd space
cmdSD = "df -h /dev/sda1 | awk '{print $5}'" # Available sd space
cmdRam = "free -h"
temp = 0
#Run shell command
def run_cmd(cmd):
p = Popen(cmd, shell=True, stdout=PIPE)
output = p.communicate()[0]
return output
#Initalises temp device
def initialise_temp():
#Initialise
system("sudo modprobe w1-gpio")
system("sudo modprobe w1-therm")
#Find device
devicedir = glob("/sys/bus/w1/devices/28-*")
device = devicedir[0]+"/w1_slave"
return device
#Gets temp
def get_temp(device):
f = open (device, 'r')
sensor = f.readlines()
f.close()
#parse results from the file
crc=sensor[0].split()[-1]
temp=float(sensor[1].split()[-1].strip('t='))
temp_C=(temp/1000.000)
temp_F = ( temp_C * 9.0 / 5.0 ) + 32
#output
return temp_C
#Gets time
def get_time():
return datetime.now().strftime('%b %d %H:%M:%S\n')
#Gets uptime
def get_uptime():
with open('/proc/uptime', 'r') as f:
seconds = float(f.readline().split()[0])
array = str(timedelta(seconds = seconds)).split('.')
string = array[0].split(' ')
totalString = string[0] + ":" + string[2]
return totalString
#Gets average load
def get_load():
array = getloadavg()
average = 0
for i in array:
average += i
average = average / 3
average = average * 100
average = "%.2f" % average
return str(average + "%")
#def get_ram():
def get_ram():
ram = run_cmd(cmdRam)
strippedRam = ram.replace("\n"," ");
splitRam = strippedRam.split(' ')
totalRam = int(splitRam[52].rstrip("M"))
usedRam = int(splitRam[59].rstrip("M"))
percentage = "%.2f" % ((float(usedRam) / float(totalRam)) * 100)
return percentage + "%"
#Gets the SD usage
def get_sd():
sd = run_cmd(cmdSD)
strippedSD = sd.lstrip("Use%\n")
return strippedSD
#Gets the HD usage
def get_hd():
hd = run_cmd(cmdSD)
strippedHD = hd.lstrip("Use%\n")
return strippedHD
def scroll():
while(1):
lcd.scrollDisplayLeft()
sleep(0.5)
#Uptime and IP
def screen1():
uptime = get_uptime()
lcd.message('Uptime %s\n' % (uptime))
ipaddr = run_cmd(cmdIP)
lcd.message('IP %s' % (ipaddr))
#Ram and load
def screen2():
ram = get_ram()
lcd.message('Ram Used %s\n' % (ram))
load = get_load()
lcd.message('Avg Load %s' % (load))
#Temp and time
def screen3():
time = get_time();
lcd.message('%s\n' % (time))
lcd.message('Temp %s' % (temp))
#HD and SD usage
def screen4():
sd = get_sd()
lcd.message('SD Used %s\n' % (sd))
hd = get_hd()
lcd.message('HD Used %s' % (hd))
#Pause and clear
def screenPause(time):
sleep(time)
#In here to reduce lag
global temp
temp = str(get_temp(device));
lcd.clear()
###########################################################################################################
#Initialise
lcd.begin(16,2)
device = initialise_temp()
lcd.clear()
#Testing
#Main loop
while(1):
screen1()
screenPause(5)
screen2()
screenPause(5)
screen3()
screenPause(5)
screen4()
screenPause(5)
I know i probably havnt done things the write way but its the first attempt.
My startup script is in /etc/init.d This is the script:
#! /bin/sh
### BEGIN INIT INFO
# Provides: LCD looping
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: LCD daemon
# Description: This file should be used to construct scripts to be
# placed in /etc/init.d.
### END INIT INFO
# Author: Foo Bar <foobar#baz.org>
#
# Please remove the "Author" lines above and replace them
# with your own name if you copy and modify this script.
# Do NOT "set -e"
# PATH should only include /usr/* if it runs after the mountnfs.sh script
PATH=/sbin:/usr/sbin:/bin:/usr/bin
DESC="Loops the LCD screen through LCD.py"
NAME=startup.py
DAEMON=/home/pi/Programming/LCD/startup.py
DAEMON_ARGS=""
PIDFILE=/var/run/daemonLCD.pid
SCRIPTNAME=/etc/init.d/daemonLCD
# Exit if the package is not installed
[ -x "$DAEMON" ] || exit 0
# Read configuration variable file if it is present
[ -r /etc/default/daemonLCD ] && . /etc/default/daemonLCD
# Load the VERBOSE setting and other rcS variables
. /lib/init/vars.sh
# Define LSB log_* functions.
# Depend on lsb-base (>= 3.2-14) to ensure that this file is present
# and status_of_proc is working.
. /lib/lsb/init-functions
#
# Function that starts the daemon/service
#
do_start()
{
# Return
# 0 if daemon has been started
# 1 if daemon was already running
# 2 if daemon could not be started
start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON --test > /dev/null \
|| return 1
start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON -- \
$DAEMON_ARGS \
|| return 2
# Add code here, if necessary, that waits for the process to be ready
# to handle requests from services started subsequently which depend
# on this one. As a last resort, sleep for some time.
}
#
# Function that stops the daemon/service
#
do_stop()
{
# Return
# 0 if daemon has been stopped
# 1 if daemon was already stopped
# 2 if daemon could not be stopped
# other if a failure occurred
start-stop-daemon --stop --quiet --retry=TERM/30/KILL/5 --pidfile $PIDFILE --name $NAME
RETVAL="$?"
[ "$RETVAL" = 2 ] && return 2
# Wait for children to finish too if this is a daemon that forks
# and if the daemon is only ever run from this initscript.
# If the above conditions are not satisfied then add some other code
# that waits for the process to drop all resources that could be
# needed by services started subsequently. A last resort is to
# sleep for some time.
start-stop-daemon --stop --quiet --oknodo --retry=0/30/KILL/5 --exec $DAEMON
[ "$?" = 2 ] && return 2
# Many daemons don't delete their pidfiles when they exit.
rm -f $PIDFILE
return "$RETVAL"
#
# Function that sends a SIGHUP to the daemon/service
#
do_reload() {
#
# If the daemon can reload its configuration without
# restarting (for example, when it is sent a SIGHUP),
# then implement that here.
#
start-stop-daemon --stop --signal 1 --quiet --pidfile $PIDFILE --name $NAME
return 0
}
case "$1" in
start)
[ "$VERBOSE" != no ] && log_daemon_msg "Starting $DESC" "$NAME"
do_start
case "$?" in
0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
esac
;;
stop)
[ "$VERBOSE" != no ] && log_daemon_msg "Stopping $DESC" "$NAME"
do_stop
case "$?" in
0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
esac
;;
status)
status_of_proc "$DAEMON" "$NAME" && exit 0 || exit $?
;;
#reload|force-reload)
#
# If do_reload() is not implemented then leave this commented out
# and leave 'force-reload' as an alias for 'restart'.
#
#log_daemon_msg "Reloading $DESC" "$NAME"
#do_reload
#log_end_msg $?
#;;
restart|force-reload)
#
# If the "reload" option is implemented then remove the
# 'force-reload' alias
#
log_daemon_msg "Restarting $DESC" "$NAME"
do_stop
case "$?" in
0|1)
do_start
case "$?" in
0) log_end_msg 0 ;;
1) log_end_msg 1 ;; # Old process is still running
*) log_end_msg 1 ;; # Failed to start
esac
;;
*)
# Failed to stop
log_end_msg 1
;;
esac
;;
*)
#echo "Usage: $SCRIPTNAME {start|stop|restart|reload|force-reload}" >&2
echo "Usage: $SCRIPTNAME {start|stop|status|restart|force-reload}" >&2
exit 3
;;
esac
:
Im think i have missed something as when i type daemonLCD start it says command not found.
Any input would be great.
Thanks

Assuming you may want to manage more than one daemon in the future, let me recommend Supervisord. It's much simpler than writing and managing your own init.d scripts.
For example, starting your script would be as easy as including this in the conf:
[program:myscript]
command=/usr/bin/python /path/to/myscript.py
I use an init.d script available here. Rename it to supervisord and copy it to your /etc/init.d/ then run:
sudo update-rc.d supervisord defaults
I believe that init script has supervisord run as root as default. You can have it drop to run as another user if you like. I'm not if children run as root or not, although I'd assume not. Go ahead and check, but if they don't you can stick a sudo before the python command in your supervisord.conf where you call the script.
It that doesn't run, (or if you want supervisord to run as a non-root but still want your script run as root) you can allow for anyone (or a group of users) to run the python script as root (although you should make quite certain that this script cannot be edited by anyone other than root).
edit your sudoers file with "sudo visudo" and add the following to the end:
USERS ALL=(ALL) NOPASSWD: /path/to/myscript.py
Then make sure you have a shebang at the beginning of your python script and change the command to omit the python call, i.e:
[program:myscript]
command=sudo /path/to/myscript.py

Here's a good blog post which deals with this question: Getting a Python script to run in the background (as a service) on boot

Use daemontools from djb. It is a lot easier than the other answers provided. For starters you can install daemon tools with apt-get so you do not need to worry about grabbing an unknown script from a gist and you get updates through debian like normal. daemontools also takes care of restarting the service if it dies and provides for logging. There is a description of daemontools and debian here:
http://blog.rtwilson.com/how-to-set-up-a-simple-service-to-run-in-the-background-on-a-linux-machine-using-daemontools/
djb's page aout daemontools:
http://cr.yp.to/daemontools.html

This is a classic mistake new Unix/Linux users make. /etc/init.d isn't in your path which is why you can't just run daemonLCD. Try using the full path (/etc/init.d/daemonLCD start) or prepending ./ (./daemonLCD start).
The script needs to be executable for either of the above to work.

thanks for the code above. I've been using it to figure out how to set up a daemon on a linux machine.
With some tweaking I could get it to work quite well.
But something puzzled me. And that was checking if the process was running, by checking the exists of the /var/run/myfile.pid
That's just the pidfile - NOT the process, right?
Take a look at /lib/lsb/init-functions.status_of_proc
status_of_proc () {
local pidfile daemon name status OPTIND
pidfile=
OPTIND=1
while getopts p: opt ; do
case "$opt" in
p) pidfile="$OPTARG";;
esac
done
shift $(($OPTIND - 1))
if [ -n "$pidfile" ]; then
pidfile="-p $pidfile"
fi
daemon="$1"
name="$2"
status="0"
pidofproc $pidfile $daemon >/dev/null || status="$?"
if [ "$status" = 0 ]; then
log_success_msg "$name is running"
return 0
elif [ "$status" = 4 ]; then
log_failure_msg "could not access PID file for $name"
return $status
else
log_failure_msg "$name is not running"
return $status
fi
}
That's only dealing with the success or failure of accessing the PID file.
Now, I'm building this daemon to go on a small device. I've discovered it's using BusyBox and I don't have init-functions :-(
But I do have pidof.
So I added
log_success_msg "pidof $NAME is $(pidof -x $NAME)" >> $LOGFILE
log_success_msg "PIDFILE of $NAME is" >> $LOGFILE
sed -n '1p' < $PIDFILE >> $LOGFILE
and checked $LOGFILE and lo and behold the numbers are different.
I did pstree -s -p on both numbers and
the pidof number spits out a very short tree, so it's for the root level process
but the $PIDFILE number vomits out branch after branch, so I don't think pstree can find the process.
Yes, the do_stop in Joseph Baldwin Roberts's code will kill both processes. But if the process is killed in another way e.g. kill -9 12345, the $PIDFILE is still there. So, the daemon will falsely believe the process is already running an refuse to start.