Running a Python script at startup

Question

This question has been asked quite a few times before but I didn't seem to get it working using the existing information.

My Pi runs Raspbian. I have a Python script named dnscheck.py which loops forever.

I need it to run at boot. I know I have to create a .sh file containing something like

sudo python dnscheck.py &

What I don't know is where this file should be or if it should contain anything else. I know about the init.d folder, but seeing the skeleton example I imagine there should be a simpler way to do this simple task.

Answer 1

If you want to control the process with commands like start, stop, restart etc using the skeleton script and altering it for your purposes might be the best option.

If you just want the process to start, put the command into /etc/rc.local. (I don't have my RPi at hand, but I read online that there is an 'exit 0' line in there, you should put your command above this line)

Answer 2

2020 Update:
Nowadays modern Linux distributions, including Raspbian, use systemd instead of old style SysV as init system. For downstream compatibility SysV is only emulated by systemd but will lose support more and more by time so

you should not use SysV anymore, in particular /etc/rc.local!

For more information about this have a look at Compatibility with SysV.

With the endless loop in the script it should run in the background as service so you can use a systemd service defined with a Unit file. Here is a simple example for your script. Create it with:

rpi ~$ sudo systemctl --force --full edit dnscheck.service

In the empty editor insert these statements, save them and quit the editor:

[Unit]
Description=Check DNS queries
After=multi-user.target

[Service]
ExecStart=/usr/bin/python3 /home/pi/dnscheck.py

[Install]
WantedBy=multi-user.target

It may be possible that this is too simple and you have to add some more settings for a needed environment. Have a look at man systemd.unit and man systemd.service for additional conditions.

Enable and monitor the service with:

rpi ~$ sudo systemctl enable --now dnscheck.service
rpi ~$ systemctl status dnscheck.service

The text output of the script you will find in the journal:

rpi ~$ journalctl -b -e

Answer 3

Move your script (we will save it to the file dnscheck) to /etc/init.d/, and set the permissions so it can be run:

chmod 755 /etc/init.d/dnscheck

Add LSB init tags to the top of your script. You will probably want to change Required-Start/Stop and the Description Tags to fit your script.

### BEGIN INIT INFO
# Provides:          dnscheck
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start daemon at boot time
# Description:       Enable service provided by daemon.
### END INIT INFO

Then create the symbolic links by running

update-rc.d /etc/init.d/dnscheck defaults

Answer 4

There are many ways to do this, of course, but don't forget using cron. If you put a @reboot line in your crontab, that command will be executed on every restart.

To test, I just added the following line to my user crontab with crontab -e: @reboot echo "$(date)" >> ~/boot.txt The bonus to this method is that you can call the job as required at other intervals besides just boot time, and you don't have to edit init scripts.

Answer 5

Here is the solution that I constantly use.

Create a desktop file

xyz.desktop

type the following into it

[Desktop Entry]
Encoding=UTF-8
Type=Application
Name=<Application Name Goes here>
Comment=
Exec=  python /home/pi/Desktop/execute_on_boot.py
StartupNotify=false
Terminal=true
Hidden=false

paste this file into the

/home/pi/.config/autostart/

and restart your raspberry pi and it should automatically run your program in a new terminal

Answer 6

if you use rc.local file, this may be helpful for troubleshooting. You can add logging lines to log errors (stderr) and command output (stdout) into log file. According to this example that file saves in /tmp/rc.local.log

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

exec 2> /tmp/rc.local.log      # send stderr from rc.local to a log file
exec 1>&2                      # send stdout to the same log file

# Your other commands...

exit 0

Read more

Answer 7

I'm really surprised djb's daemontools is not mentioned here. Daemontools does proper process supervision and you can add cool features like automatically rotated logging. TL;DR if you're not familiar with any of this, your process will be restarted every time it fails and start automatically when your Pi turns on. This is great if you wrote a bad python program that has failure modes but you don't want it to just die if an error is encountered.

Install:

sudo apt-get install daemontools daemontools-run

Then follow steps to create daemonized processes:

• http://samliu.github.io/2017/01/10/daemontools-cheatsheet.html

It's mostly as simple as copying a run script into /etc/service/<my_custom_service_name> Another perk: you can run as any user or root! Details in the link.

FWIW I had a Pi project where I had 3 different python processes (each had an execution loop using CPU time so by using 3 processes I allowed each process to leverage 1 CPU core). Daemontools allowed me to make sure all 3 would automatically run and stay running after I plugged in the Pi.

Answer 8

To use a .py file, just put the line #!/usr/bin/python at the very start of your file. Then make it executable with chmod +x filename. Next, add the line /path/to/file.py & to /etc/rc.local before the exit 0 line (swapping /path/to/file.py with the path to your script). This will make your python script execute at the end of boot.

Answer 9

Here's an even easier method that worked for me. Modify the autostart in LXDE.

Open a terminal and edit the autostart file as follows:

sudo nano /home/pi/.config/lxsession/LXDE-pi/autostart

add the following line of text to the bottom(modify the path as needed to where your example.py is located)

@/usr/bin/python /home/pi/example.py

ctr-x, and save. You may need to make the python script executable as follows:

sudo chmod +x /home/pi/example.py

reference for autostart in LXDE and reference for making python executable

Answer 10

these solutions didn't work for me trying to start a python script with running Feh. The following worked. It starts a script after login.

Open a terminal session and edit the file

sudo nano /etc/profile

Add the following line to the end of the file

/home/pi/your_script_name.sh

replace the script name and path with correct name and path of your start-up script. Save and Exit

Press Ctrl+X to exit nano editor followed by Y to save the file.

Here's what my script.sh looked like:

#!/bin/sh
cd /
cd home/pi/
sudo python your_python_sript.py &
exit 0
cd /

I think I made both the script.sh and script.py executable using the chmod

sudo chmod +x home/pi/your_script_name.sh
sudo chmod +x home/pi/your_python_script.py