Running Something 24/7 and Starting it on Boot

Introduction

In this tutorial you will learn how to run "something" (e.g. a file or a script) 24/7 on Debian and Ubuntu servers and start it on boot.
For the task described in this tutorial, I will use a Python script.
I am doing this on a Debian 11 server (netcup RS 2000), but other Debian versions and Ubuntu should also work.

Requirements

You need a Debian or Ubuntu server with an internet connection.
You also need root permissions on your server.

Step 1 - Installing Cron and Python

First you need to connect to your server via SSH.
Then switch to the root user and update your system, followed by the installation of Cron and Python:

su
apt update && apt upgrade -y && apt autoremove -y
apt install wget curl sudo nano python-pip-whl cron python3 python3-pip screen -y

Step 1.1 - Starting script

In my example I use a Python script in /home/python which is named run.py. I want to start it on boot and it should run 24/7.
First, I switch into the folder and install the Python requirements that I need for the script:

cd /home/python
pip3 install py-cord py-cord[voice]

Then I proceed to start the script (replace discord-py-bot with a name and python3 run.py with the command to start):

screen -AmdS discord-py-bot python3 run.py

We use Gnu Screen to keep the script running even if the SSH connection is closed.

Step 1.1.1 - Watch console (optional)

If you want to see the output of the console, run the following command (replace discord-py-bot with the name you defined in Step 1.1):

screen -r discord-py-bot

If you want to return to your normal console, press CTRL + A and then CTRL + D.

Step 1.2 - Setting up "start on boot"

If you want the file to start on boot, run the following command (replace screen -AmdS discord-py-bot python3 run.py with the entire start command of Step 1.1 and /home/python with the folder path of your file):

{ crontab -l 2>/dev/null; echo "@reboot sleep 10 && cd /home/python && screen -AmdS discord-py-bot python3 run.py" ; } | crontab -

Step 1.2.1 - Testing your setup

If you want to test whether your setup works, reboot your server:

reboot

After rebooting, check if you can see the console (replace discord-py-bot with the name you defined in Step 1.1):

screen -r discord-py-bot

Conclusion

Now, every time you reboot your server, the file (in our example, the Python file) is also started and executed in the background.

License

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

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Contributor's Certificate of Origin

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1. The contribution was created in whole or in part by me and I have the right to submit it under the license indicated in the file; or

2. The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same license (unless I am permitted to submit under a different license), as indicated in the file; or

3. The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it.

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