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I have written some simple python scripts and I would like to run them on my raspberry pi even when I am not logged in. So far, I can log in to the machine via ssh and run the script without a problem. As soon as I have to disconnect the ssh session, I notice that the script breaks or stops. Thus, I was wondering if there is a way to keep the script running after the end of the ssh connection.

Here is the system I am using: Raspberry pi 3B+ with ubuntu 22.04 LTS, and here is how I run my script:

ssh [email protected]
cd myapp/
python3 runapp.py

3

Answers


  1. if there is a way to keep the script running after the end of the ssh connection.

    Just run it in the background.

    python3 runapp.py &
    

    You could store the logs to system log.

    python3 runapp.py | logger &
    

    You could learn about screen and tmux virtual terminals, so that you can view the logs later. You could start a tmux session, run the command inside and detach the session.

    You could setup a systemd service file with the program, and run is "as a service".

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  2. You can use nohup to stop hangup signals affecting your process. Here are three different ways of doing it.


    This is a "single shot" command, I mean you type it all in one go:

    ssh SOMEHOST "cd SOMEWHERE && nohup python3 SOMESCRIPT &"
    

    Or here, you log in, change directory and get a new prompt in the remote host, run some commands and then, at some point, exit the ssh session:

    ssh SOMEHOST
    cd SOMEWHERE
    nohup python SOMESCRIPT &
    exit
    

    Or, this is another "single shot" where you won’t get another prompt till you type EOF

    ssh SOMEHOST <<EOF
    cd SOMEWHERE
    nohup python SOMESCRIPT &
    EOF
    
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  3. If atd is running you can use at to schedule commands to be executed at a particular time.

    Examples:

    $ echo "python3 /path/to/runapp.py"|at 11:00
    job 10 at Fri Jun  3 11:00:00 2022
    
    $ echo "python3 /path/to/runapp.py" | at now
    job 11 at Thu Jun  2 19:57:00 2022
    
    # after minutes/hours/days/....
    $ echo "python3 /path/to/runapp.py" | at now +5 minutes
    $ echo "python3 /path/to/runapp.py" | at now +2 hours
    
    
    $ ssh user@host "echo 'python3 /path/to/runapp.py'| at now"
    

    Jobs created with at are executed only once.

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