Python stdout goes where under systemd? (Was: Example of python service running under systemd?)

[Travis Griggs]

Thanks all for the help/advice. I’m getting there.

To experiment/learn, I made a simple python program (/Foo/cyclic.py):
 
    #!/usr/bin/env python3

    import time

    while True:
        time.sleep(5)	
        with open('sound', 'r') as file:
            currentValue = file.read()
        otherValue = 'tick' if currentValue == 'tock' else 'tock'
        with open('sound', 'w') as file:
            file.write(otherValue)
        print(currentValue, '->', otherValue)

Run from the command line, this tick-tocks nicely, both outputting, as well as updating the ‘/Foo/sound’ file on a 5 second period.

I then created a simple .service file:

    [Unit]
    Description=Foo for learning service
    After=network-online.target
    
    [Service]
    Type=simple
    ExecStart=/Foo/cyclic.py
    WorkingDirectory=/Foo
    StandardOutput=journal
    
    [Install]
    WantedBy=multi-user.target

I chose to be “explicit” with some of the default options (Type and StandardOutput).
I finally executed:

    systemctl --system daemon-reload
    systemctl enable foo
    systemctl start foo

It seems to work. Almost. The file is being updated regularly (watch cat /Foo/sound shows the change happening). But I can’t seem to find the output from my print() statement. journalctl -f doesn’t show anything. Nor does tail -f /var/log/syslog or any of the others. It just seems to be going nowhere? Is there something I need to do special to get the print() output going somewhere logable?