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?
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