Redirect stdout stderr of systemd service

See https://www.freedesktop.org/software/systemd/man/systemd.exec.html#StandardOutput=

Edit /lib/systemd/system/pisugar-server.service

StandardOutput=append:/tmp/pisugar.log
StandardError=append:/tmp/pisugar-error.log

Then reload the service

sudo systemctl daemon-reload
sudo systemctl restart pisugar-server
``