Bug: str2str_tcp service fails silently due to background process execution

[GeorgeTownsendd]

Observed Behavior

When the service fails to connect to GPS hardware, logs show:

Mar 21 04:17:05 gnss-host2 run_cast.sh[451]: stream server start error
Mar 21 04:17:05 gnss-host2 systemd[1]: str2str_tcp.service: Deactivated successfully.
Mar 21 04:17:05 gnss-host2 systemd[1]: Started str2str_tcp.service - RTKBase Tcp.

Despite the connection error, systemd reports the process exited with success and doesn't trigger the Restart=on-failure directive.

Technical Cause

The script launches str2str as a background process:

${cast} -in ${!1} -out ${out_tcp} -b 1 -t ${level} -fl ${logdir}/str2str_tcp.log &

This causes the parent script to exit with success (0) regardless of whether the background process connects successfully. Systemd interprets this exit code as a successful service completion rather than a failure.

Impact

• Dependent gpsd service fails to start: ExecStartPre=systemctl is-active str2str_tcp.service (code=exited, status=3)
• GPS functionality unavailable until manual intervention
• Automatic recovery mechanisms ineffective

Workaround

For now I have set Restart=Always in the systemd file. This works because the only time the str2str exits is when there is a failure. I think it relies on how systemd handles Type=forking (it watches the subprocess after the parent exits).

Thanks

Thanks very much for this project- we are using it at the University of Newcastle to help study GNSS interferometric reflectometry.

[Stefal]

Thank you for the report.

I remember I've tested many configurations with Type=forking/simple/... and launching str2str in background or not. But it's old, and I don't remember why I ended up with forking and running str2str in a background process.

After a few quick tests, it seems to work correctly with Type=simple and removing the & at the various str2str line end in run_cast.sh

I'd be happy if you could test this way and give me some feedback.