error with nohup

[anandadake]

The Example shown above is not work in background with nohup command...

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Document Details

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• ID: 05d8137c-88a5-3476-42a1-ccf3b00d4a2f
• Version Independent ID: 4bb8981f-bde1-5701-aa4e-4cd8f53dcbbf
• Content: Quickstart - connect a device and send telemetry to Azure IoT Central
• Content Source: articles/iot-develop/quickstart-send-telemetry-central.md
• Service: iot-develop
• GitHub Login: @timlt
• Microsoft Alias: timlt

[RamanathanChinnappan-MSFT]

@anandadake

Thanks for your feedback! We will investigate and update as appropriate.

[SatishBoddu-MSFT]

Hello @anandadake Could you please point us to the section where we see the nohup command. //?

[anandadake]

Hello @SatishBoddu-MSFT

I'm referring bellowed article https://learn.microsoft.com/en-us/azure/iot-develop/quickstart-send-telemetry-central?pivots=programming-language-python

and after all prerequisite i trying this nohup ./venv/bin/python ./temp_controller_with_thermostats.py but fails and gives error related to asyncio...

Note : without nohup script works fine .

[anandadake]

Additionally i'm using Python 3.8.0

[timlt]

@anandake, thanks for running the quickstart! The sample script is tested with Python and runs on the versions and OS's listed at start of article. It is not tested or supported for running with the 'nohup' command which tries to run the process in the background.

[anandadake]

Is that mean that the script is not capable to run in background? If not, then how the actual device sends the telemetry ?

[timlt]

@ryanwinter for comment on script sending telemetry.

[ryanwinter]

This is likely cause by the environment variables required by the script not being available in the nohup subprocess.

Can you provide:

1. The stack trace of the error you are seeing so I can look at the exact line
2. The output for export

[ryanwinter]

I replicated the error with the following output:

The problem is that the sample waits for input from the user, however stdin isn't available with nohup.

Device was assigned
iotc-79c9aa46-aade-403d-8722-829500ee91b5.azure-devices.net
python
Updating pnp properties for root interface
{'serialNumber': 'some_serial_number'}
Updating pnp properties for thermostat1
{'thermostat1': {'maxTempSinceLastReboot': 98.34, '__t': 'c'}}
Updating pnp properties for thermostat2
{'thermostat2': {'maxTempSinceLastReboot': 48.92, '__t': 'c'}}
Updating pnp properties for deviceInformation
{'deviceInformation': {'swVersion': '5.5', 'manufacturer': 'Contoso Device Corporation', 'model': 'Contoso 4762B-turbo', 'osName': 'Mac Os', 'processorArchitecture': 'x86-64', 'processorManufacturer': 'Intel', 'totalStorage': 1024, 'totalMemory': 32, '__t': 'c'}}
Listening for command requests and property updates
Press Q to quit
Sending telemetry from various components
Traceback (most recent call last):
  File "temp_controller_with_thermostats.py", line 419, in <module>
    asyncio.run(main())
  File "/usr/lib/python3.8/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "temp_controller_with_thermostats.py", line 398, in main
    await user_finished
  File "/usr/lib/python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "temp_controller_with_thermostats.py", line 237, in stdin_listener
    selection = input("Press Q to quit\n")
OSError: [Errno 9] Bad file descriptor
ERROR:asyncio:_GatheringFuture exception was never retrieved
future: <_GatheringFuture finished exception=CancelledError()>
asyncio.exceptions.CancelledError
ERROR:asyncio:_GatheringFuture exception was never retrieved
future: <_GatheringFuture finished exception=CancelledError()>
asyncio.exceptions.CancelledError

[timlt]

Thanks @ryanwinter

@anandadake thanks again for running the quickstart sample and raising the question. You have the info to run the script at this point, just run as indicated in the doc (copy and paste the code, without using 'nohup' command). Thank you!

please-close

[anandadake]

Then how could i run in background process ? My intention is to run the script on VM and it should keep running even after i close the shell or logout from VM

[ryanwinter]

Hi @anandadake,

This is a sample is was not written to be run as a background task, hence the reliance on user input during execution. This is not a supported scenario for any of our samples and guides.

You could modify the script to remove the STDIN reliance as a first step to what you are looking for.

Ryan