Sending operations to device

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1

What product/components do you use and which version/fix level are you on?

Cumulocity IoT v 10.13

Is your question related to the free trial, or to a production (customer) instance?

Customer instance

What are you trying to achieve? Please describe it in detail.

I am looking to send OS commands to a device. For instance, I want to send the command to a Windows device of “mkdir c:\users\public\testdir”

Do you get any error messages? Please provide a full error message screenshot and log file.

  • Failure reasonUnhandled exception. exception=[WinError 2] The system cannot find the file specified
  • DescriptionExecute shell command: Test command
  • StatusFAILED
  • Result-

I can send the command “show help” and I get this response:

  • DescriptionShell command
  • StatusSUCCESSFUL
  • Resultshow packages show processes show memory show cpu-usage show disk-usage show agent logs remove apt-lists show logs [ERROR|WARN|INFO|DEBUG] show uptime show uptime since show uptime seconds exec reboot

Have you installed all the latest fixes for the products and systems you are using?

We are on 10.13 - we’re not ready to update to 10.14 yet

2

The error you are seeing is happening on the device while processing your command. The device agent there is responsible for error handling in this case (see: Device management library - Cumulocity IoT Guides). Can you describe the device agent you are using and what kind of operation you are sending to it?

3

That makes sense, thanks! I’m using the Python agent available on GitHub. I’m sending mkdir c:\users\public\testdir

4

The DM-Agent only supports the commands which are shown in the show help output (and on linux OS only).
It can be extended: Adding windows commands here and support could be easily done. You can rebuild the agent afterwards.

5

Thanks! I’ve found that I can add commands to local/lib/python3.10/site-packages/c8ydm/agentmodules/command_handler.py for Linux and those run after rebooting. For some reason that hasn’t worked on Windows yet…

6

It depends on how you run the dm-agent. When running from it’s sources (git clone).

pip3 install .
c8ydm.start

the changes should be recognized.

If you run

pip3 install c8ydm

the pre-packaged version from pypi is fetched and installed in

C:\users\<user>\AppData\Local\Programs\Python\<yourPythonVersion\Lib\site-packages

which is overwritten each time a new release if c8ydm is available. So not the proper way to do that.

I would prefer you clone the repo and use the first approach to build your own version of c8ydm.

7

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