Problems about executing the flow graph and pythonpath

Hello everybody!

I am new to GNU Radio and met some problems. I wrote an OOT module and compiled it successfully. However, when I used GRC to execute the flow graph including OOT blocks, it shows that "ModuleNotFoundError: No module named 'gadget'".

I searched a lot about that. And I found that the OOT python packages are installed in /usr/local/lib/python3/dist-packages, which is not in sys.path of Python. So I added 'export PYTHONPATH=/usr/local/lib/python3/dist-packages:$PATHONPATH'  to .bashrc. Luckily, I can import OOT module and execute the flow graph in terminal using 'python3 flow_graph.py' but in GRC it still not works and prints the same error message.

My Environment:

Ubuntu 20.04.1, GNURadio 3.8.1.0,  obtained from apt tools.

Thank you in advance!

idrey