update raspi notes

content/notes/raspberry-pi/index.md

@@ -81,6 +81,31 @@ $ sudo apt full-upgrade
 $ sudo reboot
 ~~~
 
+### Python 3
+
+#### Installing non-packaged modules
+
+I could not find `aprslib` as a package, so I had to install this myself.
+Debian did not allow the installation as it did before, so I had to create
+a virtual environment. And it went like this:
+
+~~~console
+$ python -m venv ~/.env
+$ source ~/.env/bin/activate
+$ pip install aprslib
+$ deactivate
+~~~
+
+I now have a similar line in my crontab:
+
+~~~crontab
+3 * * * * /home/dominic/.env/bin/python /home/dominic/bin/aprs_sendstatus.py
+~~~
+
+We could also create virtual environments per application, module, package etc.
+
+<https://www.raspberrypi.com/documentation/computers/os.html#python-on-raspberry-pi>
+
 ## Raspberry Pi 3
 
 ## Raspberry Pi 2