aws: not found

Once I'm in the shell, I get the following error no matter what command I run:

/bin/sh: 1: aws: not found

I'm trying to run this on Ubuntu under Windows 10' WSL.

As an aside-but might be related--when trying to run aws-shell, I had to change the first line from:

#!/usr/bin/python

to:

#!/usr/bin/python3