WARNING: The script pip3.8 is installed in ‘/usr/local/bin’ which is not on PATH

This question has been answered on the serverfaults forum: Here is a link to the question.

You need to add the following line to your ~/.bash_profile or ~/.bashrc file.

 export PATH="/usr/local/bin:$PATH"

You will then need to profile, do this by either running the command:

source ~/.bash_profile

Or by simply closing your terminal and opening a new session. You should continue to check your PATH to make sure it includes the path.

echo $PATH