Python does not get environment variable when using cron.

[Shawn Milochik]

Here's a more "English" version of what people are trying to explain:

When you log into a Unix session, certain files in your home directory
are read and add environment variables to your session. When you run a
cron job, it does not do this. It still runs as "you" as far as
permissions go, but it is not identical to you typing the command in
an interactive session.

The easiest solution (in my opinion) is to write a bash script to
execute your Python script, and use that bash script to add those
environment variables. The most likely file you'll want to run is
.bashrc in your home directory. If you're on a Mac, it's .bash_login
instead.

Example:

#/usr/bin/env bash

source ~/.bashrc
path/my_script.py

Something like that should take care of it. If not, get creative --
add the "env" command to your bash script and have it send the output
to a file: env > cron_env.txt

Then run env in your interactive session and look for differences.

Shawn