%env magic command not properly expanding environment variables in Google Colab

Question

Setting environment variables in Google Colab with %env doesn't seem to properly expand existing environment variables when prefixed by $:

> !echo $PATH
/usr/local/nvidia/bin:/usr/local/cuda/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/tools/node/bin:/tools/google-cloud-sdk/bin:/opt/bin

> %env PATH=$PATH
env: PATH=$PATH

> !echo PATH
PATH

I don't think setting environment variables with !export works either. Does anyone know a way around this?

Answer 1

This worked for me

!echo $PATH
OLD_ENV_PATH = %env PATH
%env PATH=$OLD_ENV_PATH:/test
!echo $PATH

%env uses python expansion, so you need to store value for env variable in some python variable, and then set env var referencing it.