How To: Run a script on conda activate

I recently noticed that using a conda environment can come with a couple inconveniences. For example, since the default Python executable changes when activating conda, this means that the $PATH variable has been modified and some software can not be found anymore.

For instance, I can’t call PyMol from command line when in a conda environment because it somehow depends on the Python executable, it seems.

I recently installed some software into a conda env, that needs a couple of environment variables to run but which I only really need (or want) when running this software in this conda env because it messes with $PATH and disrupts my workflow otherwise.

Solution: it’s possible to have conda source a (shell) script that is only run when it’s actually activated. So put whatever commands you want (e.g. for setting environment variables) into a small script and place it in

[path_to_your_conda]/envs/[conda env name]/etc/conda/activate.d

Done. When you next fire up that env the script will be sourced.