How to update an existing Conda environment with a .yml file

Question

How can a pre-existing conda environment be updated with another .yml file. This is extremely helpful when working on projects that have multiple requirement files, i.e.

Answer 1

Try using conda env update:

conda activate myenv
conda env update --file local.yml

Or without the need to activate the environment (thanks @NumesSanguis):

conda env update --name myenv --file local.yml