Sometimes in a GitHub Actions workflow, we want to inject environment variables from a .env.<environment-name> file.

For example, .env.test:

# .env.test
FOO=bar
BAZ=1

In order to do that, it’s quite tempting to use a third-party action (eg. action-dotenv-to-setenv) to do this, like so:

- uses: c-py/action-dotenv-to-setenv@v2
  with:
    env-file: .env.test

- run: echo $FOO # Will output `bar`

But now that GitHub Actions supports appending new environment variables to the $GITHUB_ENV file, I realized it would be pretty simple to replace this action with a one-liner script:

- run: grep -v '^\(#.*\|\s\?\)$' .env.test >> $GITHUB_ENV

- run: echo $FOO # Will output `bar`

We use a regular expression (❤️) to filter out (grep -v) empty and commented out lines (^(#.*|\s?)$) from .env.test, then we pipe the output to $GITHUB_ENV.