You can’t use shell syntax in the env: definition. What you can do is use a set-env command in a previous step:

- name: set NOW
  run: |
    echo "::set-env name=NOW::$(date +'%Y-%m-%dT%H:%M:%S')"

After that env.NOW will be available. Note however that there’s a currently open bug that may lead to the date being reformatted, a workaround has been discussed on this forum: ISO 8601 string in job output is automatically parsed

Did not work. Getting the same validation errors.
How do I have to reference variable NOW in tag property?

${{ env.NOW }}?
${{ NOW }}?
$NOW?
${{ $NOW }}?

${{ env.NOW }} should work, yes. Mind that it the step using the variable must be a separate step after the one setting the environment variable. Saying more about possible reasons isn’t really possible without the workflow code, I’m afraid.

Okay, thanks a lot! I just changed the pattern to:

echo "::set-env name=NOW::v$(date +'%Y%m%d.%H%M%S')"

This way the date is accepted by the release-action tag. It looks like that which satisfies my needs: v20200623.092227

An update as of January 2022, when I tried to use the code mentioned above, I got a warning that GitHub deprecated the “set-env” command:

The set-env command is disabled. Please upgrade to using Environment Files or opt into unsecure command execution by setting the ACTIONS_ALLOW_UNSECURE_COMMANDS environment variable to true. For more information see: GitHub Actions: Deprecating set-env and add-path commands | GitHub Changelog

Instead, this is what I got working (note I wanted my time in the format of “2021.12.31” ):

run: echo “NOW=$(date +’%Y.%m.%d’)” >> $GITHUB_ENV

and when using in a field somewhere, it’s the same as before, such as:

title: “${{ env.NOW }}”

So my in the context of all my steps it looks like this, where I wanted the tags and titles to be the date:

steps:
  # ...
  - name: set env
    run: echo "NOW=$(date +'%Y.%m.%d')" >> $GITHUB_ENV


name: "Build & test"

run: |

echo "done!"


uses: "marvinpinto/action-automatic-releases@latest"

with:

repo_token: "${{ secrets.GITHUB_TOKEN }}"

automatic_release_tag: "${{ env.NOW }}"

prerelease: false

title: "${{ env.NOW }}"

files: |

test.txt