How to Pass an Env Var Between Steps With GITHUB_ENV in GitHub Actions

A shell export dies when its step ends; appending to GITHUB_ENV makes the value a real env var for later steps.

Append NAME=value to the $GITHUB_ENV file in the producing step. Every subsequent step in the same job reads $NAME (or ${{ env.NAME }}).

Steps

• In the producing step, append NAME=value to $GITHUB_ENV.
• Reference $NAME or ${{ env.NAME }} in any later step.
• Remember the producing step itself cannot read the new value.

Workflow

steps:
  - run: echo "BUILD_TAG=${GITHUB_SHA::7}" >> "$GITHUB_ENV"
  - run: echo "Building $BUILD_TAG"
  - run: docker build -t app:${{ env.BUILD_TAG }} .

Gotchas

• Multiline values need a heredoc delimiter so the parser knows where the value ends.
• Never write secrets to $GITHUB_ENV; reference secrets.NAME so they stay masked.

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