GitHub Actions Tutorial — Step Outputs

Step Outputs

Steps within the same job share a runner, so you can pass data between them using step outputs ($GITHUB_OUTPUT) and environment files ($GITHUB_ENV). These mechanisms replace the deprecated set-output and set-env commands.

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GITHUB_OUTPUT — Step Outputs

Write key-value pairs to $GITHUB_OUTPUT to create step outputs:

steps:
  - name: Set output
    id: my-step
    run: echo "version=2.1.0" >> "$GITHUB_OUTPUT"

  - name: Use output
    run: echo "Version is ${{ steps.my-step.outputs.version }}"

Multiple Outputs

steps:
  - name: Set multiple outputs
    id: info
    run: |
      echo "version=2.1.0" >> "$GITHUB_OUTPUT"
      echo "sha=${GITHUB_SHA::7}" >> "$GITHUB_OUTPUT"
      echo "branch=${GITHUB_REF_NAME}" >> "$GITHUB_OUTPUT"

  - name: Use all outputs
    run: |
      echo "Version: ${{ steps.info.outputs.version }}"
      echo "SHA: ${{ steps.info.outputs.sha }}"
      echo "Branch: ${{ steps.info.outputs.branch }}"

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GITHUB_ENV — Persistent Environment Variables

Variables set with $GITHUB_ENV are available in all subsequent steps in the same job:

steps:
  - name: Set env var
    run: echo "MY_VERSION=2.1.0" >> "$GITHUB_ENV"

  - name: Use env var (next step)
    run: echo "Version is $MY_VERSION"

  - name: Use in expression
    run: echo "Also available as ${{ env.MY_VERSION }}"

GITHUB_OUTPUT vs GITHUB_ENV

Feature	$GITHUB_OUTPUT	$GITHUB_ENV
Scope	Step-to-step (via expressions)	All subsequent steps
Access	${{ steps.id.outputs.key }}	$KEY or ${{ env.KEY }}
Use case	Structured data, conditionals	Env vars for commands
Cross-job	Yes (via job outputs)	No (same job only)

Rule of thumb:

• Use $GITHUB_OUTPUT for data you’ll use in if: conditions or pass to other jobs
• Use $GITHUB_ENV for environment variables your shell commands need

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GITHUB_PATH — Add to PATH

Add directories to the system PATH for subsequent steps:

steps:
  - name: Install custom tool
    run: |
      mkdir -p "$HOME/my-tools"
      cp my-binary "$HOME/my-tools/"
      echo "$HOME/my-tools" >> "$GITHUB_PATH"

  - name: Use custom tool
    run: my-binary --version     # now available in PATH

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Multi-Line Outputs

For values containing newlines, use a delimiter:

steps:
  - name: Set multi-line output
    id: changelog
    run: |
      EOF=$(dd if=/dev/urandom bs=15 count=1 status=none | base64)
      echo "content<<$EOF" >> "$GITHUB_OUTPUT"
      echo "Line 1: Bug fixes" >> "$GITHUB_OUTPUT"
      echo "Line 2: New features" >> "$GITHUB_OUTPUT"
      echo "$EOF" >> "$GITHUB_OUTPUT"

  - name: Use multi-line output
    run: echo "${{ steps.changelog.outputs.content }}"

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Step Outcome and Conclusion

Every step has an outcome you can check:

steps:
  - name: Risky step
    id: risky
    continue-on-error: true
    run: exit 1

  - name: Check outcome
    run: |
      echo "Outcome: ${{ steps.risky.outcome }}"         # failure
      echo "Conclusion: ${{ steps.risky.conclusion }}"    # success (because continue-on-error)

Property	With continue-on-error: true	Without
outcome	failure (actual result)	failure
conclusion	success (after applying continue-on-error)	failure

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Common Mistakes

Mistake	Fix
Using deprecated ::set-output	Use echo "key=value" >> "$GITHUB_OUTPUT"
Using deprecated ::set-env	Use echo "KEY=value" >> "$GITHUB_ENV"
Missing step id:	Outputs require an id: on the producing step
Env var not available	$GITHUB_ENV only affects subsequent steps, not the current one
Multi-line value truncated	Use the delimiter syntax with <<EOF

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Quick Reference

File	Purpose	Access
$GITHUB_OUTPUT	Step outputs	${{ steps.id.outputs.key }}
$GITHUB_ENV	Persistent env vars	$KEY or ${{ env.KEY }}
$GITHUB_PATH	Add to PATH	Available in next steps
$GITHUB_STEP_SUMMARY	Job summary markdown	Renders in Actions UI

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