github-and-codesandbox-guide/.github/workflows/github-pages.yml

name: github-pages
on:
  push:
    branches: [master]
jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: build
        run: |
          git -c "user.name=bot" -c "user.email=bot@example" subtree add --prefix pages origin gh-pages
          npx @marp-team/marp-cli README.md -o pages/index.html
      - id: git_status
        run: echo "::set-output name=mod::$(git status pages --porcelain)"
      - name: push
        if: steps.git_status.outputs.mod != ''
        run: |
          git -c "user.name=bot" -c "user.email=bot@example" commit -a -m update
          git subtree push --prefix pages origin gh-pages