example that uses PIPESTATUS

check_utf.yml

name: Check UTF-8

# This workflow is triggered on pushes to the repository.
on: push

# see https://tldp.org/LDP/abs/html/internalvariables.html#PIPESTATUSREF
jobs:
  check_files:
    runs-on: self-hosted
    steps:
      - uses: actions/checkout@v2
        name: Check out repository
      - run: |
          ./check_utf8.sh 2>&1| tee failed_files.txt
          exit ${PIPESTATUS[0]}
        name: Run check_utf8.sh
      - uses: actions/upload-artifact@v2
        name: Upload artifact
        with:
          name: failed_files.txt
          path: failed_files.txt