Protect a branch from direct push

This pre-push command blocks a push when the current branch is main or
master. You can still push by setting an env var for that one push.

# lefthook.yml

pre-push:
  commands:
    protect-main:
      run: |
        branch="$(git rev-parse --abbrev-ref HEAD)"
        case "$branch" in
          main|master)
            if [ "$ALLOW_PUSH_TO_MAIN" != "1" ]; then
              echo "Refusing direct push from protected branch '$branch'." >&2
              echo "Push a feature branch and open a PR instead, or set ALLOW_PUSH_TO_MAIN=1 to override." >&2
              exit 1
            fi
            ;;
        esac

Override for one push:

ALLOW_PUSH_TO_MAIN=1 git push