Does --hardlink work safely on Windows? What happens if a hardlink fails mid-way?

[amasen02]

I am using dupehunter on Windows 11 and want to use to reclaim space. A few questions:

1. Are NTFS hardlinks on Windows supported, or is Linux/macOS only?
2. If the process is interrupted mid-way (power failure, Ctrl+C), will I end up with partial hardlinks or corrupt files?
3. Is there a dry-run mode I can use to preview exactly what will be hardlinked before committing?

[amasen02]

All three questions answered below.

1. NTFS hardlinks on Windows

Yes — dupehunter fully supports NTFS hardlinks on Windows. NTFS has supported hardlinks since Windows Vista, and the Node.js call that dupehunter uses is cross-platform. There is one NTFS-specific constraint: hardlinks cannot cross drive letters (e.g., you cannot hardlink → ). dupehunter automatically detects this — files on different volumes are never suggested as hardlink candidates.

2. Safety during interruption

dupehunter uses an atomic two-step operation for each hardlink:

1. Create the hardlink at the destination path.
2. Only if step 1 succeeds, remove the original.

If the process is interrupted between step 1 and step 2, you get two paths pointing to the same inode (no data loss). Re-running dupehunter after an interrupted session correctly identifies these as already-hardlinked and reports 0 bytes reclaimable — so the idempotent re-run is always safe.

If interrupted before step 1 completes (e.g., during a large batch), the files already processed are safe (hardlinked), and unprocessed files are untouched originals. No partial or corrupt state is possible.

3. Dry-run mode

Use the flag to preview all operations without touching the filesystem:

dupehunter --hardlink --dry-run ~/Downloads

This outputs the same summary table as a real run, including which files would be hardlinked and how much space would be reclaimed, but makes zero filesystem changes. It is the recommended first step before any destructive operation.