DedupCommandofinds identical files on Linux and ZFS and reclaims the space safely · v0.9.2

Read me.txt — Notepad

DedupCommando — a terminal dedup commander for Proxmox ZFS pools. It finds identical files, gathers them into groups and gives terabytes back — with a safety snapshot before every action. · one binary, no daemon, over SSH · blake3 + byte-for-byte verify, atomic ops · exercised on a production Proxmox host: 6+ TB Double-click the icons to open the sections.

GitHub

Proxmox® is a registered trademark of Proxmox Server Solutions GmbH. DedupCommando is an independent project, not affiliated with or endorsed by Proxmox Server Solutions GmbH.

dedcom.exe — ssh root@pve

▶ autoplay

── the live demo needs JavaScript ──

An animated demo of the dedcom interface: a pool scan, a table of duplicate groups and an action dialog that starts with a snapshot.

Features

Dual-pane TUI

Groups on the left, files on the right, all from the keyboard. SSH, tmux, even an IPMI console. First run? The --classic wizard.

Snapshot before action

A ZFS snapshot is taken automatically before any delete or hardlink. Undo is one command.

Verify, don’t trust

blake3, byte-for-byte group compare and a re-hash right before acting. One changed byte cancels it.

Atomic or nothing

renameat2(RENAME_NOREPLACE) instead of “check, then rename”. No races by construction.

Idle profile

Scanning yields the disks to VMs and backups. The production host won’t notice.

Checkpoints

State lives in dedcom.db: interrupt a scan and it resumes where it stopped.

One Rust binary

The dedcom file is all there is. No dependencies, daemons or web UI.

Headless for scripts

--scan, --stats, --export-csv — for cron and reports.

Objects: 8Hidden features: 0

Data sheet — DC-SPEC-09

Item: dedcom
Type: TUI deduplication utility
Platform: Linux x86-64 / arm64 · OpenZFS ≥ 2.1
Habitat: Proxmox VE (native)
Hashing: blake3 + byte-for-byte verify
Status: v0.9.2 (beta) · 2026

Properties: Safety

The safety protocol is built in and cannot be switched off — that’s why the boxes are greyed out:

✓Safety snapshot

A ZFS snapshot automatically before every action. Seconds on a production pool — and terabytes saved.

✓Re-verification

A re-hash right before acting. Any mismatch stops it; the group goes back for review.

✓Atomic operations

renameat2(RENAME_NOREPLACE): the race condition is ruled out by the syscall itself.

✓Quarantine, not the void

“Deleting” moves files to quarantine. Bring one back precisely, without a full rollback.

⚠ On ZFS a destructive batch cannot run without its snapshot: if the snapshot fails, the batch is aborted. An invariant in the code, not a setting. Without ZFS there is no snapshot, so applying actions there is not recommended.

Install dedcom

Parameter	Value
OS	Linux x86-64 or arm64, glibc ≥ 2.39
FS	OpenZFS ≥ 2.1 (tested on 2.4.3)
Habitat	Proxmox VE; any host with ZFS will do
Terminal	any 256-color one, over SSH and in tmux
Access	root on the pool host

Listing 1 — install from the APT repository (Debian 13, Proxmox VE 9+)

# as root (the Proxmox default); on Debian without root run: sudo -i
curl -fsSL https://dedupcommando.github.io/apt/dedcom-archive-keyring.gpg \
  -o /usr/share/keyrings/dedcom-archive-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/dedcom-archive-keyring.gpg] https://dedupcommando.github.io/apt stable main" \
  | tee /etc/apt/sources.list.d/dedcom.list
apt update && apt install dedcom
dedcom --classic            # step-by-step wizard for the first run

Listing 2 — rehearse first

# a disposable loopback pool with duplicates: a risk-free playground
./scripts/make-test-pool.sh
dedcom                      # practice, then go production

Other Linux systems with glibc 2.39 or newer: download a release from GitHub, verify it and copy the binary to the host. Details: installation chapter of the manual.

Help: questions and answers

How safe is this on a production host?

Before any destructive action — an automatic ZFS snapshot, re-verification and atomic operations. “Deleted” files go to quarantine. The worst case is a one-command snapshot rollback. The Idle profile never starves VMs of I/O.

Hardlink? What about block cloning?

The classic mode is hardlink. Where OpenZFS supports block cloning, reflink is available — files stay independent but share blocks. The result is checked against the actual data placement, not indirect counters.

Why a TUI and not a web UI?

An extra daemon and an open port on storage cost security. You already have SSH, and dedcom draws its interface in any terminal. For scripting there are headless modes: --scan, --stats, --export-csv.

A terabyte-scale scan got interrupted — start over?

No: state is checkpointed to dedcom.db, so after a restart the scan resumes where it stopped.

What do I need to run it?

Linux x86-64 or arm64 with glibc 2.39 or newer (Debian 13, Ubuntu 24.04, Proxmox VE 9), an OpenZFS pool and a terminal. One binary, no daemon. Proxmox VE is the native habitat, but any ZFS host works.

Download dedcom

On Debian 13 and Proxmox VE 9 install it with apt (see the “Install” window). On other Linux systems with glibc 2.39 or newer, download a release from GitHub, verify it and copy the binary to the host.

Open releases

Documentation — Help Topics

Help topics are ordinary web pages. The manual and the release notes follow the latest release.

Install and first scan — APT, release binary, first run
User manual — 14 chapters: safety, scanning, actions, Commando, headless, hotkeys
Safety, recovery and limitations
Release notes — latest: v0.9.2
Verifying releases — checksums, signatures, provenance

Guides: file-level deduplication on ZFS · duplicate files on Proxmox VE storage · hardlink vs reflink · Linux duplicate file finder · questions and answers · compared with other tools

Releases on GitHub Source on GitHub

Regional Settings — language

This site in other languages. The program and its manual are in English.

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