TX (Rust)

Pack & unpack

Target inferred from extension; primary + parity, hashed throughout. Grab a binary below or cargo run -p tx-cli --.

tx-cli pack /data backup.tx
tx-cli unpack backup.tx ./restore

Inspect & verify

List members, check hashes/Merkle + signatures, see stats.

tx-cli list -l backup.tx
tx-cli verify backup.tx
tx-cli stats --json backup.tx

Sign & trust

Ed25519 keys; verification is fail-closed once a trust store exists.

tx-cli gen-key ~/.tx/key
tx-cli pack /data backup.tx --sign-key ~/.tx/key
tx-cli trust add <pubkey>

Pack ISO

Index (index.idx) embedded and sorted first on disk.

tx-cli pack /data image.iso

Resilience

Primary + redundancy, Merkle + hashes, trustable signatures.

• Tar → zstd → shards (parity by default) or full backup, hashed & signed.
• Tar-compatible: .tx starts with .tx/manifest.json as the first tar entry, then the payload and shards/backup; tar xf still works.
• Optional Ed25519 signatures; trust-store enforcement.

ISO Path

Index-first images with manifest embedded.

• Staging copy with index.idx + iso-manifest.json.
• mkisofs/genisoimage/xorriso/xorrisofs places index first.
• Mount directly; no sidecars.

Signing

Passphrase and ssh-agent friendly.

export TX_SIGN_KEY=~/.ssh/colossus
export TX_SIGN_PASSPHRASE='hunter42'   # if encrypted
export TX_SIGN_USE_AGENT=1            # prefer ssh-agent if loaded

Recovery Modes

Archive vs. file-aware repair.

• Default parity: per-group shards (small files grouped, large files per group) → repair individual groups/files with ~25–30% overhead.
• --duplicate: full backup blob (larger, simpler) → whole-archive recovery if primary is bad.
• Plain tar fallback: tx unpack also extracts .tar/.tgz/.tbz2/.tzst when no TX metadata is present (no verification).

Tar surface

The everyday bsdtar flags, covered.

• list/-l, --strip-components, --exclude, --path include.
• stdin/stdout (-), -v verbose, --files-from/-T.
• Codec autodetect by magic (gzip/bzip2/zstd/xz), with a decompression-bomb cap.

Sparse files

Holes never touch RAM or disk.

• Pack emits real GNU sparse entries via SEEK_DATA/SEEK_HOLE.
• A 200 MB sparse image packs at ~20 MB RSS, not 200.
• Unpack re-punches holes (--sparse), verified by block count.

Incremental & append

Snapshots and in-place edits.

• --listed-incremental snapshots (path/mtime/size); deletions replayed on restore.
• append/update reconstruct, merge by path, re-pack and re-sign.

Metadata

Preserved end to end.

• perms + mtime by default; ownership via --preserve-owner.
• xattrs / ACLs / SELinux as SCHILY.xattr.* PAX records.
• POSIX special files (FIFO, char/block devices).

Streaming

RAM-bounded packing.

• Tar spools to a temp file; parity shards stream to disk one group at a time.
• A 1 GB pack runs in ~8 MB RSS (was 2.4 GB).

Trust & safety

Fail-closed by construction.

• Verifier recomputes the Merkle root from hashes; a transplanted signature is rejected.
• Unsigned archives rejected when a trust store is configured.
• Bounded allocations + a 64 GiB decompressed backstop; zip-slip guarded.

TX vs PAR2

How it differs.

• TX is tar-compatible (tar xf *.tx works); PAR2 is a sidecar over files/tars.
• TX stores manifest/hashes/signatures inside the archive; PAR2 does not sign.
• TX parity defaults to per-group shards; PAR2 parity is per-file/chunk across multiple files.
• TX is one artifact (metadata+data); PAR2 requires managing .par2 sets separately.

TX vs 7zip

Format & trust differences.

• TX is tar-compatible (tar xf works); 7zip is its own container.
• TX embeds manifest/hashes/signatures; 7zip has checksums but no signing.
• TX has built-in parity; 7zip needs external parity.
• TX is one artifact (metadata+data); 7zip often paired with sidecar parity.

Inside .tx

• Front: uncompressed tar so tar xf works.
• Metadata: .tx/manifest.json is the first entry (hashes, signatures, group map); tar users see it upfront.
• Data: .tx/groups/<gid>/shard.N.bin (parity mode) or .tx/backup.tar.zst (duplicate mode).

TX Pack

walk → tar → zstd → hash/merkle → optional sign → write primary+backup.

ISO Pack

stage → index/manifest → mkisofs sorted so index is first track.

Unpack

verify manifest/signatures → validate hashes → fallback to backup → untar.

Linux

Native and musl.

cargo build --release
CC_x86_64_unknown_linux_musl=musl-gcc \
  cargo build --release --target x86_64-unknown-linux-musl

Windows

MinGW toolchain required.

CC_x86_64_pc_windows_gnu=x86_64-w64-mingw32-gcc \
  cargo build --release --target x86_64-pc-windows-gnu

macOS

Build on macOS or with Apple SDK/clang (osxcross).

cargo build --release --target x86_64-apple-darwin

Linux

• tx-cli-linux-amd64 — x86_64, static musl
• tx-cli-linux-arm64 — aarch64, static musl

macOS

• tx-cli-macos-arm64 — Apple silicon
• tx-cli-macos-amd64 — Intel

Windows

• tx-cli-windows-amd64.exe — x86_64