rargz

rargz is a fast parallel tar + zstd archiver. It walks a directory, emits a deterministic tar stream, and compresses chunks concurrently with independent zstd workers.

Features

• Parallel tar stream generation with independent zstd workers
• Optional progress indicator (auto-disables when stderr is not a TTY)
• Produces standard .tar.zst by default (compatible with tar --zstd or zstd -d)
• Opt-in .rargz chunked format with cooperative parallel decompression
• Streaming extraction (stdin to filesystem) with automatic format detection
• Metadata inspection via --list and --count

Installation

cargo install rargz

From source:

cargo install --path .

Archiving

Create a standard .tar.zst archive and write it to stdout:

rargz path/to/input > archive.tar.zst

Enable the chunked .rargz format:

rargz --format rargz path/to/input > archive.rargz

Tune chunk size and thread count:

rargz --chunk-size 4MiB --jobs 8 path/to/input > archive.tar.zst

Disable the progress spinner explicitly when scripting:

rargz --no-progress path/to/input > archive.tar.zst

Extraction

Extraction reads from stdin (or a path argument) and writes the output to the directory specified with -o/--output:

rargz --extract archive.tar.zst -o ./output

Or stream over stdin:

cat archive.tar.zst | rargz --extract -o ./output

rargz auto-detects plain .tar.zst streams versus chunked .rargz streams. Standard archives are decompressed sequentially for compatibility. Chunked archives fan out to the worker pool for parallel decompression and untar.

Progress is enabled by default; disable it with --no-progress or by piping stderr.

Inspecting archives

Scan metadata without unpacking by either piping the archive or passing it as an argument:

rargz --list archive.tar.zst
rargz --count archive.rargz

--list prints each entry path (similar to tar -tf), while --count emits a single total. Both modes skip extracting payloads and work with either format. When no path is supplied, the commands read from stdin (so you can still pipe data in).

Format details

• .tar.zst mode produces a pure tar stream compressed with zstd. Fully compatible with standard tools:

  • tar --zstd -xf archive.tar.zst
  • zstd -d archive.tar.zst | tar -xf -

• .rargz mode adds a small header (RARGZ\0, version, chunk size) and length-prefixes each compressed chunk. The extra framing allows rargz to decompress different chunks in parallel during extraction or inspection.

Safety

• Parent directory components (..) are removed from archive paths to prevent extraction from writing outside the target tree.
• Any error in the pipeline cancels all worker threads immediately.

License

MIT. See LICENSE for details.