Bare downloader (aria2c replacement)

peel --no-extract is a parallel-ranged-GET downloader with mirror fan-out, SHA-256 verification, and resume. It covers the same surface as aria2c, minus the extract step.

The basic case

peel https://example.com/big-file.iso --no-extract

Behavior:

• Issues 4 parallel ranged GETs against the URL.
• Writes the bytes to <basename>.peel.part (sparse).
• On clean completion, renames to the final filename (big-file.iso).

The bytes never pass through a decoder. No hole-punching occurs, since no decoder advances the puncher. The part-file grows to the full Content-Length.

--download-only is an alias for callers who prefer aria2c-style naming.

With explicit output path

peel https://example.com/big-file.iso --no-extract -o /downloads/
peel https://example.com/big-file.iso --no-extract -o /downloads/renamed.iso

Same semantics as extract mode: a trailing slash makes -o a directory, otherwise it is the final file path.

With hash verification

peel https://example.com/big-file.iso \
  --no-extract \
  --sha256 ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad

The SHA-256 is checked against the downloaded bytes. This is the same hash that sha256sum big-file.iso would produce after the download finishes, without the separate hash step.

With mirror fan-out

peel https://primary.example.com/big-file.iso \
  --mirror https://eu.mirror.example.com/big-file.iso \
  --mirror https://us.mirror.example.com/big-file.iso \
  --sha256 ba7816bf... \
  --no-extract

All Multi-mirror downloads machinery applies: parallel HEAD validation at startup, per-mirror health tracking, 30s exclusion on failure, aggregate bandwidth cap.

With bandwidth cap

peel https://example.com/big-file.iso \
  --no-extract \
  --max-bandwidth 10MB/s

Useful when:

• Downloading on a shared link where saturating the pipe is disruptive.
• Cron-scheduled downloads that should run at steady-state rather than burst-and-idle.

With resume across kills

--no-extract has the same resume guarantee as extract mode. Ctrl-C / kill -9 / network drop / OOM:

peel https://example.com/big-file.iso --no-extract
# ... interrupted at 40% ...

peel https://example.com/big-file.iso --no-extract
# Picks up where it left off, completes the rest.

The sidecars (big-file.iso.peel.part and big-file.iso.peel.ckpt) stay on disk between runs.

Choosing peel --no-extract over aria2c

peel --no-extract applies when callers want the streaming/resumable/parallel guarantee without a separate extract step. For a plain download (no archive) where the eventual extract is not a concern, it offers aria2c-level UX in one binary.

A typical script

#!/usr/bin/env bash
set -euo pipefail

URL=https://example.com/big-file.iso
SHA256=ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad
OUT=/downloads/big-file.iso

peel "$URL" \
  --no-extract \
  --sha256 "$SHA256" \
  --max-bandwidth 50MB/s \
  -o "$OUT"

echo "Downloaded and verified: $OUT"

Re-running this script after any failure resumes from the last checkpoint. Re-running it after a clean completion is a no-op (the file is already at $OUT, the sidecars are gone, and the next invocation downloads from scratch because there is no checkpoint to resume from).

For "only download if not already present" semantics, wrap with a check:

if [ ! -s "$OUT" ]; then
  peel "$URL" --no-extract --sha256 "$SHA256" -o "$OUT"
fi

(The -s test checks for non-empty, which catches both "missing" and "empty partial".)

Non-goals

• Torrent client. No DHT, no peers.
• Protocol-coercing tool. HTTP / HTTPS only.
• Auth-aware downloader. No OAuth flow, no browser-cookie import. For URLs that require auth, pre-sign or pass a custom Authorization header via a reverse proxy. peel honours HTTP_PROXY / HTTPS_PROXY / NO_PROXY env vars.