start-prefetch will attempt to fetch a runtime closure for an attribute path via bittorrent using aria2. At the moment the closure is computed by following References: headers in the .narinfos, so the whole closure must be available. Later on we might be able to work around incomplete runtime closures by using the build-time closure instead.

Config is currently done by changing variables at the top of the source file.

0. ./dev to get a nix-shell with deps
1. Start aria2c: aria2c -D --enable-rpc=true --bt-detach-seed-only=true
2. Checkout a repo of torrent & narinfos, e.g. https://github.com/srd424/aux-torrent, set REPO_DIR to checkout dir
3. Set NIX_EXPR to a path containing a nix expression, e.g. a checkout of https://github.com/auxolotl/core
4. Set ATTR_PATH to a nix attribute path, e.g. stdenv
5. run start-prefetch

aria2p show can be used to monitor download progress; downloads will go to DL_DIR, by default ~/.cache/nibbit/nix. When finished, nix --extra-experimental-features nix-command copy --from file://$HOME/.cache/nibbit/nix <STORE_PATH>should import the cached binaries into your nix store (the top-level <STORE_PATH> is printed by start-prefetch.)

• a proper command line
• a config file
• tool to check if the download of a given closure has finished (which could then automatically import the nars)
• a proper tool to 'publish' torrents
• a cleanup/prune tool to remove older torrents (maybe anything that's not in the subscribed/published closures, possibly plus a few older files up to a defined limit)
• support for multiple simultaneous expression + attribute combinations