nix3-show-derivation(1)

📦
version 2.8.0 · 2 versions
, in debian bookworm

💅 nix3-show-derivation(1) — General Commands Manual

okay bestie, welcome to the nix3-show-derivation page 🌸 this is the General Commands Manual version, and we're about to get into it.

⚠️ Warning: This program is experimental and its interface is subject to change. no cap, that's literally in the manual. it might get a glow-up and change on you, so don't get too attached to the exact vibes. 😭

✨ Name ✨

nix show-derivation — show the contents of a store derivation 🎀

🌈 Synopsis 🌈

nix show-derivation [option…] installables…

🦋 Examples 🦋

okay so here's the tea, three iconic little scenarios:

  • Show the store derivation that results from evaluating the Hello package:
# nix show-derivation nixpkgs#hello
{
"/nix/store/s6rn4jz1sin56rf4qj5b5v8jxjm32hlk-hello-2.10.drv": {
  …
}
}
  • Show the full derivation graph (if available) that produced your NixOS system:
# nix show-derivation -r /run/current-system
  • Print all files fetched using fetchurl by Firefox’s dependency graph:
# nix show-derivation -r nixpkgs#firefox \
| jq -r '.[] | select(.outputs.out.hash and .env.urls) | .env.urls' \
| uniq | sort
💡 Note that .outputs.out.hash selects fixed-output derivations (derivations that produce output with a specified content hash), while .env.urls selects derivations with a urls attribute. iykyk, that's the whole trick 🧚

💖 Description 💖

This command prints on standard output a JSON representation of the store derivations to which installables evaluate. Store derivations are used internally by Nix — they're lowkey the main characters of the build system. They are store paths with extension .drv that represent the build-time dependency graph to which a Nix expression evaluates. periodt. 👑

By default, this command only shows top-level derivations, but with --recursive, it also shows their dependencies. so if you want the whole family tree, you know what to do 🌳

The JSON output is a JSON object whose keys are the store paths of the derivations, and whose values are a JSON object with the following fields:

  • outputs: Information about the output paths of the derivation. This is a JSON object with one member per output, where the key is the output name and the value is a JSON object with these fields:
    • path: The output path.
    • hashAlgo: For fixed-output derivations, the hashing algorithm (e.g. sha256), optionally prefixed by r: if hash denotes a NAR hash rather than a flat file hash.
    • hash: For fixed-output derivations, the expected content hash in base-16.

Example:

"outputs": {
"out": {
  "path": "/nix/store/2543j7c6jn75blc3drf4g5vhb1rhdq29-source",
  "hashAlgo": "r:sha256",
  "hash": "6fc80dcc62179dbc12fc0b5881275898f93444833d21b89dfe5f7fbcbb1d0d62"
}
}
  • inputSrcs: A list of store paths on which this derivation depends.
  • inputDrvs: A JSON object specifying the derivations on which this derivation depends, and what outputs of those derivations. For example,
"inputDrvs": {
"/nix/store/6lkh5yi7nlb7l6dr8fljlli5zfd9hq58-curl-7.73.0.drv": ["dev"],
"/nix/store/fn3kgnfzl5dzym26j8g907gq3kbm8bfh-unzip-6.0.drv": ["out"]
}
💅 specifies that this derivation depends on the dev output of curl, and the out output of unzip. slay.
  • system: The system type on which this derivation is to be built (e.g. x86_64-linux).
  • builder: The absolute path of the program to be executed to run the build. Typically this is the bash shell (e.g. /nix/store/r3j288vpmczbl500w6zz89gyfa4nr0b1-bash-4.4-p23/bin/bash). iconic.
  • args: The command-line arguments passed to the builder.
  • env: The environment passed to the builder.

👑 Options 👑

  • --recursive, -r — Include the dependencies of the specified derivations. get the whole squad 🫶

🌸 Common evaluation options 🌸

  • --arg name expr — Pass the value expr as the argument name to Nix functions.
  • --argstr name string — Pass the string string as the argument name to Nix functions.
  • --eval-store store-url — The Nix store to use for evaluations.
  • --impure — Allow access to mutable paths and repositories. living dangerously, we love that for you 🙈
  • --include, -I path — Add path to the list of locations used to look up <...> file names.
  • --override-flake original-ref resolved-ref — Override the flake registries, redirecting original-ref to resolved-ref.
  • --commit-lock-file — Commit changes to the flake’s lock file.
  • --inputs-from flake-url — Use the inputs of the specified flake as registry entries.
  • --no-registries — Don’t allow lookups in the flake registries. ⚠️ This option is deprecated; use --no-use-registries instead.
  • --no-update-lock-file — Do not allow any updates to the flake’s lock file.
  • --no-write-lock-file — Do not write the flake’s newly generated lock file.
  • --override-input input-path flake-url — Override a specific flake input (e.g. dwarffs/nixpkgs). This implies --no-write-lock-file.
  • --recreate-lock-file — Recreate the flake’s lock file from scratch.
  • --update-input input-path — Update a specific flake input (ignoring its previous entry in the lock file).

⭐ Options that change the interpretation of installables ⭐

  • --derivation — Operate on the store derivation rather than its outputs.
  • --expr expr — Interpret installables as attribute paths relative to the Nix expression expr.
  • --file, -f file — Interpret installables as attribute paths relative to the Nix expression stored in file. If file is the character -, then a Nix expression will be read from standard input. cute AND useful 💜

and that's the whole page bestie, you ate that 💅✨ this was nix3-show-derivation(1) from the General Commands Manual, so if you ever need to cite it, that's the source and version right there — go forth and inspect some derivations, mwah 🎀🦋💖

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