nix3-formatter-run(1)

📦 version 2.35.3, in fedora 44

💅 nix3-formatter-run(1) — the Nix manual, bestie edition ✨

okay so you're reading the manual page for nix3-formatter-run(1) from the Nix general commands manual, and honestly? it's giving glow-up-for-your-code. let's go 🫶

⚠️ Warning — this program is experimental and its interface is subject to change. no cap. treat it like a situationship, not a marriage 💀

🌸 Name 🌸

nix formatter run — reformat your code in the standard style ✨ (basically it makes your files pretty, but like, correctly pretty, not just vibes)

🎀 Synopsis 🎀

nix formatter run [option…] args…

🦋 Description 🦋

so nix fmt (which is literally just an alias for nix formatter run, same girl different name 💅) calls the formatter that's specified in the flake. that's it. that's the whole job.

want to send some flags to the formatter itself? use -- and then the flags. that's the doorway 🚪✨

any arguments you pass get forwarded to the formatter too. bestie, typically those are the files you want formatted. like, the whole point.

also!!! the environment variable PRJ_ROOT (according to prj-spec) will be set to the absolute path to the directory containing the closest parent flake.nix relative to the current directory. it goes looking upward for its home 🏠🔍

🌈 Example 🌈

want to use the official Nix formatter? say less:

# flake.nix
{
  outputs = { nixpkgs, self }: {
    formatter.x86_64-linux = nixpkgs.legacyPackages.${system}.nixfmt-tree;
  };
}

iconic. periodt. 👑

✨ Options ✨

  • --json — produce output in JSON format, suitable for consumption by another program. feeding the robots 🤖
  • --no-pretty — print compact JSON output on a single line, even when the output is a terminal. some commands may print multiple JSON objects on separate lines. see --pretty.
  • --pretty — print multi-line, indented JSON output for readability.
    • Default: indent if output is to a terminal.
    • This option is only effective when --json is also specified. (no --json, no party 🙈)

💜 Common evaluation options 💜

  • --arg name expr — pass the value expr as the argument name to Nix functions.
  • --arg-from-file name path — pass the contents of file path as the argument name to Nix functions.
  • --arg-from-stdin name — pass the contents of stdin as the argument name to Nix functions.
  • --argstr name string — pass the string string as the argument name to Nix functions.
  • --debugger — start an interactive environment if evaluation fails. it's giving "we'll figure it out together" 🫂
  • --eval-store store-url — the URL of the Nix store to use for evaluation, i.e. to store derivations (.drv files) and inputs referenced by them.
  • --impure — allow access to mutable paths and repositories. living dangerously, we love that for you 💀✨
  • --include / -I path — add path to search path entries used to resolve lookup paths.
    • This option may be given multiple times.
    • Paths added through -I take precedence over the nix-path configuration setting and the NIX_PATH environment variable. she's got seniority 💅
  • --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. commitment issues? not today 🎀
  • --inputs-from flake-url — use the inputs of the specified flake as registry entries.
  • --no-registries — don't allow lookups in the flake registries.
DEPRECATED — use --no-use-registries instead. she's retired, let her rest 😭
  • --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.
  • --output-lock-file flake-lock-path — write the given lock file instead of flake.lock within the top-level flake.
  • --override-input input-path flake-url — override a specific flake input (e.g. dwarffs/nixpkgs). the input path must not be empty. this implies --no-write-lock-file.
  • --recreate-lock-file — recreate the flake's lock file from scratch.
DEPRECATED — use nix flake update instead. ok boo, we've moved on 🫶
  • --reference-lock-file flake-lock-path — read the given lock file instead of flake.lock within the top-level flake.
  • --update-input input-path — update a specific flake input (ignoring its previous entry in the lock file).
DEPRECATED — use nix flake update instead. same energy, new era ✨
  • --debug — set the logging verbosity level to debug.
  • --log-format format — set the format of log output; one of raw, internal-json, bar or bar-with-logs.
  • --print-build-logs / -L — print full build logs on standard error.
  • --quiet — decrease the logging verbosity level. shhh 🤫
  • --verbose / -v — increase the logging verbosity level. tell me EVERYTHING 👀

🌟 Miscellaneous global options 🌟

  • --help — show usage information.
  • --offline — disable substituters and consider all previously downloaded files up-to-date.
  • --option name value — set the Nix configuration setting name to value (overriding nix.conf).
  • --refresh — consider all previously downloaded files out-of-date.
  • --repair — during evaluation, rewrite missing or corrupted files in the Nix store. during building, rebuild missing or corrupted store paths. she's a healer 🩹
  • --version — show version information.

💖 Options that change the interpretation of installables 💖

  • --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 is read from standard input. implies --impure.
Note — see man nix.conf for overriding configuration settings with command line flags.

and that's the whole page bestie, you ate that 🫶 hope your code comes out ✨immaculate✨. this was nix3-formatter-run(1) from the Nix general commands manual — go forth and format, main character 💅👑

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