nix3-fmt(1)

📦
version 2.35.3 · 12 versions
, in fedora 44

✨ nix fmt — nix3-fmt(1) ✨

okay bestie, welcome to the manual page for nix fmt, coming at you straight from the General Commands Manual 💖

⚠️ Warning ⚠️ This program is experimental and its interface is subject to change. Like, do not get attached to the exact vibes, they WILL shift. 😭

🌸 Name 🌸

nix fmt — reformat your code in the standard style ✨

🎀 Synopsis 🎀

nix fmt [option…] args…

💅 Description 💅

nix fmt (which is literally just an alias for nix formatter run, no cap) calls the formatter that's specified in the flake. The flake decides, you just vibe. 🦋

Wanna send flags over to the formatter? Easy. Drop -- first, then your flags, and they get forwarded. Periodt.

Any arguments you hand over also get forwarded to the formatter. Usually those args are the files you want formatted. 📄✨

Oh and 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. So it always knows where home is. 🏡

🌈 Example 🌈

Wanna use the official Nix formatter? Say less:

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

⭐ Options ⭐

  • --json — produce output in JSON format, suitable for consumption by another program. It's giving machine-readable 🤖
  • --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.

🧚 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. Lowkey a safe space for when things go sideways 🫶
  • --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 💀
  • --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. Main character energy for real 👑

  • --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.
DEPRECATED — use --no-use-registries instead. She's retired, bestie. ✨
  • --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. 😭
  • --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. 😭
  • --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. 🤫
  • --verbose, -v — increase the logging verbosity level. 🗣️

👑 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.
  • --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 💖 this was nix3-fmt(1) out of the General Commands Manual — go format something cute and slay the day, ily 🎀✨👑

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