nix3-fmt - (unknown subject)

Name  Synopsis  Description  Example  Options  Common evaluation options  Common flake-related options  Logging-related options  Miscellaneous global options  Options that change the interpretation of installables 

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Warning
This program is experimental and its interface is subject to change.

Name

nix fmt - reformat your code in the standard style

Synopsis

nix fmt [option…] args…

Description

nix fmt (an alias for nix formatter run) calls the formatter specified in the flake.

Flags can be forwarded to the formatter by using -- followed by the flags.

Any arguments will be forwarded to the formatter. Typically these are the files to format.

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.

Example

To use the official Nix formatter:

# 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.

•

--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.

•

--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.

•

--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.

•

--override-flake original-ref resolved-ref

Override the flake registries, redirecting original-ref to resolved-ref.

Common flake-related options

•

--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.

•

--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). 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.

Logging-related options

•

--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.

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--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.

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