Ubuntu Manpage: nix flake metadata

Provided by: nix-bin_2.24.9+dfsg-2ubuntu2_amd64

Name

       nix flake metadata - show flake metadata

Synopsis

       nix flake metadata [option…] flake-url

Examples

       •  Show what dwarffs resolves to:

       # nix flake metadata dwarffs
       Resolved URL:  github:edolstra/dwarffs
       Locked URL:    github:edolstra/dwarffs/f691e2c991e75edb22836f1dbe632c40324215c5
       Description:   A filesystem that fetches DWARF debug info from the Internet on demand
       Path:          /nix/store/769s05vjydmc2lcf6b02az28wsa9ixh1-source
       Revision:      f691e2c991e75edb22836f1dbe632c40324215c5
       Last modified: 2021-01-21 15:41:26
       Inputs:
       ├───nix: github:NixOS/nix/6254b1f5d298ff73127d7b0f0da48f142bdc753c
       │   ├───lowdown-src: github:kristapsdz/lowdown/1705b4a26fbf065d9574dce47a94e8c7c79e052f
       │   └───nixpkgs: github:NixOS/nixpkgs/ad0d20345219790533ebe06571f82ed6b034db31
       └───nixpkgs follows input 'nix/nixpkgs'

       •  Show information about dwarffs in JSON format:

       # nix flake metadata dwarffs --json | jq .
       {
       "description": "A filesystem that fetches DWARF debug info from the Internet on demand",
       "lastModified": 1597153508,
       "locked": {
         "lastModified": 1597153508,
         "narHash": "sha256-VHg3MYVgQ12LeRSU2PSoDeKlSPD8PYYEFxxwkVVDRd0=",
         "owner": "edolstra",
         "repo": "dwarffs",
         "rev": "d181d714fd36eb06f4992a1997cd5601e26db8f5",
         "type": "github"
       },
       "locks": { ... },
       "original": {
         "id": "dwarffs",
         "type": "indirect"
       },
       "originalUrl": "flake:dwarffs",
       "path": "/nix/store/hang3792qwdmm2n0d9nsrs5n6bsws6kv-source",
       "resolved": {
         "owner": "edolstra",
         "repo": "dwarffs",
         "type": "github"
       },
       "resolvedUrl": "github:edolstra/dwarffs",
       "revision": "d181d714fd36eb06f4992a1997cd5601e26db8f5",
       "url": "github:edolstra/dwarffs/d181d714fd36eb06f4992a1997cd5601e26db8f5"
       }

Description

This command shows information about the flake specified by the flake reference flake-url. It resolves
the flake reference using the flake registry, fetches it, and prints some meta data. This includes:

• Resolved URL: If flake-url is a flake identifier, then this is the flake reference that specifies its
actual location, looked up in the flake registry.

• Locked URL: A flake reference that contains a commit or content hash and thus uniquely identifies a
specific flake version.

• Description: A one-line description of the flake, taken from the description field in flake.nix.

• Path: The store path containing the source code of the flake.

• Revision: The Git or Mercurial commit hash of the locked flake.

• Revisions: The number of ancestors of the Git or Mercurial commit of the locked flake. Note that this
is not available for github flakes.

• Last modified: For Git or Mercurial flakes, this is the commit time of the commit of the locked flake;
for tarball flakes, it’s the most recent timestamp of any file inside the tarball.

• Inputs: The flake inputs with their corresponding lock file entries.

With --json, the output is a JSON object with the following fields:

• original and originalUrl: The flake reference specified by the user (flake-url) in attribute set and
URL representation.

• resolved and resolvedUrl: The resolved flake reference (see above) in attribute set and URL
representation.

• locked and lockedUrl: The locked flake reference (see above) in attribute set and URL representation.

• description: See Description above.

• path: See Path above.

• revision: See Revision above.

• revCount: See Revisions above.

• lastModified: See Last modified above.

• locks: The contents of flake.lock.

Options

• --json

Produce output in JSON format, suitable for consumption by another program.

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.

Note

See man nix.conf for overriding configuration settings with command line flags.

nix3-flake-metadata(1)