---
name: "nix3-flake-prefetch"
section: "1"
platform: "linux"
package: "nix-bin"
version: "2.26.3+dfsg-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/nix3-flake-prefetch"
---

# nix3-flake-prefetch(1)

download the source tree denoted by a flake reference into the Nix store

**Warning** \
 This program is **experimental** ⟨@docroot@/development/experimental-features.md#xp-feature-nix-command⟩ and its interface is subject to change.

## Name

`nix flake prefetch` - download the source tree denoted by a flake reference into the Nix store

## Synopsis

`nix flake prefetch` \[*option*…\] *flake-url*

## Examples

- •

  Download a tarball and unpack it:

```
# nix flake prefetch https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.5.tar.xz
Downloaded 'https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.5.tar.xz?narHash=sha256-3XYHZANT6AFBV0BqegkAZHbba6oeDkIUCDwbATLMhAY='
to '/nix/store/sl5vvk8mb4ma1sjyy03kwpvkz50hd22d-source' (hash
'sha256-3XYHZANT6AFBV0BqegkAZHbba6oeDkIUCDwbATLMhAY=').
```

- •

  Download the `dwarffs` flake (looked up in the flake registry):

```
# nix flake prefetch dwarffs --json
{"hash":"sha256-VHg3MYVgQ12LeRSU2PSoDeKlSPD8PYYEFxxwkVVDRd0="
,"storePath":"/nix/store/hang3792qwdmm2n0d9nsrs5n6bsws6kv-source"}
```

## Description

This command downloads the source tree denoted by flake reference *flake-url*. Note that this does not need to be a flake (i.e. it does not have to contain a `flake.nix` file).

## Options

- •

  `--json` ⟨#opt-json⟩

-

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

### Common evaluation options

- •

  `--arg` ⟨#opt-arg⟩ *name* *expr*

-

  Pass the value *expr* as the argument *name* to Nix functions.

- •

  `--arg-from-file` ⟨#opt-arg-from-file⟩ *name* *path*

-

  Pass the contents of file *path* as the argument *name* to Nix functions.

- •

  `--arg-from-stdin` ⟨#opt-arg-from-stdin⟩ *name*

-

  Pass the contents of stdin as the argument *name* to Nix functions.

- •

  `--argstr` ⟨#opt-argstr⟩ *name* *string*

-

  Pass the string *string* as the argument *name* to Nix functions.

- •

  `--debugger` ⟨#opt-debugger⟩

-

  Start an interactive environment if evaluation fails.

- •

  `--eval-store` ⟨#opt-eval-store⟩ *store-url*

-

  The URL of the Nix store ⟨@docroot@/store/types/index.md#store-url-format⟩ to use for evaluation, i.e. to store derivations (`.drv` files) and inputs referenced by them.

- •

  `--impure` ⟨#opt-impure⟩

-

  Allow access to mutable paths and repositories.

- •

  `--include` ⟨#opt-include⟩ / `-I` *path*

-

  Add *path* to search path entries used to resolve lookup paths ⟨@docroot@/language/constructs/lookup-path.md⟩

-

  This option may be given multiple times.

-

  Paths added through `-I` take precedence over the `nix-path` configuration setting ⟨@docroot@/command-ref/conf-file.md#conf-nix-path⟩ and the `NIX_PATH` environment variable ⟨@docroot@/command-ref/env-common.md#env-NIX\_PATH⟩\\c .

- •

  `--override-flake` ⟨#opt-override-flake⟩ *original-ref* *resolved-ref*

-

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

### Common flake-related options

- •

  `--commit-lock-file` ⟨#opt-commit-lock-file⟩

-

  Commit changes to the flake’s lock file.

- •

  `--inputs-from` ⟨#opt-inputs-from⟩ *flake-url*

-

  Use the inputs of the specified flake as registry entries.

- •

  `--no-registries` ⟨#opt-no-registries⟩

-

  Don’t allow lookups in the flake registries.

  -

    **DEPRECATED**

  -

    Use `--no-use-registries` ⟨@docroot@/command-ref/conf-file.md#conf-use-registries⟩ instead.

- •

  `--no-update-lock-file` ⟨#opt-no-update-lock-file⟩

-

  Do not allow any updates to the flake’s lock file.

- •

  `--no-write-lock-file` ⟨#opt-no-write-lock-file⟩

-

  Do not write the flake’s newly generated lock file.

- •

  `--output-lock-file` ⟨#opt-output-lock-file⟩ *flake-lock-path*

-

  Write the given lock file instead of `flake.lock` within the top-level flake.

- •

  `--override-input` ⟨#opt-override-input⟩ *input-path* *flake-url*

-

  Override a specific flake input (e.g. `dwarffs/nixpkgs`). This implies `--no-write-lock-file`.

- •

  `--recreate-lock-file` ⟨#opt-recreate-lock-file⟩

-

  Recreate the flake’s lock file from scratch.

  -

    **DEPRECATED**

  -

    Use `nix flake update` ⟨@docroot@/command-ref/new-cli/nix3-flake-update.md⟩ instead.

- •

  `--reference-lock-file` ⟨#opt-reference-lock-file⟩ *flake-lock-path*

-

  Read the given lock file instead of `flake.lock` within the top-level flake.

- •

  `--update-input` ⟨#opt-update-input⟩ *input-path*

-

  Update a specific flake input (ignoring its previous entry in the lock file).

  -

    **DEPRECATED**

  -

    Use `nix flake update` ⟨@docroot@/command-ref/new-cli/nix3-flake-update.md⟩ instead.

### Logging-related options

- •

  `--debug` ⟨#opt-debug⟩

-

  Set the logging verbosity level to ‘debug’.

- •

  `--log-format` ⟨#opt-log-format⟩ *format*

-

  Set the format of log output; one of `raw`, `internal-json`, `bar` or `bar-with-logs`.

- •

  `--print-build-logs` ⟨#opt-print-build-logs⟩ / `-L`

-

  Print full build logs on standard error.

- •

  `--quiet` ⟨#opt-quiet⟩

-

  Decrease the logging verbosity level.

- •

  `--verbose` ⟨#opt-verbose⟩ / `-v`

-

  Increase the logging verbosity level.

### Miscellaneous global options

- •

  `--help` ⟨#opt-help⟩

-

  Show usage information.

- •

  `--offline` ⟨#opt-offline⟩

-

  Disable substituters and consider all previously downloaded files up-to-date.

- •

  `--option` ⟨#opt-option⟩ *name* *value*

-

  Set the Nix configuration setting *name* to *value* (overriding `nix.conf`).

- •

  `--refresh` ⟨#opt-refresh⟩

-

  Consider all previously downloaded files out-of-date.

- •

  `--repair` ⟨#opt-repair⟩

-

  During evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths.

- •

  `--version` ⟨#opt-version⟩

-

  Show version information.

  **Note**

  See `man nix.conf` ⟨@docroot@/command-ref/conf-file.md#command-line-flags⟩ for overriding configuration settings with command line flags.