nix3-flake-prefetch - Man Page

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

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

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 --out-link ./result
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=').

# cat ./result/README
Linux kernel
…

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
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`.

--out-link / -o path
Create symlink named path to the resulting store path.
--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.
Note
See man nix.conf for overriding configuration settings with command line flags.