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


nix flake lock - create missing lock file entries


nix flake lock [option...] flake-url


  • Update the nixpkgs and nix inputs of the flake in the current directory:

    # nix flake lock --update-input nixpkgs --update-input nix
    * Updated 'nix': 'github:NixOS/nix/9fab14adbc3810d5cc1f88672fde1eee4358405c' -> 'github:NixOS/nix/8927cba62f5afb33b01016d5c4f7f8b7d0adde3c'
    * Updated 'nixpkgs': 'github:NixOS/nixpkgs/3d2d8f281a27d466fa54b469b5993f7dde198375' -> 'github:NixOS/nixpkgs/a3a3dda3bacf61e8a39258a0ed9c924eeca8e293'


This command updates the lock file of a flake (flake.lock) so that it contains a lock for every flake input specified in flake.nix. Existing lock file entries are not updated unless required by a flag such as --update-input.

Note that every command that operates on a flake will also update the lock file if needed, and supports the same flags. Therefore,

# nix flake lock --update-input nixpkgs
# nix build

is equivalent to:

# nix build --update-input nixpkgs

Thus, this command is only useful if you want to update the lock file separately from any other action such as building.


  • --debugger
    start an interactive environment if evaluation fails

Common evaluation options:

  • --arg name expr
    Pass the value expr as the argument name to Nix functions.

  • --argstr name string
    Pass the string string as the argument name to Nix functions.

  • --eval-store store-url
    The Nix store to use for evaluations.

  • --impure
    Allow access to mutable paths and repositories.

  • --include / -I path
    Add path to the list of locations used to look up <...> file names.

  • --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. This option is deprecated; use --no-use-registries.

  • --no-update-lock-file
    Do not allow any updates to the flake's lock file.

  • --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.

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