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


nix copy - copy paths between Nix stores


nix copy [option...] installables...


  • Copy Firefox from the local store to a binary cache in /tmp/cache:

    # nix copy --to file:///tmp/cache $(type -p firefox)

    Note the file:// - without this, the destination is a chroot store, not a binary cache.

  • Copy all store paths from a local binary cache in /tmp/cache to the local store:

    # nix copy --all --from file:///tmp/cache
  • Copy the entire current NixOS system closure to another machine via SSH:

    # nix copy --substitute-on-destination --to ssh://server /run/current-system

    The -s flag causes the remote machine to try to substitute missing store paths, which may be faster if the link between the local and remote machines is slower than the link between the remote machine and its substituters (e.g. https://cache.nixos.org).

  • Copy a closure from another machine via SSH:

    # nix copy --from ssh://server /nix/store/a6cnl93nk1wxnq84brbbwr6hxw9gp2w9-blender-2.79-rc2
  • Copy Hello to a binary cache in an Amazon S3 bucket:

    # nix copy --to s3://my-bucket?region=eu-west-1 nixpkgs#hello

    or to an S3-compatible storage system:

    # nix copy --to s3://my-bucket?region=eu-west-1&endpoint=example.com nixpkgs#hello

    Note that this only works if Nix is built with AWS support.

  • Copy a closure from /nix/store to the chroot store /tmp/nix/nix/store:

    # nix copy --to /tmp/nix nixpkgs#hello --no-check-sigs


nix copy copies store path closures between two Nix stores. The source store is specified using --from and the destination using --to. If one of these is omitted, it defaults to the local store.


  • --from store-uri

    URL of the source Nix store.

  • --no-check-sigs

    Do not require that paths are signed by trusted keys.

  • --stdin

    Read installables from the standard input. No default installable applied.

  • --substitute-on-destination / -s

    Whether to try substitutes on the destination store (only supported by SSH stores).

  • --to store-uri

    URL of the destination Nix store.

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 the Nix search path. The Nix search path is initialized from the colon-separated NIX_PATH environment variable, and is used to look up the location of Nix expressions using paths enclosed in angle brackets (i.e., <nixpkgs>).

    For instance, passing

    -I /home/eelco/Dev
    -I /etc/nixos

    will cause Nix to look for paths relative to /home/eelco/Dev and /etc/nixos, in that order. This is equivalent to setting the NIX_PATH environment variable to


    It is also possible to match paths against a prefix. For example, passing

    -I nixpkgs=/home/eelco/Dev/nixpkgs-branch
    -I /etc/nixos

    will cause Nix to search for <nixpkgs/path> in /home/eelco/Dev/nixpkgs-branch/path and /etc/nixos/nixpkgs/path.

    If a path in the Nix search path starts with http:// or https://, it is interpreted as the URL of a tarball that will be downloaded and unpacked to a temporary location. The tarball must consist of a single top-level directory. For example, passing

    -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/master.tar.gz

    tells Nix to download and use the current contents of the master branch in the nixpkgs repository.

    The URLs of the tarballs from the official nixos.org channels (see the manual page for nix-channel) can be abbreviated as channel:<channel-name>. For instance, the following two flags are equivalent:

    -I nixpkgs=channel:nixos-21.05
    -I nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xz

    You can also fetch source trees using flake URLs and add them to the search path. For instance,

    -I nixpkgs=flake:nixpkgs

    specifies that the prefix nixpkgs shall refer to the source tree downloaded from the nixpkgs entry in the flake registry. Similarly,

    -I nixpkgs=flake:github:NixOS/nixpkgs/nixos-22.05

    makes <nixpkgs> refer to a particular branch of the NixOS/nixpkgs repository on GitHub.

  • --override-flake original-ref resolved-ref

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

  • --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

  • --all

    Apply the operation to every store path.

  • --derivation

    Operate on the store derivation rather than its outputs.

  • --expr expr

    Interpret installables as attribute paths relative to the Nix expression expr.

  • --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 will be read from standard input. Implies --impure.

  • --no-recursive

    Apply operation to specified paths only.


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