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


nix store optimise - replace identical files in the store by hard links


nix store optimise [option...]


  • Optimise the Nix store:

    nix store optimise


This command deduplicates the Nix store: it scans the store for regular files with identical contents, and replaces them with hard links to a single instance.

Note that you can also set auto-optimise-store to true in nix.conf to perform this optimisation incrementally whenever a new path is added to the Nix store. To make this efficient, Nix maintains a content-addressed index of all the files in the Nix store in the directory /nix/store/.links/.


  • --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    Consider all previously downloaded files out-of-date.

  • --version

    Show version information.


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