Release 2.19 (2023-11-17)

• The experimental nix command can now act as a shebang interpreter by appending the contents of any #! nix lines and the script's location into a single call.

• URL flake references now support percent-encoded characters.

• Path-like flake references now accept arbitrary unicode characters (except # and ?).

• The experimental feature repl-flake is no longer needed, as its functionality is now part of the flakes experimental feature. To get the previous behavior, use the --file/--expr flags accordingly.

• There is a new flake installable syntax flakeref#.attrPath where the "." prefix specifies that attrPath is interpreted from the root of the flake outputs, with no searching of default attribute prefixes like packages.<SYSTEM> or legacyPackages.<SYSTEM>.

• Nix adds apple-virt to the default system features on macOS systems that support virtualization. This is similar to what's done for the kvm system feature on Linux hosts.

• Add a new built-in function builtins.convertHash.

• nix-shell shebang lines now support single-quoted arguments.

• builtins.fetchTree is now its own experimental feature, fetch-tree. This allows stabilising it independently of the rest of what is encompassed by flakes.

• The interface for creating and updating lock files has been overhauled:

  • nix flake lock only creates lock files and adds missing inputs now. It will never update existing inputs.

  • nix flake update does the same, but will update inputs.

    • Passing no arguments will update all inputs of the current flake, just like it already did.
    • Passing input names as arguments will ensure only those are updated. This replaces the functionality of nix flake lock --update-input
    • To operate on a flake outside the current directory, you must now pass --flake path/to/flake.

  • The flake-specific flags --recreate-lock-file and --update-input have been removed from all commands operating on installables. They are superceded by nix flake update.

• Commit signature verification for the builtins.fetchGit is added as the new verified-fetches experimental feature.

• nix path-info --json (experimental) now returns a JSON map rather than JSON list. The path field of each object has instead become the key in the outer map, since it is unique. The valid field also goes away because we just use null instead.

  • Old way:

    [
      {
        "path": "/nix/store/8fv91097mbh5049i9rglc73dx6kjg3qk-bash-5.2-p15",
        "valid": true,
        // ...
      },
      {
        "path": "/nix/store/wffw7l0alvs3iw94cbgi1gmmbmw99sqb-home-manager-path",
        "valid": false
      }
    ]
    

  • New way

    {
      "/nix/store/8fv91097mbh5049i9rglc73dx6kjg3qk-bash-5.2-p15": {
        // ...
      },
      "/nix/store/wffw7l0alvs3iw94cbgi1gmmbmw99sqb-home-manager-path": null,
    }
    

  This makes it match nix derivation show, which also maps store paths to information.

• When Nix is installed using the binary installer, in supported shells (Bash, Zsh, Fish) XDG_DATA_DIRS is now populated with the path to the /share subdirectory of the current profile. This means that command completion scripts, .desktop files, and similar artifacts installed via nix-env or nix profile (experimental) can be found by any program that follows the XDG Base Directory Specification.

• A new command nix store add has been added. It replaces nix store add-file and nix store add-path which are now deprecated.

• A new option always-allow-substitutes has been added.

  When set to true, Nix will always try to substitute a derivation, even if it has the allowSubstitutes attribute set to false.