# Release 1.7 (2014-04-11)

In addition to the usual bug fixes, this release has the following new
features:

  - Antiquotation is now allowed inside of quoted attribute names (e.g.
    `set."${foo}"`). In the case where the attribute name is just a
    single antiquotation, the quotes can be dropped (e.g. the above
    example can be written `set.${foo}`). If an attribute name inside of
    a set declaration evaluates to `null` (e.g. `{ ${null} = false; }`),
    then that attribute is not added to the set.

  - Experimental support for cryptographically signed binary caches. See
    [the commit for
    details](https://github.com/NixOS/nix/commit/0fdf4da0e979f992db75cc17376e455ddc5a96d8).

  - An experimental new substituter, `download-via-ssh`, that fetches
    binaries from remote machines via SSH. Specifying the flags
    `--option
                    use-ssh-substituter true --option ssh-substituter-hosts
                    user@hostname` will cause Nix to download binaries from the
    specified machine, if it has them.

  - `nix-store -r` and `nix-build` have a new flag, `--check`, that
    builds a previously built derivation again, and prints an error
    message if the output is not exactly the same. This helps to verify
    whether a derivation is truly deterministic. For example:
    
        $ nix-build '<nixpkgs>' -A patchelf
        …
        $ nix-build '<nixpkgs>' -A patchelf --check
        …
        error: derivation `/nix/store/1ipvxs…-patchelf-0.6' may not be deterministic:
          hash mismatch in output `/nix/store/4pc1dm…-patchelf-0.6.drv'

  - The `nix-instantiate` flags `--eval-only` and `--parse-only` have
    been renamed to `--eval` and `--parse`, respectively.

  - `nix-instantiate`, `nix-build` and `nix-shell` now have a flag
    `--expr` (or `-E`) that allows you to specify the expression to be
    evaluated as a command line argument. For instance, `nix-instantiate
    --eval -E
                    '1 + 2'` will print `3`.

  - `nix-shell` improvements:
    
      - It has a new flag, `--packages` (or `-p`), that sets up a build
        environment containing the specified packages from Nixpkgs. For
        example, the command
        
            $ nix-shell -p sqlite xorg.libX11 hello
        
        will start a shell in which the given packages are present.
    
      - It now uses `shell.nix` as the default expression, falling back
        to `default.nix` if the former doesn’t exist. This makes it
        convenient to have a `shell.nix` in your project to set up a
        nice development environment.
    
      - It evaluates the derivation attribute `shellHook`, if set. Since
        `stdenv` does not normally execute this hook, it allows you to
        do `nix-shell`-specific setup.
    
      - It preserves the user’s timezone setting.

  - In chroots, Nix now sets up a `/dev` containing only a minimal set
    of devices (such as `/dev/null`). Note that it only does this if you
    *don’t* have `/dev` listed in your `build-chroot-dirs` setting;
    otherwise, it will bind-mount the `/dev` from outside the chroot.