## Keyboard shortcuts

Press `←` or `→` to navigate between chapters

Press `S` or `/` to search in the book

Press `?` to show this help

Press `Esc` to hide this help

# Release 1.4 (2013-02-26)

This release fixes a security bug in multi-user operation. It was possible for derivations to cause the mode of files outside of the Nix store to be changed to 444 (read-only but world-readable) by creating hard links to those files (details).

There are also the following improvements:

- New built-in function: `builtins.hashString`.

- Build logs are now stored in `/nix/var/log/nix/drvs/XX/`, where XX is the first two characters of the derivation. This is useful on machines that keep a lot of build logs (such as Hydra servers).

- The function `corepkgs/fetchurl` can now make the downloaded file executable. This will allow getting rid of all bootstrap binaries in the Nixpkgs source tree.

- Language change: The expression `"${./path} ..."` now evaluates to a string instead of a path.