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doc/manual/src/release-notes/rl-0.11.md

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+# Release 0.11 (2007-12-31)
+
+Nix 0.11 has many improvements over the previous stable release. The
+most important improvement is secure multi-user support. It also
+features many usability enhancements and language extensions, many of
+them prompted by NixOS, the purely functional Linux distribution based
+on Nix. Here is an (incomplete) list:
+
+  - Secure multi-user support. A single Nix store can now be shared
+    between multiple (possible untrusted) users. This is an important
+    feature for NixOS, where it allows non-root users to install
+    software. The old setuid method for sharing a store between multiple
+    users has been removed. Details for setting up a multi-user store
+    can be found in the manual.
+
+  - The new command `nix-copy-closure` gives you an easy and efficient
+    way to exchange software between machines. It copies the missing
+    parts of the closure of a set of store path to or from a remote
+    machine via `ssh`.
+
+  - A new kind of string literal: strings between double single-quotes
+    (`''`) have indentation “intelligently” removed. This allows large
+    strings (such as shell scripts or configuration file fragments in
+    NixOS) to cleanly follow the indentation of the surrounding
+    expression. It also requires much less escaping, since `''` is less
+    common in most languages than `"`.
+
+  - `nix-env` `--set` modifies the current generation of a profile so
+    that it contains exactly the specified derivation, and nothing else.
+    For example, `nix-env -p /nix/var/nix/profiles/browser --set
+            firefox` lets the profile named `browser` contain just Firefox.
+
+  - `nix-env` now maintains meta-information about installed packages in
+    profiles. The meta-information is the contents of the `meta`
+    attribute of derivations, such as `description` or `homepage`. The
+    command `nix-env -q --xml
+            --meta` shows all meta-information.
+
+  - `nix-env` now uses the `meta.priority` attribute of derivations to
+    resolve filename collisions between packages. Lower priority values
+    denote a higher priority. For instance, the GCC wrapper package and
+    the Binutils package in Nixpkgs both have a file `bin/ld`, so
+    previously if you tried to install both you would get a collision.
+    Now, on the other hand, the GCC wrapper declares a higher priority
+    than Binutils, so the former’s `bin/ld` is symlinked in the user
+    environment.
+
+  - `nix-env -i / -u`: instead of breaking package ties by version,
+    break them by priority and version number. That is, if there are
+    multiple packages with the same name, then pick the package with the
+    highest priority, and only use the version if there are multiple
+    packages with the same priority.
+    
+    This makes it possible to mark specific versions/variant in Nixpkgs
+    more or less desirable than others. A typical example would be a
+    beta version of some package (e.g., `gcc-4.2.0rc1`) which should not
+    be installed even though it is the highest version, except when it
+    is explicitly selected (e.g., `nix-env -i
+            gcc-4.2.0rc1`).
+
+  - `nix-env --set-flag` allows meta attributes of installed packages to
+    be modified. There are several attributes that can be usefully
+    modified, because they affect the behaviour of `nix-env` or the user
+    environment build script:
+    
+      - `meta.priority` can be changed to resolve filename clashes (see
+        above).
+    
+      - `meta.keep` can be set to `true` to prevent the package from
+        being upgraded or replaced. Useful if you want to hang on to an
+        older version of a package.
+    
+      - `meta.active` can be set to `false` to “disable” the package.
+        That is, no symlinks will be generated to the files of the
+        package, but it remains part of the profile (so it won’t be
+        garbage-collected). Set it back to `true` to re-enable the
+        package.
+
+  - `nix-env -q` now has a flag `--prebuilt-only` (`-b`) that causes
+    `nix-env` to show only those derivations whose output is already in
+    the Nix store or that can be substituted (i.e., downloaded from
+    somewhere). In other words, it shows the packages that can be
+    installed “quickly”, i.e., don’t need to be built from source. The
+    `-b` flag is also available in `nix-env -i` and `nix-env -u` to
+    filter out derivations for which no pre-built binary is available.
+
+  - The new option `--argstr` (in `nix-env`, `nix-instantiate` and
+    `nix-build`) is like `--arg`, except that the value is a string. For
+    example, `--argstr system
+            i686-linux` is equivalent to `--arg system
+            \"i686-linux\"` (note that `--argstr` prevents annoying quoting
+    around shell arguments).
+
+  - `nix-store` has a new operation `--read-log` (`-l`) `paths` that
+    shows the build log of the given paths.
+
+  - Nix now uses Berkeley DB 4.5. The database is upgraded
+    automatically, but you should be careful not to use old versions of
+    Nix that still use Berkeley DB 4.4.
+
+  - The option `--max-silent-time` (corresponding to the configuration
+    setting `build-max-silent-time`) allows you to set a timeout on
+    builds — if a build produces no output on `stdout` or `stderr` for
+    the given number of seconds, it is terminated. This is useful for
+    recovering automatically from builds that are stuck in an infinite
+    loop.
+
+  - `nix-channel`: each subscribed channel is its own attribute in the
+    top-level expression generated for the channel. This allows
+    disambiguation (e.g. `nix-env
+            -i -A nixpkgs_unstable.firefox`).
+
+  - The substitutes table has been removed from the database. This makes
+    operations such as `nix-pull` and `nix-channel --update` much, much
+    faster.
+
+  - `nix-pull` now supports bzip2-compressed manifests. This speeds up
+    channels.
+
+  - `nix-prefetch-url` now has a limited form of caching. This is used
+    by `nix-channel` to prevent unnecessary downloads when the channel
+    hasn’t changed.
+
+  - `nix-prefetch-url` now by default computes the SHA-256 hash of the
+    file instead of the MD5 hash. In calls to `fetchurl` you should pass
+    the `sha256` attribute instead of `md5`. You can pass either a
+    hexadecimal or a base-32 encoding of the hash.
+
+  - Nix can now perform builds in an automatically generated “chroot”.
+    This prevents a builder from accessing stuff outside of the Nix
+    store, and thus helps ensure purity. This is an experimental
+    feature.
+
+  - The new command `nix-store
+            --optimise` reduces Nix store disk space usage by finding identical
+    files in the store and hard-linking them to each other. It typically
+    reduces the size of the store by something like 25-35%.
+
+  - `~/.nix-defexpr` can now be a directory, in which case the Nix
+    expressions in that directory are combined into an attribute set,
+    with the file names used as the names of the attributes. The command
+    `nix-env
+            --import` (which set the `~/.nix-defexpr` symlink) is removed.
+
+  - Derivations can specify the new special attribute
+    `allowedReferences` to enforce that the references in the output of
+    a derivation are a subset of a declared set of paths. For example,
+    if `allowedReferences` is an empty list, then the output must not
+    have any references. This is used in NixOS to check that generated
+    files such as initial ramdisks for booting Linux don’t have any
+    dependencies.
+
+  - The new attribute `exportReferencesGraph` allows builders access to
+    the references graph of their inputs. This is used in NixOS for
+    tasks such as generating ISO-9660 images that contain a Nix store
+    populated with the closure of certain paths.
+
+  - Fixed-output derivations (like `fetchurl`) can define the attribute
+    `impureEnvVars` to allow external environment variables to be passed
+    to builders. This is used in Nixpkgs to support proxy configuration,
+    among other things.
+
+  - Several new built-in functions: `builtins.attrNames`,
+    `builtins.filterSource`, `builtins.isAttrs`, `builtins.isFunction`,
+    `builtins.listToAttrs`, `builtins.stringLength`, `builtins.sub`,
+    `builtins.substring`, `throw`, `builtins.trace`,
+    `builtins.readFile`.