Merge branch 'master' of github.com:thatdocslady/nix

Conflicts:
	doc/manual/release-notes.xml
	doc/manual/writing-nix-expressions.xml

1 files changed, 157 insertions, 0 deletions

diff --git a/doc/manual/release-notes/rl-12.xml b/doc/manual/release-notes/rl-12.xml
new file mode 100644
index 000000000000..72d164f00c01
--- /dev/null
+++ b/doc/manual/release-notes/rl-12.xml
@@ -0,0 +1,157 @@
+<chapter xmlns="http://docbook.org/ns/docbook"
+      xmlns:xlink="http://www.w3.org/1999/xlink"
+      xmlns:xi="http://www.w3.org/2001/XInclude"
+      version="5.0"
+      xml:id="ssec-relnotes-1.2">
+
+<title>Release 1.2 (December 6, 2012)</title>
+
+<para>This release has the following improvements and changes:</para>
+
+<itemizedlist>
+
+  <listitem>
+    <para>Nix has a new binary substituter mechanism: the
+    <emphasis>binary cache</emphasis>.  A binary cache contains
+    pre-built binaries of Nix packages.  Whenever Nix wants to build a
+    missing Nix store path, it will check a set of binary caches to
+    see if any of them has a pre-built binary of that path.  The
+    configuration setting <option>binary-caches</option> contains a
+    list of URLs of binary caches.  For instance, doing
+<screen>
+$ nix-env -i thunderbird --option binary-caches http://cache.nixos.org
+</screen>
+    will install Thunderbird and its dependencies, using the available
+    pre-built binaries in <uri>http://cache.nixos.org</uri>.
+    The main advantage over the old “manifest”-based method of getting
+    pre-built binaries is that you don’t have to worry about your
+    manifest being in sync with the Nix expressions you’re installing
+    from; i.e., you don’t need to run <command>nix-pull</command> to
+    update your manifest.  It’s also more scalable because you don’t
+    need to redownload a giant manifest file every time.
+    </para>
+
+    <para>A Nix channel can provide a binary cache URL that will be
+    used automatically if you subscribe to that channel.  If you use
+    the Nixpkgs or NixOS channels
+    (<uri>http://nixos.org/channels</uri>) you automatically get the
+    cache <uri>http://cache.nixos.org</uri>.</para>
+
+    <para>Binary caches are created using <command>nix-push</command>.
+    For details on the operation and format of binary caches, see the
+    <command>nix-push</command> manpage.  More details are provided in
+    <link xlink:href="http://lists.science.uu.nl/pipermail/nix-dev/2012-September/009826.html">this
+    nix-dev posting</link>.</para>
+  </listitem>
+
+  <listitem>
+    <para>Multiple output support should now be usable.  A derivation
+    can declare that it wants to produce multiple store paths by
+    saying something like
+<programlisting>
+outputs = [ "lib" "headers" "doc" ];
+</programlisting>
+    This will cause Nix to pass the intended store path of each output
+    to the builder through the environment variables
+    <literal>lib</literal>, <literal>headers</literal> and
+    <literal>doc</literal>.  Other packages can refer to a specific
+    output by referring to
+    <literal><replaceable>pkg</replaceable>.<replaceable>output</replaceable></literal>,
+    e.g.
+<programlisting>
+buildInputs = [ pkg.lib pkg.headers ];
+</programlisting>
+    If you install a package with multiple outputs using
+    <command>nix-env</command>, each output path will be symlinked
+    into the user environment.</para>
+  </listitem>
+
+  <listitem>
+    <para>Dashes are now valid as part of identifiers and attribute
+    names.</para>
+  </listitem>
+
+  <listitem>
+    <para>The new operation <command>nix-store --repair-path</command>
+    allows corrupted or missing store paths to be repaired by
+    redownloading them.  <command>nix-store --verify --check-contents
+    --repair</command> will scan and repair all paths in the Nix
+    store.  Similarly, <command>nix-env</command>,
+    <command>nix-build</command>, <command>nix-instantiate</command>
+    and <command>nix-store --realise</command> have a
+    <option>--repair</option> flag to detect and fix bad paths by
+    rebuilding or redownloading them.</para>
+  </listitem>
+
+  <listitem>
+    <para>Nix no longer sets the immutable bit on files in the Nix
+    store.  Instead, the recommended way to guard the Nix store
+    against accidental modification on Linux is to make it a read-only
+    bind mount, like this:
+
+<screen>
+$ mount --bind /nix/store /nix/store
+$ mount -o remount,ro,bind /nix/store
+</screen>
+
+    Nix will automatically make <filename>/nix/store</filename>
+    writable as needed (using a private mount namespace) to allow
+    modifications.</para>
+  </listitem>
+
+  <listitem>
+    <para>Store optimisation (replacing identical files in the store
+    with hard links) can now be done automatically every time a path
+    is added to the store.  This is enabled by setting the
+    configuration option <literal>auto-optimise-store</literal> to
+    <literal>true</literal> (disabled by default).</para>
+  </listitem>
+
+  <listitem>
+    <para>Nix now supports <command>xz</command> compression for NARs
+    in addition to <command>bzip2</command>.  It compresses about 30%
+    better on typical archives and decompresses about twice as
+    fast.</para>
+  </listitem>
+
+  <listitem>
+    <para>Basic Nix expression evaluation profiling: setting the
+    environment variable <envar>NIX_COUNT_CALLS</envar> to
+    <literal>1</literal> will cause Nix to print how many times each
+    primop or function was executed.</para>
+  </listitem>
+
+  <listitem>
+    <para>New primops: <varname>concatLists</varname>,
+    <varname>elem</varname>, <varname>elemAt</varname> and
+    <varname>filter</varname>.</para>
+  </listitem>
+
+  <listitem>
+    <para>The command <command>nix-copy-closure</command> has a new
+    flag <option>--use-substitutes</option> (<option>-s</option>) to
+    download missing paths on the target machine using the substitute
+    mechanism.</para>
+  </listitem>
+
+  <listitem>
+    <para>The command <command>nix-worker</command> has been renamed
+    to <command>nix-daemon</command>.  Support for running the Nix
+    worker in “slave” mode has been removed.</para>
+  </listitem>
+
+  <listitem>
+    <para>The <option>--help</option> flag of every Nix command now
+    invokes <command>man</command>.</para>
+  </listitem>
+
+  <listitem>
+    <para>Chroot builds are now supported on systemd machines.</para>
+  </listitem>
+
+</itemizedlist>
+
+<para>This release has contributions from Eelco Dolstra, Florian
+Friesdorf, Mats Erik Andersson and Shea Levy.</para>
+
+</chapter>
\ No newline at end of file