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

Conflicts: doc/manual/release-notes.xml doc/manual/writing-nix-expressions.xml
author: Eelco Dolstra <eelco.dolstra@logicblox.com> 2014-09-16T12·13+0200
committer: Eelco Dolstra <eelco.dolstra@logicblox.com> 2014-09-16T12·13+0200
commit: f0ef6b74b93344798e44c6dc527f88a78b75a32f (patch)
tree: 8975a82b25a4410e2fc36e80cc042d74675396d7 /doc/manual/release-notes.xml
parent: 67e5dd3ce9f46f810c06e16671e98f8e56b4e25c (diff)
parent: 8901acc97664aa8ebf687ee904428aa57a5192be (diff)
1 files changed, 0 insertions, 2533 deletions
diff --git a/doc/manual/release-notes.xml b/doc/manual/release-notes.xml
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@@ -1,2533 +0,0 @@
-<article xmlns="http://docbook.org/ns/docbook"
-         xmlns:xlink="http://www.w3.org/1999/xlink"
-         xml:id="sec-relnotes">
-
-<title>Nix Release Notes</title>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.8"><title>Release 1.8 (TBA)</title>
-
-<para>TODO</para>
-
-<itemizedlist>
-
-  <listitem><para>Derivations can specify the new special attribute
-  <varname>allowedRequisites</varname>, which has a similar meaning to
-  <varname>allowedReferences</varname>. But instead of only enforcing
-  to explicitly specify the immediate references, it requires the
-  derivation to specify all the dependencies recursively (hence the
-  name, requisites) that are used by the resulting
-  output.</para></listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.7"><title>Release 1.7 (April 11, 2014)</title>
-
-<para>In addition to the usual bug fixes, this release has the
-following new features:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>Antiquotation is now allowed inside of quoted attribute
-    names (e.g. <literal>set."${foo}"</literal>). In the case where
-    the attribute name is just a single antiquotation, the quotes can
-    be dropped (e.g. the above example can be written
-    <literal>set.${foo}</literal>). If an attribute name inside of a
-    set declaration evaluates to <literal>null</literal> (e.g.
-    <literal>{ ${null} = false; }</literal>), then that attribute is
-    not added to the set.</para>
-  </listitem>
-
-  <listitem>
-    <para>Experimental support for cryptographically signed binary
-    caches.  See <link
-    xlink:href="https://github.com/NixOS/nix/commit/0fdf4da0e979f992db75cc17376e455ddc5a96d8">the
-    commit for details</link>.</para>
-  </listitem>
-
-  <listitem>
-    <para>An experimental new substituter,
-    <command>download-via-ssh</command>, that fetches binaries from
-    remote machines via SSH.  Specifying the flags <literal>--option
-    use-ssh-substituter true --option ssh-substituter-hosts
-    <replaceable>user@hostname</replaceable></literal> will cause Nix
-    to download binaries from the specified machine, if it has
-    them.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-store -r</command> and
-    <command>nix-build</command> have a new flag,
-    <option>--check</option>, that builds a previously built
-    derivation again, and prints an error message if the output is not
-    exactly the same. This helps to verify whether a derivation is
-    truly deterministic.  For example:
-
-<screen>
-$ nix-build '&lt;nixpkgs>' -A patchelf
-<replaceable>…</replaceable>
-$ nix-build '&lt;nixpkgs>' -A patchelf --check
-<replaceable>…</replaceable>
-error: derivation `/nix/store/1ipvxs…-patchelf-0.6' may not be deterministic:
-  hash mismatch in output `/nix/store/4pc1dm…-patchelf-0.6.drv'
-</screen>
-
-    </para>
-
-  </listitem>
-
-  <listitem>
-    <para>The <command>nix-instantiate</command> flags
-    <option>--eval-only</option> and <option>--parse-only</option>
-    have been renamed to <option>--eval</option> and
-    <option>--parse</option>, respectively.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-instantiate</command>,
-    <command>nix-build</command> and <command>nix-shell</command> now
-    have a flag <option>--expr</option> (or <option>-E</option>) that
-    allows you to specify the expression to be evaluated as a command
-    line argument.  For instance, <literal>nix-instantiate --eval -E
-    '1 + 2'</literal> will print <literal>3</literal>.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-shell</command> improvements:</para>
-
-    <itemizedlist>
-
-      <listitem>
-        <para>It has a new flag, <option>--packages</option> (or
-        <option>-p</option>), that sets up a build environment
-        containing the specified packages from Nixpkgs. For example,
-        the command
-
-<screen>
-$ nix-shell -p sqlite xorg.libX11 hello
-</screen>
-
-        will start a shell in which the given packages are
-        present.</para>
-      </listitem>
-
-      <listitem>
-        <para>It now uses <filename>shell.nix</filename> as the
-        default expression, falling back to
-        <filename>default.nix</filename> if the former doesn’t
-        exist.  This makes it convenient to have a
-        <filename>shell.nix</filename> in your project to set up a
-        nice development environment.</para>
-      </listitem>
-
-      <listitem>
-        <para>It evaluates the derivation attribute
-        <varname>shellHook</varname>, if set. Since
-        <literal>stdenv</literal> does not normally execute this hook,
-        it allows you to do <command>nix-shell</command>-specific
-        setup.</para>
-      </listitem>
-
-      <listitem>
-        <para>It preserves the user’s timezone setting.</para>
-      </listitem>
-
-    </itemizedlist>
-
-  </listitem>
-
-  <listitem>
-    <para>In chroots, Nix now sets up a <filename>/dev</filename>
-    containing only a minimal set of devices (such as
-    <filename>/dev/null</filename>). Note that it only does this if
-    you <emphasis>don’t</emphasis> have <filename>/dev</filename>
-    listed in your <option>build-chroot-dirs</option> setting;
-    otherwise, it will bind-mount the <literal>/dev</literal> from
-    outside the chroot.</para>
-
-    <para>Similarly, if you don’t have <filename>/dev/pts</filename> listed
-    in <option>build-chroot-dirs</option>, Nix will mount a private
-    <literal>devpts</literal> filesystem on the chroot’s
-    <filename>/dev/pts</filename>.</para>
-
-  </listitem>
-
-  <listitem>
-    <para>New built-in function: <function>builtins.toJSON</function>,
-    which returns a JSON representation of a value.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-env -q</command> has a new flag
-    <option>--json</option> to print a JSON representation of the
-    installed or available packages.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-env</command> now supports meta attributes with
-    more complex values, such as attribute sets.</para>
-  </listitem>
-
-  <listitem>
-    <para>The <option>-A</option> flag now allows attribute names with
-    dots in them, e.g.
-
-<screen>
-$ nix-instantiate --eval '&lt;nixos>' -A 'config.systemd.units."nscd.service".text'
-</screen>
-
-    </para>
-  </listitem>
-
-  <listitem>
-    <para>The <option>--max-freed</option> option to
-    <command>nix-store --gc</command> now accepts a unit
-    specifier. For example, <literal>nix-store --gc --max-freed
-    1G</literal> will free up to 1 gigabyte of disk space.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-collect-garbage</command> has a new flag
-    <option>--delete-older-than</option>
-    <replaceable>N</replaceable><literal>d</literal>, which deletes
-    all user environment generations older than
-    <replaceable>N</replaceable> days.  Likewise, <command>nix-env
-    --delete-generations</command> accepts a
-    <replaceable>N</replaceable><literal>d</literal> age limit.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix now heuristically detects whether a build failure was
-    due to a disk-full condition. In that case, the build is not
-    flagged as “permanently failed”. This is mostly useful for Hydra,
-    which needs to distinguish between permanent and transient build
-    failures.</para>
-  </listitem>
-
-  <listitem>
-    <para>There is a new symbol <literal>__curPos</literal> that
-    expands to an attribute set containing its file name and line and
-    column numbers, e.g. <literal>{ file = "foo.nix"; line = 10;
-    column = 5; }</literal>.  There also is a new builtin function,
-    <varname>unsafeGetAttrPos</varname>, that returns the position of
-    an attribute.  This is used by Nixpkgs to provide location
-    information in error messages, e.g.
-
-<screen>
-$ nix-build '&lt;nixpkgs>' -A libreoffice --argstr system x86_64-darwin
-error: the package ‘libreoffice-4.0.5.2’ in ‘.../applications/office/libreoffice/default.nix:263’
-  is not supported on ‘x86_64-darwin’
-</screen>
-
-    </para>
-  </listitem>
-
-  <listitem>
-    <para>The garbage collector is now more concurrent with other Nix
-    processes because it releases certain locks earlier.</para>
-  </listitem>
-
-  <listitem>
-    <para>The binary tarball installer has been improved.  You can now
-    install Nix by running:
-
-<screen>
-$ bash &lt;(curl https://nixos.org/nix/install)
-</screen>
-
-    </para>
-  </listitem>
-
-  <listitem>
-    <para>More evaluation errors include position information. For
-    instance, selecting a missing attribute will print something like
-
-<screen>
-error: attribute `nixUnstabl' missing, at /etc/nixos/configurations/misc/eelco/mandark.nix:216:15
-</screen>
-
-    </para>
-  </listitem>
-
-  <listitem>
-    <para>The command <command>nix-setuid-helper</command> is
-    gone.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix no longer uses Automake, but instead has a
-    non-recursive, GNU Make-based build system.</para>
-  </listitem>
-
-  <listitem>
-    <para>All installed libraries now have the prefix
-    <literal>libnix</literal>.  In particular, this gets rid of
-    <literal>libutil</literal>, which could clash with libraries with
-    the same name from other packages.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix now requires a compiler that supports C++11.</para>
-  </listitem>
-
-</itemizedlist>
-
-<para>This release has contributions from Danny Wilson, Domen Kožar,
-Eelco Dolstra, Ian-Woo Kim, Ludovic Courtès, Maxim Ivanov, Petr
-Rockai, Ricardo M. Correia and Shea Levy.</para>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.6.1"><title>Release 1.6.1 (October 28, 2013)</title>
-
-<para>This is primarily a bug fix release.  Changes of interest
-are:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>Nix 1.6 accidentally changed the semantics of antiquoted
-    paths in strings, such as <literal>"${/foo}/bar"</literal>.  This
-    release reverts to the Nix 1.5.3 behaviour.</para>
-  </listitem>
-
-  <listitem>
-    <para>Previously, Nix optimised expressions such as
-    <literal>"${<replaceable>expr</replaceable>}"</literal> to
-    <replaceable>expr</replaceable>.  Thus it neither checked whether
-    <replaceable>expr</replaceable> could be coerced to a string, nor
-    applied such coercions.  This meant that
-    <literal>"${123}"</literal> evaluatued to <literal>123</literal>,
-    and <literal>"${./foo}"</literal> evaluated to
-    <literal>./foo</literal> (even though
-    <literal>"${./foo} "</literal> evaluates to
-    <literal>"/nix/store/<replaceable>hash</replaceable>-foo "</literal>).
-    Nix now checks the type of antiquoted expressions and
-    applies coercions.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix now shows the exact position of undefined variables.  In
-    particular, undefined variable errors in a <literal>with</literal>
-    previously didn't show <emphasis>any</emphasis> position
-    information, so this makes it a lot easier to fix such
-    errors.</para>
-  </listitem>
-
-  <listitem>
-    <para>Undefined variables are now treated consistently.
-    Previously, the <function>tryEval</function> function would catch
-    undefined variables inside a <literal>with</literal> but not
-    outside.  Now <function>tryEval</function> never catches undefined
-    variables.</para>
-  </listitem>
-
-  <listitem>
-    <para>Bash completion in <command>nix-shell</command> now works
-    correctly.</para>
-  </listitem>
-
-  <listitem>
-    <para>Stack traces are less verbose: they no longer show calls to
-    builtin functions and only show a single line for each derivation
-    on the call stack.</para>
-  </listitem>
-
-  <listitem>
-    <para>New built-in function: <function>builtins.typeOf</function>,
-    which returns the type of its argument as a string.</para>
-  </listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.6.0"><title>Release 1.6 (September 10, 2013)</title>
-
-<para>In addition to the usual bug fixes, this release has several new
-features:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>The command <command>nix-build --run-env</command> has been
-    renamed to <command>nix-shell</command>.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-shell</command> now sources
-    <filename>$stdenv/setup</filename> <emphasis>inside</emphasis> the
-    interactive shell, rather than in a parent shell.  This ensures
-    that shell functions defined by <literal>stdenv</literal> can be
-    used in the interactive shell.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-shell</command> has a new flag
-    <option>--pure</option> to clear the environment, so you get an
-    environment that more closely corresponds to the “real” Nix build.
-    </para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-shell</command> now sets the shell prompt
-    (<envar>PS1</envar>) to ensure that Nix shells are distinguishable
-    from your regular shells.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-env</command> no longer requires a
-    <literal>*</literal> argument to match all packages, so
-    <literal>nix-env -qa</literal> is equivalent to <literal>nix-env
-    -qa '*'</literal>.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-env -i</command> has a new flag
-    <option>--remove-all</option> (<option>-r</option>) to remove all
-    previous packages from the profile.  This makes it easier to do
-    declarative package management similar to NixOS’s
-    <option>environment.systemPackages</option>.  For instance, if you
-    have a specification <filename>my-packages.nix</filename> like this:
-
-<programlisting>
-with import &lt;nixpkgs> {};
-[ thunderbird
-  geeqie
-  ...
-]
-</programlisting>
-
-    then after any change to this file, you can run:
-
-<screen>
-$ nix-env -f my-packages.nix -ir
-</screen>
-
-    to update your profile to match the specification.</para>
-  </listitem>
-
-  <listitem>
-    <para>The ‘<literal>with</literal>’ language construct is now more
-    lazy.  It only evaluates its argument if a variable might actually
-    refer to an attribute in the argument.  For instance, this now
-    works:
-
-<programlisting>
-let
-  pkgs = with pkgs; { foo = "old"; bar = foo; } // overrides;
-  overrides = { foo = "new"; };
-in pkgs.bar
-</programlisting>
-
-    This evaluates to <literal>"new"</literal>, while previously it
-    gave an “infinite recursion” error.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix now has proper integer arithmetic operators. For
-    instance, you can write <literal>x + y</literal> instead of
-    <literal>builtins.add x y</literal>, or <literal>x &lt;
-    y</literal> instead of <literal>builtins.lessThan x y</literal>.
-    The comparison operators also work on strings.</para>
-  </listitem>
-
-  <listitem>
-    <para>On 64-bit systems, Nix integers are now 64 bits rather than
-    32 bits.</para>
-  </listitem>
-
-  <listitem>
-    <para>When using the Nix daemon, the <command>nix-daemon</command>
-    worker process now runs on the same CPU as the client, on systems
-    that support setting CPU affinity.  This gives a significant speedup
-    on some systems.</para>
-  </listitem>
-
-  <listitem>
-    <para>If a stack overflow occurs in the Nix evaluator, you now get
-    a proper error message (rather than “Segmentation fault”) on some
-    systems.</para>
-  </listitem>
-
-  <listitem>
-    <para>In addition to directories, you can now bind-mount regular
-    files in chroots through the (now misnamed) option
-    <option>build-chroot-dirs</option>.</para>
-  </listitem>
-
-</itemizedlist>
-
-<para>This release has contributions from Domen Kožar, Eelco Dolstra,
-Florian Friesdorf, Gergely Risko, Ivan Kozik, Ludovic Courtès and Shea
-Levy.</para>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.5.3"><title>Release 1.5.3 (June 17, 2013)</title>
-
-<para>This is primarily a bug fix release.  The following changes are
-noteworthy:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>Yet another security bug involving hard links to files
-    outside the store was fixed.  This bug only affected multi-user
-    installations that do not have hard link restrictions
-    enabled.  (NixOS is thus not vulnerable.)</para>
-  </listitem>
-
-  <listitem>
-    <para>The default binary cache URL has changed from
-    <uri>http://nixos.org/binary-cache</uri> to
-    <uri>http://cache.nixos.org</uri>.  The latter is hosted on Amazon
-    CloudFront (courtesy of <link
-    xlink:href="http://www.logicblox.com/">LogicBlox</link>) and
-    should provide better performance for users in both Europe and
-    North America.</para>
-  </listitem>
-
-  <listitem>
-    <para>The binary cache substituter now prints a warning message if
-    fetching information from the cache takes more than five seconds.
-    Thus network or server problems no longer make Nix appear to just
-    hang.</para>
-  </listitem>
-
-  <listitem>
-    <para>Stack traces now show function names, e.g.
-<screen>
-while evaluating `concatMapStrings' at `<replaceable>...</replaceable>/nixpkgs/pkgs/lib/strings.nix:18:25':
-</screen>
-      Also, if a function is called with an unexpected argument, Nix
-      now shows the name of the argument.
-    </para>
-  </listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.5.2"><title>Release 1.5.2 (May 13, 2013)</title>
-
-<para>This is primarily a bug fix release.  It has contributions from
-Eelco Dolstra, Lluís Batlle i Rossell and Shea Levy.</para>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.5.1"><title>Release 1.5.1 (February 28, 2013)</title>
-
-<para>The bug fix to the bug fix had a bug itself, of course.  But
-this time it will work for sure!</para>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.5"><title>Release 1.5 (February 27, 2013)</title>
-
-<para>This is a brown paper bag release to fix a regression introduced
-by the hard link security fix in 1.4.</para>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.4"><title>Release 1.4 (February 26, 2013)</title>
-
-<para>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 (<link
-xlink:href="https://github.com/NixOS/nix/commit/5526a282b5b44e9296e61e07d7d2626a79141ac4">details</link>).</para>
-
-<para>There are also the following improvements:</para>
-
-<itemizedlist>
-
-  <listitem><para>New built-in function:
-  <function>builtins.hashString</function>.</para></listitem>
-
-  <listitem><para>Build logs are now stored in
-  <filename>/nix/var/log/nix/drvs/<replaceable>XX</replaceable>/</filename>,
-  where <replaceable>XX</replaceable> is the first two characters of
-  the derivation.  This is useful on machines that keep a lot of build
-  logs (such as Hydra servers).</para></listitem>
-
-  <listitem><para>The function <function>corepkgs/fetchurl</function>
-  can now make the downloaded file executable.  This will allow
-  getting rid of all bootstrap binaries in the Nixpkgs source
-  tree.</para></listitem>
-
-  <listitem><para>Language change: The expression <literal>"${./path}
-  ..."</literal> now evaluates to a string instead of a
-  path.</para></listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.3"><title>Release 1.3 (January 4, 2013)</title>
-
-<para>This is primarily a bug fix release.  When this version is first
-run on Linux, it removes any immutable bits from the Nix store and
-increases the schema version of the Nix store.  (The previous release
-removed support for setting the immutable bit; this release clears any
-remaining immutable bits to make certain operations more
-efficient.)</para>
-
-<para>This release has contributions from Eelco Dolstra and Stuart
-Pernsteiner.</para>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.2"><title>Release 1.2 (December 6, 2012)</title>
-
-<para>This release has the following improvements and changes:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>Nix has a new binary substituter mechanism: the
-    <emphasis>binary cache</emphasis>.  A binary cache contains
-    pre-built binaries of Nix packages.  Whenever Nix wants to build a
-    missing Nix store path, it will check a set of binary caches to
-    see if any of them has a pre-built binary of that path.  The
-    configuration setting <option>binary-caches</option> contains a
-    list of URLs of binary caches.  For instance, doing
-<screen>
-$ 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>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.1"><title>Release 1.1 (July 18, 2012)</title>
-
-<para>This release has the following improvements:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>On Linux, when doing a chroot build, Nix now uses various
-    namespace features provided by the Linux kernel to improve
-    build isolation.  Namely:
-    <itemizedlist>
-      <listitem><para>The private network namespace ensures that
-      builders cannot talk to the outside world (or vice versa): each
-      build only sees a private loopback interface.  This also means
-      that two concurrent builds can listen on the same port (e.g. as
-      part of a test) without conflicting with each
-      other.</para></listitem>
-      <listitem><para>The PID namespace causes each build to start as
-      PID 1.  Processes outside of the chroot are not visible to those
-      on the inside.  On the other hand, processes inside the chroot
-      <emphasis>are</emphasis> visible from the outside (though with
-      different PIDs).</para></listitem>
-      <listitem><para>The IPC namespace prevents the builder from
-      communicating with outside processes using SysV IPC mechanisms
-      (shared memory, message queues, semaphores).  It also ensures
-      that all IPC objects are destroyed when the builder
-      exits.</para></listitem>
-      <listitem><para>The UTS namespace ensures that builders see a
-      hostname of <literal>localhost</literal> rather than the actual
-      hostname.</para></listitem>
-      <listitem><para>The private mount namespace was already used by
-      Nix to ensure that the bind-mounts used to set up the chroot are
-      cleaned up automatically.</para></listitem>
-    </itemizedlist>
-    </para>
-  </listitem>
-
-  <listitem>
-    <para>Build logs are now compressed using
-    <command>bzip2</command>.  The command <command>nix-store
-    -l</command> decompresses them on the fly.  This can be disabled
-    by setting the option <literal>build-compress-log</literal> to
-    <literal>false</literal>.</para>
-  </listitem>
-
-  <listitem>
-    <para>The creation of build logs in
-    <filename>/nix/var/log/nix/drvs</filename> can be disabled by
-    setting the new option <literal>build-keep-log</literal> to
-    <literal>false</literal>.  This is useful, for instance, for Hydra
-    build machines.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix now reserves some space in
-    <filename>/nix/var/nix/db/reserved</filename> to ensure that the
-    garbage collector can run successfully if the disk is full.  This
-    is necessary because SQLite transactions fail if the disk is
-    full.</para>
-  </listitem>
-
-  <listitem>
-    <para>Added a basic <function>fetchurl</function> function.  This
-    is not intended to replace the <function>fetchurl</function> in
-    Nixpkgs, but is useful for bootstrapping; e.g., it will allow us
-    to get rid of the bootstrap binaries in the Nixpkgs source tree
-    and download them instead.  You can use it by doing
-    <literal>import &lt;nix/fetchurl.nix> { url =
-    <replaceable>url</replaceable>; sha256 =
-    "<replaceable>hash</replaceable>"; }</literal>. (Shea Levy)</para>
-  </listitem>
-
-  <listitem>
-    <para>Improved RPM spec file. (Michel Alexandre Salim)</para>
-  </listitem>
-
-  <listitem>
-    <para>Support for on-demand socket-based activation in the Nix
-    daemon with <command>systemd</command>.</para>
-  </listitem>
-
-  <listitem>
-    <para>Added a manpage for
-    <citerefentry><refentrytitle>nix.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
-  </listitem>
-
-  <listitem>
-    <para>When using the Nix daemon, the <option>-s</option> flag in
-    <command>nix-env -qa</command> is now much faster.</para>
-  </listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-1.0"><title>Release 1.0 (May 11, 2012)</title>
-
-<para>There have been numerous improvements and bug fixes since the
-previous release.  Here are the most significant:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>Nix can now optionally use the Boehm garbage collector.
-    This significantly reduces the Nix evaluator’s memory footprint,
-    especially when evaluating large NixOS system configurations.  It
-    can be enabled using the <option>--enable-gc</option> configure
-    option.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix now uses SQLite for its database.  This is faster and
-    more flexible than the old <emphasis>ad hoc</emphasis> format.
-    SQLite is also used to cache the manifests in
-    <filename>/nix/var/nix/manifests</filename>, resulting in a
-    significant speedup.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix now has an search path for expressions.  The search path
-    is set using the environment variable <envar>NIX_PATH</envar> and
-    the <option>-I</option> command line option.  In Nix expressions,
-    paths between angle brackets are used to specify files that must
-    be looked up in the search path.  For instance, the expression
-    <literal>&lt;nixpkgs/default.nix></literal> looks for a file
-    <filename>nixpkgs/default.nix</filename> relative to every element
-    in the search path.</para>
-  </listitem>
-
-  <listitem>
-    <para>The new command <command>nix-build --run-env</command>
-    builds all dependencies of a derivation, then starts a shell in an
-    environment containing all variables from the derivation.  This is
-    useful for reproducing the environment of a derivation for
-    development.</para>
-  </listitem>
-
-  <listitem>
-    <para>The new command <command>nix-store --verify-path</command>
-    verifies that the contents of a store path have not
-    changed.</para>
-  </listitem>
-
-  <listitem>
-    <para>The new command <command>nix-store --print-env</command>
-    prints out the environment of a derivation in a format that can be
-    evaluated by a shell.</para>
-  </listitem>
-
-  <listitem>
-    <para>Attribute names can now be arbitrary strings.  For instance,
-    you can write <literal>{ "foo-1.2" = …; "bla bla" = …; }."bla
-    bla"</literal>.</para>
-  </listitem>
-
-  <listitem>
-    <para>Attribute selection can now provide a default value using
-    the <literal>or</literal> operator.  For instance, the expression
-    <literal>x.y.z or e</literal> evaluates to the attribute
-    <literal>x.y.z</literal> if it exists, and <literal>e</literal>
-    otherwise.</para>
-  </listitem>
-
-  <listitem>
-    <para>The right-hand side of the <literal>?</literal> operator can
-    now be an attribute path, e.g., <literal>attrs ?
-    a.b.c</literal>.</para>
-  </listitem>
-
-  <listitem>
-    <para>On Linux, Nix will now make files in the Nix store immutable
-    on filesystems that support it.  This prevents accidental
-    modification of files in the store by the root user.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix has preliminary support for derivations with multiple
-    outputs.  This is useful because it allows parts of a package to
-    be deployed and garbage-collected separately.  For instance,
-    development parts of a package such as header files or static
-    libraries would typically not be part of the closure of an
-    application, resulting in reduced disk usage and installation
-    time.</para>
-  </listitem>
-
-  <listitem>
-    <para>The Nix store garbage collector is faster and holds the
-    global lock for a shorter amount of time.</para>
-  </listitem>
-
-  <listitem>
-    <para>The option <option>--timeout</option> (corresponding to the
-    configuration setting <literal>build-timeout</literal>) allows you
-    to set an absolute timeout on builds — if a build runs for more than
-    the given number of seconds, it is terminated.  This is useful for
-    recovering automatically from builds that are stuck in an infinite
-    loop but keep producing output, and for which
-    <literal>--max-silent-time</literal> is ineffective.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix development has moved to GitHub (<link
-    xlink:href="https://github.com/NixOS/nix" />).</para>
-  </listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-0.16"><title>Release 0.16 (August 17, 2010)</title>
-
-<para>This release has the following improvements:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>The Nix expression evaluator is now much faster in most
-    cases: typically, <link
-    xlink:href="http://www.mail-archive.com/nix-dev@cs.uu.nl/msg04113.html">3
-    to 8 times compared to the old implementation</link>.  It also
-    uses less memory.  It no longer depends on the ATerm
-    library.</para>
-  </listitem>
-
-  <listitem>
-    <para>
-      Support for configurable parallelism inside builders.  Build
-      scripts have always had the ability to perform multiple build
-      actions in parallel (for instance, by running <command>make -j
-      2</command>), but this was not desirable because the number of
-      actions to be performed in parallel was not configurable.  Nix
-      now has an option <option>--cores
-      <replaceable>N</replaceable></option> as well as a configuration
-      setting <varname>build-cores =
-      <replaceable>N</replaceable></varname> that causes the
-      environment variable <envar>NIX_BUILD_CORES</envar> to be set to
-      <replaceable>N</replaceable> when the builder is invoked.  The
-      builder can use this at its discretion to perform a parallel
-      build, e.g., by calling <command>make -j
-      <replaceable>N</replaceable></command>.  In Nixpkgs, this can be
-      enabled on a per-package basis by setting the derivation
-      attribute <varname>enableParallelBuilding</varname> to
-      <literal>true</literal>.
-    </para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-store -q</command> now supports XML output
-    through the <option>--xml</option> flag.</para>
-  </listitem>
-
-  <listitem>
-    <para>Several bug fixes.</para>
-  </listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-0.15"><title>Release 0.15 (March 17, 2010)</title>
-
-<para>This is a bug-fix release.  Among other things, it fixes
-building on Mac OS X (Snow Leopard), and improves the contents of
-<filename>/etc/passwd</filename> and <filename>/etc/group</filename>
-in <literal>chroot</literal> builds.</para>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-0.14"><title>Release 0.14 (February 4, 2010)</title>
-
-<para>This release has the following improvements:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>The garbage collector now starts deleting garbage much
-    faster than before.  It no longer determines liveness of all paths
-    in the store, but does so on demand.</para>
-  </listitem>
-
-  <listitem>
-    <para>Added a new operation, <command>nix-store --query
-    --roots</command>, that shows the garbage collector roots that
-    directly or indirectly point to the given store paths.</para>
-  </listitem>
-
-  <listitem>
-    <para>Removed support for converting Berkeley DB-based Nix
-    databases to the new schema.</para>
-  </listitem>
-
-  <listitem>
-    <para>Removed the <option>--use-atime</option> and
-    <option>--max-atime</option> garbage collector options.  They were
-    not very useful in practice.</para>
-  </listitem>
-
-  <listitem>
-    <para>On Windows, Nix now requires Cygwin 1.7.x.</para>
-  </listitem>
-
-  <listitem>
-    <para>A few bug fixes.</para>
-  </listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-0.13"><title>Release 0.13 (November 5,
-2009)</title>
-
-<para>This is primarily a bug fix release.  It has some new
-features:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>Syntactic sugar for writing nested attribute sets.  Instead of
-
-<programlisting>
-{
-  foo = {
-    bar = 123;
-    xyzzy = true;
-  };
-  a = { b = { c = "d"; }; };
-}
-</programlisting>
-
-    you can write
-
-<programlisting>
-{
-  foo.bar = 123;
-  foo.xyzzy = true;
-  a.b.c = "d";
-}
-</programlisting>
-
-    This is useful, for instance, in NixOS configuration files.</para>
-
-  </listitem>
-
-  <listitem>
-    <para>Support for Nix channels generated by Hydra, the Nix-based
-    continuous build system.  (Hydra generates NAR archives on the
-    fly, so the size and hash of these archives isn’t known in
-    advance.)</para>
-  </listitem>
-
-  <listitem>
-    <para>Support <literal>i686-linux</literal> builds directly on
-    <literal>x86_64-linux</literal> Nix installations.  This is
-    implemented using the <function>personality()</function> syscall,
-    which causes <command>uname</command> to return
-    <literal>i686</literal> in child processes.</para>
-  </listitem>
-
-  <listitem>
-    <para>Various improvements to the <literal>chroot</literal>
-    support.  Building in a <literal>chroot</literal> works quite well
-    now.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix no longer blocks if it tries to build a path and another
-    process is already building the same path.  Instead it tries to
-    build another buildable path first.  This improves
-    parallelism.</para>
-  </listitem>
-
-  <listitem>
-    <para>Support for large (> 4 GiB) files in NAR archives.</para>
-  </listitem>
-
-  <listitem>
-    <para>Various (performance) improvements to the remote build
-    mechanism.</para>
-  </listitem>
-
-  <listitem>
-    <para>New primops: <varname>builtins.addErrorContext</varname> (to
-    add a string to stack traces — useful for debugging),
-    <varname>builtins.isBool</varname>,
-    <varname>builtins.isString</varname>,
-    <varname>builtins.isInt</varname>,
-    <varname>builtins.intersectAttrs</varname>.</para>
-  </listitem>
-
-  <listitem>
-    <para>OpenSolaris support (Sander van der Burg).</para>
-  </listitem>
-
-  <listitem>
-    <para>Stack traces are no longer displayed unless the
-    <option>--show-trace</option> option is used.</para>
-  </listitem>
-
-  <listitem>
-    <para>The scoping rules for <literal>inherit
-    (<replaceable>e</replaceable>) ...</literal> in recursive
-    attribute sets have changed.  The expression
-    <replaceable>e</replaceable> can now refer to the attributes
-    defined in the containing set.</para>
-  </listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-0.12"><title>Release 0.12 (November 20,
-2008)</title>
-
-<itemizedlist>
-
-  <listitem>
-    <para>Nix no longer uses Berkeley DB to store Nix store metadata.
-    The principal advantages of the new storage scheme are: it works
-    properly over decent implementations of NFS (allowing Nix stores
-    to be shared between multiple machines); no recovery is needed
-    when a Nix process crashes; no write access is needed for
-    read-only operations; no more running out of Berkeley DB locks on
-    certain operations.</para>
-
-    <para>You still need to compile Nix with Berkeley DB support if
-    you want Nix to automatically convert your old Nix store to the
-    new schema.  If you don’t need this, you can build Nix with the
-    <filename>configure</filename> option
-    <option>--disable-old-db-compat</option>.</para>
-
-    <para>After the automatic conversion to the new schema, you can
-    delete the old Berkeley DB files:
-
-    <screen>
-$ cd /nix/var/nix/db
-$ rm __db* log.* derivers references referrers reserved validpaths DB_CONFIG</screen>
-
-    The new metadata is stored in the directories
-    <filename>/nix/var/nix/db/info</filename> and
-    <filename>/nix/var/nix/db/referrer</filename>.  Though the
-    metadata is stored in human-readable plain-text files, they are
-    not intended to be human-editable, as Nix is rather strict about
-    the format.</para>
-
-    <para>The new storage schema may or may not require less disk
-    space than the Berkeley DB environment, mostly depending on the
-    cluster size of your file system.  With 1 KiB clusters (which
-    seems to be the <literal>ext3</literal> default nowadays) it
-    usually takes up much less space.</para>
-  </listitem>
-
-  <listitem><para>There is a new substituter that copies paths
-  directly from other (remote) Nix stores mounted somewhere in the
-  filesystem.  For instance, you can speed up an installation by
-  mounting some remote Nix store that already has the packages in
-  question via NFS or <literal>sshfs</literal>.  The environment
-  variable <envar>NIX_OTHER_STORES</envar> specifies the locations of
-  the remote Nix directories,
-  e.g. <literal>/mnt/remote-fs/nix</literal>.</para></listitem>
-
-  <listitem><para>New <command>nix-store</command> operations
-  <option>--dump-db</option> and <option>--load-db</option> to dump
-  and reload the Nix database.</para></listitem>
-
-  <listitem><para>The garbage collector has a number of new options to
-  allow only some of the garbage to be deleted.  The option
-  <option>--max-freed <replaceable>N</replaceable></option> tells the
-  collector to stop after at least <replaceable>N</replaceable> bytes
-  have been deleted.  The option <option>--max-links
-  <replaceable>N</replaceable></option> tells it to stop after the
-  link count on <filename>/nix/store</filename> has dropped below
-  <replaceable>N</replaceable>.  This is useful for very large Nix
-  stores on filesystems with a 32000 subdirectories limit (like
-  <literal>ext3</literal>).  The option <option>--use-atime</option>
-  causes store paths to be deleted in order of ascending last access
-  time.  This allows non-recently used stuff to be deleted.  The
-  option <option>--max-atime <replaceable>time</replaceable></option>
-  specifies an upper limit to the last accessed time of paths that may
-  be deleted.  For instance,
-
-    <screen>
-    $ nix-store --gc -v --max-atime $(date +%s -d "2 months ago")</screen>
-
-  deletes everything that hasn’t been accessed in two months.</para></listitem>
-
-  <listitem><para><command>nix-env</command> now uses optimistic
-  profile locking when performing an operation like installing or
-  upgrading, instead of setting an exclusive lock on the profile.
-  This allows multiple <command>nix-env -i / -u / -e</command>
-  operations on the same profile in parallel.  If a
-  <command>nix-env</command> operation sees at the end that the profile
-  was changed in the meantime by another process, it will just
-  restart.  This is generally cheap because the build results are
-  still in the Nix store.</para></listitem>
-
-  <listitem><para>The option <option>--dry-run</option> is now
-  supported by <command>nix-store -r</command> and
-  <command>nix-build</command>.</para></listitem>
-
-  <listitem><para>The information previously shown by
-  <option>--dry-run</option> (i.e., which derivations will be built
-  and which paths will be substituted) is now always shown by
-  <command>nix-env</command>, <command>nix-store -r</command> and
-  <command>nix-build</command>.  The total download size of
-  substitutable paths is now also shown.  For instance, a build will
-  show something like
-
-    <screen>
-the following derivations will be built:
-  /nix/store/129sbxnk5n466zg6r1qmq1xjv9zymyy7-activate-configuration.sh.drv
-  /nix/store/7mzy971rdm8l566ch8hgxaf89x7lr7ik-upstart-jobs.drv
-  ...
-the following paths will be downloaded/copied (30.02 MiB):
-  /nix/store/4m8pvgy2dcjgppf5b4cj5l6wyshjhalj-samba-3.2.4
-  /nix/store/7h1kwcj29ip8vk26rhmx6bfjraxp0g4l-libunwind-0.98.6
-  ...</screen>
-
-  </para></listitem>
-
-  <listitem><para>Language features:
-
-    <itemizedlist>
-
-      <listitem><para>@-patterns as in Haskell.  For instance, in a
-      function definition
-
-      <programlisting>f = args @ {x, y, z}: <replaceable>...</replaceable>;</programlisting>
-
-      <varname>args</varname> refers to the argument as a whole, which
-      is further pattern-matched against the attribute set pattern
-      <literal>{x, y, z}</literal>.</para></listitem>
-
-      <listitem><para>“<literal>...</literal>” (ellipsis) patterns.
-      An attribute set pattern can now say <literal>...</literal>  at
-      the end of the attribute name list to specify that the function
-      takes <emphasis>at least</emphasis> the listed attributes, while
-      ignoring additional attributes.  For instance,
-
-      <programlisting>{stdenv, fetchurl, fuse, ...}: <replaceable>...</replaceable></programlisting>
-
-      defines a function that accepts any attribute set that includes
-      at least the three listed attributes.</para></listitem>
-
-      <listitem><para>New primops:
-      <varname>builtins.parseDrvName</varname> (split a package name
-      string like <literal>"nix-0.12pre12876"</literal> into its name
-      and version components, e.g. <literal>"nix"</literal> and
-      <literal>"0.12pre12876"</literal>),
-      <varname>builtins.compareVersions</varname> (compare two version
-      strings using the same algorithm that <command>nix-env</command>
-      uses), <varname>builtins.length</varname> (efficiently compute
-      the length of a list), <varname>builtins.mul</varname> (integer
-      multiplication), <varname>builtins.div</varname> (integer
-      division).
-      <!-- <varname>builtins.genericClosure</varname> -->
-      </para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-  <listitem><para><command>nix-prefetch-url</command> now supports
-  <literal>mirror://</literal> URLs, provided that the environment
-  variable <envar>NIXPKGS_ALL</envar> points at a Nixpkgs
-  tree.</para></listitem>
-
-  <listitem><para>Removed the commands
-  <command>nix-pack-closure</command> and
-  <command>nix-unpack-closure</command>.   You can do almost the same
-  thing but much more efficiently by doing <literal>nix-store --export
-  $(nix-store -qR <replaceable>paths</replaceable>) > closure</literal> and
-  <literal>nix-store --import &lt;
-  closure</literal>.</para></listitem>
-
-  <listitem><para>Lots of bug fixes, including a big performance bug in
-  the handling of <literal>with</literal>-expressions.</para></listitem>
-
-</itemizedlist>
-
-</section>
-
-
-<!--==================================================================-->
-
-<section xml:id="ssec-relnotes-0.11"><title>Release 0.11 (December 31,
-2007)</title>
-
-<para>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:</para>
-
-
-<itemizedlist>
-
-
-  <listitem><para>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.</para></listitem>
-
-
-  <listitem><para>The new command <command>nix-copy-closure</command>
-  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
-  <command>ssh</command>.</para></listitem>
-
-
-  <listitem><para>A new kind of string literal: strings between double
-  single-quotes (<literal>''</literal>) 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 <literal>''</literal> is less common in
-  most languages than <literal>"</literal>.</para></listitem>
-
-
-  <listitem><para><command>nix-env</command> <option>--set</option>
-  modifies the current generation of a profile so that it contains
-  exactly the specified derivation, and nothing else.  For example,
-  <literal>nix-env -p /nix/var/nix/profiles/browser --set
-  firefox</literal> lets the profile named
-  <filename>browser</filename> contain just Firefox.</para></listitem>
-
-
-  <listitem><para><command>nix-env</command> now maintains
-  meta-information about installed packages in profiles.  The
-  meta-information is the contents of the <varname>meta</varname>
-  attribute of derivations, such as <varname>description</varname> or
-  <varname>homepage</varname>.  The command <literal>nix-env -q --xml
-  --meta</literal> shows all meta-information.</para></listitem>
-
-
-  <listitem><para><command>nix-env</command> now uses the
-  <varname>meta.priority</varname> 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
-  <filename>bin/ld</filename>, 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
-  <filename>bin/ld</filename> is symlinked in the user
-  environment.</para></listitem>
-
-
-  <listitem><para><command>nix-env -i / -u</command>: 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.</para>
-
-  <para>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.,
-  <literal>gcc-4.2.0rc1</literal>) which should not be installed even
-  though it is the highest version, except when it is explicitly
-  selected (e.g., <literal>nix-env -i
-  gcc-4.2.0rc1</literal>).</para></listitem>
-
-
-  <listitem><para><command>nix-env --set-flag</command> allows meta
-  attributes of installed packages to be modified.  There are several
-  attributes that can be usefully modified, because they affect the
-  behaviour of <command>nix-env</command> or the user environment
-  build script:
-
-    <itemizedlist>
-
-      <listitem><para><varname>meta.priority</varname> can be changed
-      to resolve filename clashes (see above).</para></listitem>
-
-      <listitem><para><varname>meta.keep</varname> can be set to
-      <literal>true</literal> to prevent the package from being
-      upgraded or replaced.  Useful if you want to hang on to an older
-      version of a package.</para></listitem>
-
-      <listitem><para><varname>meta.active</varname> can be set to
-      <literal>false</literal> 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 <literal>true</literal> to re-enable the
-      package.</para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-
-  <listitem><para><command>nix-env -q</command> now has a flag
-  <option>--prebuilt-only</option> (<option>-b</option>) that causes
-  <command>nix-env</command> 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 <option>-b</option> flag is also available in
-  <command>nix-env -i</command> and <command>nix-env -u</command> to
-  filter out derivations for which no pre-built binary is
-  available.</para></listitem>
-
-
-  <listitem><para>The new option <option>--argstr</option> (in
-  <command>nix-env</command>, <command>nix-instantiate</command> and
-  <command>nix-build</command>) is like <option>--arg</option>, except
-  that the value is a string.  For example, <literal>--argstr system
-  i686-linux</literal> is equivalent to <literal>--arg system
-  \"i686-linux\"</literal> (note that <option>--argstr</option>
-  prevents annoying quoting around shell arguments).</para></listitem>
-
-
-  <listitem><para><command>nix-store</command> has a new operation
-  <option>--read-log</option> (<option>-l</option>)
-  <parameter>paths</parameter> that shows the build log of the given
-  paths.</para></listitem>
-
-
-  <!--
-  <listitem><para>TODO: semantic cleanups of string concatenation
-  etc. (mostly in r6740).</para></listitem>
-  -->
-
-
-  <listitem><para>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.</para></listitem>
-
-
-  <!-- foo
-  <listitem><para>TODO: option <option>- -reregister</option> in
-  <command>nix-store - -register-validity</command>.</para></listitem>
-  -->
-
-
-  <listitem><para>The option <option>--max-silent-time</option>
-  (corresponding to the configuration setting
-  <literal>build-max-silent-time</literal>) allows you to set a
-  timeout on builds — if a build produces no output on
-  <literal>stdout</literal> or <literal>stderr</literal> for the given
-  number of seconds, it is terminated.  This is useful for recovering
-  automatically from builds that are stuck in an infinite
-  loop.</para></listitem>
-
-
-  <listitem><para><command>nix-channel</command>: each subscribed
-  channel is its own attribute in the top-level expression generated
-  for the channel.  This allows disambiguation (e.g. <literal>nix-env
-  -i -A nixpkgs_unstable.firefox</literal>).</para></listitem>
-
-
-  <listitem><para>The substitutes table has been removed from the
-  database.  This makes operations such as <command>nix-pull</command>
-  and <command>nix-channel --update</command> much, much
-  faster.</para></listitem>
-
-
-  <listitem><para><command>nix-pull</command> now supports
-  bzip2-compressed manifests.  This speeds up
-  channels.</para></listitem>
-
-
-  <listitem><para><command>nix-prefetch-url</command> now has a
-  limited form of caching.  This is used by
-  <command>nix-channel</command> to prevent unnecessary downloads when
-  the channel hasn’t changed.</para></listitem>
-
-
-  <listitem><para><command>nix-prefetch-url</command> now by default
-  computes the SHA-256 hash of the file instead of the MD5 hash.  In
-  calls to <function>fetchurl</function> you should pass the
-  <literal>sha256</literal> attribute instead of
-  <literal>md5</literal>.  You can pass either a hexadecimal or a
-  base-32 encoding of the hash.</para></listitem>
-
-
-  <listitem><para>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.</para></listitem>
-
-
-  <listitem><para>The new command <command>nix-store
-  --optimise</command> 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%.</para></listitem>
-
-
-  <listitem><para><filename>~/.nix-defexpr</filename> 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 <command>nix-env
-  --import</command> (which set the
-  <filename>~/.nix-defexpr</filename> symlink) is
-  removed.</para></listitem>
-
-
-  <listitem><para>Derivations can specify the new special attribute
-  <varname>allowedReferences</varname> to enforce that the references
-  in the output of a derivation are a subset of a declared set of
-  paths.  For example, if <varname>allowedReferences</varname> 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.</para></listitem>
-
-
-  <listitem><para>The new attribute
-  <varname>exportReferencesGraph</varname> 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.</para></listitem>
-
-
-  <listitem><para>Fixed-output derivations (like
-  <function>fetchurl</function>) can define the attribute
-  <varname>impureEnvVars</varname> to allow external environment
-  variables to be passed to builders.  This is used in Nixpkgs to
-  support proxy configuration, among other things.</para></listitem>
-
-
-  <listitem><para>Several new built-in functions:
-  <function>builtins.attrNames</function>,
-  <function>builtins.filterSource</function>,
-  <function>builtins.isAttrs</function>,
-  <function>builtins.isFunction</function>,
-  <function>builtins.listToAttrs</function>,
-  <function>builtins.stringLength</function>,
-  <function>builtins.sub</function>,
-  <function>builtins.substring</function>,
-  <function>throw</function>,
-  <function>builtins.trace</function>,
-  <function>builtins.readFile</function>.</para></listitem>
-
-
-</itemizedlist>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.10.1 (October 11, 2006)</title>
-
-<para>This release fixes two somewhat obscure bugs that occur when
-evaluating Nix expressions that are stored inside the Nix store
-(<literal>NIX-67</literal>).  These do not affect most users.</para>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.10 (October 6, 2006)</title>
-
-<note><para>This version of Nix uses Berkeley DB 4.4 instead of 4.3.
-The database is upgraded automatically, but you should be careful not
-to use old versions of Nix that still use Berkeley DB 4.3.  In
-particular, if you use a Nix installed through Nix, you should run
-
-<screen>
-$ nix-store --clear-substitutes</screen>
-
-first.</para></note>
-
-<warning><para>Also, the database schema has changed slighted to fix a
-performance issue (see below).  When you run any Nix 0.10 command for
-the first time, the database will be upgraded automatically.  This is
-irreversible.</para></warning>
-
-<itemizedlist>
-
-
-  <!-- Usability / features -->
-
-
-  <listitem><para><command>nix-env</command> usability improvements:
-
-    <itemizedlist>
-
-      <listitem><para>An option <option>--compare-versions</option>
-      (or <option>-c</option>) has been added to <command>nix-env
-      --query</command> to allow you to compare installed versions of
-      packages to available versions, or vice versa.  An easy way to
-      see if you are up to date with what’s in your subscribed
-      channels is <literal>nix-env -qc \*</literal>.</para></listitem>
-
-      <listitem><para><literal>nix-env --query</literal> now takes as
-      arguments a list of package names about which to show
-      information, just like <option>--install</option>, etc.: for
-      example, <literal>nix-env -q gcc</literal>.  Note that to show
-      all derivations, you need to specify
-      <literal>\*</literal>.</para></listitem>
-
-      <listitem><para><literal>nix-env -i
-      <replaceable>pkgname</replaceable></literal> will now install
-      the highest available version of
-      <replaceable>pkgname</replaceable>, rather than installing all
-      available versions (which would probably give collisions)
-      (<literal>NIX-31</literal>).</para></listitem>
-
-      <listitem><para><literal>nix-env (-i|-u) --dry-run</literal> now
-      shows exactly which missing paths will be built or
-      substituted.</para></listitem>
-
-      <listitem><para><literal>nix-env -qa --description</literal>
-      shows human-readable descriptions of packages, provided that
-      they have a <literal>meta.description</literal> attribute (which
-      most packages in Nixpkgs don’t have yet).</para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-
-  <listitem><para>New language features:
-
-    <itemizedlist>
-
-      <listitem><para>Reference scanning (which happens after each
-      build) is much faster and takes a constant amount of
-      memory.</para></listitem>
-
-      <listitem><para>String interpolation.  Expressions like
-
-<programlisting>
-"--with-freetype2-library=" + freetype + "/lib"</programlisting>
-
-      can now be written as
-
-<programlisting>
-"--with-freetype2-library=${freetype}/lib"</programlisting>
-
-      You can write arbitrary expressions within
-      <literal>${<replaceable>...</replaceable>}</literal>, not just
-      identifiers.</para></listitem>
-
-      <listitem><para>Multi-line string literals.</para></listitem>
-
-      <listitem><para>String concatenations can now involve
-      derivations, as in the example <code>"--with-freetype2-library="
-      + freetype + "/lib"</code>.  This was not previously possible
-      because we need to register that a derivation that uses such a
-      string is dependent on <literal>freetype</literal>.  The
-      evaluator now properly propagates this information.
-      Consequently, the subpath operator (<literal>~</literal>) has
-      been deprecated.</para></listitem>
-
-      <listitem><para>Default values of function arguments can now
-      refer to other function arguments; that is, all arguments are in
-      scope in the default values
-      (<literal>NIX-45</literal>).</para></listitem>
-
-      <!--
-      <listitem><para>TODO: domain checks (r5895).</para></listitem>
-      -->
-
-      <listitem><para>Lots of new built-in primitives, such as
-      functions for list manipulation and integer arithmetic.  See the
-      manual for a complete list.  All primops are now available in
-      the set <varname>builtins</varname>, allowing one to test for
-      the availability of primop in a backwards-compatible
-      way.</para></listitem>
-
-      <listitem><para>Real let-expressions: <literal>let x = ...;
-      ... z = ...; in ...</literal>.</para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-
-  <listitem><para>New commands <command>nix-pack-closure</command> and
-  <command>nix-unpack-closure</command> than can be used to easily
-  transfer a store path with all its dependencies to another machine.
-  Very convenient whenever you have some package on your machine and
-  you want to copy it somewhere else.</para></listitem>
-
-
-  <listitem><para>XML support:
-
-    <itemizedlist>
-
-      <listitem><para><literal>nix-env -q --xml</literal> prints the
-      installed or available packages in an XML representation for
-      easy processing by other tools.</para></listitem>
-
-      <listitem><para><literal>nix-instantiate --eval-only
-      --xml</literal> prints an XML representation of the resulting
-      term.  (The new flag <option>--strict</option> forces ‘deep’
-      evaluation of the result, i.e., list elements and attributes are
-      evaluated recursively.)</para></listitem>
-
-      <listitem><para>In Nix expressions, the primop
-      <function>builtins.toXML</function> converts a term to an XML
-      representation.  This is primarily useful for passing structured
-      information to builders.</para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-
-  <listitem><para>You can now unambiguously specify which derivation to
-  build or install in <command>nix-env</command>,
-  <command>nix-instantiate</command> and <command>nix-build</command>
-  using the <option>--attr</option> / <option>-A</option> flags, which
-  takes an attribute name as argument.  (Unlike symbolic package names
-  such as <literal>subversion-1.4.0</literal>, attribute names in an
-  attribute set are unique.)  For instance, a quick way to perform a
-  test build of a package in Nixpkgs is <literal>nix-build
-  pkgs/top-level/all-packages.nix -A
-  <replaceable>foo</replaceable></literal>.  <literal>nix-env -q
-  --attr</literal> shows the attribute names corresponding to each
-  derivation.</para></listitem>
-
-
-  <listitem><para>If the top-level Nix expression used by
-  <command>nix-env</command>, <command>nix-instantiate</command> or
-  <command>nix-build</command> evaluates to a function whose arguments
-  all have default values, the function will be called automatically.
-  Also, the new command-line switch <option>--arg
-  <replaceable>name</replaceable>
-  <replaceable>value</replaceable></option> can be used to specify
-  function arguments on the command line.</para></listitem>
-
-
-  <listitem><para><literal>nix-install-package --url
-  <replaceable>URL</replaceable></literal> allows a package to be
-  installed directly from the given URL.</para></listitem>
-
-
-  <listitem><para>Nix now works behind an HTTP proxy server; just set
-  the standard environment variables <envar>http_proxy</envar>,
-  <envar>https_proxy</envar>, <envar>ftp_proxy</envar> or
-  <envar>all_proxy</envar> appropriately.  Functions such as
-  <function>fetchurl</function> in Nixpkgs also respect these
-  variables.</para></listitem>
-
-
-  <listitem><para><literal>nix-build -o
-  <replaceable>symlink</replaceable></literal> allows the symlink to
-  the build result to be named something other than
-  <literal>result</literal>.</para></listitem>
-
-
-  <!-- Stability / performance / etc. -->
-
-
-  <listitem><para>Platform support:
-
-    <itemizedlist>
-
-      <listitem><para>Support for 64-bit platforms, provided a <link
-      xlink:href="http://bugzilla.sen.cwi.nl:8080/show_bug.cgi?id=606">suitably
-      patched ATerm library</link> is used.  Also, files larger than 2
-      GiB are now supported.</para></listitem>
-
-      <listitem><para>Added support for Cygwin (Windows,
-      <literal>i686-cygwin</literal>), Mac OS X on Intel
-      (<literal>i686-darwin</literal>) and Linux on PowerPC
-      (<literal>powerpc-linux</literal>).</para></listitem>
-
-      <listitem><para>Users of SMP and multicore machines will
-      appreciate that the number of builds to be performed in parallel
-      can now be specified in the configuration file in the
-      <literal>build-max-jobs</literal> setting.</para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-
-  <listitem><para>Garbage collector improvements:
-
-    <itemizedlist>
-
-      <listitem><para>Open files (such as running programs) are now
-      used as roots of the garbage collector.  This prevents programs
-      that have been uninstalled from being garbage collected while
-      they are still running.  The script that detects these
-      additional runtime roots
-      (<filename>find-runtime-roots.pl</filename>) is inherently
-      system-specific, but it should work on Linux and on all
-      platforms that have the <command>lsof</command>
-      utility.</para></listitem>
-
-      <listitem><para><literal>nix-store --gc</literal>
-      (a.k.a. <command>nix-collect-garbage</command>) prints out the
-      number of bytes freed on standard output.  <literal>nix-store
-      --gc --print-dead</literal> shows how many bytes would be freed
-      by an actual garbage collection.</para></listitem>
-
-      <listitem><para><literal>nix-collect-garbage -d</literal>
-      removes all old generations of <emphasis>all</emphasis> profiles
-      before calling the actual garbage collector (<literal>nix-store
-      --gc</literal>).  This is an easy way to get rid of all old
-      packages in the Nix store.</para></listitem>
-
-      <listitem><para><command>nix-store</command> now has an
-      operation <option>--delete</option> to delete specific paths
-      from the Nix store.  It won’t delete reachable (non-garbage)
-      paths unless <option>--ignore-liveness</option> is
-      specified.</para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-
-  <listitem><para>Berkeley DB 4.4’s process registry feature is used
-  to recover from crashed Nix processes.</para></listitem>
-
-  <!--  <listitem><para>TODO: shared stores.</para></listitem> -->
-
-  <listitem><para>A performance issue has been fixed with the
-  <literal>referer</literal> table, which stores the inverse of the
-  <literal>references</literal> table (i.e., it tells you what store
-  paths refer to a given path).  Maintaining this table could take a
-  quadratic amount of time, as well as a quadratic amount of Berkeley
-  DB log file space (in particular when running the garbage collector)
-  (<literal>NIX-23</literal>).</para></listitem>
-
-  <listitem><para>Nix now catches the <literal>TERM</literal> and
-  <literal>HUP</literal> signals in addition to the
-  <literal>INT</literal> signal.  So you can now do a <literal>killall
-  nix-store</literal> without triggering a database
-  recovery.</para></listitem>
-
-  <listitem><para><command>bsdiff</command> updated to version
-  4.3.</para></listitem>
-
-  <listitem><para>Substantial performance improvements in expression
-  evaluation and <literal>nix-env -qa</literal>, all thanks to <link
-  xlink:href="http://valgrind.org/">Valgrind</link>.  Memory use has
-  been reduced by a factor 8 or so.  Big speedup by memoisation of
-  path hashing.</para></listitem>
-
-  <listitem><para>Lots of bug fixes, notably:
-
-    <itemizedlist>
-
-      <listitem><para>Make sure that the garbage collector can run
-      successfully when the disk is full
-      (<literal>NIX-18</literal>).</para></listitem>
-
-      <listitem><para><command>nix-env</command> now locks the profile
-      to prevent races between concurrent <command>nix-env</command>
-      operations on the same profile
-      (<literal>NIX-7</literal>).</para></listitem>
-
-      <listitem><para>Removed misleading messages from
-      <literal>nix-env -i</literal> (e.g., <literal>installing
-      `foo'</literal> followed by <literal>uninstalling
-      `foo'</literal>) (<literal>NIX-17</literal>).</para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-  <listitem><para>Nix source distributions are a lot smaller now since
-  we no longer include a full copy of the Berkeley DB source
-  distribution (but only the bits we need).</para></listitem>
-
-  <listitem><para>Header files are now installed so that external
-  programs can use the Nix libraries.</para></listitem>
-
-</itemizedlist>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.9.2 (September 21, 2005)</title>
-
-<para>This bug fix release fixes two problems on Mac OS X:
-
-<itemizedlist>
-
-  <listitem><para>If Nix was linked against statically linked versions
-  of the ATerm or Berkeley DB library, there would be dynamic link
-  errors at runtime.</para></listitem>
-
-  <listitem><para><command>nix-pull</command> and
-  <command>nix-push</command> intermittently failed due to race
-  conditions involving pipes and child processes with error messages
-  such as <literal>open2: open(GLOB(0x180b2e4), >&amp;=9) failed: Bad
-  file descriptor at /nix/bin/nix-pull line 77</literal> (issue
-  <literal>NIX-14</literal>).</para></listitem>
-
-</itemizedlist>
-
-</para>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.9.1 (September 20, 2005)</title>
-
-<para>This bug fix release addresses a problem with the ATerm library
-when the <option>--with-aterm</option> flag in
-<command>configure</command> was <emphasis>not</emphasis> used.</para>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.9 (September 16, 2005)</title>
-
-<para>NOTE: this version of Nix uses Berkeley DB 4.3 instead of 4.2.
-The database is upgraded automatically, but you should be careful not
-to use old versions of Nix that still use Berkeley DB 4.2.  In
-particular, if you use a Nix installed through Nix, you should run
-
-<screen>
-$ nix-store --clear-substitutes</screen>
-
-first.</para>
-
-
-<itemizedlist>
-
-  <listitem><para>Unpacking of patch sequences is much faster now
-  since we no longer do redundant unpacking and repacking of
-  intermediate paths.</para></listitem>
-
-  <listitem><para>Nix now uses Berkeley DB 4.3.</para></listitem>
-
-  <listitem><para>The <function>derivation</function> primitive is
-  lazier.  Attributes of dependent derivations can mutually refer to
-  each other (as long as there are no data dependencies on the
-  <varname>outPath</varname> and <varname>drvPath</varname> attributes
-  computed by <function>derivation</function>).</para>
-
-  <para>For example, the expression <literal>derivation
-  attrs</literal> now evaluates to (essentially)
-
-  <programlisting>
-attrs // {
-  type = "derivation";
-  outPath = derivation! attrs;
-  drvPath = derivation! attrs;
-}</programlisting>
-
-  where <function>derivation!</function> is a primop that does the
-  actual derivation instantiation (i.e., it does what
-  <function>derivation</function> used to do).  The advantage is that
-  it allows commands such as <command>nix-env -qa</command> and
-  <command>nix-env -i</command> to be much faster since they no longer
-  need to instantiate all derivations, just the
-  <varname>name</varname> attribute.</para>
-
-  <para>Also, it allows derivations to cyclically reference each
-  other, for example,
-
-  <programlisting>
-webServer = derivation {
-  ...
-  hostName = "svn.cs.uu.nl";
-  services = [svnService];
-};
-&#x20;
-svnService = derivation {
-  ...
-  hostName = webServer.hostName;
-};</programlisting>
-
-  Previously, this would yield a black hole (infinite recursion).</para>
-
-  </listitem>
-
-  <listitem><para><command>nix-build</command> now defaults to using
-  <filename>./default.nix</filename> if no Nix expression is
-  specified.</para></listitem>
-
-  <listitem><para><command>nix-instantiate</command>, when applied to
-  a Nix expression that evaluates to a function, will call the
-  function automatically if all its arguments have
-  defaults.</para></listitem>
-
-  <listitem><para>Nix now uses libtool to build dynamic libraries.
-  This reduces the size of executables.</para></listitem>
-
-  <listitem><para>A new list concatenation operator
-  <literal>++</literal>.  For example, <literal>[1 2 3] ++ [4 5
-  6]</literal> evaluates to <literal>[1 2 3 4 5
-  6]</literal>.</para></listitem>
-
-  <listitem><para>Some currently undocumented primops to support
-  low-level build management using Nix (i.e., using Nix as a Make
-  replacement).  See the commit messages for <literal>r3578</literal>
-  and <literal>r3580</literal>.</para></listitem>
-
-  <listitem><para>Various bug fixes and performance
-  improvements.</para></listitem>
-
-</itemizedlist>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.8.1 (April 13, 2005)</title>
-
-<para>This is a bug fix release.</para>
-
-<itemizedlist>
-
-  <listitem><para>Patch downloading was broken.</para></listitem>
-
-  <listitem><para>The garbage collector would not delete paths that
-  had references from invalid (but substitutable)
-  paths.</para></listitem>
-
-</itemizedlist>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.8 (April 11, 2005)</title>
-
-<para>NOTE: the hashing scheme in Nix 0.8 changed (as detailed below).
-As a result, <command>nix-pull</command> manifests and channels built
-for Nix 0.7 and below will now work anymore.  However, the Nix
-expression language has not changed, so you can still build from
-source.  Also, existing user environments continue to work.  Nix 0.8
-will automatically upgrade the database schema of previous
-installations when it is first run.</para>
-
-<para>If you get the error message
-
-<screen>
-you have an old-style manifest `/nix/var/nix/manifests/[...]'; please
-delete it</screen>
-
-you should delete previously downloaded manifests:
-
-<screen>
-$ rm /nix/var/nix/manifests/*</screen>
-
-If <command>nix-channel</command> gives the error message
-
-<screen>
-manifest `http://catamaran.labs.cs.uu.nl/dist/nix/channels/[channel]/MANIFEST'
-is too old (i.e., for Nix &lt;= 0.7)</screen>
-
-then you should unsubscribe from the offending channel
-(<command>nix-channel --remove
-<replaceable>URL</replaceable></command>; leave out
-<literal>/MANIFEST</literal>), and subscribe to the same URL, with
-<literal>channels</literal> replaced by <literal>channels-v3</literal>
-(e.g., <link
-xlink:href='http://catamaran.labs.cs.uu.nl/dist/nix/channels-v3/nixpkgs-unstable'
-/>).</para>
-
-<para>Nix 0.8 has the following improvements:
-
-<itemizedlist>
-
-  <listitem><para>The cryptographic hashes used in store paths are now
-  160 bits long, but encoded in base-32 so that they are still only 32
-  characters long (e.g.,
-  <filename>/nix/store/csw87wag8bqlqk7ipllbwypb14xainap-atk-1.9.0</filename>).
-  (This is actually a 160 bit truncation of a SHA-256
-  hash.)</para></listitem>
-
-  <listitem><para>Big cleanups and simplifications of the basic store
-  semantics.  The notion of “closure store expressions” is gone (and
-  so is the notion of “successors”); the file system references of a
-  store path are now just stored in the database.</para>
-
-  <para>For instance, given any store path, you can query its closure:
-
-  <screen>
-$ nix-store -qR $(which firefox)
-... lots of paths ...</screen>
-
-  Also, Nix now remembers for each store path the derivation that
-  built it (the “deriver”):
-
-  <screen>
-$ nix-store -qR $(which firefox)
-/nix/store/4b0jx7vq80l9aqcnkszxhymsf1ffa5jd-firefox-1.0.1.drv</screen>
-
-  So to see the build-time dependencies, you can do
-
-  <screen>
-$ nix-store -qR $(nix-store -qd $(which firefox))</screen>
-
-  or, in a nicer format:
-
-  <screen>
-$ nix-store -q --tree $(nix-store -qd $(which firefox))</screen>
-
-  </para>
-
-  <para>File system references are also stored in reverse.  For
-  instance, you can query all paths that directly or indirectly use a
-  certain Glibc:
-
-  <screen>
-$ nix-store -q --referrers-closure \
-    /nix/store/8lz9yc6zgmc0vlqmn2ipcpkjlmbi51vv-glibc-2.3.4</screen>
-
-  </para>
-
-  </listitem>
-
-  <listitem><para>The concept of fixed-output derivations has been
-  formalised.  Previously, functions such as
-  <function>fetchurl</function> in Nixpkgs used a hack (namely,
-  explicitly specifying a store path hash) to prevent changes to, say,
-  the URL of the file from propagating upwards through the dependency
-  graph, causing rebuilds of everything.  This can now be done cleanly
-  by specifying the <varname>outputHash</varname> and
-  <varname>outputHashAlgo</varname> attributes.  Nix itself checks
-  that the content of the output has the specified hash.  (This is
-  important for maintaining certain invariants necessary for future
-  work on secure shared stores.)</para></listitem>
-
-  <listitem><para>One-click installation :-) It is now possible to
-  install any top-level component in Nixpkgs directly, through the web
-  — see, e.g., <link
-  xlink:href='http://catamaran.labs.cs.uu.nl/dist/nixpkgs-0.8/' />.
-  All you have to do is associate
-  <filename>/nix/bin/nix-install-package</filename> with the MIME type
-  <literal>application/nix-package</literal> (or the extension
-  <filename>.nixpkg</filename>), and clicking on a package link will
-  cause it to be installed, with all appropriate dependencies.  If you
-  just want to install some specific application, this is easier than
-  subscribing to a channel.</para></listitem>
-
-  <listitem><para><command>nix-store -r
-  <replaceable>PATHS</replaceable></command> now builds all the
-  derivations PATHS in parallel.  Previously it did them sequentially
-  (though exploiting possible parallelism between subderivations).
-  This is nice for build farms.</para></listitem>
-
-  <listitem><para><command>nix-channel</command> has new operations
-  <option>--list</option> and
-  <option>--remove</option>.</para></listitem>
-
-  <listitem><para>New ways of installing components into user
-  environments:
-
-  <itemizedlist>
-
-    <listitem><para>Copy from another user environment:
-
-    <screen>
-$ nix-env -i --from-profile .../other-profile firefox</screen>
-
-    </para></listitem>
-
-    <listitem><para>Install a store derivation directly (bypassing the
-    Nix expression language entirely):
-
-    <screen>
-$ nix-env -i /nix/store/z58v41v21xd3...-aterm-2.3.1.drv</screen>
-
-    (This is used to implement <command>nix-install-package</command>,
-    which is therefore immune to evolution in the Nix expression
-    language.)</para></listitem>
-
-    <listitem><para>Install an already built store path directly:
-
-    <screen>
-$ nix-env -i /nix/store/hsyj5pbn0d9i...-aterm-2.3.1</screen>
-
-    </para></listitem>
-
-    <listitem><para>Install the result of a Nix expression specified
-    as a command-line argument:
-
-    <screen>
-$ nix-env -f .../i686-linux.nix -i -E 'x: x.firefoxWrapper'</screen>
-
-    The difference with the normal installation mode is that
-    <option>-E</option> does not use the <varname>name</varname>
-    attributes of derivations.  Therefore, this can be used to
-    disambiguate multiple derivations with the same
-    name.</para></listitem>
-
-  </itemizedlist></para></listitem>
-
-  <listitem><para>A hash of the contents of a store path is now stored
-  in the database after a successful build.  This allows you to check
-  whether store paths have been tampered with: <command>nix-store
-  --verify --check-contents</command>.</para></listitem>
-
-  <listitem>
-
-    <para>Implemented a concurrent garbage collector.  It is now
-    always safe to run the garbage collector, even if other Nix
-    operations are happening simultaneously.</para>
-
-    <para>However, there can still be GC races if you use
-    <command>nix-instantiate</command> and <command>nix-store
-    --realise</command> directly to build things.  To prevent races,
-    use the <option>--add-root</option> flag of those commands.</para>
-
-  </listitem>
-
-  <listitem><para>The garbage collector now finally deletes paths in
-  the right order (i.e., topologically sorted under the “references”
-  relation), thus making it safe to interrupt the collector without
-  risking a store that violates the closure
-  invariant.</para></listitem>
-
-  <listitem><para>Likewise, the substitute mechanism now downloads
-  files in the right order, thus preserving the closure invariant at
-  all times.</para></listitem>
-
-  <listitem><para>The result of <command>nix-build</command> is now
-  registered as a root of the garbage collector.  If the
-  <filename>./result</filename> link is deleted, the GC root
-  disappears automatically.</para></listitem>
-
-  <listitem>
-
-    <para>The behaviour of the garbage collector can be changed
-    globally by setting options in
-    <filename>/nix/etc/nix/nix.conf</filename>.
-
-    <itemizedlist>
-
-      <listitem><para><literal>gc-keep-derivations</literal> specifies
-      whether deriver links should be followed when searching for live
-      paths.</para></listitem>
-
-      <listitem><para><literal>gc-keep-outputs</literal> specifies
-      whether outputs of derivations should be followed when searching
-      for live paths.</para></listitem>
-
-      <listitem><para><literal>env-keep-derivations</literal>
-      specifies whether user environments should store the paths of
-      derivations when they are added (thus keeping the derivations
-      alive).</para></listitem>
-
-    </itemizedlist>
-
-  </para></listitem>
-
-  <listitem><para>New <command>nix-env</command> query flags
-  <option>--drv-path</option> and
-  <option>--out-path</option>.</para></listitem>
-
-  <listitem><para><command>fetchurl</command> allows SHA-1 and SHA-256
-  in addition to MD5.  Just specify the attribute
-  <varname>sha1</varname> or <varname>sha256</varname> instead of
-  <varname>md5</varname>.</para></listitem>
-
-  <listitem><para>Manual updates.</para></listitem>
-
-</itemizedlist>
-
-</para>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.7 (January 12, 2005)</title>
-
-<itemizedlist>
-
-  <listitem><para>Binary patching.  When upgrading components using
-  pre-built binaries (through nix-pull / nix-channel), Nix can
-  automatically download and apply binary patches to already installed
-  components instead of full downloads.  Patching is “smart”: if there
-  is a <emphasis>sequence</emphasis> of patches to an installed
-  component, Nix will use it.  Patches are currently generated
-  automatically between Nixpkgs (pre-)releases.</para></listitem>
-
-  <listitem><para>Simplifications to the substitute
-  mechanism.</para></listitem>
-
-  <listitem><para>Nix-pull now stores downloaded manifests in
-  <filename>/nix/var/nix/manifests</filename>.</para></listitem>
-
-  <listitem><para>Metadata on files in the Nix store is canonicalised
-  after builds: the last-modified timestamp is set to 0 (00:00:00
-  1/1/1970), the mode is set to 0444 or 0555 (readable and possibly
-  executable by all; setuid/setgid bits are dropped), and the group is
-  set to the default.  This ensures that the result of a build and an
-  installation through a substitute is the same; and that timestamp
-  dependencies are revealed.</para></listitem>
-
-</itemizedlist>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.6 (November 14, 2004)</title>
-
-<itemizedlist>
-
-  <listitem>
-    <para>Rewrite of the normalisation engine.
-
-    <itemizedlist>
-
-      <listitem><para>Multiple builds can now be performed in parallel
-      (option <option>-j</option>).</para></listitem>
-
-      <listitem><para>Distributed builds.  Nix can now call a shell
-      script to forward builds to Nix installations on remote
-      machines, which may or may not be of the same platform
-      type.</para></listitem>
-
-      <listitem><para>Option <option>--fallback</option> allows
-      recovery from broken substitutes.</para></listitem>
-
-      <listitem><para>Option <option>--keep-going</option> causes
-      building of other (unaffected) derivations to continue if one
-      failed.</para></listitem>
-
-    </itemizedlist>
-
-    </para>
-
-  </listitem>
-
-  <listitem><para>Improvements to the garbage collector (i.e., it
-  should actually work now).</para></listitem>
-
-  <listitem><para>Setuid Nix installations allow a Nix store to be
-  shared among multiple users.</para></listitem>
-
-  <listitem><para>Substitute registration is much faster
-  now.</para></listitem>
-
-  <listitem><para>A utility <command>nix-build</command> to build a
-  Nix expression and create a symlink to the result int the current
-  directory; useful for testing Nix derivations.</para></listitem>
-
-  <listitem><para>Manual updates.</para></listitem>
-
-  <listitem>
-
-    <para><command>nix-env</command> changes:
-
-    <itemizedlist>
-
-      <listitem><para>Derivations for other platforms are filtered out
-      (which can be overridden using
-      <option>--system-filter</option>).</para></listitem>
-
-      <listitem><para><option>--install</option> by default now
-      uninstall previous derivations with the same
-      name.</para></listitem>
-
-      <listitem><para><option>--upgrade</option> allows upgrading to a
-      specific version.</para></listitem>
-
-      <listitem><para>New operation
-      <option>--delete-generations</option> to remove profile
-      generations (necessary for effective garbage
-      collection).</para></listitem>
-
-      <listitem><para>Nicer output (sorted,
-      columnised).</para></listitem>
-
-    </itemizedlist>
-
-    </para>
-
-  </listitem>
-
-  <listitem><para>More sensible verbosity levels all around (builder
-  output is now shown always, unless <option>-Q</option> is
-  given).</para></listitem>
-
-  <listitem>
-
-    <para>Nix expression language changes:
-
-    <itemizedlist>
-
-      <listitem><para>New language construct: <literal>with
-      <replaceable>E1</replaceable>;
-      <replaceable>E2</replaceable></literal> brings all attributes
-      defined in the attribute set <replaceable>E1</replaceable> in
-      scope in <replaceable>E2</replaceable>.</para></listitem>
-
-      <listitem><para>Added a <function>map</function>
-      function.</para></listitem>
-
-      <listitem><para>Various new operators (e.g., string
-      concatenation).</para></listitem>
-
-    </itemizedlist>
-
-    </para>
-
-  </listitem>
-
-  <listitem><para>Expression evaluation is much
-  faster.</para></listitem>
-
-  <listitem><para>An Emacs mode for editing Nix expressions (with
-  syntax highlighting and indentation) has been
-  added.</para></listitem>
-
-  <listitem><para>Many bug fixes.</para></listitem>
-
-</itemizedlist>
-
-</section>
-
-
-
-<!--==================================================================-->
-
-<section><title>Release 0.5 and earlier</title>
-
-<para>Please refer to the Subversion commit log messages.</para>
-
-</section>
-
-
-
-</article>
author	Eelco Dolstra <eelco.dolstra@logicblox.com>	2014-09-16T12·13+0200
committer	Eelco Dolstra <eelco.dolstra@logicblox.com>	2014-09-16T12·13+0200
commit	f0ef6b74b93344798e44c6dc527f88a78b75a32f (patch)
tree	8975a82b25a4410e2fc36e80cc042d74675396d7 /doc/manual/release-notes.xml
parent	67e5dd3ce9f46f810c06e16671e98f8e56b4e25c (diff)
parent	8901acc97664aa8ebf687ee904428aa57a5192be (diff)