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-rw-r--r--third_party/nix/doc/manual/advanced-topics/advanced-topics.xml14
-rw-r--r--third_party/nix/doc/manual/advanced-topics/cores-vs-jobs.xml121
-rw-r--r--third_party/nix/doc/manual/advanced-topics/diff-hook.xml205
-rw-r--r--third_party/nix/doc/manual/advanced-topics/distributed-builds.xml190
-rw-r--r--third_party/nix/doc/manual/advanced-topics/post-build-hook.xml160
5 files changed, 0 insertions, 690 deletions
diff --git a/third_party/nix/doc/manual/advanced-topics/advanced-topics.xml b/third_party/nix/doc/manual/advanced-topics/advanced-topics.xml
deleted file mode 100644
index 871b7eb1d37b..000000000000
--- a/third_party/nix/doc/manual/advanced-topics/advanced-topics.xml
+++ /dev/null
@@ -1,14 +0,0 @@
-<part xmlns="http://docbook.org/ns/docbook"
-      xmlns:xlink="http://www.w3.org/1999/xlink"
-      xmlns:xi="http://www.w3.org/2001/XInclude"
-      xml:id="part-advanced-topics"
-      version="5.0">
-
-<title>Advanced Topics</title>
-
-<xi:include href="distributed-builds.xml" />
-<xi:include href="cores-vs-jobs.xml" />
-<xi:include href="diff-hook.xml" />
-<xi:include href="post-build-hook.xml" />
-
-</part>
diff --git a/third_party/nix/doc/manual/advanced-topics/cores-vs-jobs.xml b/third_party/nix/doc/manual/advanced-topics/cores-vs-jobs.xml
deleted file mode 100644
index eba645faf879..000000000000
--- a/third_party/nix/doc/manual/advanced-topics/cores-vs-jobs.xml
+++ /dev/null
@@ -1,121 +0,0 @@
-<chapter xmlns="http://docbook.org/ns/docbook"
-      xmlns:xlink="http://www.w3.org/1999/xlink"
-      xmlns:xi="http://www.w3.org/2001/XInclude"
-      version="5.0"
-      xml:id="chap-tuning-cores-and-jobs">
-
-<title>Tuning Cores and Jobs</title>
-
-<para>Nix has two relevant settings with regards to how your CPU cores
-will be utilized: <xref linkend="conf-cores" /> and
-<xref linkend="conf-max-jobs" />. This chapter will talk about what
-they are, how they interact, and their configuration trade-offs.</para>
-
-<variablelist>
-  <varlistentry>
-    <term><xref linkend="conf-max-jobs" /></term>
-    <listitem><para>
-      Dictates how many separate derivations will be built at the same
-      time. If you set this to zero, the local machine will do no
-      builds. Nix will still substitute from binary caches, and build
-      remotely if remote builders are configured.
-    </para></listitem>
-  </varlistentry>
-  <varlistentry>
-    <term><xref linkend="conf-cores" /></term>
-    <listitem><para>
-      Suggests how many cores each derivation should use. Similar to
-      <command>make -j</command>.
-    </para></listitem>
-  </varlistentry>
-</variablelist>
-
-<para>The <xref linkend="conf-cores" /> setting determines the value of
-<envar>NIX_BUILD_CORES</envar>. <envar>NIX_BUILD_CORES</envar> is equal
-to <xref linkend="conf-cores" />, unless <xref linkend="conf-cores" />
-equals <literal>0</literal>, in which case <envar>NIX_BUILD_CORES</envar>
-will be the total number of cores in the system.</para>
-
-<para>The total number of consumed cores is a simple multiplication,
-<xref linkend="conf-cores" /> * <envar>NIX_BUILD_CORES</envar>.</para>
-
-<para>The balance on how to set these two independent variables depends
-upon each builder's workload and hardware. Here are a few example
-scenarios on a machine with 24 cores:</para>
-
-<table>
-  <caption>Balancing 24 Build Cores</caption>
-  <thead>
-    <tr>
-      <th><xref linkend="conf-max-jobs" /></th>
-      <th><xref linkend="conf-cores" /></th>
-      <th><envar>NIX_BUILD_CORES</envar></th>
-      <th>Maximum Processes</th>
-      <th>Result</th>
-    </tr>
-  </thead>
-  <tbody>
-    <tr>
-      <td>1</td>
-      <td>24</td>
-      <td>24</td>
-      <td>24</td>
-      <td>
-        One derivation will be built at a time, each one can use 24
-        cores. Undersold if a job can’t use 24 cores.
-      </td>
-    </tr>
-
-    <tr>
-      <td>4</td>
-      <td>6</td>
-      <td>6</td>
-      <td>24</td>
-      <td>
-        Four derivations will be built at once, each given access to
-        six cores.
-      </td>
-    </tr>
-    <tr>
-      <td>12</td>
-      <td>6</td>
-      <td>6</td>
-      <td>72</td>
-      <td>
-        12 derivations will be built at once, each given access to six
-        cores. This configuration is over-sold. If all 12 derivations
-        being built simultaneously try to use all six cores, the
-        machine's performance will be degraded due to extensive context
-        switching between the 12 builds.
-      </td>
-    </tr>
-    <tr>
-      <td>24</td>
-      <td>1</td>
-      <td>1</td>
-      <td>24</td>
-      <td>
-        24 derivations can build at the same time, each using a single
-        core. Never oversold, but derivations which require many cores
-        will be very slow to compile.
-      </td>
-    </tr>
-    <tr>
-      <td>24</td>
-      <td>0</td>
-      <td>24</td>
-      <td>576</td>
-      <td>
-        24 derivations can build at the same time, each using all the
-        available cores of the machine. Very likely to be oversold,
-        and very likely to suffer context switches.
-      </td>
-    </tr>
-  </tbody>
-</table>
-
-<para>It is up to the derivations' build script to respect
-host's requested cores-per-build by following the value of the
-<envar>NIX_BUILD_CORES</envar> environment variable.</para>
-
-</chapter>
diff --git a/third_party/nix/doc/manual/advanced-topics/diff-hook.xml b/third_party/nix/doc/manual/advanced-topics/diff-hook.xml
deleted file mode 100644
index fb4bf819f94b..000000000000
--- a/third_party/nix/doc/manual/advanced-topics/diff-hook.xml
+++ /dev/null
@@ -1,205 +0,0 @@
-<chapter xmlns="http://docbook.org/ns/docbook"
-      xmlns:xlink="http://www.w3.org/1999/xlink"
-      xmlns:xi="http://www.w3.org/2001/XInclude"
-      xml:id="chap-diff-hook"
-      version="5.0"
-      >
-
-<title>Verifying Build Reproducibility with <option linkend="conf-diff-hook">diff-hook</option></title>
-
-<subtitle>Check build reproducibility by running builds multiple times
-and comparing their results.</subtitle>
-
-<para>Specify a program with Nix's <xref linkend="conf-diff-hook" /> to
-compare build results when two builds produce different results. Note:
-this hook is only executed if the results are not the same, this hook
-is not used for determining if the results are the same.</para>
-
-<para>For purposes of demonstration, we'll use the following Nix file,
-<filename>deterministic.nix</filename> for testing:</para>
-
-<programlisting>
-let
-  inherit (import &lt;nixpkgs&gt; {}) runCommand;
-in {
-  stable = runCommand "stable" {} ''
-    touch $out
-  '';
-
-  unstable = runCommand "unstable" {} ''
-    echo $RANDOM > $out
-  '';
-}
-</programlisting>
-
-<para>Additionally, <filename>nix.conf</filename> contains:
-
-<programlisting>
-diff-hook = /etc/nix/my-diff-hook
-run-diff-hook = true
-</programlisting>
-
-where <filename>/etc/nix/my-diff-hook</filename> is an executable
-file containing:
-
-<programlisting>
-#!/bin/sh
-exec &gt;&amp;2
-echo "For derivation $3:"
-/run/current-system/sw/bin/diff -r "$1" "$2"
-</programlisting>
-
-</para>
-
-<para>The diff hook is executed by the same user and group who ran the
-build. However, the diff hook does not have write access to the store
-path just built.</para>
-
-<section>
-  <title>
-    Spot-Checking Build Determinism
-  </title>
-
-  <para>
-    Verify a path which already exists in the Nix store by passing
-    <option>--check</option> to the build command.
-  </para>
-
-  <para>If the build passes and is deterministic, Nix will exit with a
-  status code of 0:</para>
-
-  <screen>
-$ nix-build ./deterministic.nix -A stable
-these derivations will be built:
-  /nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv
-building '/nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv'...
-/nix/store/yyxlzw3vqaas7wfp04g0b1xg51f2czgq-stable
-
-$ nix-build ./deterministic.nix -A stable --check
-checking outputs of '/nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv'...
-/nix/store/yyxlzw3vqaas7wfp04g0b1xg51f2czgq-stable
-</screen>
-
-  <para>If the build is not deterministic, Nix will exit with a status
-  code of 1:</para>
-
-  <screen>
-$ nix-build ./deterministic.nix -A unstable
-these derivations will be built:
-  /nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv
-building '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv'...
-/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable
-
-$ nix-build ./deterministic.nix -A unstable --check
-checking outputs of '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv'...
-error: derivation '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv' may not be deterministic: output '/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable' differs
-</screen>
-
-<para>In the Nix daemon's log, we will now see:
-<screen>
-For derivation /nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv:
-1c1
-&lt; 8108
----
-&gt; 30204
-</screen>
-</para>
-
-  <para>Using <option>--check</option> with <option>--keep-failed</option>
-  will cause Nix to keep the second build's output in a special,
-  <literal>.check</literal> path:</para>
-
-  <screen>
-$ nix-build ./deterministic.nix -A unstable --check --keep-failed
-checking outputs of '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv'...
-note: keeping build directory '/tmp/nix-build-unstable.drv-0'
-error: derivation '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv' may not be deterministic: output '/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable' differs from '/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable.check'
-</screen>
-
-  <para>In particular, notice the
-  <literal>/nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable.check</literal>
-  output. Nix has copied the build results to that directory where you
-  can examine it.</para>
-
-  <note xml:id="check-dirs-are-unregistered">
-    <title><literal>.check</literal> paths are not registered store paths</title>
-
-    <para>Check paths are not protected against garbage collection,
-    and this path will be deleted on the next garbage collection.</para>
-
-    <para>The path is guaranteed to be alive for the duration of
-    <xref linkend="conf-diff-hook" />'s execution, but may be deleted
-    any time after.</para>
-
-    <para>If the comparison is performed as part of automated tooling,
-    please use the diff-hook or author your tooling to handle the case
-    where the build was not deterministic and also a check path does
-    not exist.</para>
-  </note>
-
-  <para>
-    <option>--check</option> is only usable if the derivation has
-    been built on the system already. If the derivation has not been
-    built Nix will fail with the error:
-    <screen>
-error: some outputs of '/nix/store/hzi1h60z2qf0nb85iwnpvrai3j2w7rr6-unstable.drv' are not valid, so checking is not possible
-</screen>
-
-    Run the build without <option>--check</option>, and then try with
-    <option>--check</option> again.
-  </para>
-</section>
-
-<section>
-  <title>
-    Automatic and Optionally Enforced Determinism Verification
-  </title>
-
-  <para>
-    Automatically verify every build at build time by executing the
-    build multiple times.
-  </para>
-
-  <para>
-    Setting <xref linkend="conf-repeat" /> and
-    <xref linkend="conf-enforce-determinism" /> in your
-    <filename>nix.conf</filename> permits the automated verification
-    of every build Nix performs.
-  </para>
-
-  <para>
-    The following configuration will run each build three times, and
-    will require the build to be deterministic:
-
-    <programlisting>
-enforce-determinism = true
-repeat = 2
-</programlisting>
-  </para>
-
-  <para>
-    Setting <xref linkend="conf-enforce-determinism" /> to false as in
-    the following configuration will run the build multiple times,
-    execute the build hook, but will allow the build to succeed even
-    if it does not build reproducibly:
-
-    <programlisting>
-enforce-determinism = false
-repeat = 1
-</programlisting>
-  </para>
-
-  <para>
-    An example output of this configuration:
-    <screen>
-$ nix-build ./test.nix -A unstable
-these derivations will be built:
-  /nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv
-building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 1/2)...
-building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 2/2)...
-output '/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable' of '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' differs from '/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable.check' from previous round
-/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable
-</screen>
-  </para>
-</section>
-</chapter>
diff --git a/third_party/nix/doc/manual/advanced-topics/distributed-builds.xml b/third_party/nix/doc/manual/advanced-topics/distributed-builds.xml
deleted file mode 100644
index 9ac4a92cd5b1..000000000000
--- a/third_party/nix/doc/manual/advanced-topics/distributed-builds.xml
+++ /dev/null
@@ -1,190 +0,0 @@
-<chapter xmlns="http://docbook.org/ns/docbook"
-      xmlns:xlink="http://www.w3.org/1999/xlink"
-      xmlns:xi="http://www.w3.org/2001/XInclude"
-      version="5.0"
-      xml:id='chap-distributed-builds'>
-
-<title>Remote Builds</title>
-
-<para>Nix supports remote builds, where a local Nix installation can
-forward Nix builds to other machines.  This allows multiple builds to
-be performed in parallel and allows Nix to perform multi-platform
-builds in a semi-transparent way.  For instance, if you perform a
-build for a <literal>x86_64-darwin</literal> on an
-<literal>i686-linux</literal> machine, Nix can automatically forward
-the build to a <literal>x86_64-darwin</literal> machine, if
-available.</para>
-
-<para>To forward a build to a remote machine, it’s required that the
-remote machine is accessible via SSH and that it has Nix
-installed. You can test whether connecting to the remote Nix instance
-works, e.g.
-
-<screen>
-$ nix ping-store --store ssh://mac
-</screen>
-
-will try to connect to the machine named <literal>mac</literal>. It is
-possible to specify an SSH identity file as part of the remote store
-URI, e.g.
-
-<screen>
-$ nix ping-store --store ssh://mac?ssh-key=/home/alice/my-key
-</screen>
-
-Since builds should be non-interactive, the key should not have a
-passphrase. Alternatively, you can load identities ahead of time into
-<command>ssh-agent</command> or <command>gpg-agent</command>.</para>
-
-<para>If you get the error
-
-<screen>
-bash: nix-store: command not found
-error: cannot connect to 'mac'
-</screen>
-
-then you need to ensure that the <envar>PATH</envar> of
-non-interactive login shells contains Nix.</para>
-
-<warning><para>If you are building via the Nix daemon, it is the Nix
-daemon user account (that is, <literal>root</literal>) that should
-have SSH access to the remote machine. If you can’t or don’t want to
-configure <literal>root</literal> to be able to access to remote
-machine, you can use a private Nix store instead by passing
-e.g. <literal>--store ~/my-nix</literal>.</para></warning>
-
-<para>The list of remote machines can be specified on the command line
-or in the Nix configuration file. The former is convenient for
-testing. For example, the following command allows you to build a
-derivation for <literal>x86_64-darwin</literal> on a Linux machine:
-
-<screen>
-$ uname
-Linux
-
-$ nix build \
-  '(with import &lt;nixpkgs> { system = "x86_64-darwin"; }; runCommand "foo" {} "uname > $out")' \
-  --builders 'ssh://mac x86_64-darwin'
-[1/0/1 built, 0.0 MiB DL] building foo on ssh://mac
-
-$ cat ./result
-Darwin
-</screen>
-
-It is possible to specify multiple builders separated by a semicolon
-or a newline, e.g.
-
-<screen>
-  --builders 'ssh://mac x86_64-darwin ; ssh://beastie x86_64-freebsd'
-</screen>
-</para>
-
-<para>Each machine specification consists of the following elements,
-separated by spaces. Only the first element is required.
-To leave a field at its default, set it to <literal>-</literal>.
-
-<orderedlist>
-
-  <listitem><para>The URI of the remote store in the format
-  <literal>ssh://[<replaceable>username</replaceable>@]<replaceable>hostname</replaceable></literal>,
-  e.g. <literal>ssh://nix@mac</literal> or
-  <literal>ssh://mac</literal>. For backward compatibility,
-  <literal>ssh://</literal> may be omitted. The hostname may be an
-  alias defined in your
-  <filename>~/.ssh/config</filename>.</para></listitem>
-
-  <listitem><para>A comma-separated list of Nix platform type
-  identifiers, such as <literal>x86_64-darwin</literal>.  It is
-  possible for a machine to support multiple platform types, e.g.,
-  <literal>i686-linux,x86_64-linux</literal>. If omitted, this
-  defaults to the local platform type.</para></listitem>
-
-  <listitem><para>The SSH identity file to be used to log in to the
-  remote machine. If omitted, SSH will use its regular
-  identities.</para></listitem>
-
-  <listitem><para>The maximum number of builds that Nix will execute
-  in parallel on the machine.  Typically this should be equal to the
-  number of CPU cores.  For instance, the machine
-  <literal>itchy</literal> in the example will execute up to 8 builds
-  in parallel.</para></listitem>
-
-  <listitem><para>The “speed factor”, indicating the relative speed of
-  the machine.  If there are multiple machines of the right type, Nix
-  will prefer the fastest, taking load into account.</para></listitem>
-
-  <listitem><para>A comma-separated list of <emphasis>supported
-  features</emphasis>.  If a derivation has the
-  <varname>requiredSystemFeatures</varname> attribute, then Nix will
-  only perform the derivation on a machine that has the specified
-  features.  For instance, the attribute
-
-<programlisting>
-requiredSystemFeatures = [ "kvm" ];
-</programlisting>
-
-  will cause the build to be performed on a machine that has the
-  <literal>kvm</literal> feature.</para></listitem>
-
-  <listitem><para>A comma-separated list of <emphasis>mandatory
-  features</emphasis>.  A machine will only be used to build a
-  derivation if all of the machine’s mandatory features appear in the
-  derivation’s <varname>requiredSystemFeatures</varname>
-  attribute..</para></listitem>
-
-</orderedlist>
-
-For example, the machine specification
-
-<programlisting>
-nix@scratchy.labs.cs.uu.nl  i686-linux      /home/nix/.ssh/id_scratchy_auto        8 1 kvm
-nix@itchy.labs.cs.uu.nl     i686-linux      /home/nix/.ssh/id_scratchy_auto        8 2
-nix@poochie.labs.cs.uu.nl   i686-linux      /home/nix/.ssh/id_scratchy_auto        1 2 kvm benchmark
-</programlisting>
-
-specifies several machines that can perform
-<literal>i686-linux</literal> builds. However,
-<literal>poochie</literal> will only do builds that have the attribute
-
-<programlisting>
-requiredSystemFeatures = [ "benchmark" ];
-</programlisting>
-
-or
-
-<programlisting>
-requiredSystemFeatures = [ "benchmark" "kvm" ];
-</programlisting>
-
-<literal>itchy</literal> cannot do builds that require
-<literal>kvm</literal>, but <literal>scratchy</literal> does support
-such builds. For regular builds, <literal>itchy</literal> will be
-preferred over <literal>scratchy</literal> because it has a higher
-speed factor.</para>
-
-<para>Remote builders can also be configured in
-<filename>nix.conf</filename>, e.g.
-
-<programlisting>
-builders = ssh://mac x86_64-darwin ; ssh://beastie x86_64-freebsd
-</programlisting>
-
-Finally, remote builders can be configured in a separate configuration
-file included in <option>builders</option> via the syntax
-<literal>@<replaceable>file</replaceable></literal>. For example,
-
-<programlisting>
-builders = @/etc/nix/machines
-</programlisting>
-
-causes the list of machines in <filename>/etc/nix/machines</filename>
-to be included. (This is the default.)</para>
-
-<para>If you want the builders to use caches, you likely want to set
-the option <link linkend='conf-builders-use-substitutes'><literal>builders-use-substitutes</literal></link>
-in your local <filename>nix.conf</filename>.</para>
-
-<para>To build only on remote builders and disable building on the local machine,
-you can use the option <option>--max-jobs 0</option>.</para>
-
-</chapter>
diff --git a/third_party/nix/doc/manual/advanced-topics/post-build-hook.xml b/third_party/nix/doc/manual/advanced-topics/post-build-hook.xml
deleted file mode 100644
index 3dc43ee795b1..000000000000
--- a/third_party/nix/doc/manual/advanced-topics/post-build-hook.xml
+++ /dev/null
@@ -1,160 +0,0 @@
-<chapter xmlns="http://docbook.org/ns/docbook"
-      xmlns:xlink="http://www.w3.org/1999/xlink"
-      xmlns:xi="http://www.w3.org/2001/XInclude"
-      xml:id="chap-post-build-hook"
-      version="5.0"
-      >
-
-<title>Using the <xref linkend="conf-post-build-hook" /></title>
-<subtitle>Uploading to an S3-compatible binary cache after each build</subtitle>
-
-
-<section xml:id="chap-post-build-hook-caveats">
-  <title>Implementation Caveats</title>
-  <para>Here we use the post-build hook to upload to a binary cache.
-  This is a simple and working example, but it is not suitable for all
-  use cases.</para>
-
-  <para>The post build hook program runs after each executed build,
-  and blocks the build loop. The build loop exits if the hook program
-  fails.</para>
-
-  <para>Concretely, this implementation will make Nix slow or unusable
-  when the internet is slow or unreliable.</para>
-
-  <para>A more advanced implementation might pass the store paths to a
-  user-supplied daemon or queue for processing the store paths outside
-  of the build loop.</para>
-</section>
-
-<section>
-  <title>Prerequisites</title>
-
-  <para>
-    This tutorial assumes you have configured an S3-compatible binary cache
-    according to the instructions at
-    <xref linkend="ssec-s3-substituter-authenticated-writes" />, and
-    that the <literal>root</literal> user's default AWS profile can
-    upload to the bucket.
-  </para>
-</section>
-
-<section>
-  <title>Set up a Signing Key</title>
-  <para>Use <command>nix-store --generate-binary-cache-key</command> to
-  create our public and private signing keys. We will sign paths
-  with the private key, and distribute the public key for verifying
-  the authenticity of the paths.</para>
-
-  <screen>
-# nix-store --generate-binary-cache-key example-nix-cache-1 /etc/nix/key.private /etc/nix/key.public
-# cat /etc/nix/key.public
-example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM=
-</screen>
-
-<para>Then, add the public key and the cache URL to your
-<filename>nix.conf</filename>'s <xref linkend="conf-trusted-public-keys" />
-and <xref linkend="conf-substituters" /> like:</para>
-
-<programlisting>
-substituters = https://cache.nixos.org/ s3://example-nix-cache
-trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM=
-</programlisting>
-
-<para>we will restart the Nix daemon a later step.</para>
-</section>
-
-<section>
-  <title>Implementing the build hook</title>
-  <para>Write the following script to
-  <filename>/etc/nix/upload-to-cache.sh</filename>:
-  </para>
-
-  <programlisting>
-#!/bin/sh
-
-set -eu
-set -f # disable globbing
-export IFS=' '
-
-echo "Signing paths" $OUT_PATHS
-nix sign-paths --key-file /etc/nix/key.private $OUT_PATHS
-echo "Uploading paths" $OUT_PATHS
-exec nix copy --to 's3://example-nix-cache' $OUT_PATHS
-</programlisting>
-
-  <note>
-    <title>Should <literal>$OUT_PATHS</literal> be quoted?</title>
-    <para>
-      The <literal>$OUT_PATHS</literal> variable is a space-separated
-      list of Nix store paths. In this case, we expect and want the
-      shell to perform word splitting to make each output path its
-      own argument to <command>nix sign-paths</command>. Nix guarantees
-      the paths will not contain any spaces, however a store path
-      might contain glob characters. The <command>set -f</command>
-      disables globbing in the shell.
-    </para>
-  </note>
-  <para>
-    Then make sure the hook program is executable by the <literal>root</literal> user:
-    <screen>
-# chmod +x /etc/nix/upload-to-cache.sh
-</screen></para>
-</section>
-
-<section>
-  <title>Updating Nix Configuration</title>
-
-  <para>Edit <filename>/etc/nix/nix.conf</filename> to run our hook,
-  by adding the following configuration snippet at the end:</para>
-
-  <programlisting>
-post-build-hook = /etc/nix/upload-to-cache.sh
-</programlisting>
-
-<para>Then, restart the <command>nix-daemon</command>.</para>
-</section>
-
-<section>
-  <title>Testing</title>
-
-  <para>Build any derivation, for example:</para>
-
-  <screen>
-$ nix-build -E '(import &lt;nixpkgs&gt; {}).writeText "example" (builtins.toString builtins.currentTime)'
-these derivations will be built:
-  /nix/store/s4pnfbkalzy5qz57qs6yybna8wylkig6-example.drv
-building '/nix/store/s4pnfbkalzy5qz57qs6yybna8wylkig6-example.drv'...
-running post-build-hook '/home/grahamc/projects/github.com/NixOS/nix/post-hook.sh'...
-post-build-hook: Signing paths /nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example
-post-build-hook: Uploading paths /nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example
-/nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example
-</screen>
-
-  <para>Then delete the path from the store, and try substituting it from the binary cache:</para>
-  <screen>
-$ rm ./result
-$ nix-store --delete /nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example
-</screen>
-
-<para>Now, copy the path back from the cache:</para>
-<screen>
-$ nix store --realize /nix/store/ibcyipq5gf91838ldx40mjsp0b8w9n18-example
-copying path '/nix/store/m8bmqwrch6l3h8s0k3d673xpmipcdpsa-example from 's3://example-nix-cache'...
-warning: you did not specify '--add-root'; the result might be removed by the garbage collector
-/nix/store/m8bmqwrch6l3h8s0k3d673xpmipcdpsa-example
-</screen>
-</section>
-<section>
-  <title>Conclusion</title>
-  <para>
-    We now have a Nix installation configured to automatically sign and
-    upload every local build to a remote binary cache.
-  </para>
-
-  <para>
-    Before deploying this to production, be sure to consider the
-    implementation caveats in <xref linkend="chap-post-build-hook-caveats" />.
-  </para>
-</section>
-</chapter>