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diff --git a/doc/manual/expressions/builder-syntax.xml b/doc/manual/expressions/builder-syntax.xml deleted file mode 100644 index e51bade44..000000000 --- a/doc/manual/expressions/builder-syntax.xml +++ /dev/null @@ -1,119 +0,0 @@ -<section 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='sec-builder-syntax'> - -<title>Builder Syntax</title> - -<example xml:id='ex-hello-builder'><title>Build script for GNU Hello -(<filename>builder.sh</filename>)</title> -<programlisting> -source $stdenv/setup <co xml:id='ex-hello-builder-co-1' /> - -PATH=$perl/bin:$PATH <co xml:id='ex-hello-builder-co-2' /> - -tar xvfz $src <co xml:id='ex-hello-builder-co-3' /> -cd hello-* -./configure --prefix=$out <co xml:id='ex-hello-builder-co-4' /> -make <co xml:id='ex-hello-builder-co-5' /> -make install</programlisting> -</example> - -<para><xref linkend='ex-hello-builder' /> shows the builder referenced -from Hello's Nix expression (stored in -<filename>pkgs/applications/misc/hello/ex-1/builder.sh</filename>). -The builder can actually be made a lot shorter by using the -<emphasis>generic builder</emphasis> functions provided by -<varname>stdenv</varname>, but here we write out the build steps to -elucidate what a builder does. It performs the following -steps:</para> - -<calloutlist> - - <callout arearefs='ex-hello-builder-co-1'> - - <para>When Nix runs a builder, it initially completely clears the - environment (except for the attributes declared in the - derivation). For instance, the <envar>PATH</envar> variable is - empty<footnote><para>Actually, it's initialised to - <filename>/path-not-set</filename> to prevent Bash from setting it - to a default value.</para></footnote>. This is done to prevent - undeclared inputs from being used in the build process. If for - example the <envar>PATH</envar> contained - <filename>/usr/bin</filename>, then you might accidentally use - <filename>/usr/bin/gcc</filename>.</para> - - <para>So the first step is to set up the environment. This is - done by calling the <filename>setup</filename> script of the - standard environment. The environment variable - <envar>stdenv</envar> points to the location of the standard - environment being used. (It wasn't specified explicitly as an - attribute in <xref linkend='ex-hello-nix' />, but - <varname>mkDerivation</varname> adds it automatically.)</para> - - </callout> - - <callout arearefs='ex-hello-builder-co-2'> - - <para>Since Hello needs Perl, we have to make sure that Perl is in - the <envar>PATH</envar>. The <envar>perl</envar> environment - variable points to the location of the Perl package (since it - was passed in as an attribute to the derivation), so - <filename><replaceable>$perl</replaceable>/bin</filename> is the - directory containing the Perl interpreter.</para> - - </callout> - - <callout arearefs='ex-hello-builder-co-3'> - - <para>Now we have to unpack the sources. The - <varname>src</varname> attribute was bound to the result of - fetching the Hello source tarball from the network, so the - <envar>src</envar> environment variable points to the location in - the Nix store to which the tarball was downloaded. After - unpacking, we <command>cd</command> to the resulting source - directory.</para> - - <para>The whole build is performed in a temporary directory - created in <varname>/tmp</varname>, by the way. This directory is - removed after the builder finishes, so there is no need to clean - up the sources afterwards. Also, the temporary directory is - always newly created, so you don't have to worry about files from - previous builds interfering with the current build.</para> - - </callout> - - <callout arearefs='ex-hello-builder-co-4'> - - <para>GNU Hello is a typical Autoconf-based package, so we first - have to run its <filename>configure</filename> script. In Nix - every package is stored in a separate location in the Nix store, - for instance - <filename>/nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1</filename>. - Nix computes this path by cryptographically hashing all attributes - of the derivation. The path is passed to the builder through the - <envar>out</envar> environment variable. So here we give - <filename>configure</filename> the parameter - <literal>--prefix=$out</literal> to cause Hello to be installed in - the expected location.</para> - - </callout> - - <callout arearefs='ex-hello-builder-co-5'> - - <para>Finally we build Hello (<literal>make</literal>) and install - it into the location specified by <envar>out</envar> - (<literal>make install</literal>).</para> - - </callout> - -</calloutlist> - -<para>If you are wondering about the absence of error checking on the -result of various commands called in the builder: this is because the -shell script is evaluated with Bash's <option>-e</option> option, -which causes the script to be aborted if any command fails without an -error check.</para> - -</section>
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