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    You can use them programmatically, or on the command line: <programlisting>

     

       
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nix-build &lt;nixpkgs&gt; --arg crossSystem '(import &lt;nixpkgs/lib&gt;).systems.examples.fooBarBaz' -A whatever</programlisting>

     

       
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  </para>

     

       
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  <note>

     

       
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    <para>

     

       
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      Eventually we would like to make these platform examples an unnecessary convenience so that <programlisting>

     

       
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nix-build &lt;nixpkgs&gt; --arg crossSystem.config '&lt;arch&gt;-&lt;os&gt;-&lt;vendor&gt;-&lt;abi&gt;' -A whatever</programlisting>

     

       
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      works in the vast majority of cases.

     

       
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      The problem today is dependencies on other sorts of configuration which aren't given proper defaults.

     

       
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      We rely on the examples to crudely to set those configuration parameters in some vaguely sane manner on the users behalf.

     

       
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      Issue <link xlink:href="https://github.com/NixOS/nixpkgs/issues/34274">#34274</link> tracks this inconvenience along with its root cause in crufty configuration options.

     

       
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    </para>

     

       
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  </note>

     

       
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  <para>

     

       
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    While one is free to pass both parameters in full, there's a lot of logic to fill in missing fields.

     

       
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    As discussed in the previous section, only one of <varname>system</varname>, <varname>config</varname>, and <varname>parsed</varname> is needed to infer the other two.