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48 lines
1.7 KiB
XML
48 lines
1.7 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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version="5.0"
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xml:id="ch-simple-expression">
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<title>A Simple Nix Expression</title>
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<para>This section shows how to add and test the <link
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xlink:href='http://www.gnu.org/software/hello/hello.html'>GNU Hello
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package</link> to the Nix Packages collection. Hello is a program
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that prints out the text <quote>Hello, world!</quote>.</para>
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<para>To add a package to the Nix Packages collection, you generally
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need to do three things:
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<orderedlist>
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<listitem><para>Write a Nix expression for the package. This is a
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file that describes all the inputs involved in building the package,
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such as dependencies, sources, and so on.</para></listitem>
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<listitem><para>Write a <emphasis>builder</emphasis>. This is a
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shell script<footnote><para>In fact, it can be written in any
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language, but typically it's a <command>bash</command> shell
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script.</para></footnote> that actually builds the package from
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the inputs.</para></listitem>
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<listitem><para>Add the package to the file
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<filename>pkgs/top-level/all-packages.nix</filename>. The Nix
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expression written in the first step is a
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<emphasis>function</emphasis>; it requires other packages in order
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to build it. In this step you put it all together, i.e., you call
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the function with the right arguments to build the actual
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package.</para></listitem>
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</orderedlist>
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</para>
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<xi:include href="expression-syntax.xml" />
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<xi:include href="build-script.xml" />
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<xi:include href="arguments-variables.xml" />
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<xi:include href="simple-building-testing.xml" />
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<xi:include href="generic-builder.xml" />
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</chapter>
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