forked from lix-project/lix
Merge pull request #2945 from danidiaz/doc001
Expanded documentation for .nix-defexpr
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@ -221,31 +221,53 @@ also <xref linkend="sec-common-options" />.</phrase></para>
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<varlistentry><term><filename>~/.nix-defexpr</filename></term>
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<listitem><para>A directory that contains the default Nix
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<listitem><para>The source for the default Nix
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expressions used by the <option>--install</option>,
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<option>--upgrade</option>, and <option>--query
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--available</option> operations to obtain derivations. The
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<option>--file</option> option may be used to override this
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default.</para>
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<para>The Nix expressions in this directory are combined into a
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single set, with each file as an attribute that has the name of
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the file. Thus, if <filename>~/.nix-defexpr</filename> contains
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two files, <filename>foo</filename> and <filename>bar</filename>,
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<para>If <filename>~/.nix-defexpr</filename> is a file,
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it is loaded as a Nix expression. If the expression
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is a set, it is used as the default Nix expression.
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If the expression is a function, an empty set is passed
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as argument and the return value is used as
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the default Nix expression.</para>
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<para>If <filename>~/.nix-defexpr</filename> is a directory
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containing a <filename>default.nix</filename> file, that file
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is loaded as in the above paragraph.</para>
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<para>If <filename>~/.nix-defexpr</filename> is a directory without
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a <filename>default.nix</filename> file, then its contents
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(both files and subdirectories) are loaded as Nix expressions.
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The expressions are combined into a single set, each expression
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under an attribute with the same name as the original file
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or subdirectory.
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</para>
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<para>For example, if <filename>~/.nix-defexpr</filename> contains
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two files, <filename>foo.nix</filename> and <filename>bar.nix</filename>,
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then the default Nix expression will essentially be
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<programlisting>
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{
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foo = import ~/.nix-defexpr/foo;
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bar = import ~/.nix-defexpr/bar;
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foo = import ~/.nix-defexpr/foo.nix;
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bar = import ~/.nix-defexpr/bar.nix;
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}</programlisting>
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</para>
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<para>The file <filename>manifest.nix</filename> is always ignored.
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Subdirectories without a <filename>default.nix</filename> file
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are traversed recursively in search of more Nix expressions,
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but the names of these intermediate directories are not
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added to the attribute paths of the default Nix expression.</para>
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<para>The command <command>nix-channel</command> places symlinks
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to the downloaded Nix expressions from each subscribed channel in
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this directory.</para>
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</listitem>
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</varlistentry>
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