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diff --git a/doc/functions/trivial-builders.xml b/doc/functions/trivial-builders.xml new file mode 100644 index 00000000000..92a07aedb5b --- /dev/null +++ b/doc/functions/trivial-builders.xml @@ -0,0 +1,124 @@ +<section xmlns="http://docbook.org/ns/docbook" + xmlns:xlink="http://www.w3.org/1999/xlink" + xmlns:xi="http://www.w3.org/2001/XInclude" + xml:id="sec-trivial-builders"> + <title>Trivial builders</title> + + <para> + Nixpkgs provides a couple of functions that help with building + derivations. The most important one, + <function>stdenv.mkDerivation</function>, has already been + documented above. The following functions wrap + <function>stdenv.mkDerivation</function>, making it easier to use + in certain cases. + </para> + + <variablelist> + <varlistentry> + <term> + <literal>runCommand</literal> + </term> + <listitem> + <para> + This takes three arguments, <literal>name</literal>, + <literal>env</literal>, and <literal>buildCommand</literal>. + <literal>name</literal> is just the name that Nix will append + to the store path in the same way that + <literal>stdenv.mkDerivation</literal> uses its + <literal>name</literal> attribute. <literal>env</literal> is an + attribute set specifying environment variables that will be set + for this derivation. These attributes are then passed to the + wrapped <literal>stdenv.mkDerivation</literal>. + <literal>buildCommand</literal> specifies the commands that + will be run to create this derivation. Note that you will need + to create <literal>$out</literal> for Nix to register the + command as successful. + </para> + <para> + An example of using <literal>runCommand</literal> is provided + below. + </para> + <programlisting> + (import <nixpkgs> {}).runCommand "my-example" {} '' + echo My example command is running + + mkdir $out + + echo I can write data to the Nix store > $out/message + + echo I can also run basic commands like: + + echo ls + ls + + echo whoami + whoami + + echo date + date + '' + </programlisting> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>runCommandCC</literal> + </term> + <listitem> + <para> + This works just like <literal>runCommand</literal>. The only + difference is that it also provides a C compiler in + <literal>buildCommand</literal>’s environment. To minimize your + dependencies, you should only use this if you are sure you will + need a C compiler as part of running your command. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>writeTextFile</literal>, <literal>writeText</literal>, + <literal>writeTextDir</literal>, <literal>writeScript</literal>, + <literal>writeScriptBin</literal> + </term> + <listitem> + <para> + These functions write <literal>text</literal> to the Nix store. + This is useful for creating scripts from Nix expressions. + <literal>writeTextFile</literal> takes an attribute set and + expects two arguments, <literal>name</literal> and + <literal>text</literal>. <literal>name</literal> corresponds to + the name used in the Nix store path. <literal>text</literal> + will be the contents of the file. You can also set + <literal>executable</literal> to true to make this file have + the executable bit set. + </para> + <para> + Many more commands wrap <literal>writeTextFile</literal> + including <literal>writeText</literal>, + <literal>writeTextDir</literal>, + <literal>writeScript</literal>, and + <literal>writeScriptBin</literal>. These are convenience + functions over <literal>writeTextFile</literal>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <literal>symlinkJoin</literal> + </term> + <listitem> + <para> + This can be used to put many derivations into the same directory + structure. It works by creating a new derivation and adding + symlinks to each of the paths listed. It expects two arguments, + <literal>name</literal>, and <literal>paths</literal>. + <literal>name</literal> is the name used in the Nix store path + for the created derivation. <literal>paths</literal> is a list of + paths that will be symlinked. These paths can be to Nix store + derivations or any other subdirectory contained within. + </para> + </listitem> + </varlistentry> + </variablelist> + +</section> |