<refentry 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-nix-build"> <refmeta> <refentrytitle>nix-build</refentrytitle> <manvolnum>1</manvolnum> <refmiscinfo class="source">Nix</refmiscinfo> <refmiscinfo class="version"><xi:include href="../version.txt" parse="text"/></refmiscinfo> </refmeta> <refnamediv> <refname>nix-build</refname> <refpurpose>build a Nix expression</refpurpose> </refnamediv> <refsynopsisdiv> <cmdsynopsis> <command>nix-build</command> <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="opt-common-syn.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(/db:nop/*)" /> <arg><option>--arg</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg> <arg><option>--argstr</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg> <arg> <group choice='req'> <arg choice='plain'><option>--attr</option></arg> <arg choice='plain'><option>-A</option></arg> </group> <replaceable>attrPath</replaceable> </arg> <arg><option>--no-out-link</option></arg> <arg><option>--dry-run</option></arg> <arg> <group choice='req'> <arg choice='plain'><option>--out-link</option></arg> <arg choice='plain'><option>-o</option></arg> </group> <replaceable>outlink</replaceable> </arg> <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg> </cmdsynopsis> </refsynopsisdiv> <refsection><title>Description</title> <para>The <command>nix-build</command> command builds the derivations described by the Nix expressions in <replaceable>paths</replaceable>. If the build succeeds, it places a symlink to the result in the current directory. The symlink is called <filename>result</filename>. If there are multiple Nix expressions, or the Nix expressions evaluate to multiple derivations, multiple sequentially numbered symlinks are created (<filename>result</filename>, <filename>result-2</filename>, and so on).</para> <para>If no <replaceable>paths</replaceable> are specified, then <command>nix-build</command> will use <filename>default.nix</filename> in the current directory, if it exists.</para> <para>If an element of <replaceable>paths</replaceable> starts with <literal>http://</literal> or <literal>https://</literal>, it is interpreted as the URL of a tarball that will be downloaded and unpacked to a temporary location. The tarball must include a single top-level directory containing at least a file named <filename>default.nix</filename>.</para> <para><command>nix-build</command> is essentially a wrapper around <link linkend="sec-nix-instantiate"><command>nix-instantiate</command></link> (to translate a high-level Nix expression to a low-level store derivation) and <link linkend="rsec-nix-store-realise"><command>nix-store --realise</command></link> (to build the store derivation).</para> <warning><para>The result of the build is automatically registered as a root of the Nix garbage collector. This root disappears automatically when the <filename>result</filename> symlink is deleted or renamed. So don’t rename the symlink.</para></warning> </refsection> <refsection><title>Options</title> <para>All options not listed here are passed to <command>nix-store --realise</command>, except for <option>--arg</option> and <option>--attr</option> / <option>-A</option> which are passed to <command>nix-instantiate</command>. <phrase condition="manual">See also <xref linkend="sec-common-options" />.</phrase></para> <variablelist> <varlistentry><term><option>--no-out-link</option></term> <listitem><para>Do not create a symlink to the output path. Note that as a result the output does not become a root of the garbage collector, and so might be deleted by <command>nix-store --gc</command>.</para></listitem> </varlistentry> <varlistentry><term><option>--dry-run</option></term> <listitem><para>Show what store paths would be built or downloaded.</para></listitem> </varlistentry> <varlistentry xml:id='opt-out-link'><term><option>--out-link</option> / <option>-o</option> <replaceable>outlink</replaceable></term> <listitem><para>Change the name of the symlink to the output path created from <filename>result</filename> to <replaceable>outlink</replaceable>.</para></listitem> </varlistentry> </variablelist> <para>The following common options are supported:</para> <variablelist condition="manpage"> <xi:include href="opt-common.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(//db:variablelist[@xml:id='opt-common']/*)" /> </variablelist> </refsection> <refsection><title>Examples</title> <screen> $ nix-build '<nixpkgs>' -A firefox store derivation is /nix/store/qybprl8sz2lc...-firefox-1.5.0.7.drv /nix/store/d18hyl92g30l...-firefox-1.5.0.7 $ ls -l result lrwxrwxrwx <replaceable>...</replaceable> result -> /nix/store/d18hyl92g30l...-firefox-1.5.0.7 $ ls ./result/bin/ firefox firefox-config</screen> <para>If a derivation has multiple outputs, <command>nix-build</command> will build the default (first) output. You can also build all outputs: <screen> $ nix-build '<nixpkgs>' -A openssl.all </screen> This will create a symlink for each output named <filename>result-<replaceable>outputname</replaceable></filename>. The suffix is omitted if the output name is <literal>out</literal>. So if <literal>openssl</literal> has outputs <literal>out</literal>, <literal>bin</literal> and <literal>man</literal>, <command>nix-build</command> will create symlinks <literal>result</literal>, <literal>result-bin</literal> and <literal>result-man</literal>. It’s also possible to build a specific output: <screen> $ nix-build '<nixpkgs>' -A openssl.man </screen> This will create a symlink <literal>result-man</literal>.</para> <para>Build a Nix expression given on the command line: <screen> $ nix-build -E 'with import <nixpkgs> { }; runCommand "foo" { } "echo bar > $out"' $ cat ./result bar </screen> </para> <para>Build the GNU Hello package from the latest revision of the master branch of Nixpkgs: <screen> $ nix-build https://github.com/NixOS/nixpkgs/archive/master.tar.gz -A hello </screen> </para> </refsection> <refsection condition="manpage"><title>Environment variables</title> <variablelist> <xi:include href="env-common.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(//db:variablelist[@xml:id='env-common']/*)" /> </variablelist> </refsection> </refentry>