<refentry> <refnamediv> <refname>nix-build</refname> <refpurpose>build a Nix expression</refpurpose> </refnamediv> <refsynopsisdiv> <cmdsynopsis> <command>nix-build</command> <arg><option>--add-drv-link</option></arg> <arg><option>--no-link</option></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> <note><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></note> <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> <variablelist> <varlistentry><term><option>--add-drv-link</option></term> <listitem><para>Add a symlink in the current directory to the store derivation produced by <command>nix-instantiate</command>. The symlink is called <filename>derivation</filename> (which is numbered in the case of multiple derivations). The derivation is a root of the garbage collector until the symlink is deleted or renamed.</para></listitem> </varlistentry> <varlistentry><term><option>--no-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> </variablelist> </refsection> </refentry>