<chapter 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="ch-env-variables"> <title>Environment Variables</title> <para>To use Nix, some environment variables should be set. In particular, <envar>PATH</envar> should contain the directories <filename><replaceable>prefix</replaceable>/bin</filename> and <filename>~/.nix-profile/bin</filename>. The first directory contains the Nix tools themselves, while <filename>~/.nix-profile</filename> is a symbolic link to the current <emphasis>user environment</emphasis> (an automatically generated package consisting of symlinks to installed packages). The simplest way to set the required environment variables is to include the file <filename><replaceable>prefix</replaceable>/etc/profile.d/nix.sh</filename> in your <filename>~/.profile</filename> (or similar), like this:</para> <screen> source <replaceable>prefix</replaceable>/etc/profile.d/nix.sh</screen> </chapter>