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			XML
		
	
	
	
	
	
			
		
		
	
	
			233 lines
		
	
	
	
		
			9 KiB
		
	
	
	
		
			XML
		
	
	
	
	
	
<?xml version="1.0" encoding="utf-8"?>
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<chapter xmlns="http://docbook.org/ns/docbook"
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         xmlns:xlink="http://www.w3.org/1999/xlink"
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         xml:id="chap-installation">
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<title>Installation</title>
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<section><title>Obtaining Nix</title>
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<para>The easiest way to obtain Nix is to download a <link
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xlink:href="http://www.cs.uu.nl/groups/ST/Trace/Nix">source
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distribution</link>.  RPMs for Red Hat, SuSE, and Fedora Core are also
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available.</para>
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<para>Alternatively, the most recent sources of Nix can be obtained
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from its <link
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xlink:href="https://svn.cs.uu.nl:12443/repos/trace/nix/trunk">Subversion
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repository</link>.  For example, the following command will check out
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the latest revision into a directory called
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<filename>nix</filename>:</para>
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<screen>
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$ svn checkout https://svn.cs.uu.nl:12443/repos/trace/nix/trunk nix</screen>
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<para>Likewise, specific releases can be obtained from the <link
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xlink:href="https://svn.cs.uu.nl:12443/repos/trace/nix/tags">tags
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directory</link> of the repository.  If you don't have Subversion, you
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can also download an automatically generated <link
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xlink:href="https://svn.cs.uu.nl:12443/dist/trace/">compressed
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tar-file</link> of the head revision of the trunk.</para>
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</section>
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<section><title>Prerequisites</title>
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<para><emphasis>The following prerequisites only apply when you build
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from source</emphasis>.  Binary releases (e.g., RPMs) have no
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prerequisites.</para>
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<para>A fairly recent version of GCC/G++ is required.  Version 2.95
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and higher should work.</para>
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<para>To build this manual and the man-pages you need the
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<command>xmllint</command> and <command>xsltproc</command> programs,
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which are part of the <literal>libxml2</literal> and
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<literal>libxslt</literal> packages, respectively.  You also need the
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<link
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xlink:href="http://docbook.sourceforge.net/projects/xsl/">DocBook XSL
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stylesheets</link> and optionally the <link
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xlink:href="http://www.docbook.org/schemas/5x"> DocBook 5.0 RELAX NG
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schemas</link>.  Note that these are only required if you modify the
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manual sources or when you are building from the Subversion
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repository.</para>
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<para>To build the parser, very <emphasis>recent</emphasis> versions
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of Bison and Flex are required.  (This is because Nix needs GLR
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support in Bison and reentrancy support in Flex.)  For Bison, you need
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version 1.875c or higher (1.875 does <emphasis>not</emphasis> work),
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which can be obtained from the <link
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xlink:href="ftp://alpha.gnu.org/pub/gnu/bison">GNU FTP server</link>.
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For Flex, you need version 2.5.31, which is available on <link
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xlink:href="http://lex.sourceforge.net/">SourceForge</link>.  Slightly
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older versions may also work, but ancient versions like the ubiquitous
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2.5.4a won't.  Note that these are only required if you modify the
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parser or when you are building from the Subversion repository.</para>
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<para>Nix uses Sleepycat's Berkeley DB and CWI's ATerm library.  These
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are included in the Nix source distribution.  If you build from the
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Subversion repository, you must download them yourself and place them
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in the <filename>externals/</filename> directory.  See
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<filename>externals/Makefile.am</filename> for the precise URLs of
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these packages.  Alternatively, if you already have them installed,
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you can use <command>configure</command>'s <option>--with-bdb</option>
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and <option>--with-aterm</option> options to point to their respective
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locations.  Note that Berkeley DB <emphasis>must</emphasis> be version
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4.4; other versions may not have compatible database formats.</para>
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</section>
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<section><title>Building Nix from source</title>
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<para>After unpacking or checking out the Nix sources, issue the
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following commands:
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    </para>
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<screen>
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$ ./configure <replaceable>options...</replaceable>
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$ make
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$ make install</screen>
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<para>When building from the Subversion repository, these should be
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preceded by the command:
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    </para>
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<screen>
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$ autoreconf -i</screen>
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<para>The installation path can be specified by passing the
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<option>--prefix=<replaceable>prefix</replaceable></option> to
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<command>configure</command>.  The default installation directory is
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<filename>/nix</filename>.  You can change this to any location you
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like.  You must have write permission to the
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<replaceable>prefix</replaceable> path.</para>
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<warning><para>It is best <emphasis>not</emphasis> to change the
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installation prefix from its default, since doing so makes it
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impossible to use pre-built binaries from the standard Nixpkgs
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channels.</para></warning>
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<para>If you want to rebuilt the documentation, pass the full path to
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the DocBook RELAX NG schemas and to the DocBook XSL stylesheets using
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the
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<option>--with-docbook-rng=<replaceable>path</replaceable></option>
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and
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<option>--with-docbook-xsl=<replaceable>path</replaceable></option>
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options.</para>
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</section>
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<section><title>Installing from RPMs</title>
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<para>RPM packages of Nix can be downloaded from <uri
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xlink:href="http://www.cs.uu.nl/groups/ST/Trace/Nix">http://www.cs.uu.nl/groups/ST/Trace/Nix</uri>.
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These RPMs should work for most fairly recent releases of SuSE and Red
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Hat Linux.  They have been known to work work on SuSE Linux 8.1 and
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9.0, and Red Hat 9.0.  In fact, it should work on any RPM-based Linux
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distribution based on <literal>glibc</literal> 2.3 or later.</para>
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<para>Once downloaded, the RPMs can be installed or upgraded using
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<command>rpm -U</command>.  For example,</para>
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<screen>
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$ rpm -U nix-0.5pre664-1.i386.rpm</screen>
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<para>The RPMs install into the directory <filename>/nix</filename>.
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Nix can be uninstalled using <command>rpm -e nix</command>.  After
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this it will be necessary to manually remove the Nix store and other
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auxiliary data:</para>
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<screen>
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$ rm -rf /nix/store
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$ rm -rf /nix/var</screen>
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</section>
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<section><title>Upgrading Nix through Nix</title>
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<para>You can install the latest stable version of Nix through Nix
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itself by subscribing to the channel <link
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xlink:href="http://nix.cs.uu.nl/dist/nix/channels-v3/nix-stable" /> ,
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or the latest unstable version by subscribing to the channel<link
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xlink:href="http://nix.cs.uu.nl/dist/nix/channels-v3/nix-unstable" />.
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You can also do a <link linkend="sec-one-click">one-click
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installation</link> by clicking on the package links at <link
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xlink:href="http://nix.cs.uu.nl/dist/nix/" />.</para>
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</section>
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<section><title>Permissions</title>
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<para>All Nix operations must be performed under the user ID that owns
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the Nix store and database
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(<filename><replaceable>prefix</replaceable>/store</filename> and
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<filename><replaceable>prefix</replaceable>/var/nix/db</filename>,
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respectively).  When installed from the RPM packages, these
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directories are owned by <systemitem class="username">root</systemitem>.</para>
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<section><title>Setuid installation</title>
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<para>As a somewhat <emphasis>ad hoc</emphasis> hack, you can also
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install the Nix binaries <quote>setuid</quote> so that a Nix store can
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be shared among several users.  To do this, configure Nix with the
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<emphasis>--enable-setuid</emphasis> option.  Nix will be installed as
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owned by a user and group specified by the
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<option>--with-nix-user=</option><parameter>user</parameter> and
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<option>--with-nix-group=</option><parameter>group</parameter>
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options.  E.g.,
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<screen>
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$ ./configure --enable-setuid --with-nix-user=my_nix_user --with-nix-group=my_nix_group</screen>
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The user and group default to <literal>nix</literal>.  You should make
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sure that both the user and the group exist.  Any <quote>real</quote>
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users that you want to allow access should be added to the Nix
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group.</para>
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<warning><para>A setuid installation should only by used if the users
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in the Nix group are mutually trusted, since any user in that group
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has the ability to change anything in the Nix store or database.  For
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instance, they could install a trojan horse in executables used by
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other users.</para></warning>
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<warning><para>On some platforms, the Nix binaries will be installed
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as setuid <literal>root</literal>.  They drop root privileges
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immediately after startup and switch to the Nix user.  The reason for
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this is that both the real and effective user must be set to the Nix
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user, and POSIX has no system call to do this.  This is not the case
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on systems that have the <function>setresuid()</function> system call
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(such as Linux and FreeBSD), so on those systems the binaries are
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simply owned by the Nix user.</para></warning>
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</section>
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</section>
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<section><title>Using Nix</title>
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<para>To use Nix, some environment variables should be set.  In
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particular, <envar>PATH</envar> should contain the directories
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<filename><replaceable>prefix</replaceable>/bin</filename> and
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<filename>~/.nix-profile/bin</filename>.  The first directory contains
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the Nix tools themselves, while <filename>~/.nix-profile</filename> is
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a symbolic link to the current <emphasis>user environment</emphasis>
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(an automatically generated package consisting of symlinks to
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installed packages).  The simplest way to set the required environment
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variables is to include the file
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<filename><replaceable>prefix</replaceable>/etc/profile.d/nix.sh</filename>
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in your <filename>~/.bashrc</filename> (or similar), like this:</para>
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<screen>
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source <replaceable>prefix</replaceable>/etc/profile.d/nix.sh</screen>
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</section>
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</chapter>
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