<chapter id='chap-installation'>
<title>Installation</title>
<sect1>
<title>Obtaining Nix</title>
<para>
The easiest way to obtain Nix is to download a <ulink
url='http://www.cs.uu.nl/groups/ST/Trace/Nix'>source
distribution</ulink>. RPMs for SuSE and Red Hat are also
available. These distributions are generated automatically.
</para>
<para>
Alternatively, the most recent sources of Nix can be obtained from its
<ulink url='https://svn.cs.uu.nl:12443/repos/trace/nix/trunk'>Subversion
repository</ulink>. For example, the following command will check out
the latest revision into a directory called <filename>nix</filename>:
</para>
<screen>
$ svn checkout https://svn.cs.uu.nl:12443/repos/trace/nix/trunk nix</screen>
<para>
Likewise, specific releases can be obtained from the <ulink
url='https://svn.cs.uu.nl:12443/repos/trace/nix/tags'>tags
directory</ulink> of the repository. If you don't have Subversion, you
can also download an automatically generated <ulink
url='https://svn.cs.uu.nl:12443/dist/trace/'>compressed
tar-file</ulink> of the head revision of the trunk.
</para>
</sect1>
<sect1>
<title>Prerequisites</title>
<para>
The following prerequisites only apply when you build from
source. Binary releases (e.g., RPMs) have no prerequisites.
</para>
<para>
A fairly recent version of GCC/G++ is required. Version 2.95
and higher should work.
</para>
<para>
To build this manual and the man-pages you need the
<command>xmllint</command> and <command>xsltproc</command>
programs, which are part of the <literal>libxml2</literal> and
<literal>libxslt</literal> packages, respectively. You also
need the <ulink
url='http://docbook.sourceforge.net/projects/xsl/'>DocBook XSL
stylesheets</ulink> and optionally the <ulink
url='http://www.oasis-open.org/docbook/xml/4.2/docbook-xml-4.2.zip'>
DocBook XML 4.2 DTD</ulink>. Note that these are only required
if you modify the manual sources or when you are building from
the Subversion repository.
</para>
<para>
To build the parser, very <emphasis>recent</emphasis> versions
of Bison and Flex are required. (This is because Nix needs GLR
support in Bison and reentrancy support in Flex.) For Bison,
you need version 1.875c or higher (1.875 does
<emphasis>not</emphasis> work), which can be obtained from the
<ulink url='ftp://alpha.gnu.org/pub/gnu/bison'>GNU FTP
server</ulink>. For Flex, you need version 2.5.31, which is
available on <ulink
url='http://lex.sourceforge.net/'>SourceForge</ulink>. Slightly
older versions may also work, but ancient versions like the
ubiquitous 2.5.4a won't. Note that these are only required if
you modify the parser or when you are building from the
Subversion repository.
</para>
<para>
Nix uses Sleepycat's Berkeley DB and CWI's ATerm library. These
are included in the Nix source distribution. If you build from
the Subversion repository, you must download them yourself and
place them in the <filename>externals/</filename> directory.
See <filename>externals/Makefile.am</filename> for the precise
URLs of these packages.
</para>
</sect1>
<sect1>
<title>Building Nix from source</title>
<para>
After unpacking or checking out the Nix sources, issue the following
commands:
</para>
<screen>
$ ./configure <replaceable>options...</replaceable>
$ make
$ make install</screen>
<para>
When building from the Subversion repository, these should be preceded by
the command:
</para>
<screen>
$ autoreconf -i</screen>
<para>
The installation path can be specified by passing the
<option>--prefix=<replaceable>prefix</replaceable></option> to
<command>configure</command>. The default installation directory is
<filename>/nix</filename>. You can change this to any location you like.
You must have write permission to the <replaceable>prefix</replaceable>
path.
</para>
<warning>
<para>
It is advisable <emphasis>not</emphasis> to change the installation
prefix from its default, since doing so will in all likelihood make it
impossible to use derivations built on other systems.
</para>
</warning>
<para>
If you want to rebuilt the documentation, pass the full path to the
DocBook XML catalog file (<filename>docbook.cat</filename>) and to the
DocBook XSL stylesheets using the
<option>--with-docbook-catalog=<replaceable>path</replaceable></option>
and <option>--with-docbook-xsl=<replaceable>path</replaceable></option>
options.
</para>
</sect1>
<sect1>
<title>Installing from RPMs</title>
<para>
RPM packages of Nix can be downloaded from <ulink
url='http://www.cs.uu.nl/groups/ST/Trace/Nix' />. These RPMs
should work for most fairly recent releases of SuSE and Red Hat
Linux. They have been known to work work on SuSE Linux 8.1 and
9.0, and Red Hat 9.0. In fact, it should work on any RPM-based
Linux distribution based on <literal>glibc</literal> 2.3 or
later.
</para>
<para>
Once downloaded, the RPMs can be installed or upgraded using
<command>rpm -U</command>. For example,
</para>
<screen>
rpm -U nix-0.5pre664-1.i386.rpm</screen>
<para>
The RPMs install into the directory <filename>/nix</filename>.
Nix can be uninstalled using <command>rpm -e nix</command>.
After this it will be necessary to manually remove the Nix store
and other auxiliary data:
</para>
<screen>
rm -rf /nix/store
rm -rf /nix/var</screen>
</sect1>
<sect1>
<title>Permissions</title>
<para>
All Nix operations must be performed under the user ID that owns
the Nix store and database
(<filename><replaceable>prefix</replaceable>/store</filename>
and
<filename><replaceable>prefix</replaceable>/var/nix/db</filename>,
respectively). When installed from the RPM packages, these
directories are owned by <systemitem
class='username'>root</systemitem>.
</para>
</sect1>
<sect1>
<title>Using Nix</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>~/.bashrc</filename> (or similar), like this:
</para>
<screen>
. <replaceable>prefix</replaceable>/etc/profile.d/nix.sh</screen>
</sect1>
</chapter>