<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE sections SYSTEM "/dtd/book.dtd">

<!-- The content of this document is licensed under the CC-BY-SA license -->
<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->

<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-system.xml,v 1.125 2012/07/24 12:12:52 swift Exp $ -->

<sections>

<abstract>
After installing and configuring a stage3, the eventual result is that you
have a Gentoo base system at your disposal. This chapter describes how
to progress to that state.
</abstract>

<version>17</version>
<date>2012-07-24</date>

<section>
<title>Chrooting</title>
<subsection>
<title>Optional: Selecting Mirrors</title>
<body>

<p>
In order to download source code quickly it is recommended to select a fast
mirror. Portage will look in your <path>make.conf</path> file for the
GENTOO_MIRRORS variable and use the mirrors listed therein. You can surf to
our <uri link="/main/en/mirrors.xml">mirror list</uri> and search
for a mirror (or mirrors) close to you (as those are most frequently the 
fastest ones), but we provide a nice tool called <c>mirrorselect</c> which
provides you with a nice interface to select the mirrors you want. Just 
navigate to the mirrors of choice and press spacebar to select one or more
mirrors.
</p>
  
<pre caption="Using mirrorselect for the GENTOO_MIRRORS variable">
# <i>mirrorselect -i -o &gt;&gt; /mnt/gentoo/etc/portage/make.conf</i>
</pre>

<p>
A second important setting is the SYNC setting in <path>make.conf</path>. This
variable contains the rsync server you want to use when updating your Portage
tree (the collection of ebuilds, scripts containing all the information Portage
needs to download and install software). Although you can manually enter a SYNC
server for yourself, <c>mirrorselect</c> can ease that operation for you:
</p>

<pre caption="Selecting an rsync mirror using mirrorselect">
# <i>mirrorselect -i -r -o &gt;&gt; /mnt/gentoo/etc/portage/make.conf</i>
</pre>

<p>
After running <c>mirrorselect</c> it is adviseable to double-check the settings
in <path>/mnt/gentoo/etc/portage/make.conf</path> !
</p>

<note>
If you want to manually set a SYNC server in <path>make.conf</path>, you should
check out the <uri link="/main/en/mirrors-rsync.xml">community mirrors
list</uri> for the mirrors closest to you. We recommend choosing a
<e>rotation</e>, such as <c>rsync.us.gentoo.org</c>, rather than choosing a
single mirror. This helps spread out the load and provides a failsafe in case a
specific mirror is offline.
</note>

</body>
</subsection>
<subsection>
<title>Copy DNS Info</title>
<body>

<p>
One thing still remains to be done before we enter the new environment and that
is copying over the DNS information in <path>/etc/resolv.conf</path>. You need
to do this to ensure that networking still works even after entering the new
environment. <path>/etc/resolv.conf</path> contains the nameservers for your
network.
</p>

<pre caption="Copy over DNS information">
<comment>(The "-L" option is needed to make sure we don't copy a symbolic link)</comment>
# <i>cp -L /etc/resolv.conf /mnt/gentoo/etc/</i>
</pre>

</body>
</subsection>
<subsection test="not(func:keyval('arch')='IA64')">
<title>Mounting the necessary Filesystems</title>
<body>

<p>
In a few moments, we will change the Linux root towards the new location. To
make sure that the new environment works properly, we need to make certain file
systems available there as well.
</p>

<p>
Mount the <path>/proc</path> filesystem on <path>/mnt/gentoo/proc</path> to
allow the installation to use the kernel-provided information within the
chrooted environment, and then mount-bind the <path>/dev</path> and
<path>/sys</path> filesystems.
</p>

<pre caption="Mounting /proc and /dev">
# <i>mount -t proc none /mnt/gentoo/proc</i>
# <i>mount --rbind /sys /mnt/gentoo/sys</i>
# <i>mount --rbind /dev /mnt/gentoo/dev</i>
</pre>

</body>
</subsection>
<subsection test="func:keyval('arch')='IA64'">
<title>Mounting the /proc, /sys and /dev Filesystems</title>
<body>

<p>
Mount the <path>/proc</path> filesystem on <path>/mnt/gentoo/proc</path> to
allow the installation to use the kernel-provided information within the
chrooted environment, and then mount-bind the <path>/dev</path> and
<path>/sys</path> filesystems.
</p>

<pre caption="Mounting /proc /sys and /dev">
# <i>mount -t proc none /mnt/gentoo/proc</i>
# <i>mount --rbind /dev /mnt/gentoo/dev</i>
# <i>mount --rbind /sys /mnt/gentoo/sys</i>
</pre>

</body>
</subsection>
<subsection>
<title>Entering the new Environment</title>
<body>

<p>
Now that all partitions are initialized and the base environment
installed, it is time to enter our new installation environment by
<e>chrooting</e> into it. This means that we change from the current
installation environment (Installation CD or other installation medium) to your
installation system (namely the initialized partitions).
</p>

<p>
This chrooting is done in three steps. First we will change the root
from <path>/</path> (on the installation medium) to <path>/mnt/gentoo</path> 
(on your partitions) using <c>chroot</c>. Then we will create a new environment
using <c>env-update</c>, which essentially creates environment variables.
Finally, we load those variables into memory using <c>source</c>.
</p>

<pre caption = "Chrooting into the new environment">
# <i>chroot /mnt/gentoo /bin/bash</i>
# <i>env-update</i>
>> Regenerating /etc/ld.so.cache...
# <i>source /etc/profile</i>
# <i>export PS1="(chroot) $PS1"</i>
</pre>

<p>
Congratulations! You are now inside your own Gentoo Linux environment.
Of course it is far from finished, which is why the installation still
has some sections left :-)
</p>

<p>
If you at any time would need another terminal or console to access the chroot
environment, all you need to do is to execute the above steps again.
</p>

</body>
</subsection>
</section>

<section>
<title>Configuring Portage</title>
<subsection>
<title>Updating the Portage tree</title>
<body>

<p>
You should now update your Portage tree to the latest version. <c>emerge 
--sync</c> does this for you.
</p>

<pre caption="Updating the Portage tree">
# <i>emerge --sync</i>
<comment>(If you're using a slow terminal like some framebuffers or a serial
console, you can add the --quiet option to speed up this process:)</comment>
# <i>emerge --sync --quiet</i>
</pre>

<p>
If you are behind a firewall that blocks rsync traffic, you can use
<c>emerge-webrsync</c> which will download and install a portage snapshot for
you.
</p>

<p>
If you are warned that a new Portage version is available and that you should
update Portage, you should do it now using <c>emerge --oneshot portage</c>.
</p>

</body>
</subsection>
<subsection>
<title>Choosing the Right Profile</title>
<body>

<p>
First, a small definition is in place.
</p>

<p>
A profile is a building block for any Gentoo system. Not only does it specify
default values for USE, CFLAGS and other important variables, it also locks
the system to a certain range of package versions. This is all maintained by the
Gentoo developers.
</p>

<p>
Previously, such a profile was untouched by the users. However, there may be
certain situations in which you may decide a profile change is necessary.
</p>

<p>
You can see what profile you are currently using with the following command:
</p>

<pre caption="Verifying system profile">
# <i>eselect profile list</i>
Available profile symlink targets:
  [1]   <keyval id="profile"/> *
  [2]   <keyval id="profile"/>/desktop
  [3]   <keyval id="profile"/>/server
</pre>

<p>
As you can see, there are also <c>desktop</c> and <c>server</c> subprofiles available for some
architectures. Running <c>eselect profile list</c> will show all available
profiles.
</p>

<p>
After viewing the available profiles for your architecture, you can use a
different one if you wish:
</p>

<pre caption="Changing profiles">
# <i>eselect profile set 2</i>
</pre>

<p test="func:keyval('arch')='AMD64'">
If you want to have a pure 64-bit environment, with no 32-bit applications or
libraries, you should use a non-multilib profile:
</p>

<pre test="func:keyval('arch')='AMD64'" caption="Switching to a non-multilib profile">
# <i>eselect profile list</i>
Available profile symlink targets:
  [1]   <keyval id="profile"/> *
  [2]   <keyval id="profile"/>/desktop
  [3]   <keyval id="profile"/>/no-multilib
  [4]   <keyval id="profile"/>/server
<comment>(Choose the no-multilib profile)</comment>
# <i>eselect profile set 3</i>
<comment>(Verify the change)</comment>
# <i>eselect profile list</i>
Available profile symlink targets:
  [1]   <keyval id="profile"/>
  [2]   <keyval id="profile"/>/desktop
  [3]   <keyval id="profile"/>/no-multilib *
  [4]   <keyval id="profile"/>/server
</pre>

<note>
The <c>developer</c> subprofile is specifically for Gentoo Linux development
tasks. It is <e>not</e> meant to help set up general development environments.
</note>

</body>
</subsection>
<subsection id="configure_USE">
<title>Configuring the USE variable</title>
<body>

<p>
<c>USE</c> is one of the most powerful variables Gentoo provides to its users.
Several programs can be compiled with or without optional support for certain
items. For instance, some programs can be compiled with gtk-support, or with
qt-support. Others can be compiled with or without SSL support. Some programs
can even be compiled with framebuffer support (svgalib) instead of X11 support
(X-server).
</p>

<p>
Most distributions compile their packages with support for as much as possible,
increasing the size of the programs and startup time, not to mention an enormous
amount of dependencies. With Gentoo you can define what options a package 
should be compiled with. This is where <c>USE</c> comes into play.
</p>

<p>
In the <c>USE</c> variable you define keywords which are mapped onto
compile-options. For instance, <e>ssl</e> will compile ssl-support in the
programs that support it. <e>-X</e> will remove X-server support (note the
minus sign in front). <e>gnome gtk -kde -qt4</e> will compile your
programs with gnome (and gtk) support, and not with kde (and qt) support,
making your system fully tweaked for GNOME.
</p>

<p>
The default <c>USE</c> settings are placed in the <path>make.defaults</path> 
files of your profile. You will find <path>make.defaults</path> files in the
directory which <path>/etc/portage/make.profile</path> points to and all parent 
directories as well. The default <c>USE</c> setting is the sum of all <c>USE</c>
settings in all <path>make.defaults</path> files. What you place in
<path>/etc/portage/make.conf</path> is calculated against these defaults
settings. If you add something to the <c>USE</c> setting, it is added to the
default list. If you remove something from the <c>USE</c> setting (by placing
a minus sign in front of it) it is removed from the default list (if it was
in the default list at all). <e>Never</e> alter anything inside the
<path>/etc/portage/make.profile</path> directory; it gets overwritten when
you update Portage!
</p>

<p>
A full description on <c>USE</c> can be found in the second part of the Gentoo
Handbook, <uri link="?part=2&amp;chap=2">USE flags</uri>. A full description on
the available USE flags can be found on your system in
<path>/usr/portage/profiles/use.desc</path>. 
</p>

<pre caption="Viewing available USE flags">
# <i>less /usr/portage/profiles/use.desc</i>
<comment>(You can scroll using your arrow keys, exit by pressing 'q')</comment>
</pre>

<p>
As an example we show a <c>USE</c> setting for a KDE-based system with DVD, ALSA
and CD Recording support:
</p>

<pre caption="Opening /etc/portage/make.conf">
# <i>nano -w /etc/portage/make.conf</i>
</pre>

<pre caption="USE setting">
USE="-gtk -gnome qt4 kde dvd alsa cdr"
</pre>

</body>
</subsection>
</section>
</sections>
