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6. Chrooting into the Gentoo Base System
Mounting the /proc and /dev Filesystems
Mount the /proc filesystem on /mnt/gentoo/proc to
allow the installation to use the kernel-provided information within the
chrooted environment, and then mount-bind the /dev filesystem.
Code Listing 1.1: Mounting /proc and /dev
# mount -t proc none /mnt/gentoo/proc
# mount -o bind /dev /mnt/gentoo/dev
Entering the new Environment
Now that all partitions are initialized and the base environment
installed, it is time to enter our new installation environment by
chrooting into it. This means that we change from the current
installation environment to your installation system (namely the
This chrooting is done in three steps. First we will change the root
from / (on the installation medium) to /mnt/gentoo
(on your partitions) using chroot. Then we will create a new environment
using env-update, which essentially creates environment variables.
Finally, we load those variables into memory using source.
Code Listing 1.2: Chrooting into the new environment
# chroot /mnt/gentoo /bin/bash
>>> Regenerating /etc/ld.so.cache...
# source /etc/profile
# export PS1="(chroot) $PS1"
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 :-)
Creating the Portage cache
You have already installed the Portage tree, but you should now build the
Portage cache to speed up future emerges. emerge --metadata does this
Code Listing 1.3: Creating the Portage cache
# emerge --metadata
6.b. Configuring the USE Variable
What is the USE Variable?
USE 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
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 USE comes into play.
In the USE variable you define keywords which are mapped onto
compile-options. For instance, ssl will compile ssl-support in the
programs that support it. -X will remove X-server support (note the
minus sign in front). gnome gtk -kde -qt4 will compile your
programs with gnome (and gtk) support, and not with kde (and qt) support,
making your system fully tweaked for GNOME.
Modifying the USE Variable
Do not make any modifications to the USE variable yet if you plan to use our
prebuilt packages (GRP set). You can alter the USE variable after having
installed the packages you want. Gremlins are known to attack your system
if you ignore this warning!
The default USE settings are placed in
/etc/make.profile/make.defaults. What you place in
/etc/make.conf is calculated against these defaults settings. If
you add something to the USE setting, it is added to the default list. If
you remove something from the USE 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). Never alter anything inside the /etc/make.profile
directory; it gets overwritten when you update Portage!
A full description on USE can be found in the second part of the Gentoo
Handbook, USE flags. A full description on
the available USE flags can be found on your system in
Code Listing 2.1: Viewing available USE flags
# less /usr/portage/profiles/use.desc
As an example we show a USE setting for a KDE-based system with DVD, ALSA
and CD Recording support:
Code Listing 2.2: Opening /etc/make.conf
# nano -w /etc/make.conf
Code Listing 2.3: USE setting
USE="-gtk -gnome qt4 kde dvd alsa cdr"
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