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6. Installing the Gentoo Base System


6.a. Chrooting

Optional: Selecting Mirrors

In order to download source code quickly it is recommended to select a fast mirror. Portage will look in your make.conf file for the GENTOO_MIRRORS variable and use the mirrors listed therein. You can surf to our mirror list 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 mirrorselect 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.

Code Listing 1.1: Using mirrorselect for the GENTOO_MIRRORS variable

# mirrorselect -i -o >> /mnt/gentoo/etc/portage/make.conf

A second important setting is the SYNC setting in make.conf. 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, mirrorselect can ease that operation for you:

Code Listing 1.2: Selecting an rsync mirror using mirrorselect

# mirrorselect -i -r -o >> /mnt/gentoo/etc/portage/make.conf

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

Note: If you want to manually set a SYNC server in make.conf, you should check out the community mirrors list for the mirrors closest to you. We recommend choosing a rotation, such as, rather than choosing a single mirror. This helps spread out the load and provides a failsafe in case a specific mirror is offline.

Copy DNS Info

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

Code Listing 1.3: Copy over DNS information

(The "-L" option is needed to make sure we don't copy a symbolic link)
# cp -L /etc/resolv.conf /mnt/gentoo/etc/

Mounting the necessary Filesystems

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.

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 and /sys filesystems.

Code Listing 1.4: Mounting /proc and /dev

# mount -t proc proc /mnt/gentoo/proc
# mount --rbind /sys /mnt/gentoo/sys
# mount --rbind /dev /mnt/gentoo/dev

Warning: When using non-Gentoo installation media, this might not be sufficient. Some distributions make /dev/shm a symbolic link to /run/shm which, after the chroot, becomes invalid. Making /dev/shm a proper tmpfs-mount up front can fix this.

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 (Installation CD or other installation medium) to your installation system (namely the initialized partitions).

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 reload some settings, as provided by /etc/profile, in memory using source. The last step is to redefine the primary prompt to help us remember that we are inside a chroot environment.

Code Listing 1.5: Chrooting into the new environment

# chroot /mnt/gentoo /bin/bash
# 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 :-)

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.

6.b. Configuring Portage

Installing a Portage Snapshot

You now have to install a Portage snapshot, a collection of files that inform Portage what software titles you can install, which profiles are available, etc.

We recommend the use of emerge-webrsync. This will fetch the latest portage snapshot (which Gentoo releases on a daily basis) from one of our mirrors and install it onto your system.

Code Listing 2.1: Running emerge-webrsync to install a Portage snapshot

# emerge-webrsync

Note: During this operation, emerge-webrsync might complain about a missing /usr/portage location. This is to be expected and nothing to worry about - the tool will create the location for us.

From this point onward, Portage might mention that certain updates are recommended to be executed. This is because certain system packages installed through the stage3 file might have newer versions available, and Portage is now aware of this because a new Portage snapshot is installed. You can safely ignore this for now and update after the Gentoo installation has finished.

Optional: Updating the Portage tree

You can now update your Portage tree to the latest version. emerge --sync will use the rsync protocol to update the Portage tree (which you fetched earlier on through emerge-webrsync) to the latest state.

Code Listing 2.2: Updating the Portage tree

# emerge --sync
(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:)
# emerge --sync --quiet

If you are behind a firewall that blocks rsync traffic, you safely ignore this step as you already have a quite up-to-date Portage tree.

If you are warned that a new Portage version is available and that you should update Portage, you should do it now using emerge --oneshot portage. You might also be notified that "news items need reading". More on that next.

Reading News Items

When a Portage tree is synchronized to your system, Portage might warn you with the following:

Code Listing 2.3: Portage informing that news items are available

 * IMPORTANT: 2 news items need reading for repository 'gentoo'.
 * Use eselect news to read news items.

Portage news items were created to provide a communication medium to push critical messages to users via the rsync tree. To manage them you will need to use eselect news. With the read subcommand, you can read all news items. With list you can get an overview of the available news items, and with purge you can remove them once you have read them and have no further need for the item(s) anymore.

Code Listing 2.4: Handling Portage news

# eselect news list
# eselect news read

More information about the newsreader is available through its manual page: man news.eselect.

Choosing the Right Profile

First, a small definition is in place.

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.

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.

You can see what profile you are currently using with the following command:

Note: The output of the command below is just an example and evolves over time.

Code Listing 2.5: Verifying system profile

# eselect profile list
Available profile symlink targets:
  [1]   default/linux/x86/13.0 *
  [2]   default/linux/x86/13.0/desktop
  [3]   default/linux/x86/13.0/desktop/gnome
  [4]   default/linux/x86/13.0/desktop/kde

As you can see, there are also desktop subprofiles available for some architectures. Running eselect profile list will show all available profiles.

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

Code Listing 2.6: Changing profiles

# eselect profile set 2

Note: The developer subprofile is specifically for Gentoo Linux development tasks. It is not meant to help set up general development environments.

Configuring 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 (X-server).

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.

The default USE settings are placed in the make.defaults files of your profile. You will find make.defaults files in the directory which /etc/portage/make.profile points to and all parent directories as well. The default USE setting is the sum of all USE settings in all make.defaults files. What you place in /etc/portage/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/portage/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 /usr/portage/profiles/use.desc.

Code Listing 2.7: Viewing available USE flags

# less /usr/portage/profiles/use.desc
(You can scroll using your arrow keys, exit by pressing 'q')

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

Code Listing 2.8: Opening /etc/portage/make.conf

# nano -w /etc/portage/make.conf

Code Listing 2.9: USE setting

USE="-gtk -gnome qt4 kde dvd alsa cdr"

6.c. Optional: Using systemd

The remainder of the Gentoo Handbook focuses on OpenRC as the default init support system. If you want to use systemd instead, or are planning to use Gnome 3.8 and later (which requires systemd), please consult the systemd page on the Gentoo wiki as it elaborates on the different configuration settings and methods.

The Gentoo Handbook can then be followed with that page in mind.

6.d. Timezone

Finally select your timezone so that your system knows where it is physically located. Look for your timezone in /usr/share/zoneinfo, then write it in the /etc/timezone file.

Code Listing 4.1: Setting the timezone information

# ls /usr/share/zoneinfo
(Suppose you want to use Europe/Brussels)
# echo "Europe/Brussels" > /etc/timezone

Please avoid the /usr/share/zoneinfo/Etc/GMT* timezones as their names do not indicate the expected zones. For instance, GMT-8 is in fact GMT+8.

Next, reconfigure the timezone-data package, which will update the /etc/localtime file for us, based on the /etc/timezone entry. The /etc/localtime file is used by the system C library to know the timezone the system is in.

Code Listing 4.2: Reconfiguring timezone-data

# emerge --config sys-libs/timezone-data

6.e. Configure locales

You will probably only use one or maybe two locales on your system. You have to specify locales you will need in /etc/locale.gen.

Code Listing 5.1: Opening /etc/locale.gen

# nano -w /etc/locale.gen

The following locales are an example to get both English (United States) and German (Germany) with the accompanying character formats (like UTF-8).

Code Listing 5.2: Specify your locales

en_US ISO-8859-1
en_US.UTF-8 UTF-8
de_DE ISO-8859-1
de_DE@euro ISO-8859-15

Note: You can select your desired locales in the list given by running locale -a.

Warning: We strongly suggest that you should use at least one UTF-8 locale because some applications may require it.

The next step is to run locale-gen. It will generate all the locales you have specified in the /etc/locale.gen file.

Code Listing 5.3: Running locale-gen

# locale-gen

You can verify that your selected locales are available by running locale -a.

Once done, you now have the possibility to set the system-wide locale settings. With eselect locale list, the available targets are displayed:

Code Listing 5.4: Displaying the available LANG settings

# eselect locale list
Available targets for the LANG variable:
  [1] C
  [2] POSIX
  [3] en_US
  [4] en_US.iso88591
  [5] en_US.utf8
  [6] de_DE
  [7] de_DE.iso88591
  [8] de_DE.iso885915
  [9] de_DE.utf8
  [ ] (free form)

With eselect locale set <value> the correct locale can be set:

Code Listing 5.5: Setting the LANG variable

# eselect locale set 9

Manually, this can still be accomplished through the /etc/env.d/02locale file:

Code Listing 5.6: Setting the default system locale in /etc/env.d/02locale


Make sure a locale is set, as you could otherwise get warnings and errors during kernel builds and other software deployments later in the installation.

Don't forget to reload your environment:

Code Listing 5.7: Reload shell environment

# env-update && source /etc/profile

We made a full Localization Guide to help you through this process. You can also read the detailed UTF-8 article for very specific informations to enable UTF-8 on your system.

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Page updated August 17, 2014

Summary: 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.

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