text:
1.a. Introduction
First of all, welcome to Gentoo. You are about to enter the world
of choices and performance. Gentoo is all about choices. When
installing Gentoo, this is made clear to you several times -- you can
choose how much you want to compile yourself, how to install Gentoo,
what system logger you want, etc.
Gentoo is a fast, modern metadistribution with a clean and flexible
design. Gentoo is built around free software and doesn't hide from its
users what is beneath the hood. Portage, the package maintenance system
which Gentoo uses, is written in Python, meaning you can easily view and
modify the source code. Gentoo's packaging system uses source code
(although support for precompiled packages is included too) and
configuring Gentoo happens through regular textfiles. In other words,
openness everywhere.
It is very important that you understand that choices are what
makes Gentoo run. We try not to force you onto anything you don't like.
If you feel like we do, please bugreport it.
How is the Installation Structured?
The Gentoo Installation can be seen as a 10-step procedure,
corresponding to chapters 2 - 11. Every step results in
a certain state:
When you are given a certain choice, we try our best to explain what the pros
and cons are. We will continue then with a default
choice, identified by "Default: " in the title. The other
possibilities are marked by "Alternative: ". Do not
think that the default is what we recommend. It is however what we
believe most users will use.
Sometimes you can pursue an optional step. Such steps are marked as
"Optional: " and are therefore not needed to install Gentoo.
However, some optional steps are dependent on a previous decision you
made. We will inform you when this happens, both when you make the
decision, and right before the optional step is described.
What are my Options?
You can install Gentoo in many different ways. You can download and install from
one of our Installation CDs, from a distribution already installed, from a
non-Gentoo bootable CD (such as Knoppix), from a netbooted environment, from
a rescue floppy, etc.
This document covers the installation using a Gentoo Installation CD or,
in certain cases, netbooting. This installation assumes that you want to install
the latest available version of each package.
For help on the other installation approaches, including using non-Gentoo CDs,
please read our Alternative Installation
We also provide a Gentoo
Installation Tips & Tricks document that might be useful to read as
well. If you are an experienced Gentoo user and just need a brief installation
checklist, feel free to use our Quick Installation Guide available from our Documentation
Overview if your architecture has
such a document available.
You also have several possibilities: you can compile your entire system from
scratch or use a prebuilt environment to have your Gentoo environment up and
running in no time. And of course you have intermediate solutions in which you
don't compile everything but start from a semi-ready system.
If you find a problem in the installation (or in the installation
documentation), please visit our bugtracking
system and check if the bug is known. If not, please create a bugreport
for it so we can take care of it. Do not be afraid of the developers who are
assigned to (your) bugs -- they generally don't eat people.
Note though that, although the document you are now reading is
architecture-specific, it will contain references to other architectures as
well. This is due to the fact that large parts of the Gentoo Handbook use source
code that is common for all architectures (to avoid duplication of efforts and
starvation of development resources). We will try to keep this to a minimum
to avoid confusion.
If you are uncertain if the problem is a user-problem (some error you
made despite having read the documentation carefully) or a
software-problem (some error we made despite having tested the
installation/documentation carefully) you are free to join #gentoo on
irc.freenode.net. Of course, you are welcome otherwise too as our chat channel
covers the broad Gentoo spectrum :)
Speaking of which, if you have a question regarding Gentoo, check out our Frequently Asked Questions, available from the Gentoo Wiki. You can also view the FAQs on our
2.a. Hardware Requirements
Before we start, we first list what hardware requirements you need to
successfully install Gentoo on your box.
Hardware Requirements
You should check the Gentoo
AMD64 Project Page before proceeding.
2.b. The Gentoo Installation CDs
The Gentoo Installation CDs are bootable CDs which contain a
self-sustained Gentoo environment. They allow you to boot Linux from the CD.
During the boot process your hardware is detected and the appropriate drivers
are loaded. They are maintained by Gentoo developers.
All Installation CDs allow you to boot, set up networking, initialize your
partitions and start installing Gentoo from the Internet.
Gentoo Minimal Installation CD
The Minimal Installation CD is called install-amd64-minimal-<release>.iso and
takes up around 200 MB of diskspace. You can use this
Installation CD to install Gentoo, but only with a working Internet
Gentoo Linux LiveDVDs
Every 6 months (give or take), a special DVD is crafted by the Gentoo Ten
project which can be used to install Gentoo with too. The instructions further
down this chapter target the Minimal Installation CDs so might be a bit
different. However, the LiveDVD (or any other bootable
Linux environment) supports getting a root prompt by just invoking sudo
su - or sudo -i on a terminal.
The Stage3 Tarball
A stage3 tarball is an archive containing a minimal Gentoo environment,
suitable to continue the Gentoo installation using the instructions in this
manual. Previously, the Gentoo Handbook described the installation using one of
three stage tarballs. While Gentoo still offers stage1 and stage2 tarballs, the
official installation method uses the stage3 tarball. If you are interested in
performing a Gentoo installation using a stage1 or stage2 tarball, please read
the Gentoo FAQ on How
do I Install Gentoo Using a Stage1 or Stage2 Tarball?
Stage3 tarballs can be downloaded from releases/amd64/autobuilds/current-stage3/ on any of the Official Gentoo Mirrors and are not provided
on the LiveDVD.
2.c. Download, Burn and Boot a Gentoo Installation CD
Downloading and Burning the Installation CDs
You have chosen to use a Gentoo Installation CD. We'll first start by
downloading and burning the chosen Installation CD. We previously discussed
the several available Installation CDs, but where can you find them?
You can download any of the Installation CDs from one of our mirrors. The Installation CDs are located in
the releases/amd64/autobuilds/current-iso/ directory.
Inside that directory you'll find ISO files. Those are full CD images which you
can write on a CD-R.
In case you wonder if your downloaded file is corrupted or not, you can check
its SHA-2 checksum and compare it with the SHA-2 checksum we provide (such as
install-amd64-minimal-<release>.iso.DIGESTS). You can check the SHA-2
checksum with the sha512sum tool under Linux/Unix or Checksums calculator for Windows.
The tool will attempt to verify the checksums in the list, even if the checksum
is made with a different algorithm. Therefore, the output of the command might
give both success (for SHA checksums) and failures (for other checksums). At
least one OK needs to be provided for each file.
Code Listing 3.1: Verifying the SHA-2 checksum
$ sha512sum -c <downloaded iso.DIGESTS>
If you get the message that no properly formatted SHA checksum was found, take a
look at the DIGESTS file yourself to see what the supported checksums are.
Another way to check the validity of the downloaded file is to use GnuPG to
verify the cryptographic signature that we provide (the file ending with
.asc). Download the signature file and obtain the public keys whose
key ids can be found on the release
engineering project site.
Code Listing 3.2: Obtaining the public key
(... Substitute the key ids with those mentioned on the release engineering site ...)
$ gpg --keyserver subkeys.pgp.net --recv-keys 96D8BF6D 2D182910 17072058
Now verify the signature:
Code Listing 3.3: Verify the files
$ gpg --verify <downloaded iso.DIGESTS.asc>
$ sha512sum -c <downloaded iso.DIGESTS.asc>
To burn the downloaded ISO(s), you have to select raw-burning. How you
do this is highly program-dependent. We will discuss cdrecord and
K3B here; more information can be found in our Gentoo FAQ.
Booting the Installation CD
Once you have burnt your installation CD, it is time to boot it.
Remove all CDs from your CD drives, reboot your system and enter the BIOS.
This is usually done by hitting DEL, F1 or ESC, depending on your BIOS. Inside
the BIOS, change the boot order so that the CD-ROM is tried before the hard
disk. This is often found under "CMOS Setup". If you don't do this, your system
will just reboot from the hard disk, ignoring the CD-ROM.
Now place the installation CD in the CD-ROM drive and reboot. You should see a
boot prompt. At this screen, you can hit Enter to begin the boot process with
the default boot options, or boot the Installation CD with custom boot options
by specifying a kernel followed by boot options and then hitting Enter.
When the boot prompt is shown, you get the option of displaying the available
kernels (F1) and boot options (F2). If you make no selection
within 15 seconds (either displaying information or using a kernel) then the
LiveDVD will fall back to booting from disk. This allows installations to reboot
and try out their installed environment without the need to remove the CD from
the tray (something well appreciated for remote installations).
Now we mentioned specifying a kernel. On our Installation CDs, we provide
several kernels. The default one is gentoo. Other kernels are for
specific hardware needs and the -nofb variants which disable
Below you'll find a short overview on the available kernels:
You can also provide kernel options. They represent optional settings you can
(de)activate at will.
Hardware options:
Volume/Device Management:
Other options:
The CD will check for "no*" options before "do*" options, so that you can
override any option in the exact order you specify.
Now boot your CD, select a kernel (if you are not happy with the default
gentoo kernel) and boot options. As an example, we show you how
to boot the gentoo kernel, with dopcmcia as kernel
Code Listing 3.4: Booting an Installation CD
boot: gentoo dopcmcia
You will then be greeted with a boot screen and progress bar. If you are
installing Gentoo on a system with a non-US keyboard, make sure you immediately
press Alt-F1 to switch to verbose mode and follow the prompt. If no selection
is made in 10 seconds the default (US keyboard) will be accepted and the boot
process will continue. Once the boot process completes, you will be
automatically logged in to the "Live" Gentoo Linux as "root", the super user.
You should have a root ("#") prompt on the current console and can also switch
to other consoles by pressing Alt-F2, Alt-F3 and Alt-F4. Get back to the one
you started on by pressing Alt-F1.
Now continue with Extra Hardware Configuration.
Extra Hardware Configuration
When the Installation CD boots, it tries to detect all your hardware devices and
loads the appropriate kernel modules to support your hardware. In the
vast majority of cases, it does a very good job. However, in some cases it may
not auto-load the kernel
modules you need. If the PCI auto-detection missed some of your system's
hardware, you will have to load the appropriate kernel modules manually.
In the next example we try to load the 8139too module (support for
certain kinds of network interfaces):
Code Listing 3.5: Loading kernel modules
# modprobe 8139too
Optional: User Accounts
If you plan on giving other people access to your installation
environment or you want to chat using irssi without root privileges (for
security reasons), you need to create the necessary user accounts and change
the root password.
To change the root password, use the passwd utility:
Code Listing 3.6: Changing the root password
# passwd
New password: (Enter your new password)
Re-enter password: (Re-enter your password)
To create a user account, we first enter their credentials, followed by
its password. We use useradd and passwd for these tasks.
In the next example, we create a user called "john".
Code Listing 3.7: Creating a user account
# useradd -m -G users john
# passwd john
New password: (Enter john's password)
Re-enter password: (Re-enter john's password)
You can change your user id from root to the newly created user by using
Code Listing 3.8: Changing user id
# su - john
Optional: Viewing Documentation while Installing
If you want to view the Gentoo Handbook during the installation, make sure you
have created a user account (see Optional: User
Accounts). Then press Alt-F2 to go to a new terminal.
You can view the handbook using links, once you have completed the
Configuring your Network chapter (otherwise you won't be able to go on
the Internet to view the document):
Code Listing 3.9: Viewing the Online Documentation
# links http://www.gentoo.org/doc/en/handbook/handbook-amd64.xml
You can go back to your original terminal by pressing Alt-F1.
Optional: Starting the SSH Daemon
If you want to allow other users to access your computer during the
Gentoo installation (perhaps because those users are going to help you
install Gentoo, or even do it for you), you need to create a user
account for them and perhaps even provide them with your root password
(only do that if you fully trust that user).
To fire up the SSH daemon, execute the following command:
Code Listing 3.10: Starting the SSH daemon
# /etc/init.d/sshd start
If you (or other users) log on to the system, they will get a message that the
host key for this system needs to be confirmed (through what is called a
fingerprint). This is to be expected as it is the first time people log on
to the system.
However, later when your system is set up and you log on to the newly created
system, your SSH client will warn you that the host key has been changed. This
is because you now log on to - for SSH - a different server (namely your freshly
installed Gentoo system rather than the live environment you are on right now).
When you hit that warning, follow the instructions given on the screen then
to replace the host key on the client system.
To be able to use sshd, you first need to set up your networking. Continue with
the chapter on Configuring your Network.
3.a. Automatic Network Detection
Maybe it just works?
If your system is plugged into an Ethernet network with a DHCP server, it is
very likely that your networking configuration has already been set up
automatically for you. If so, you should be able to take advantage of the many
included network-aware commands on the Installation CD such as ssh,
scp, ping, irssi, wget and links, among
If networking has been configured for you, the ifconfig command
should list some network interfaces besides lo, such as eth0:
Code Listing 1.1: ifconfig for a working network configuration
# ifconfig
eth0 Link encap:Ethernet HWaddr 00:50:BA:8F:61:7A
inet addr:192.168.0.2 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::50:ba8f:617a/10 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1498792 errors:0 dropped:0 overruns:0 frame:0
TX packets:1284980 errors:0 dropped:0 overruns:0 carrier:0
collisions:1984 txqueuelen:100
RX bytes:485691215 (463.1 Mb) TX bytes:123951388 (118.2 Mb)
Interrupt:11 Base address:0xe800
The interface name on your system can be quite different from eth0. Recent
installation media might show regular network interfaces names like eno0, ens1
or enp5s0. Just seek the interface in the ifconfig output that has an IP
address related to your local network.
In the remainder of this document, we will assume that the interface is called
Optional: Configure any Proxies
If you access the Internet through a proxy, you might need to set up proxy
information during the installation. It is very easy to define a proxy: you just
need to define a variable which contains the proxy server information.
In most cases, you can just define the variables using the server hostname. As
an example, we assume the proxy is called proxy.gentoo.org and the port
is 8080.
Code Listing 1.2: Defining proxy servers
(If the proxy filters HTTP traffic)
# export http_proxy="http://proxy.gentoo.org:8080"
(If the proxy filters FTP traffic)
# export ftp_proxy="ftp://proxy.gentoo.org:8080"
(If the proxy filters RSYNC traffic)
# export RSYNC_PROXY="proxy.gentoo.org:8080"
If your proxy requires a username and password, you should use the following
syntax for the variable:
Code Listing 1.3: Adding username/password to the proxy variable
Testing the Network
You may want to try pinging your ISP's DNS server (found in
/etc/resolv.conf) and a Web site of your choice, just to make sure
that your packets are reaching the net, DNS name resolution is working
correctly, etc.
Code Listing 1.4: Further network testing
# ping -c 3 www.gentoo.org
If you are now able to use your network, you can skip the rest of this
section and continue with Preparing the
Disks. If not, read on.
3.b. Automatic Network Configuration
If the network doesn't work immediately, some installation media allow you to
use net-setup (for regular or wireless networks), pppoe-setup
(for ADSL-users) or pptp (for PPTP-users - available on x86, amd64,
alpha, ppc and ppc64).
If your installation medium does not contain any of these tools or your network
doesn't function yet, continue with Manual Network
Default: Using net-setup
The simplest way to set up networking if it didn't get configured
automatically is to run the net-setup script:
Code Listing 2.1: Running the net-setup script
# net-setup eth0
net-setup will ask you some questions about your network
environment. When all is done, you should have a working network
connection. Test your network connection as stated before. If the tests
are positive, congratulations! You are now ready to install Gentoo. Skip
the rest of this section and continue with Preparing the Disks.
If your network still doesn't work, continue with Manual
Network Configuration.
Alternative: Using PPP
Assuming you need PPPoE to connect to the internet, the Installation CD (any
version) has made things easy for you by including ppp. Use the provided
pppoe-setup script to configure your connection. You will be prompted for
the ethernet device that is connected to your adsl modem, your username and
password, the IPs of your DNS servers and if you need a basic firewall or not.
Code Listing 2.2: Using ppp
# pppoe-setup
# pppoe-start
If something goes wrong, double-check that you correctly typed your username and
password by looking at /etc/ppp/pap-secrets or
/etc/ppp/chap-secrets and make sure you are using the right
ethernet device. If your ethernet device doesn't exist, you will have to load
the appropriate network modules. In that case you should continue with
Manual Network Configuration as we explain how to
load the appropriate network modules there.
If everything worked, continue with Preparing the
Alternative: Using PPTP
If you need PPTP support, you can use pptpclient which is provided by our
Installation CDs. But first you need to make sure that your configuration is
correct. Edit /etc/ppp/pap-secrets or
/etc/ppp/chap-secrets so it contains the correct username/password
Code Listing 2.3: Editing /etc/ppp/chap-secrets
# nano -w /etc/ppp/chap-secrets
Then adjust /etc/ppp/options.pptp if necessary:
Code Listing 2.4: Editing /etc/ppp/options.pptp
# nano -w /etc/ppp/options.pptp
When all that is done, just run pptp (along with the options you couldn't
set in options.pptp) to connect the server:
Code Listing 2.5: Connection to a dial-in server
# pptp <server ip>
Now continue with Preparing the Disks.
3.c. Manual Network Configuration
Loading the Appropriate Network Modules
When the Installation CD boots, it tries to detect all your hardware devices and
loads the appropriate kernel modules (drivers) to support your hardware. In the
vast majority of cases, it does a very good job. However, in some cases,
it may not auto-load the kernel modules you need.
If net-setup or pppoe-setup failed, then it is possible that
your network card wasn't found immediately. This means you may have to load
the appropriate kernel modules manually.
To find out what kernel modules we provide for networking, use
Code Listing 3.1: Searching for provided modules
# ls /lib/modules/`uname -r`/kernel/drivers/net
If you find a driver for your network card, use modprobe to load
the kernel module:
Code Listing 3.2: Using modprobe to load a kernel module
(As an example, we load the pcnet32 module)
# modprobe pcnet32
To check if your network card is now detected, use ifconfig. A
detected network card would result in something like this (again, eth0 here is
just an example):
Code Listing 3.3: Testing availability of your network card, successful
# ifconfig eth0
eth0 Link encap:Ethernet HWaddr FE:FD:00:00:00:00
BROADCAST NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
If however you receive the following error, the network card is not
Code Listing 3.4: Testing availability of your network card, failed
# ifconfig eth0
eth0: error fetching interface information: Device not found
The available network interface names on your system can be listed through the
/sys file system:
Code Listing 3.5: Viewing the available network interfaces
# ls /sys/class/net
dummy0 eth0 lo sit0 tap0 wlan0
In the above example, 6 interfaces are found. The eth0 one is most likely the
(wired) Ethernet adapter whereas wlan0 is the wireless one.
Assuming that you now have a detected network card, you can
retry net-setup or pppoe-setup again (which should work
now), but for the hardcore people amongst you we explain how to configure your
network manually.
Select one of the following sections based on your network setup:
Using DHCP
DHCP (Dynamic Host Configuration Protocol) makes it possible to
automatically receive networking information (IP address, netmask,
broadcast address, gateway, nameservers etc.). This only works if you
have a DHCP server in your network (or if your provider provides a DHCP
service). To have a network interface receive this information automatically,
use dhcpcd:
Code Listing 3.6: Using dhcpcd
# dhcpcd eth0
Some network admins require that you use the
hostname and domainname provided by the DHCP server.
In that case, use
# dhcpcd -HD eth0
If this works (try pinging some internet server, like Google), then you are all set and
ready to continue. Skip the rest of this section and continue with Preparing the Disks.
Preparing for Wireless Access
Support for the iwconfig command is only available on x86, amd64 and ppc
Installation CDs. You can still get the extensions working otherwise
by following the instructions of the
If you are using a wireless (802.11) card, you may need to configure your
wireless settings before going any further. To see the current wireless settings
on your card, you can use iwconfig. Running iwconfig might show
something like:
Code Listing 3.7: Showing the current wireless settings
# iwconfig eth0
eth0 IEEE 802.11-DS ESSID:"GentooNode"
Mode:Managed Frequency:2.442GHz Access Point: 00:09:5B:11:CC:F2
Bit Rate:11Mb/s Tx-Power=20 dBm Sensitivity=0/65535
Retry limit:16 RTS thr:off Fragment thr:off
Power Management:off
Link Quality:25/10 Signal level:-51 dBm Noise level:-102 dBm
Rx invalid nwid:5901 Rx invalid crypt:0 Rx invalid frag:0 Tx
excessive retries:237 Invalid misc:350282 Missed beacon:84
Some wireless cards may have a device name of wlan0 or ra0 instead
of eth0. Run iwconfig without any command-line parameters to
determine the correct device name.
For most users, there are only two settings that might be important to change,
the ESSID (aka wireless network name) or the WEP key. If the ESSID and Access
Point address listed are already that of your access point and you are not using
WEP, then your wireless is working. If you need to change your ESSID, or add a
WEP key, you can issue the following commands:
If your wireless network is set up with WPA or WPA2, you will need to use
wpa_supplicant. For more information on configuring wireless networking
in Gentoo Linux, please read the Wireless
Networking chapter in the Gentoo Handbook.
Code Listing 3.8: Changing ESSID and/or adding WEP key
(This sets the network name to "GentooNode")
# iwconfig eth0 essid GentooNode
(This sets a hex WEP key)
# iwconfig eth0 key 1234123412341234abcd
(This sets an ASCII key - prefix it with "s:")
# iwconfig eth0 key s:some-password
You can then confirm your wireless settings again by using iwconfig.
Once you have wireless working, you can continue configuring the IP level
networking options as described in the next section (Understanding Network Terminology) or use the
net-setup tool as described previously.
Understanding Network Terminology
If you know your IP address, broadcast address, netmask and nameservers,
then you can skip this subsection and continue with Using ifconfig and route.
If all of the above fails, you will have to configure your network manually.
This is not difficult at all. However, you need to be familiar with some
network terminology, as you will need it to be able to
configure your network to your satisfaction. After reading this, you
will know what a gateway is, what a netmask serves for,
how a broadcast address is formed and why you need
In a network, hosts are identified by their IP address (Internet
Protocol address). Such an address is a combination of four numbers
between 0 and 255. Well, at least that is how we perceive it. In
reality, such an IP address consists of 32 bits (ones and zeros). Let's
view an example:
Code Listing 3.9: Example of an IP address
IP Address (numbers): 192.168.0.2
IP Address (bits): 11000000 10101000 00000000 00000010
-------- -------- -------- --------
192 168 0 2
Such an IP address is unique to a host as far as all accessible networks are
concerned (i.e. every host that you are able to reach must have a unique IP
address). In order to distinguish between hosts inside and outside a
network, the IP address is divided in two parts: the
network part and the host part.
The separation is written down with the netmask, a collection of
ones followed by a collection of zeros. The part of the IP that can be
mapped on the ones is the network-part, the other one is the host-part.
As usual, the netmask can be written down as an IP-address.
Code Listing 3.10: Example of network/host separation
IP-address: 192 168 0 2
11000000 10101000 00000000 00000010
Netmask: 11111111 11111111 11111111 00000000
255 255 255 0
Network Host
In other words, 192.168.0.14 is still part of our example network, but
192.168.1.2 is not.
The broadcast address is an IP-address with the same network-part
as your network, but with only ones as host-part. Every host on your
network listens to this IP address. It is truly meant for broadcasting
Code Listing 3.11: Broadcast address
IP-address: 192 168 0 2
11000000 10101000 00000000 00000010
Broadcast: 11000000 10101000 00000000 11111111
192 168 0 255
Network Host
To be able to surf on the internet, you must know which host shares the
Internet connection. This host is called the gateway. Since it is
a regular host, it has a regular IP address (for instance 192.168.0.1).
We previously stated that every host has its own IP address. To be able
to reach this host by a name (instead of an IP address) you need a
service that translates a name (such as dev.gentoo.org) to an IP
address (such as 18.104.22.168). Such a service is called a name
service. To use such a service, you must define the necessary name
servers in /etc/resolv.conf.
In some cases, your gateway also serves as nameserver. Otherwise you
will have to enter the nameservers provided by your ISP.
To summarise, you will need the following information before continuing:
Using ifconfig and route
Setting up your network consists of three steps. First we assign
ourselves an IP address using ifconfig. Then we set up routing to
the gateway using route. Then we finish up by placing the
nameserver IPs in /etc/resolv.conf.
To assign an IP address, you will need your IP address, broadcast
address and netmask. Then execute the following command, substituting
${IP_ADDR} with your IP address, ${BROADCAST} with your
broadcast address and ${NETMASK} with your netmask:
Code Listing 3.12: Using ifconfig
# ifconfig eth0 ${IP_ADDR} broadcast ${BROADCAST} netmask ${NETMASK} up
Now set up routing using route. Substitute ${GATEWAY} with
your gateway IP address:
Code Listing 3.13: Using route
# route add default gw ${GATEWAY}
Now open /etc/resolv.conf with your favorite editor (in our
example, we use nano):
Code Listing 3.14: Creating /etc/resolv.conf
# nano -w /etc/resolv.conf
Now fill in your nameserver(s) using the following as a template. Make
sure you substitute ${NAMESERVER1} and ${NAMESERVER2} with
the appropriate nameserver addresses:
Code Listing 3.15: /etc/resolv.conf template
nameserver ${NAMESERVER1}
nameserver ${NAMESERVER2}
That's it. Now test your network by pinging some Internet server (like
Google). If this works,
congratulations then. You are now ready to install Gentoo. Continue with Preparing the Disks.
4.a. Introduction to Block Devices
Block Devices
We'll take a good look at disk-oriented aspects of Gentoo Linux
and Linux in general, including Linux filesystems, partitions and block devices.
Then, once you're familiar with the ins and outs of disks and filesystems,
you'll be guided through the process of setting up partitions and filesystems
for your Gentoo Linux installation.
To begin, we'll introduce block devices. The most famous block device is
probably the one that represents the first drive in a Linux system, namely
/dev/sda. SCSI and Serial ATA drives are both labeled
/dev/sd*; even IDE drives are labeled /dev/sd* with
the new libata framework in the kernel. If you're using the old device
framework, then your first IDE drive is /dev/hda.
The block devices above represent an abstract interface to the disk. User
programs can use these block devices to interact with your disk without worrying
about whether your drives are IDE, SCSI or something else. The program can
simply address the storage on the disk as a bunch of contiguous,
randomly-accessible 512-byte blocks.
Although it is theoretically possible to use a full disk to house your Linux
system, this is almost never done in practice. Instead, full disk block devices
are split up in smaller, more manageable block devices. On AMD64
systems, these are called partitions. There are currently two standard
partitioning technologies in use: MBR and GPT.
The MBR (Master Boot Record) setup uses 32-bit identifiers for
the start sector and length of the partitions, and supports three partition
types: primary,
extended and logical. Primary partitions have their information
stored in the master boot record itself - a very small (usually 512 bytes)
location at the very beginning of a disk. Due to this small space, only four
primary partitions are supported (for instance, /dev/sda1 to
To support more partitions, one of the primary partitions can be marked as an
extended partition. This partition can then contain logical partitions
(partitions within a partition).
Each partition is limited to 2 TB in size (due to the 32-bit identifiers).
Also, the MBR setup does not provide any backup-MBR, so if an application
or user overwrites the MBR, all partition information is lost.
The GPT (GUID Partition table) setup uses 64-bit identifiers for
the partitions. The location in which it stores the partition information
is also much bigger than the 512 bytes of an MBR, and there is no limit on
the amount of partitions. Also the size of a partition is bounded by a much
greater limit (almost 8 ZB - yes, zettabytes).
When a system's software interface between the operating system and firmware
is UEFI (instead of BIOS), GPT is almost mandatory as compatibility issues will
arise with MBR here.
GPT also has the advantage that it has a backup GPT at the end of the disk,
which can be used to recover damage of the primary GPT at the beginning. GPT
also carries CRC32 checksums to detect errors in the header and partition
So, GPT or MBR?
From the description above, one might think that using GPT should always be the
recommended approach. But there are a few caveats with this.
Using GPT on a BIOS-based computer works, but you cannot dual-boot then with a
Microsoft Windows operating system. The reason is that Microsoft Windows will
boot in EFI mode if it detects a GPT partition label.
Some buggy BIOSes or EFIs configured to boot in BIOS/CSM/legacy mode might also
have problems with booting from GPT labeled disks. If that is the case, you
might be able to work around the problem by adding the boot/active flag on the
protective MBR partition which has to be done through fdisk
(parted understands the GPT tables and would not show the protective
MBR partition):
Code Listing 1.1: Enabling boot flag on protective MBR
# fdisk /dev/sda
WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk
doesn't support GPT. Use GNU Parted.
Command (m for help): a
Partition number (1-4): 1
Command (m for help): w
Advanced Storage
The AMD64 Installation CDs provide support for LVM2.
LVM2 increases the flexibility offered by your partitioning setup.
During the installation instructions, we will focus on "regular" partitions,
but it is still good to know LVM2 is supported as well.
4.b. Designing a Partitioning Scheme
Default Partitioning Scheme
If you are not interested in drawing up a partitioning scheme for your system,
you can use the partitioning scheme we use throughout this book.
If you are interested in knowing how big a partition should be, or even how
many partitions you need, read on. Otherwise continue now with partitioning
your disk by reading Default: Using parted to Partition
your Disk (or Alternative: Using fdisk to Partition
your Disk). Both are partitioning tools, fdisk is well known and stable,
parted is a bit more recent but supports partitions larger than
How Many and How Big?
The number of partitions is highly dependent on your environment. For instance,
if you have lots of users, you will most likely want to have your
/home separate as it increases security and makes backups easier.
If you are installing Gentoo to perform as a mailserver, your
/var should be separate as all mails are stored inside
/var. A good choice of filesystem will then maximise your
performance. Gameservers will have a separate /opt as most gaming
servers are installed there. The reason is similar for /home:
security and backups. You will definitely want to keep /usr big:
not only will it contain the majority of applications, the Portage tree alone
takes around 500 Mbyte excluding the various sources that are stored in it.
As you can see, it very much depends on what you want to achieve. Separate
partitions or volumes have the following advantages:
However, multiple partitions have disadvantages as well. If not configured
properly, you will have a system with lots of free space on one partition and
none on another. Another nuisance is that separate partitions - especially
for important mountpoints like /usr or /var - often
require the administrator to boot with an initramfs to mount the partition
before other boot scripts start. This isn't always the case though, so your
results may vary.
There is also a 15-partition limit for SCSI and SATA unless you use GPT
What about swap space?
There is no perfect value for the swap partition. The purpose of swap space is
to provide disk storage to the kernel when internal memory (RAM) is under
pressure. A swap space allows for the kernel to move memory pages that are
not likely to be accessed soon to disk (swap or page-out), freeing memory. Of
course, if that memory is suddenly needed, these pages need to be put back in
memory (page-in) which will take a while (as disks are very slow compared to
internal memory).
If you are not going to run memory intensive applications or you have lots of
memory available, then you probably do not need much swap space. However, swap
space is also used to store the entire memory in case of hibernation. If you
plan on using hibernation, you will need a bigger swap space, often at least
the amount of memory you have in your system.
What is the BIOS boot partition?
A BIOS boot partition is a very small (1 to 2 MB) partition in which
bootloaders like GRUB2 can put additional data that doesn't fit in the
allocated storage (a few hundred bytes in case of MBR) and cannot place
Such partitions are not always necessary, but considering the low space
consumption and the difficulties we would have with documenting the plethora
of partitioning differences otherwise, it is recommended to create it in
either case.
For completeness, we can say that the BIOS boot partition is needed when
GPT partition layout is used with GRUB2, or when the MBR partition layout
is used with GRUB2 when the first partition starts earlier than the 1 MB
location on the disk.
4.c. Default: Using parted to Partition your Disk
In this chapter, we guide you through the creation of the example partition
layout mentioned earlier in the instructions, but repeat here again for
your convenience:
Change your partition layout according to your own preference.
Viewing the Current Partition Layout
The parted application offers a simple interface for partitioning your
disks and supports very large partitions (more than 2 TB). Fire up
parted on your disk (in our example, we use /dev/sda).
We will ask parted to use optimum alignment:
Code Listing 3.1: Starting parted
# parted -a optimal /dev/sda
GNU Parted 2.3
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
Alignment means that partitions are started on well-known boundaries within
the disk, ensuring that operations on the disk from the operating system level
(retrieve pages from the disk) use the least amount of internal disk
operations. Misaligned partitions might require the disk to fetch two pages
instead of one even if the operating system asked for a single page.
To find out about all options supported by parted, type help and
press return.
Setting the GPT Label
Most disks on x86/amd64 are prepared using an msdos label. Using
parted, we can put a GPT label on the disk using mklabel gpt:
Changing the partition type will remove all partitions from your disk. All data
on the disk will be lost.
Code Listing 3.2: Setting the GPT label
(parted) mklabel gpt
If you want the disk to have MBR layout, use mklabel msdos.
Removing all Partitions
If this isn't done yet (for instance through the mklabel operation
earlier, or because the disk is a freshly formatted one), we will first
remove all existing partitions from the disk. Type print to view the
current partitions, and rm <number> where <number> is the
partition you want to remove.
Code Listing 3.3: Removing a partition from the disk
(parted) rm 2
Do the same for all other partitions that you don't need. However, make sure you
do not make any mistakes here - parted executes the changes immediately
(unlike fdisk which stages them, allowing a user to "undo" his changes
before saving or exiting fdisk).
Creating the Partitions
Now let's create the partitions we mentioned earlier. Creating partitions with
parted isn't very difficult - all we need to do is inform parted
about the following settings:
First, we tell parted that the size unit we work with is megabytes
(actually mebibytes, abbreviated as MiB which is the "standard" notation, but
we will use MB in the text throughout as it is much more common):
Code Listing 3.4: Using MiB units
(parted) unit mib
Now create a 2 MB partition that will be used by the GRUB2 bootloader later.
We use the mkpart command for this, and inform parted to start
from 1 MB and end at 3 MB (creating a partition of 2 MB in size).
Code Listing 3.5: Creating a 2 MB partition
(parted) mkpart primary 1 3
(parted) name 1 grub
(parted) set 1 bios_grub on
(parted) print
Model: Virtio Block Device (virtblk)
Disk /dev/sda: 20480MiB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 1.00MiB 3.00MiB 2.00MiB grub bios_grub
Do the same for the boot partition (128 MB), swap partition (in the example,
512 MB) and the root partition that spans the remaining disk (for which the
end location is marked as -1, meaning the end of the disk minus one MB,
which is the farthest a partition can go).
Code Listing 3.6: Creating other partitions
(parted) mkpart primary 3 131
(parted) name 2 boot
(parted) mkpart primary 131 643
(parted) name 3 swap
(parted) mkpart primary 643 -1
(parted) name 4 rootfs
The end result looks like so:
Code Listing 3.7: Viewing the current partition layout
(parted) print
Model: Virtio Block Device (virtblk)
Disk /dev/sda: 20480MiB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 1.00MiB 3.00MiB 2.00MiB grub bios_grub
2 3.00MiB 131MiB 128MiB boot
3 131MiB 643MiB 512MiB swap
4 643MiB 20479MiB 19836MiB rootfs
When you are satisfied, use the quit command to exit parted.
4.d. Alternative: Using fdisk to Partition your Disk
If your environment will deal with partitions larger than 2 TB, please
use the Default: Using parted to Partition your Disk
instructions instead. fdisk is not able to deal with larger
partitions. Fdisk will also use the MBR partition layout. Alternative fdisk
applications, like gdisk (which Gentoo provides through the gptfdisk package)
exist that do support GPT, but might not be included on the Gentoo installation
The following parts explain how to create the example partition layout
using fdisk. The example partition layout was mentioned earlier:
fdisk is a popular and powerful tool to split your disk into partitions.
Fire up fdisk on your disk (in our example, we use
Code Listing 4.1: Starting fdisk
# fdisk /dev/sda
Once in fdisk, you'll be greeted with a prompt that looks like this:
Code Listing 4.2: fdisk prompt
Command (m for help):
Type p to display your disk's current partition configuration:
Code Listing 4.3: An example partition configuration
Command (m for help): p
Disk /dev/sda: 240 heads, 63 sectors, 2184 cylinders
Units = cylinders of 15120 * 512 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 14 105808+ 83 Linux
/dev/sda2 15 49 264600 82 Linux swap
/dev/sda3 50 70 158760 83 Linux
/dev/sda4 71 2184 15981840 5 Extended
/dev/sda5 71 209 1050808+ 83 Linux
/dev/sda6 210 348 1050808+ 83 Linux
/dev/sda7 349 626 2101648+ 83 Linux
/dev/sda8 627 904 2101648+ 83 Linux
/dev/sda9 905 2184 9676768+ 83 Linux
Command (m for help):
This particular disk is configured to house seven Linux filesystems (each with
a corresponding partition listed as "Linux") as well as a swap partition
(listed as "Linux swap").
We will first remove all existing partitions from the disk. Type d to
delete a partition. For instance, to delete an existing /dev/sda1:
Code Listing 4.4: Deleting a partition
Command (m for help): d
Partition number (1-4): 1
The partition has been scheduled for deletion. It will no longer show up if you
type p, but it will not be erased until your changes have been saved. If
you made a mistake and want to abort without saving your changes, type q
immediately and hit enter and your partition will not be deleted.
Now, assuming that you do indeed want to wipe out all the partitions on your
system, repeatedly type p to print out a partition listing and then type
d and the number of the partition to delete it. Eventually, you'll end
up with a partition table with nothing in it:
Code Listing 4.5: An empty partition table
Disk /dev/sda: 30.0 GB, 30005821440 bytes
240 heads, 63 sectors/track, 3876 cylinders
Units = cylinders of 15120 * 512 = 7741440 bytes
Device Boot Start End Blocks Id System
Command (m for help):
Now that the in-memory partition table is empty, we're ready to create the
partitions. We will use a default partitioning scheme as discussed previously.
Of course, don't follow these instructions to the letter if you don't want the
same partitioning scheme!
Creating the BIOS Boot Partition
We first create a very small BIOS boot partition. Type n to create a new
partition, then p to select a primary partition, followed by 1 to
select the first primary partition. When prompted for the first sector, make sure
it starts from 2048 (which is needed for the boot loader) and hit enter. When
prompted for the last sector, type +2M to create a partition 2 Mbyte
in size:
The start from sector 2048 is a fail-safe in case the boot loader does not
detect this partition as being available for its use.
Code Listing 4.6: Creating the BIOS boot partition
Command (m for help): n
Command action
e extended
p primary partition (1-4)
Partition number (1-4): 1
First sector (64-10486533532, default 64): 2048
Last sector, +sectors +size{M,K,G} (4096-10486533532, default 10486533532): +2M
Mark the partition for EFI purposes:
Code Listing 4.7: Marking the partition for EFI purposes
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): ef
Changed system type of partition 1 to ef (EFI (FAT-12/16/32))
Creating the Boot Partition
We now create a small boot partition. Type n to create a new partition,
then p to select a primary partition, followed by 2 to select the
second primary partition. When prompted for the first sector, accept the default
by hitting enter. When prompted for the last sector, type +128M to create a
partition 128 Mbyte in size:
Code Listing 4.8: Creating the boot partition
Command (m for help): n
Command action
e extended
p primary partition (1-4)
Partition number (1-4): 2
First sector (5198-10486533532, default 5198): (Hit enter)
Last sector, +sectors +size{M,K,G} (4096-10486533532, default 10486533532): +128M
Now, when you type p, you should see the following partition printout:
Code Listing 4.9: Created boot partition
Command (m for help): p
Disk /dev/sda: 30.0 GB, 30005821440 bytes
240 heads, 63 sectors/track, 3876 cylinders
Units = cylinders of 15120 * 512 = 7741440 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 3 5198+ ef EFI (FAT-12/16/32)
/dev/sda2 3 14 105808+ 83 Linux
We need to make this partition bootable. Type a to toggle the bootable
flag on a partition and select 2. If you press p again, you will
notice that an * is placed in the "Boot" column.
Creating the Swap Partition
Let's now create the swap partition. To do this, type n to create a new
partition, then p to tell fdisk that you want a primary partition. Then
type 3 to create the third primary partition, /dev/sda3 in
our case. When prompted for the first sector, hit enter. When prompted for
the last sector, type +512M (or any other size you need for the swap
space) to create a partition 512MB in size.
After you've done this, type t to set the partition type, 3 to select
the partition you just created and then type in 82 to set the partition
type to "Linux Swap".
Creating the Root Partition
Finally, let's create the root partition. To do this, type n to create a
new partition, then p to tell fdisk that you want a primary partition.
Then type 4 to create the fourth primary partition, /dev/sda4
in our case. When prompted for the first sector, hit enter. When prompted for
the last sector, hit enter to create a partition that takes up the rest of the
remaining space on your disk. After completing these steps, typing p
should display a partition table that looks similar to this:
Code Listing 4.10: Partition listing after creating the root partition
Command (m for help): p
Disk /dev/sda: 30.0 GB, 30005821440 bytes
240 heads, 63 sectors/track, 3876 cylinders
Units = cylinders of 15120 * 512 = 7741440 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 3 5198+ ef EFI (FAT-12/16/32)
/dev/sda2 * 3 14 105808+ 83 Linux
/dev/sda3 15 81 506520 82 Linux swap
/dev/sda4 82 3876 28690200 83 Linux
Saving the Partition Layout
To save the partition layout and exit fdisk, type w.
Code Listing 4.11: Save and exit fdisk
Command (m for help): w
Now that your partitions are created, you can continue with Creating Filesystems.
4.e. Creating Filesystems
Now that your partitions are created, it is time to place a filesystem on them.
If you don't care about what filesystem to choose and are happy with what we use
as default in this handbook, continue with Applying a Filesystem to a Partition.
Otherwise read on to learn about the available filesystems...
Several filesystems are available. Some of them are found stable on the amd64
architecture, others aren't. The following filesystems are found to be stable:
ext2, ext3, ext4 and XFS. JFS and ReiserFS may work but need more testing. If
you're really adventurous you can try the other filesystems.
ext2 is the tried and true Linux filesystem but doesn't have metadata
journaling, which means that routine ext2 filesystem checks at startup time can
be quite time-consuming. There is now quite a selection of newer-generation
journaled filesystems that can be checked for consistency very quickly and are
thus generally preferred over their non-journaled counterparts. Journaled
filesystems prevent long delays when you boot your system and your filesystem
happens to be in an inconsistent state.
ext3 is the journaled version of the ext2 filesystem, providing metadata
journaling for fast recovery in addition to other enhanced journaling modes like
full data and ordered data journaling. It uses an HTree index that enables high
performance in almost all situations. In short, ext3 is a very good and
reliable filesystem.
ext4 is a filesystem created as a fork of ext3 bringing new features,
performance improvements and removal of size limits with moderate changes
to the on-disk format. It can span volumes up to 1 EB and with maximum file
size of 16 TB. Instead of the classic ext2/3 bitmap block allocation ext4 uses
which improve large file performance and reduce fragmentation. Ext4 also provides
more sophisticated block allocation algorithms (delayed allocation and multiblock
allocation) giving the filesystem driver more ways to optimise the layout of data
on the disk. The ext4 filesystem is a compromise between production-grade code
stability and the desire to introduce extensions to an almost decade old
filesystem. Ext4 is the recommended all-purpose all-platform filesystem.
If you intend to install Gentoo on a small partition (less than 8GB), then you'll
need to tell ext2, ext3 or ext4 (if available) to reserve enough inodes when you
create the filesystem. The mke2fs application uses the "bytes-per-inode"
setting to calculate how many inodes a file system should have. By running
mke2fs -T small /dev/<device> (ext2) or mke2fs -j -T small
/dev/<device> (ext3/ext4) the number of inodes will generally
quadruple for a given file system as its "bytes-per-inode" reduces from
one every 16kB to one every 4kB. You can tune this even further by using
mke2fs -i <ratio> /dev/<device> (ext2) or mke2fs -j
-i <ratio> /dev/<device> (ext3/ext4).
JFS is IBM's high-performance journaling filesystem. JFS is a light,
fast and reliable B+tree-based filesystem with good performance in various
ReiserFS is a B+tree-based journaled filesystem that has good overall
performance, especially when dealing with many tiny files at the cost of more
CPU cycles. ReiserFS appears to be less maintained than other filesystems.
XFS is a filesystem with metadata journaling which comes with a robust
feature-set and is optimized for scalability. XFS seems to be less forgiving to
various hardware problems.
Applying a Filesystem to a Partition
To create a filesystem on a partition or volume, there are tools available for
each possible filesystem:
For instance, to have the boot partition (/dev/sda2 in our
example) in ext2 and the root partition (/dev/sda4 in our example)
in ext4 (as in our example), you would use:
Code Listing 5.1: Applying a filesystem on a partition
# mkfs.ext2 /dev/sda2
# mkfs.ext4 /dev/sda4
Now create the filesystems on your newly created partitions (or logical
Activating the Swap Partition
mkswap is the command that is used to initialize swap partitions:
Code Listing 5.2: Creating a Swap signature
# mkswap /dev/sda3
To activate the swap partition, use swapon:
Code Listing 5.3: Activating the swap partition
# swapon /dev/sda3
Create and activate the swap with the commands mentioned above.
4.f. Mounting
Now that your partitions are initialized and are housing a filesystem, it is
time to mount those partitions. Use the mount command. Don't forget to
create the necessary mount directories for every partition you created. As an
example we mount the root and boot partition:
Code Listing 6.1: Mounting partitions
# mount /dev/sda4 /mnt/gentoo
# mkdir /mnt/gentoo/boot
# mount /dev/sda2 /mnt/gentoo/boot
If you want your /tmp to reside on a separate partition, be sure to
change its permissions after mounting: chmod 1777 /mnt/gentoo/tmp. This
also holds for /var/tmp.
We will also have to mount the proc filesystem (a virtual interface with the
kernel) on /proc. But first we will need to place our files on the partitions.
Continue with Installing the Gentoo
Installation Files.
5.a. Installing a Stage Tarball
Setting the Date/Time Right
Before you continue you need to check your date/time and update it. A
misconfigured clock may lead to strange results in the future!
To verify the current date/time, run date:
Code Listing 1.1: Verifying the date/time
# date
Fri Mar 29 16:21:18 UTC 2005
If the date/time displayed is wrong, update it using the date
MMDDhhmmYYYY syntax (Month, Day, hour, minute
and Year). At this stage, you should use UTC time. You will be able to
define your timezone later on. For instance, to set the date to March 29th,
16:21 in the year 2005:
Code Listing 1.2: Setting the UTC date/time
# date 032916212005
Making your Choice
The next step you need to perform is to install the stage3 tarball onto
your system. The command uname -m can be used to help you decide which
stage file to download as it provides information on the architecture of your
5.b. Using a Stage from the Internet
Downloading the Stage Tarball
Go to the Gentoo mountpoint at which you mounted your filesystems
(most likely /mnt/gentoo):
Code Listing 2.1: Going to the Gentoo mountpoint
# cd /mnt/gentoo
Depending on your installation medium, you have a couple of tools available to
download a stage. If you have links available, then you can immediately
surf to the Gentoo mirrorlist and
choose a mirror close to you: type links http://www.gentoo.org/main/en/mirrors.xml
and press enter.
If you don't have links available you should have lynx at your
disposal. If you need to go through a proxy, export the http_proxy and
ftp_proxy variables:
Code Listing 2.2: Setting proxy information for lynx
# export http_proxy="http://proxy.server.com:port"
# export ftp_proxy="http://proxy.server.com:port"
We will now assume that you have links at your disposal.
Select a mirror closeby. Usually HTTP mirrors suffice, but other protocols are
available as well. Move to the releases/amd64/autobuilds/
directory. There you should see all available stage files for your architecture
(they might be stored within subdirectories named after the individual
subarchitectures). Select one and press D to download. When you're
finished, press Q to quit the browser.
Code Listing 2.3: Surfing to the mirror listing with links
# links http://www.gentoo.org/main/en/mirrors.xml
(If you need proxy support with links:)
# links -http-proxy proxy.server.com:8080 http://www.gentoo.org/main/en/mirrors.xml
Make sure you download a stage3 tarball - installations using a stage1
or stage2 tarball are not supported anymore (and in most cases, you will not
find stage1 or stage2 tarballs on our regular download mirrors anyway).
If you want to check the integrity of the downloaded stage tarball, use
openssl and compare the output with the checksums provided on the
mirror. The digests files provide several checksums, each taken with a different
algorithm. The recommended ones are SHA512 and Whirlpool.
Code Listing 2.4: Calculating the integrity checksum of a stage tarball
## Calculating the SHA512 checksum
# openssl dgst -r -sha512 stage3-amd64-<release>.tar.bz2
# sha512sum stage3-amd64-<release>.tar.bz2
## Calculating the Whirlpool checksum
# openssl dgst -r -whirlpool stage3-amd64-<release>.tar.bz2
Then compare the output of these commands with the value registered in the
.DIGESTS(.asc) files that can be found on the mirrors as well. The values need to
match, otherwise the downloaded file might be corrupt (or the digests file is).
Just like with the ISO file, you can also verify the cryptographic signature of
the .DIGESTS.asc file using gpg to make sure the checksums
have not been tampered with:
Code Listing 2.5: Validating the checksums using gpg
# gpg --verify stage3-amd64-<release>.tar.bz2.DIGESTS.asc
Unpacking the Stage Tarball
Now unpack your downloaded stage onto your system. We use tar to proceed
as it is the easiest method:
Code Listing 2.6: Unpacking the stage
# tar xvjpf stage3-*.tar.bz2
Make sure that you use the same options (xvjpf). The x stands for
Extract, the v for Verbose to see what happens during the
extraction process (optional), the j for Decompress with bzip2,
the p for Preserve permissions and the f to denote that we
want to extract a file, not standard input.
Now that the stage is installed, continue with Configuring the Compile Options.
5.c. Configuring the Compile Options
To optimize Gentoo, you can set a couple of variables which impact Portage
behaviour. All those variables can be set as environment variables (using
export) but that isn't permanent. To keep your settings, Portage provides
you with /etc/portage/make.conf, a configuration file for Portage.
It is this file we will edit now.
A commented listing of all possible variables can be found in
/mnt/gentoo/usr/share/portage/config/make.conf.example. For a
successful Gentoo installation you'll only need to set the variables which are
mentioned beneath.
Fire up your favorite editor (in this guide we use nano) so we can alter
the optimization variables we will discuss hereafter.
Code Listing 3.1: Opening /etc/portage/make.conf
# nano -w /mnt/gentoo/etc/portage/make.conf
As you probably noticed, the make.conf.example file is
structured in a generic way: commented lines start with "#", other lines define
variables using the VARIABLE="content" syntax. The make.conf
file uses the same syntax. Several of those variables are discussed next.
CFLAGS and CXXFLAGS
The CFLAGS and CXXFLAGS variables define the optimization flags
for the gcc C and C++ compiler respectively. Although we define those
generally here, you will only have maximum performance if you optimize these
flags for each program separately. The reason for this is because every program
is different.
In make.conf you should define the optimization flags you think
will make your system the most responsive generally. Don't place
experimental settings in this variable; too much optimization can make
programs behave bad (crash, or even worse, malfunction).
We will not explain all possible optimization options. If you want to know
them all, read the GNU
Online Manual(s) or the gcc info page (info gcc -- only
works on a working Linux system). The make.conf.example file
itself also contains lots of examples and information; don't forget to read it
A first setting is the -march= or -mtune= flag, which specifies
the name of the target architecture. Possible options are described in the
make.conf.example file (as comments). A commonly used value is
native as that tells the compiler to select the target architecture of
the current system (the one you are installing on).
A second one is the -O flag (that is a capital O, not a zero),
which specifies the gcc optimization
class flag. Possible classes are s (for size-optimized),
0 (zero - for no optimizations), 1, 2 or even 3 for more
speed-optimization flags (every class has the same flags as the one before, plus
some extras). -O2 is the recommended default. -O3 is known to
cause problems when used system-wide, so we recommend that you stick to
Another popular optimization flag is -pipe (use pipes rather than
temporary files for communication between the various stages of compilation).
It has no impact on the generated code, but uses more memory. On systems with
low memory, gcc might get killed. In that case, do not use this flag.
Using -fomit-frame-pointer (which doesn't keep the frame pointer in a
register for functions that don't need one) might have serious repercussions on
the debugging of applications.
When you define the CFLAGS and CXXFLAGS, you should combine
several optimization flags. The default values contained in the stage3 archive
you unpacked should be good enough. The following one is just an example:
Code Listing 3.2: Defining the CFLAGS and CXXFLAGS variable
CFLAGS="-march=k8 -O2 -pipe" # Intel EM64T users should use -march=core2
# Use the same settings for both variables
You may also want to view the Compilation Optimization Guide for
more information on how the various compilation options can affect your system.
With MAKEOPTS you define how many parallel compilations should occur when
you install a package. A good choice is the number of CPUs (or CPU cores) in
your system plus one, but this guideline isn't always perfect.
Code Listing 3.3: MAKEOPTS for a regular, 1-CPU system
Ready, Set, Go!
Update your /mnt/gentoo/etc/portage/make.conf to your own preference
and save (nano users would hit Ctrl-X). You are now ready to continue
with 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
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 !
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 rsync.us.gentoo.org, 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
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
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
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:
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/amd64/13.0 *
[2] default/linux/amd64/13.0/desktop
[3] default/linux/amd64/13.0/desktop/gnome
[4] default/linux/amd64/13.0/desktop/kde
As you can see, there are also desktop subprofiles available for some
architectures. Running eselect profile list will show all available
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
If you want to have a pure 64-bit environment, with no 32-bit applications or
libraries, you should use a non-multilib profile:
Code Listing 2.7: Switching to a non-multilib profile
# eselect profile list
Available profile symlink targets:
[1] default/linux/amd64/13.0 *
[2] default/linux/amd64/13.0/desktop
[3] default/linux/amd64/13.0/desktop/gnome
[4] default/linux/amd64/13.0/desktop/kde
[5] default/linux/amd64/13.0/no-multilib
(Choose the no-multilib profile)
# eselect profile set 5
(Verify the change)
# eselect profile list
Available profile symlink targets:
[1] default/linux/amd64/13.0
[2] default/linux/amd64/13.0/desktop
[3] default/linux/amd64/13.0/desktop/gnome
[4] default/linux/amd64/13.0/desktop/kde
[5] default/linux/amd64/13.0/no-multilib *
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
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
Code Listing 2.8: 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 2.9: Opening /etc/portage/make.conf
# nano -w /etc/portage/make.conf
Code Listing 2.10: 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
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
You can select your desired locales in the list given by running locale -a.
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 generates 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:
[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.
7.a. Installing the Sources
Choosing a Kernel
The core around which all distributions are built is the Linux kernel. It is the
layer between the user programs and your system hardware. Gentoo provides its
users several possible kernel sources. A full listing with description is
available at the Gentoo Kernel
For AMD64-based systems we have gentoo-sources
(kernel source patched for extra features).
Choose your kernel source and install it using emerge.
Code Listing 1.1: Installing a kernel source
# emerge gentoo-sources
When you take a look in /usr/src you should see a symlink called
linux pointing to your kernel source. In this case, the installed
kernel source points to gentoo-sources-3.4.9.
Your version may be different, so keep this in mind.
Code Listing 1.2: Viewing the kernel source symlink
# ls -l /usr/src/linux
lrwxrwxrwx 1 root root 12 Oct 13 11:04 /usr/src/linux -> linux-3.4.9
Now it is time to configure and compile your kernel source. You can use
genkernel for this, which will build a generic kernel as used by the
Installation CD. We explain the "manual" configuration first though, as it is
the best way to optimize your environment.
If you want to manually configure your kernel, continue now with Default: Manual Configuration. If you want to use
genkernel you should read Alternative: Using
genkernel instead.
7.b. Default: Manual Configuration
Manually configuring a kernel is often seen as the most difficult procedure a
Linux user ever has to perform. Nothing is less true -- after configuring a
couple of kernels you don't even remember that it was difficult ;)
However, one thing is true: you must know your system when you start
configuring a kernel manually. Most information can be gathered by emerging
pciutils (emerge pciutils) which contains lspci. You will now
be able to use lspci within the chrooted environment. You may safely
ignore any pcilib warnings (like pcilib: cannot open
/sys/bus/pci/devices) that lspci throws out. Alternatively, you can run
lspci from a non-chrooted environment. The results are the same.
You can also run lsmod to see what kernel modules the Installation CD
uses (it might provide you with a nice hint on what to enable).
Now go to your kernel source directory and execute make menuconfig. This
will fire up an ncurses-based configuration menu.
Code Listing 2.1: Invoking menuconfig
# cd /usr/src/linux
# make menuconfig
You will be greeted with several configuration sections. We'll first list some
options you must activate (otherwise Gentoo will not function, or not function
properly without additional tweaks).
Activating Required Options
Make sure that every driver that is vital to the booting of your system (such as
SCSI controller, ...) is compiled in the kernel and not as a module,
otherwise your system will not be able to boot completely.
We shall then select the exact processor type. The x86_64 kernel maintainer
strongly recommends users enable MCE features so that they are able to be
notified of any hardware problems. On x86_64, these errors are not printed to
dmesg like on other architectures, but to /dev/mcelog. This
requires the app-admin/mcelog package. Make sure you select IA32
Emulation if you want to be able to run 32-bit programs. Gentoo will install a
multilib system (mixed 32-bit/64-bit computing) by default, so this option is
If you plan to use a non-multilib profile (for a pure 64-bit system), then you
don't have to select IA32 Emulation support. However, you'll also need to follow
the instructions for
switching to a non-multilib
profile, as well as choosing the correct bootloader.
Code Listing 2.2: Selecting processor type and features
Processor type and features --->
[ ] Machine Check / overheating reporting
[ ] Intel MCE Features
[ ] AMD MCE Features
Processor family (AMD-Opteron/Athlon64) --->
( ) Opteron/Athlon64/Hammer/K8
( ) Intel P4 / older Netburst based Xeon
( ) Core 2/newer Xeon
( ) Intel Atom
( ) Generic-x86-64
Executable file formats / Emulations --->
[*] IA32 Emulation
Next select Maintain a devtmpfs file system to mount at /dev so that
critical device files are already available early in the boot process.
Code Listing 2.3: Enabling devtmpfs support
Device Drivers --->
Generic Driver Options --->
[*] Maintain a devtmpfs filesystem to mount at /dev
[ ] Automount devtmpfs at /dev, after the kernel mounted the rootfs
Now go to File Systems and select support for the filesystems you use.
Don't compile the file system you use for the root filesystem as module,
otherwise your Gentoo system will not be able to mount your partition. Also
select Virtual memory and /proc file system.
Code Listing 2.4: Selecting necessary file systems
File systems --->
(Select one or more of the following options as needed by your system)
<*> Second extended fs support
<*> Ext3 journalling file system support
<*> The Extended 4 (ext4) filesystem
<*> Reiserfs support
<*> JFS filesystem support
<*> XFS filesystem support
Pseudo Filesystems --->
[*] /proc file system support
[*] Virtual memory file system support (former shm fs)
(Enable GPT partition label support if you used that previously)
-*- Enable the block layer --->
Partition Types --->
[*] Advanced partition selection
[*] EFI GUID Partition support
If you are using PPPoE to connect to the Internet or you are using a dial-up
modem, you will need the following options in the kernel:
Code Listing 2.5: Selecting PPPoE necessary drivers
Device Drivers --->
Network device support --->
<*> PPP (point-to-point protocol) support
<*> PPP support for async serial ports
<*> PPP support for sync tty ports
The two compression options won't harm but are not definitely needed, neither
does the PPP over Ethernet option, that might only be used by ppp
when configured to do kernel mode PPPoE.
If you require it, don't forget to include support in the kernel for your
ethernet card.
If you have a multi-CPU Opteron or a multi-core (e.g. AMD64 X2) system, you
should activate "Symmetric multi-processing support":
Code Listing 2.6: Activating SMP support
Processor type and features --->
[*] Symmetric multi-processing support
In multi-core systems, each core counts as one processor.
If you use USB Input Devices (like Keyboard or Mouse) don't forget to enable
those as well:
Code Listing 2.7: Activating USB Support for Input Devices
Device Drivers --->
[*] HID Devices --->
<*> USB Human Interface Device (full HID) support
Compiling and Installing
Now that your kernel is configured, it is time to compile and install it. Exit
the configuration and start the compilation process:
Code Listing 2.8: Compiling the kernel
# make && make modules_install
When the kernel has finished compiling, copy the kernel image to
/boot. Use whatever name you feel is appropriate for your kernel
choice and remember it as you will need it later on when you configure your
bootloader. Remember to replace kernel-3.4.9-gentoo with the
name and version of your kernel.
Code Listing 2.9: Installing the kernel
# cp arch/x86_64/boot/bzImage /boot/kernel-3.4.9-gentoo
(Optional) Building an Initramfs
If you use a specific partition layout where important file system locations
(like /usr or /var) are on separate partitions, then
you will need to setup an initramfs so that this partition can be mounted before
it is needed.
Without an initramfs, you risk that the system will not boot up properly as the
tools that are responsible for mounting the file systems need information that
resides on those file systems. An initramfs will pull in the necessary files
into an archive which is used right after the kernel boots, but before the
control is handed over to the init tool. Scripts on the initramfs will
then make sure that the partitions are properly mounted before the system
continues booting.
To install an initramfs, install genkernel first, then have it
generate an initramfs for you.
Code Listing 2.10: Building an initramfs
# emerge genkernel
# genkernel --install initramfs
If you need specific support in the initramfs, such as lvm or raid, add in the
appropriate options to genkernel. See genkernel --help for more
information, or the next example which enables support for LVM and software raid
Code Listing 2.11: Building an initramfs with support for LVM and software raid
# genkernel --lvm --mdadm --install initramfs
The initramfs will be stored in /boot. You can find the file by
simply listing the files starting with initramfs:
Code Listing 2.12: Checking the initramfs file name
# ls /boot/initramfs*
Now continue with Kernel Modules.
7.c. Alternative: Using genkernel
If you are reading this section, you have chosen to use our genkernel
script to configure your kernel for you.
Now that your kernel source tree is installed, it's now time to compile your
kernel by using our genkernel script to automatically build a kernel for
you. genkernel works by configuring a kernel nearly identically to the
way our Installation CD kernel is configured. This means that when you use
genkernel to build your kernel, your system will generally detect all
your hardware at boot-time, just like our Installation CD does. Because
genkernel doesn't require any manual kernel configuration, it is an ideal
solution for those users who may not be comfortable compiling their own kernels.
Now, let's see how to use genkernel. First, emerge the genkernel ebuild:
Code Listing 3.1: Emerging genkernel
# emerge genkernel
Now, compile your kernel sources by running genkernel all. Be aware
though, as genkernel compiles a kernel that supports almost all
hardware, this compilation will take quite a while to finish!
Note that, if your boot partition doesn't use ext2 or ext3 as filesystem you
might need to manually configure your kernel using genkernel --menuconfig
all and add support for your filesystem in the kernel (i.e.
not as a module). Users of LVM2 will probably want to add --lvm
as an argument as well.
Code Listing 3.2: Running genkernel
# genkernel all
Once genkernel completes, a kernel, full set of modules and
initial ram disk (initramfs) will be created. We will use the kernel
and initrd when configuring a boot loader later in this document. Write
down the names of the kernel and initrd as you will need it when writing
the bootloader configuration file. The initrd will be started immediately after
booting to perform hardware autodetection (just like on the Installation CD)
before your "real" system starts up.
Code Listing 3.3: Checking the created kernel image name and initrd
# ls /boot/kernel* /boot/initramfs*
7.d. Kernel Modules
Configuring the Modules
You should list the modules you want automatically loaded in
/etc/conf.d/modules. You can add extra options to
the modules too if you want.
To view all available modules, run the following find command. Don't
forget to substitute "<kernel version>" with the version of the kernel you
just compiled:
Code Listing 4.1: Viewing all available modules
# find /lib/modules/<kernel version>/ -type f -iname '*.o' -or -iname '*.ko' | less
For instance, to automatically load the 3c59x.ko module (which is the
driver for a specific 3Com network card family), edit the
/etc/conf.d/modules file and enter the module name in it.
Code Listing 4.2: Editing /etc/conf.d/modules
# nano -w /etc/conf.d/modules
Continue the installation with Configuring your
8.a. Filesystem Information
What is fstab?
Under Linux, all partitions used by the system must be listed in
/etc/fstab. This file contains the mount points of those partitions
(where they are seen in the file system structure), how they should be mounted
and with what special options (automatically or not, whether users can mount
them or not, etc.)
Creating /etc/fstab
/etc/fstab uses a special syntax. Every line consists of six
fields, separated by whitespace (space(s), tabs or a mixture). Each field has
its own meaning:
The default /etc/fstab file provided by Gentoo is not a valid
fstab file. You have to create your own /etc/fstab.
Code Listing 1.1: Opening /etc/fstab
# nano -w /etc/fstab
In the remainder of the text, we use the default /dev/sd* block
device files as partition. You can also opt to use the symbolic links in the
/dev/disk/byid or /dev/disk/by-uuid. These names are
not likely to change, whereas the default block device files naming depends on
a number of factors (such as how and in what order the disks are attached to
your system). However, if you do not intend to fiddle with the disk ordering,
you can continue with the default block device files safely.
Let us take a look at how we write down the options for the /boot
partition. This is just an example, if you didn't or couldn't create a
/boot, don't copy it.
In our default AMD64 partitioning example, /boot is
usually the /dev/sda2 partition, with ext2 as
filesystem. It needs to be checked during boot, so we would write down:
Code Listing 1.2: An example /boot line for /etc/fstab
/dev/sda2 /boot ext2 defaults 0 2
Some users don't want their /boot partition to be mounted
automatically to improve their system's security. Those people should
substitute defaults with noauto. This does mean that you need to
manually mount this partition every time you want to use it.
Add the rules that match your partitioning scheme and append rules for
your CD-ROM drive(s), and of course, if you have other partitions or drives,
for those too.
Now use the example below to create your /etc/fstab:
Code Listing 1.3: A full /etc/fstab example
/dev/sda2 /boot ext2 defaults,noatime 0 2
/dev/sda3 none swap sw 0 0
/dev/sda4 / ext4 noatime 0 1
/dev/cdrom /mnt/cdrom auto noauto,user 0 0
auto makes mount guess for the filesystem (recommended for
removable media as they can be created with one of many filesystems) and
user makes it possible for non-root users to mount the CD.
To improve performance, most users would want to add the noatime
mount option, which results in a faster system since access times
aren't registered (you don't need those generally anyway). This is also
recommended for solid state drive (SSD) users, who should also enable
the discard mount option (ext4 and btrfs only for now) which
makes the TRIM command work.
Double-check your /etc/fstab, save and quit to continue.
8.b. Networking Information
Host name, Domainname, etc
One of the choices the user has to make is name his/her PC. This seems to be
quite easy, but lots of users are having difficulties finding the
appropriate name for their Linux-pc. To speed things up, know that any name you
choose can be changed afterwards. For all we care, you can just call your system
tux and domain homenetwork.
Code Listing 2.1: Setting the host name
# nano -w /etc/conf.d/hostname
(Set the hostname variable to your host name)
Second, if you need a domainname, set it in /etc/conf.d/net.
You only need a domain if your ISP or network administrator says so, or if you
have a DNS server but not a DHCP server. You don't need to worry about DNS or
domainnames if your networking is setup for DHCP.
The /etc/conf.d/net file does not exist by default, so you might
need to create it.
Code Listing 2.2: Setting the domainname
# nano -w /etc/conf.d/net
(Set the dns_domain variable to your domain name)
If you choose not to set a domainname, you can get rid of the "This is
hostname.(none)" messages at your login screen by editing
/etc/issue. Just delete the string .\O from that file.
If you have a NIS domain (if you don't know what that is, then you don't have
one), you need to define that one too:
Code Listing 2.3: Setting the NIS domainname
# nano -w /etc/conf.d/net
(Set the nis_domain variable to your NIS domain name)
For more information on configuring DNS and NIS, please read the examples
provided in /usr/share/doc/netifrc-*/net.example.bz2 which
can be read using bzless. Also, you may want to emerge openresolv
to help manage your DNS/NIS setup.
Configuring your Network
Before you get that "Hey, we've had that already"-feeling, you should remember
that the networking you set up in the beginning of the Gentoo installation was
just for the installation. Right now you are going to configure networking for
your Gentoo system permanently.
More detailed information about networking, including advanced topics like
bonding, bridging, 802.1Q VLANs or wireless networking is covered in the Gentoo Network Configuration section.
All networking information is gathered in /etc/conf.d/net. It uses
a straightforward yet not intuitive syntax if you don't know how to set up
networking manually. But don't fear, we'll explain everything. A fully
commented example that covers many different configurations is available in
DHCP is used by default. For DHCP to work, you will need to install a DHCP
client. This is described later in Installing Necessary System
Tools. Do not forget to install a DHCP client.
If you need to configure your network connection either because you need
specific DHCP options or because you do not use DHCP at all, open
/etc/conf.d/net with your favorite editor (nano is used in
this example):
Code Listing 2.4: Opening /etc/conf.d/net for editing
# nano -w /etc/conf.d/net
To enter your own IP address, netmask and gateway, you need
to set both config_eth0 and routes_eth0:
This assumes that your network interface will be called eth0. This is, however,
very system dependent. It is recommended to assume that the interface is named
the same as the interface name when booted from the installation media if
the installation media is sufficiently recent. More information can be found in
Network Interface Naming.
Code Listing 2.5: Manually setting IP information for eth0
config_eth0="192.168.0.2 netmask 255.255.255.0 brd 192.168.0.255"
routes_eth0="default via 192.168.0.1"
To use DHCP, define config_eth0:
Code Listing 2.6: Automatically obtaining an IP address for eth0
Please read /usr/share/doc/netifrc-*/net.example.bz2 for a
list of all available options. Be sure to also read your DHCP client manpage if
you need to set specific DHCP options.
If you have several network interfaces repeat the above steps for
config_eth1, config_eth2, etc.
Now save the configuration and exit to continue.
Automatically Start Networking at Boot
To have your network interfaces activated at boot, you need to add them to the
default runlevel.
Code Listing 2.7: Adding net.eth0 to the default runlevel
# cd /etc/init.d
# ln -s net.lo net.eth0
# rc-update add net.eth0 default
If you have several network interfaces, you need to create the appropriate
net.* files just like you did with net.eth0.
If you later find out the assumption about the network interface name (which we
currently document as eth0) was wrong, then
Writing Down Network Information
You now need to inform Linux about your network. This is defined in
/etc/hosts and helps in resolving host names to IP addresses for
hosts that aren't resolved by your nameserver. You need to define your system.
You may also want to define other systems on your network if you don't want to
set up your own internal DNS system.
Code Listing 2.8: Opening /etc/hosts
# nano -w /etc/hosts
Code Listing 2.9: Filling in the networking information
(This defines the current system)
127.0.0.1 tux.homenetwork tux localhost
(Define extra systems on your network,
they need to have a static IP to be defined this way.)
192.168.0.5 jenny.homenetwork jenny
192.168.0.6 benny.homenetwork benny
Save and exit the editor to continue.
If you don't have PCMCIA, you can now continue with System Information. PCMCIA-users should read the
following topic on PCMCIA.
Optional: Get PCMCIA Working
PCMCIA users should first install the pcmciautils package.
Code Listing 2.10: Installing pcmciautils
# emerge pcmciautils
8.c. System Information
Root Password
First we set the root password by typing:
Code Listing 3.1: Setting the root password
# passwd
System Information
Gentoo uses /etc/rc.conf to configure the services, startup,
and shutdown of your system. Open up /etc/rc.conf and enjoy all
the comments in the file.
Code Listing 3.2: Configuring services
# nano -w /etc/rc.conf
When you're finished configuring these two files, save them and exit.
Gentoo uses /etc/conf.d/keymaps to handle keyboard configuration.
Edit it to configure your keyboard.
Code Listing 3.3: Opening /etc/conf.d/keymaps
# nano -w /etc/conf.d/keymaps
Take special care with the keymap variable. If you select the wrong
keymap, you will get weird results when typing on your keyboard.
When you're finished configuring /etc/conf.d/keymaps, save and
Gentoo uses /etc/conf.d/hwclock to set clock options. Edit it
according to your needs.
Code Listing 3.4: Opening /etc/conf.d/hwclock
# nano -w /etc/conf.d/hwclock
If your hardware clock is not using UTC, you need to add clock="local"
to the file. Otherwise you will notice some clock skew.
When you're finished configuring /etc/conf.d/hwclock, save and
9.a. System Logger
Some tools are missing from the stage3 archive because several packages
provide the same functionality. It is now up to you to choose which ones you
want to install.
The first tool you need to decide on has to provide logging facilities for your
system. Unix and Linux have an excellent history of logging capabilities -- if
you want you can log everything that happens on your system in logfiles. This
happens through the system logger.
Gentoo offers several system loggers to choose from. There are sysklogd,
which is the traditional set of system logging daemons, syslog-ng, an
advanced system logger, and metalog which is a highly-configurable
system logger. Others might be available through Portage as well - our number of
available packages increases on a daily basis.
If you plan on using sysklogd or syslog-ng you might want to
install logrotate afterwards as those system loggers don't provide any
rotation mechanism for the log files.
To install the system logger of your choice, emerge it and have it added
to the default runlevel using rc-update. The following example installs
syslog-ng. Of course substitute with your system logger:
Code Listing 1.1: Installing a system logger
# emerge syslog-ng
# rc-update add syslog-ng default
9.b. Optional: Cron Daemon
Next is the cron daemon. Although it is optional and not required for your
system, it is wise to install one. But what is a cron daemon? A cron daemon
executes scheduled commands. It is very handy if you need to execute some
command regularly (for instance daily, weekly or monthly).
Gentoo offers several possible cron daemons, including bcron,
dcron, fcron and cronie. Installing one of them
is similar to installing a system logger. However, dcron and
fcron require an extra configuration command, namely crontab
/etc/crontab. If you don't know what to choose, use cronie.
Code Listing 2.1: Installing a cron daemon
# emerge cronie
# rc-update add cronie default
(Only if you have chosen dcron or fcron) # crontab /etc/crontab
9.c. Optional: File Indexing
If you want to index your system's files so you are able to quickly
locate them using the locate tool, you need to install
Code Listing 3.1: Installing mlocate
# emerge mlocate
9.d. Optional: Remote Access
If you need to access your system remotely after installation, don't forget to
add sshd to the default runlevel:
Code Listing 4.1: Adding sshd to the default runlevel
# rc-update add sshd default
If you need serial console access (which is possible in case of remote servers),
you might need to uncomment the serial console section in
/etc/inittab if it has not been done already automatically.
Code Listing 4.2: Editing /etc/inittab
# nano -w /etc/inittab
The following excerpt shows the uncommented section:
Code Listing 4.3: Uncommenting serial consoles in inittab
s0:12345:respawn:/sbin/agetty 9600 ttyS0 vt100
s1:12345:respawn:/sbin/agetty 9600 ttyS1 vt100
9.e. File System Tools
Depending on what file systems you are using, you need to install the necessary
file system utilities (for checking the filesystem integrity, creating
additional file systems etc.). Please note that tools for managing ext2, ext3 or
ext4 filesystems (e2fsprogs) are already installed as a part of the system.
The following table lists the tools you need to install if you use a certain
file system:
9.f. Networking Tools
If you don't require any additional networking-related tools (such as ppp or a
dhcp client) continue with Configuring the
Optional: Installing a DHCP Client
If you require Gentoo to automatically obtain an IP address for your network
interface(s), you need to install dhcpcd (or any other DHCP client --
see Modular Networking for a list of
available DHCP clients). If you don't do this now, you might not be able to
connect to the internet after the installation.
Code Listing 6.1: Installing dhcpcd
# emerge dhcpcd
Optional: Installing a PPPoE Client
If you need ppp to connect to the net, you need to install it.
Code Listing 6.2: Installing ppp
# emerge ppp
Now continue with Configuring the
10.a. Making your Choice
Now that your kernel is configured and compiled and the necessary system
configuration files are filled in correctly, it is time to install a
program that will fire up your kernel when you start the system. Such a
program is called a bootloader.
For AMD64, Gentoo Linux provides GRUB2, LILO and
GRUB Legacy.
But before we install the bootloader, we inform you how to configure
framebuffer (assuming you want it of course). With framebuffer you can run the
Linux command line with (limited) graphical features (such as using the nice
bootsplash image Gentoo provides).
Optional: Framebuffer
If you have configured your kernel with framebuffer support (or you used
genkernel default kernel configuration), you can activate it by adding a
a video statement to your bootloader configuration file.
First of all, you need to know your framebuffer device. You should have used
uvesafb as the VESA driver.
The video statement controls framebuffer display options. It needs to be
given the framebuffer driver followed by the control statements you wish to
enable. All variables are listed in
/usr/src/linux/Documentation/fb/uvesafb.txt. The most-used options
The result could be something like
video=uvesafb:mtrr:3,ywrap,1024x768-32@85. Write this setting down; you
will need it shortly.
Now continue by installing GRUB, GRUB2 or LILO.
10.b. Default: Using GRUB2
Installing GRUB2
GRUB2 is provided through the sys-boot/grub package.
Code Listing 2.1: Installing GRUB2
# emerge sys-boot/grub
The GRUB2 software is now installed on the system, but not activated yet.
Configuring GRUB2
First, let us install the necessary GRUB2 files in /boot/grub.
Assuming the first disk (the one where the system boots from) is
/dev/sda, the following command will do this for us:
Code Listing 2.2: Installing the GRUB2 files in /boot/grub
# grub2-install /dev/sda
Next, we can generate the GRUB2 configuration based on the user configuration
specified in the /etc/default/grub file and
/etc/grub.d scripts. In most cases, no configuration is needed
by users as GRUB2 will automatically detect which kernel to boot (the highest
one available in /boot) and what the root file system is.
To generate the final GRUB2 configuration, run the grub2-mkconfig
Code Listing 2.3: Generating GRUB2 configuration
# grub2-mkconfig -o /boot/grub/grub.cfg
Generating grub.cfg ...
Found linux image: /boot/kernel-3.4.9-gentoo
Found initrd image: /boot/initramfs-genkernel-amd64-3.4.9-gentoo
The output of the command must mention that at least one Linux image is
found, as those are needed to boot the system. If you use initramfs or used
genkernel to build the kernel, the correct initrd image should be
detected as well. If this is not the case, go to /boot and check
the contents using the ls command. If the files are indeed missing, go
back to the kernel configuration and installation instructions.
10.c. Alternative: Using LILO
Installing LILO
LILO, the LInuxLOader, is the tried and true workhorse of Linux
bootloaders. However, it lacks some features that GRUB has (which is
also the reason why GRUB is currently gaining popularity). The reason
why LILO is still used is that, on some systems, GRUB doesn't work and
LILO does. Of course, it is also used because some people know LILO and
want to stick with it. Either way, Gentoo supports both, and apparently
you have chosen to use LILO.
Installing LILO is a breeze; just use emerge.
Code Listing 3.1: Installing LILO
# emerge lilo
Configuring LILO
To configure LILO, you must create /etc/lilo.conf. Fire up
your favorite editor (in this handbook we use nano for
consistency) and create the file.
Code Listing 3.2: Creating /etc/lilo.conf
# nano -w /etc/lilo.conf
Some sections ago we have asked you to remember the kernel-image name
you have created. In the next example lilo.conf we use the
example partitioning scheme.
Make sure you use your kernel image filename and, if appropriate,
your initrd image filename.
If your root filesystem is JFS, you must add a append="ro"
line after each boot item since JFS needs to replay its log before it allows
read-write mounting.
Code Listing 3.3: Example /etc/lilo.conf
boot=/dev/sda # Install LILO in the MBR
prompt # Give the user the chance to select another section
timeout=50 # Wait 5 (five) seconds before booting the default section
default=gentoo # When the timeout has passed, boot the "gentoo" section
label=gentoo # Name we give to this section
read-only # Start with a read-only root. Do not alter!
root=/dev/sda4 # Location of the root filesystem
label=gentoo.rescue # Name we give to this section
read-only # Start with a read-only root. Do not alter!
root=/dev/sda4 # Location of the root filesystem
append="init=/bin/bb" # Launch the Gentoo static rescue shell
# The next two lines are only if you dualboot with a Windows system.
# In this example, Windows is hosted on /dev/sda6.
If you use a different partitioning scheme and/or kernel image, adjust
If, while building the Linux kernel, you opted to include an initramfs to boot
from, then you will need to change the configuration by referring to this
initramfs file and telling the initramfs where your real root device is at:
Code Listing 3.4: LILO snippet for initramfs-enabled kernel builds
If you need to pass any additional options to the kernel, add an
append statement to the section. As an example, we add the
video statement to enable framebuffer:
Code Listing 3.5: Using append to add kernel options
If you're using a 2.6.7 or higher kernel and you jumpered your harddrive
because the BIOS can't handle large harddrives you'll need to append
sda=stroke. Replace sda with the device that requires this option.
genkernel users should know that their kernels use the same boot options
as is used for the Installation CD. For instance, if you have SCSI devices, you
should add doscsi as kernel option.
Now save the file and exit. To finish up, you have to run /sbin/lilo so
LILO can apply the /etc/lilo.conf to your system (i.e. install
itself on the disk). Keep in mind that you'll also have to run
/sbin/lilo every time you install a new kernel or make any changes to
the menu.
Code Listing 3.6: Finishing the LILO installation
# /sbin/lilo
If you have more questions regarding LILO, please consult its wikipedia page.
You can now continue with Rebooting the System.
10.d. Alternative: Using GRUB Legacy
What is Legacy?
GRUB has been reworked and a new release dubbed GRUB2 is made available. The new
GRUB2 codebase is quite different from the current GRUB, which is why this GRUB
version is now dubbed as "GRUB Legacy".
Understanding GRUB's terminology
The most critical part of understanding GRUB is getting comfortable with how
GRUB refers to hard drives and partitions. Your Linux partition
/dev/sda2 will most likely be called (hd0,1) under
GRUB. Notice the parentheses around the hd0,1 - they are
Hard drives count from zero rather than "a" and partitions start at zero
rather than one. Be aware too that with the hd devices, only hard drives are
counted, not atapi-ide devices such as cdrom players and burners. Also, the
same construct is used with SCSI drives. (Normally they get higher numbers
than IDE drives except when the BIOS is configured to boot from SCSI devices.)
When you ask the BIOS to boot from a different hard disk (for instance your
primary slave), that harddisk is seen as hd0.
Assuming you have a hard drive on /dev/sda and two more on
/dev/sdb and /dev/sdc, /dev/sdb7 gets
translated to (hd1,6). It might sound tricky and tricky it is
indeed, but as we will see, GRUB offers a tab completion mechanism that comes
handy for those of you having a lot of hard drives and partitions and who are a
little lost in the GRUB numbering scheme.
Having gotten the feel for that, it is time to install GRUB.
Installing GRUB
To install GRUB Legacy, let's first emerge it:
If you are using a non-multilib profile and still intend to use the
GRUB Legacy (instead of GRUB2), you should not emerge
grub:0, but instead you should emerge grub-static (only possible
if you have enabled IA-32 emulation).
Code Listing 4.1: Installing GRUB
# emerge sys-boot/grub:0
Although GRUB is now installed, we still need to write up a
configuration file for it and place GRUB in our MBR so that GRUB automatically
boots your newly created kernel. Create /boot/grub/grub.conf with
nano (or, if applicable, another editor):
Code Listing 4.2: Creating /boot/grub/grub.conf
# nano -w /boot/grub/grub.conf
Now we are going to write up a grub.conf. Make
sure you use your kernel image filename and, if appropriate, your
initrd image filename.
Grub assigns device designations from the BIOS. If you change your BIOS
settings, your device letters and numbers may change, too. For example, if you
change your device boot order, you may need to change your grub configuration.
If your root filesystem is JFS, you must add " ro" to the kernel
line since JFS needs to replay its log before it allows read-write mounting.
If dualboot with Windows is used, the partitioning example used in this
book will not be sufficient (our example uses all four primary partitions
for Linux, whereas at least one would need to be extended if Windows is
installed on a logical partition). Please proceed with caution and consider
the listing to be an example that needs to be modified to suit your own needs.
Code Listing 4.3: Example grub.conf
# Which listing to boot as default. 0 is the first, 1 the second etc.
default 0
# How many seconds to wait before the default listing is booted.
timeout 30
# Nice, fat splash-image to spice things up :)
# Comment out if you don't have a graphics card installed
title Gentoo Linux 3.4.9
# Partition where the kernel image (or operating system) is located
root (hd0,1)
kernel /boot/kernel-3.4.9-gentoo root=/dev/sda4
title Gentoo Linux 3.4.9 (rescue)
# Partition where the kernel image (or operating system) is located
root (hd0,1)
kernel /boot/kernel-3.4.9-gentoo root=/dev/sda4 init=/bin/bb
# The next four lines are only if you dualboot with a Windows system.
# In this case, Windows is hosted on /dev/sda6.
title Windows XP
rootnoverify (hd0,5)
chainloader +1
Code Listing 4.4: GRUB snippet for initramfs-enabled kernel builds
title Gentoo Linux 3.4.9
root (hd0,1)
kernel /boot/3.4.9 real_root=/dev/sda4
initrd /boot/initramfs-genkernel-amd64-3.4.9-gentoo
If you used a different partitioning scheme and/or kernel image, adjust
accordingly. However, make sure that anything that follows a GRUB-device (such
as (hd0,1)) is relative to the mountpoint, not the root. In other
words, (hd0,1)/grub/splash.xpm.gz is in reality
/boot/grub/splash.xpm.gz since (hd0,1) is
Besides, if you chose to use a different partitioning scheme and did not put
/boot in a separate partition, the /boot prefix used
in the above code samples is really required. If you followed our
suggested partitioning plan, the /boot prefix it not required, but
a boot symlink makes it work. In short, the above examples should
work whether you defined a separate /boot partition or not.
If you need to pass any additional options to the kernel, simply add them to the
end of the kernel command. We're already passing one option
(root=/dev/sda4 or real_root=/dev/sda4), but you can pass others
as well, such as the video statement for framebuffer as we discussed
If your bootloader configuration file contains the real_root parameter, use the
real_rootflags parameter to set root filesystem mount options.
Now save the grub.conf file and exit. You still need to install
GRUB in the MBR (Master Boot Record) so that GRUB is automatically executed when
you boot your system.
The GRUB developers recommend the use of grub-install. However, if for
some reason grub-install fails to work correctly you still have the
option to manually install GRUB.
Continue with Default: Setting up GRUB using
grub-install or Alternative: Setting up
GRUB using manual instructions.
Default: Setting up GRUB using grub-install
To install GRUB you will need to issue the grub-install command.
However, grub-install won't work off-the-shelf since we are inside a
chrooted environment. We need to create /etc/mtab which lists all
mounted filesystems. Fortunately, there is an easy way to accomplish this -
just copy over /proc/mounts to /etc/mtab, excluding
the rootfs line if you haven't created a separate boot partition. The
following command will work in both cases:
Code Listing 4.5: Creating /etc/mtab
# grep -v rootfs /proc/mounts > /etc/mtab
When using Linux virtio disks, we need to tell grub where to find the disks as
the grub-install command will otherwise fail. This is done by adding the
device definition to the device.map file:
Code Listing 4.6: Adding the virtio disk to the device map table
# echo "(hd0) /dev/vda" >> /boot/grub/device.map
Now we can install GRUB using grub-install:
Code Listing 4.7: Running grub-install
# grub-install --no-floppy /dev/sda
If you have more questions regarding GRUB, please consult the GRUB FAQ, the GRUB Wiki, or read info
grub in your terminal.
Continue with Rebooting the System.
Alternative: Setting up GRUB using manual instructions
To start configuring GRUB, you type in grub. You'll be presented
with the grub> grub command-line prompt. Now, you need to type
in the right commands to install the GRUB boot record onto your hard drive.
Code Listing 4.8: Starting the GRUB shell
# grub --no-floppy
If your system does not have any floppy drives, add the --no-floppy
option to the above command to prevent grub from probing the (non-existing)
floppy drives.
In the example configuration we want to install GRUB so that it reads its
information from the boot partition /dev/sda2, and
installs the GRUB boot record on the hard drive's MBR (master boot record) so
that the first thing we see when we turn on the computer is the GRUB prompt. Of
course, if you haven't followed the example configuration during the
installation, change the commands accordingly.
The tab completion mechanism of GRUB can be used from within GRUB.
For instance, if you type in "root (" followed by a TAB, you will
be presented with a list of devices (such as hd0). If you
type in "root (hd0," followed by a TAB, you will receive a list
of available partitions to choose from (such as hd0,1).
By using the tab completion, setting up GRUB should be not that hard.
Now go on, configure GRUB, shall we? :-)
Code Listing 4.9: Installing GRUB in the MBR
grub> root (hd0,1) (Specify where your /boot partition resides)
grub> setup (hd0) (Install GRUB in the MBR)
grub> quit (Exit the GRUB shell)
If you want to install GRUB in a certain partition instead of the MBR,
you have to alter the setup command so it points to the right
partition. For instance, if you want GRUB installed in
/dev/sda4, then the command becomes setup (hd0,3).
Few users however want to do this.
10.e. Rebooting the System
Exit the chrooted environment and unmount all mounted partitions. Then type in
that one magical command you have been waiting for: reboot.
Code Listing 5.1: Unmounting all partitions and rebooting
# exit
cdimage ~# cd
cdimage ~# umount -l /mnt/gentoo/dev{/shm,/pts,}
cdimage ~# umount -l /mnt/gentoo{/boot,/proc,}
cdimage ~# reboot
Of course, don't forget to remove the bootable CD, otherwise the CD will be
booted again instead of your new Gentoo system.
Once rebooted in your Gentoo installation, finish up with Finalizing your Gentoo Installation.
11.a. User Administration
Adding a User for Daily Use
Working as root on a Unix/Linux system is dangerous and should be avoided
as much as possible. Therefore it is strongly recommended to add a user
for day-to-day use.
The groups the user is member of define what activities the user can perform.
The following table lists a number of important groups you might wish to use:
For instance, to create a user called john who is member of the
wheel, users and audio groups, log in as root first
(only root can create users) and run useradd:
Code Listing 1.1: Adding a user for day-to-day use
Login: root
Password: (Your root password)
# useradd -m -G users,wheel,audio -s /bin/bash john
# passwd john
Password: (Enter the password for john)
Re-enter password: (Re-enter the password to verify)
If a user ever needs to perform some task as root, they can use su -
to temporarily receive root privileges. Another way is to use the sudo
package which is, if correctly configured, very secure.
11.b. Disk Cleanup
Removing tarballs
Now that you've finished installing Gentoo and rebooted, if everything has gone
well, you can remove the downloaded stage3 tarball from
your hard disk. Remember that they were downloaded to your /
Code Listing 2.1: Removing the stage3 tarball
# rm /stage3-*.tar.bz2*
12.a. Documentation
Congratulations! You now have a working Gentoo system. But where to go from
here? What are your options now? What to explore first? Gentoo provides its
users with lots of possibilities, and therefore lots of documented (and less
documented) features.
You should definitely take a look at the next part of the Gentoo Handbook
entitled Working with Gentoo which explains
how to keep your software up to date, how to install more software, what USE
flags are, how the Gentoo init system works, etc.
We also have an official Gentoo
Wiki where additional, community-provided documentation can be found.
The documentation team also offers a
You might want to use our localization guide to make your
system feel more at home.
We also have a Gentoo Security Handbook
which is worth reading.
12.b. Gentoo Online
You are of course always welcome on our Gentoo Forums or on one of our many
Gentoo IRC channels.
We also have several mailing lists open to all
our users. Information on how to join is contained in that page.
We'll shut up now and let you enjoy your installation. :)
1.a. Welcome to Portage
Portage is probably Gentoo's most notable innovation in software management.
With its high flexibility and enormous amount of features it is frequently seen
as the best software management tool available for Linux.
Portage is completely written in Python
and Bash and therefore fully
visible to the users as both are scripting languages.
Most users will work with Portage through the emerge tool. This chapter
is not meant to duplicate the information available from the emerge man page.
For a complete rundown of emerge's options, please consult the man page:
Code Listing 1.1: Reading the emerge man page
$ man emerge
1.b. The Portage Tree
When we talk about packages, we often mean software titles that are available to
the Gentoo users through the Portage tree. The Portage tree is a collection of
ebuilds, files that contain all information Portage needs to maintain
software (install, search, query, ...). These ebuilds reside in
/usr/portage by default.
Whenever you ask Portage to perform some action regarding software titles, it
will use the ebuilds on your system as a base. It is therefore important that
you regularly update the ebuilds on your system so Portage knows about new
software, security updates, etc.
Updating the Portage Tree
The Portage tree is usually updated with rsync, a fast incremental file transfer
utility. Updating is fairly simple as the emerge command provides a
front-end for rsync:
Code Listing 2.1: Updating the Portage tree
# emerge --sync
If you are unable to rsync due to firewall restrictions you can still update
your Portage tree by using our daily generated Portage tree snapshots. The
emerge-webrsync tool automatically fetches and installs the latest
snapshot on your system:
Code Listing 2.2: Running emerge-webrsync
An additional advantage of using emerge-webrsync is that it allows the
administrator to only pull in portage tree snapshots that are signed by the
Gentoo release engineering GPG key. More information on this can be found
in the Portage Features section on
Fetching Validated Portage Tree
1.c. Maintaining Software
Searching for Software
To search through the Portage tree after software titles, you can use
emerge built-in search capabilities. By default, emerge --search
returns the names of packages whose title matches (either fully or partially)
the given search term.
For instance, to search for all packages who have "pdf" in their name:
Code Listing 3.1: Searching for pdf-named packages
$ emerge --search pdf
If you want to search through the descriptions as well you can use the
--searchdesc (or -S) switch:
Code Listing 3.2: Searching for pdf-related packages
$ emerge --searchdesc pdf
When you take a look at the output, you'll notice that it gives you a lot of
information. The fields are clearly labelled so we won't go further into their
Code Listing 3.3: Example 'emerge --search' output
* net-print/cups-pdf
Latest version available: 1.5.2
Latest version installed: [ Not Installed ]
Size of downloaded files: 15 kB
Homepage: http://cip.physik.uni-wuerzburg.de/~vrbehr/cups-pdf/
Description: Provides a virtual printer for CUPS to produce PDF files.
License: GPL-2
Installing Software
Once you've found a software title to your liking, you can easily install it
with emerge: just add the package name. For instance, to install
Code Listing 3.4: Installing gnumeric
# emerge gnumeric
Since many applications depend on each other, any attempt to install a certain
software package might result in the installation of several dependencies as
well. Don't worry, Portage handles dependencies well. If you want to find out
what Portage would install when you ask it to install a certain package,
add the --pretend switch. For instance:
Code Listing 3.5: Pretend to install gnumeric
# emerge --pretend gnumeric
When you ask Portage to install a package, it will download the necessary source
code from the internet (if necessary) and store it by default in
/usr/portage/distfiles. After this it will unpack, compile and
install the package. If you want Portage to only download the sources without
installing them, add the --fetchonly option to the emerge command:
Code Listing 3.6: Download the sourcecode for gnumeric
# emerge --fetchonly gnumeric
Finding Installed Package Documentation
Many packages come with their own documentation. Sometimes, the doc USE
flag determines whether the package documentation should be installed or not.
You can check the existence of a doc USE flag with the emerge -vp
<package name> command.
Code Listing 3.7: Checking the existence of a doc USE flag
(alsa-lib is just an example, of course.)
# emerge -vp alsa-lib
[ebuild N ] media-libs/alsa-lib-1.0.14_rc1 -debug +doc 698 kB
The best way of enabling the doc USE flag is doing it on a per-package
basis via /etc/portage/package.use, so that you get documentation
only for packages that you are interested in. Enabling this flag globally is
known to cause problems with circular dependencies. For more information, please
read the USE Flags chapter.
Once the package installed, its documentation is generally found in a
subdirectory named after the package under the /usr/share/doc
directory. You can also list all installed files with the equery tool
which is part of the app-portage/gentoolkit package.
Code Listing 3.8: Locating package documentation
# ls -l /usr/share/doc/alsa-lib-1.0.14_rc1
total 28
-rw-r--r-- 1 root root 669 May 17 21:54 ChangeLog.gz
-rw-r--r-- 1 root root 9373 May 17 21:54 COPYING.gz
drwxr-xr-x 2 root root 8560 May 17 21:54 html
-rw-r--r-- 1 root root 196 May 17 21:54 TODO.gz
(Alternatively, use equery to locate interesting files:)
# equery files alsa-lib | less
* Contents of media-libs/alsa-lib-1.0.14_rc1:
(Output truncated)
Removing Software
When you want to remove a software package from your system, use emerge
--unmerge. This will tell Portage to remove all files installed by that
package from your system except the configuration files of that
application if you have altered those after the installation. Leaving the
configuration files allows you to continue working with the package if you ever
decide to install it again.
However, a big warning applies: Portage will not check if
the package you want to remove is required by another package. It will however
warn you when you want to remove an important package that breaks your system
if you unmerge it.
Code Listing 3.9: Removing gnumeric from the system
# emerge --unmerge gnumeric
When you remove a package from your system, the dependencies of that package
that were installed automatically when you installed the software are left. To
have Portage locate all dependencies that can now be removed, use
emerge's --depclean functionality. We will talk about this later
Updating your System
To keep your system in perfect shape (and not to mention install the latest
security updates) you need to update your system regularly. Since Portage only
checks the ebuilds in your Portage tree you first have to update your Portage
tree. When your Portage tree is updated, you can update your system with
emerge --update @world. In the next example, we'll also use the
--ask switch which will tell Portage to display the list of packages it
wants to upgrade and ask you if you want to continue:
Code Listing 3.10: Updating your system
# emerge --update --ask @world
Portage will then search for newer version of the applications you have
installed. However, it will only verify the versions for the applications you
have explicitly installed (the applications listed in
/var/lib/portage/world) - it does not thoroughly check their
dependencies. If you want to update the dependencies of those packages as well,
add the --deep argument:
Code Listing 3.11: Updating your system with dependencies
# emerge --update --deep @world
Still, this doesn't mean all packages: some packages on your system are
needed during the compile and build process of packages, but once that package
is installed, these dependencies are no longer required. Portage calls those
build dependencies. To include those in an update cycle, add
Code Listing 3.12: Updating your entire system
# emerge --update --deep --with-bdeps=y @world
Since security updates also happen in packages you have not explicitly installed
on your system (but that are pulled in as dependencies of other programs), it
is recommended to run this command once in a while.
If you have altered any of your USE flags
lately you might want to add --newuse as well. Portage will then verify
if the change requires the installation of new packages or recompilation of
existing ones:
Code Listing 3.13: Performing a full update
# emerge --update --deep --with-bdeps=y --newuse @world
Some packages in the Portage tree don't have any real content but are used to
install a collection of packages. For instance, the kde-meta package will
install a complete KDE environment on your system by pulling in various
KDE-related packages as dependencies.
If you ever want to remove such a package from your system, running emerge
--unmerge on the package won't have much effect as the dependencies remain
on the system.
Portage has the functionality to remove orphaned dependencies as well, but since
the availability of software is dynamically dependent you first need to update
your entire system fully, including the new changes you applied when changing
USE flags. After this you can run emerge --depclean to remove the
orphaned dependencies. When this is done, you need to rebuild the applications
that were dynamically linked to the now-removed software titles but don't
require them anymore.
All this is handled with the following three commands:
Code Listing 3.14: Removing orphaned dependencies
# emerge --update --deep --newuse @world
# emerge --depclean
# revdep-rebuild
revdep-rebuild is provided by the gentoolkit package; don't forget
to emerge it first:
Code Listing 3.15: Installing the gentoolkit package
# emerge gentoolkit
1.d. Licenses
Beginning with Portage version 2.1.7, you can accept or reject software
installation based on its license. All packages in the tree contain a
LICENSE entry in their ebuilds. Running emerge --search
packagename will tell you the package's license.
By default, Portage permits all licenses, except End User License Agreements
(EULAs) that require reading and signing an acceptance agreement.
The variable that controls permitted licenses is ACCEPT_LICENSE, which
can be set in /etc/portage/make.conf. In the next example, this
default value is shown:
Code Listing 4.1: Setting ACCEPT_LICENSE in /etc/portage/make.conf
With this configuration, packages that require interaction during installation
to approve their EULA will not be installable. Packages without an EULA
will be installable.
You can set ACCEPT_LICENSE globally in /etc/portage/make.conf
, or you can specify it on a per-package basis in
For example, if you want to allow the truecrypt-2.7 license for
app-crypt/truecrypt, add the following to
Code Listing 4.2: Specifying a truecrypt license in package.license
app-crypt/truecrypt truecrypt-2.7
This permits installation of truecrypt versions that have the
truecrypt-2.7 license, but not versions with the truecrypt-2.8
Licenses are stored in /usr/portage/licenses, and license groups
are kept in /usr/portage/profiles/license_groups. The first entry
of each line in CAPITAL letters is the name of the license group, and every
entry after that is an individual license.
License groups defined in ACCEPT_LICENSE are prefixed with an @
sign. A commonly requested setting is to only allow the installation of free
software and documentation. To accomplish this, we can remove all currently
accepted licenses (using -*) and then only allow the licenses in the
FREE group as follows:
Code Listing 4.3: Only allowing free software and documentation licenses in /etc/portage/make.conf
In this case, "free" is mostly defined by the FSF and OSI. Any package whose license
does not meet these requirements will not be installable on your system.
1.e. When Portage is Complaining...
About SLOTs, Virtuals, Branches, Architectures and Profiles
As we stated before, Portage is extremely powerful and supports many features
that other software management tools lack. To understand this, we explain a few
aspects of Portage without going into too much detail.
With Portage different versions of a single package can coexist on a system.
While other distributions tend to name their package to those versions (like
freetype and freetype2) Portage uses a technology called
SLOTs. An ebuild declares a certain SLOT for its version. Ebuilds with
different SLOTs can coexist on the same system. For instance, the
freetype package has ebuilds with SLOT="1" and SLOT="2".
There are also packages that provide the same functionality but are implemented
differently. For instance, metalogd, sysklogd and syslog-ng
are all system loggers. Applications that rely on the availability of "a system
logger" cannot depend on, for instance, metalogd, as the other system
loggers are as good a choice as any. Portage allows for virtuals: each
system logger is listed as an "exclusive" dependency of the logging service in the
logger virtual package of the virtual category, so that
applications can depend on the virtual/logger package. When installed,
the package will pull in the first logging package mentioned in the package,
unless a logging package was already installed (in which case the virtual is
Software in the Portage tree can reside in different branches. By default your
system only accepts packages that Gentoo deems stable. Most new software titles,
when committed, are added to the testing branch, meaning more testing needs to
be done before it is marked as stable. Although you will see the ebuilds for
those software in the Portage tree, Portage will not update them before they are
placed in the stable branch.
Some software is only available for a few architectures. Or the software doesn't
work on the other architectures, or it needs more testing, or the developer that
committed the software to the Portage tree is unable to verify if the package
works on different architectures.
Each Gentoo installation adheres to a certain profile which contains,
amongst other information, the list of packages that are required for a system
to function normally.
Blocked Packages
Code Listing 5.1: Portage warning about blocked packages (with --pretend)
[blocks B ] mail-mta/ssmtp (is blocking mail-mta/postfix-2.2.2-r1)
Code Listing 5.2: Portage warning about blocked packages (without --pretend)
!!! Error: the mail-mta/postfix package conflicts with another package.
!!! both can't be installed on the same system together.
!!! Please use 'emerge --pretend' to determine blockers.
Ebuilds contain specific fields that inform Portage about its dependencies.
There are two possible dependencies: build dependencies, declared in
DEPEND and run-time dependencies, declared in RDEPEND. When one of
these dependencies explicitly marks a package or virtual as being not
compatible, it triggers a blockage.
While recent versions of Portage are smart enough to work around minor blockages
without user intervention, occasionally you will need to fix it yourself, as
explained below.
To fix a blockage, you can choose to not install the package or unmerge the
conflicting package first. In the given example, you can opt not to install
postfix or to remove ssmtp first.
You may also see blocking packages with specific atoms, such as
<media-video/mplayer-1.0_rc1-r2. In this case, updating to a more
recent version of the blocking package would remove the block.
It is also possible that two packages that are yet to be installed are blocking
each other. In this rare case, you should find out why you need to install both.
In most cases you can do with one of the packages alone. If not, please file a
bug on Gentoo's bugtracking system.
Masked Packages
Code Listing 5.3: Portage warning about masked packages
!!! all ebuilds that could satisfy "bootsplash" have been masked.
Code Listing 5.4: Portage warning about masked packages - reason
!!! possible candidates are:
- gnome-base/gnome-2.8.0_pre1 (masked by: ~x86 keyword)
- lm-sensors/lm-sensors-2.8.7 (masked by: -sparc keyword)
- sys-libs/glibc-22.214.171.12440808 (masked by: -* keyword)
- dev-util/cvsd-1.0.2 (masked by: missing keyword)
- games-fps/unreal-tournament-451 (masked by: package.mask)
- sys-libs/glibc-2.3.2-r11 (masked by: profile)
- net-im/skype-126.96.36.199 (masked by: skype-eula license(s))
When you want to install a package that isn't available for your system, you
will receive this masking error. You should try installing a different
application that is available for your system or wait until the package is put
available. There is always a reason why a package is masked:
Necessary USE Flag Changes
Code Listing 5.5: Portage warning about USE flag change requirement
The following USE changes are necessary to proceed:
#required by app-text/happypackage-2.0, required by happypackage (argument)
>=app-text/feelings-1.0.0 test
The error message might also be displayed as follows, if --autounmask
isn't set:
Code Listing 5.6: Portage error about USE flag change requirement
emerge: there are no ebuilds built with USE flags to satisfy "app-text/feelings[test]".
!!! One of the following packages is required to complete your request:
- app-text/feelings-1.0.0 (Change USE: +test)
(dependency required by "app-text/happypackage-2.0" [ebuild])
(dependency required by "happypackage" [argument])
Such warning or error occurs when you want to install a package which not only
depends on another package, but also requires that that package is built with a
particular USE flag (or set of USE flags). In the given example, the package
app-text/feelings needs to be built with USE="test", but this USE
flag is not set on the system.
To resolve this, either add the requested USE flag to your global USE flags in
/etc/portage/make.conf, or set it for the specific package in
Missing Dependencies
Code Listing 5.7: Portage warning about missing dependency
emerge: there are no ebuilds to satisfy ">=sys-devel/gcc-3.4.2-r4".
!!! Problem with ebuild sys-devel/gcc-3.4.2-r2
!!! Possibly a DEPEND/*DEPEND problem.
The application you are trying to install depends on another package that is not
available for your system. Please check bugzilla if the issue is known and if not,
please report it. Unless you are mixing branches this should not occur and is
therefore a bug.
Ambiguous Ebuild Name
Code Listing 5.8: Portage warning about ambiguous ebuild names
[ Results for search key : listen ]
[ Applications found : 2 ]
* dev-tinyos/listen [ Masked ]
Latest version available: 1.1.15
Latest version installed: [ Not Installed ]
Size of files: 10,032 kB
Homepage: http://www.tinyos.net/
Description: Raw listen for TinyOS
License: BSD
* media-sound/listen [ Masked ]
Latest version available: 0.6.3
Latest version installed: [ Not Installed ]
Size of files: 859 kB
Homepage: http://www.listen-project.org
Description: A Music player and management for GNOME
License: GPL-2
!!! The short ebuild name "listen" is ambiguous. Please specify
!!! one of the above fully-qualified ebuild names instead.
The application you want to install has a name that corresponds with more than
one package. You need to supply the category name as well. Portage will inform
you of possible matches to choose from.
Circular Dependencies
Code Listing 5.9: Portage warning about circular dependencies
!!! Error: circular dependencies:
ebuild / net-print/cups-1.1.15-r2 depends on ebuild / app-text/ghostscript-7.05.3-r1
ebuild / app-text/ghostscript-7.05.3-r1 depends on ebuild / net-print/cups-1.1.15-r2
Two (or more) packages you want to install depend on each other and can
therefore not be installed. This is most likely a bug in the Portage tree.
Please resync after a while and try again. You can also check bugzilla if the issue is known and if not,
report it.
Fetch failed
Code Listing 5.10: Portage warning about fetch failed
!!! Fetch failed for sys-libs/ncurses-5.4-r5, continuing...
!!! Some fetch errors were encountered. Please see above for details.
Portage was unable to download the sources for the given application and will
try to continue installing the other applications (if applicable). This failure
can be due to a mirror that has not synchronised correctly or because the ebuild
points to an incorrect location. The server where the sources reside can also be
down for some reason.
Retry after one hour to see if the issue still persists.
System Profile Protection
Code Listing 5.11: Portage warning about profile-protected package
!!! Trying to unmerge package(s) in system profile. 'sys-apps/portage'
!!! This could be damaging to your system.
You have asked to remove a package that is part of your system's core packages.
It is listed in your profile as required and should therefore not be removed
from the system.
Digest Verification Failures
Sometimes, when you attempt to emerge a package, it will fail with the message:
Code Listing 5.12: Digest verification failure
>>> checking ebuild checksums
!!! Digest verification failed:
This is a sign that something is wrong with the Portage tree -- often, it is
because a developer may have made a mistake when committing a package to the
When the digest verification fails, do not try to re-digest the package
yourself. Running ebuild foo manifest will not fix the problem; it will
almost certainly make it worse!
Instead, wait an hour or two for the tree to settle down. It's likely that the
error was noticed right away, but it can take a little time for the fix to
trickle down the Portage tree. While you're waiting, check Bugzilla and see if anyone has reported
the problem yet. If not, go ahead and file a bug for the broken package.
Once you see that the bug has been fixed, you may want to re-sync to pick up
the fixed digest.
This does not mean that you can re-sync your tree multiple times! As
stated in the rsync policy (when you run emerge --sync), users who sync
too often will be banned! In fact, it's better to just wait until your next
scheduled sync, so that you don't overload the rsync servers.
2.a. What are USE flags?
The ideas behind USE flags
When you are installing Gentoo (or any other distribution, or even operating
system for that matter) you make choices depending on the environment you are
working with. A setup for a server differs from a setup for a workstation.
A gaming workstation differs from a 3D rendering workstation.
This is not only true for choosing what packages you want to install, but also
what features a certain package should support. If you don't need OpenGL, why
would you bother installing OpenGL and build OpenGL support in most of your
packages? If you don't want to use KDE, why would you bother compiling packages
with KDE support if those packages work flawlessly without?
To help users in deciding what to install/activate and what not, we wanted the
user to specify his/her environment in an easy way. This forces the user into
deciding what they really want and eases the process for Portage, our package
management system, to make useful decisions.
Definition of a USE flag
Enter the USE flags. Such a flag is a keyword that embodies support and
dependency-information for a certain concept. If you define a certain USE flag,
Portage will know that you want support for the chosen keyword. Of course
this also alters the dependency information for a package.
Let us take a look at a specific example: the kde keyword. If you do not
have this keyword in your USE variable, all packages that have
optional KDE support will be compiled without KDE support. All
packages that have an optional KDE dependency will be installed
without installing the KDE libraries (as dependency). If you have defined
the kde keyword, then those packages will be compiled with KDE
support, and the KDE libraries will be installed as dependency.
By correctly defining the keywords you will receive a system tailored
specifically to your needs.
What USE flags exist?
There are two types of USE flags: global and local USE flags.
A list of available global USE flags can be found online or locally in
A list of available local USE flags can be found online or locally in
2.b. Using USE flags
Declare permanent USE flags
In the hope you are convinced of the importance of USE flags we will now inform
you how to declare USE flags.
As previously mentioned, all USE flags are declared inside the USE
variable. To make it easy for users to search and pick USE flags, we already
provide a default USE setting. This setting is a collection of USE flags
we think are commonly used by the Gentoo users. This default setting is declared
in the make.defaults files part of your profile.
The profile your system listens to is pointed to by the
/etc/portage/make.profile symlink. Each profile works on top of
another, larger profile, the end result is therefore the sum of all profiles.
The top profile is the base profile
Let us take a look at this default setting for the 13.0 profile:
Code Listing 2.1: Cumulative make.defaults USE variable for the 13.0 profile
(This example is the sum of the settings in base, default/linux,
default/linux/x86 and default/linux/x86/13.0/)
USE="a52 aac acpi alsa branding cairo cdr dbus dts dvd dvdr emboss encode exif
fam firefox flac gif gpm gtk hal jpeg lcms ldap libnotify mad mikmod mng mp3
mp4 mpeg ogg opengl pango pdf png ppds qt3support qt4 sdl spell
startup-notification svg tiff truetype vorbis unicode usb X xcb x264 xml xv
As you can see, this variable already contains quite a lot of keywords. Do
not alter any make.defaults file to tailor
the USE variable to your needs: changes in this file will be undone when
you update Portage!
To change this default setting, you need to add or remove keywords to the
USE variable. This is done globally by defining the USE variable
in /etc/portage/make.conf. In this variable you add the extra USE
flags you require, or remove the USE flags you don't want. This latter is done
by prefixing the keyword with the minus-sign ("-").
For instance, to remove support for KDE and QT but add support for ldap, the
following USE can be defined in /etc/portage/make.conf:
Code Listing 2.2: An example USE setting in /etc/portage/make.conf
USE="-kde -qt4 ldap"
Declaring USE flags for individual packages
Sometimes you want to declare a certain USE flag for one (or a couple) of
applications but not system-wide. To accomplish this, you will need to create
the /etc/portage directory (if it doesn't exist yet) and edit
/etc/portage/package.use. This is usually a single file, but can
also be a directory; see man portage for more information. The following
examples assume package.use is a single file.
For instance, if you don't want berkdb support globally but you do want
it for mysql, you would add:
Code Listing 2.3: /etc/portage/package.use example
dev-db/mysql berkdb
You can of course also explicitly disable USE flags for a certain
application. For instance, if you don't want java support in PHP:
Code Listing 2.4: /etc/portage/package.use 2nd example
dev-php/php -java
Declare temporary USE flags
Sometimes you want to set a certain USE setting only once. Instead of editing
/etc/portage/make.conf twice (to do and undo the USE changes) you
can just declare the USE variable as environment variable. Remember that, when
you re-emerge or update this application (either explicitly or as part of a
system update) your changes will be lost!
As an example we will temporarily remove java from the USE setting
during the installation of seamonkey.
Code Listing 2.5: Using USE as environment variable
# USE="-java" emerge seamonkey
Of course there is a certain precedence on what setting has priority over the
USE setting. You don't want to declare USE="-java" only to see that
java is still used due to a setting that has a higher priority.
The precedence for the USE setting is, ordered
by priority (first has lowest priority):
To view the final USE setting as seen by Portage, run emerge
--info. This will list all relevant variables (including the USE
variable) with the content used by Portage.
Code Listing 2.6: Running emerge --info
# emerge --info
Adapting your Entire System to New USE Flags
If you have altered your USE flags and you wish to update your entire system to
use the new USE flags, use emerge's --newuse option:
Code Listing 2.7: Rebuilding your entire system
# emerge --update --deep --newuse @world
Next, run Portage's depclean to remove the conditional dependencies that
were emerged on your "old" system but that have been obsoleted by the new USE
Running emerge --depclean is a dangerous operation and should be handled
with care. Double-check the provided list of "obsoleted" packages to make sure
it doesn't remove packages you need. In the following example we add the
-p switch to have depclean only list the packages without removing them.
Code Listing 2.8: Removing obsoleted packages
# emerge -p --depclean
When depclean has finished, run revdep-rebuild to rebuild the
applications that are dynamically linked against shared objects provided by
possibly removed packages. revdep-rebuild is part of the
gentoolkit package; don't forget to emerge it first.
Code Listing 2.9: Running revdep-rebuild
# revdep-rebuild
When all this is accomplished, your system is using the new USE flag settings.
2.c. Package specific USE flags
Viewing available USE flags
Let us take the example of seamonkey: what USE flags does it listen to? To
find out, we use emerge with the --pretend and --verbose
Code Listing 3.1: Viewing the used USE flags
# emerge --pretend --verbose seamonkey
These are the packages that I would merge, in order:
Calculating dependencies ...done!
[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6
-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
-moznoroaming -postgres -xinerama -xprint" 0 kB
emerge isn't the only tool for this job. In fact, we have a tool
dedicated to package information called equery which resides in the
gentoolkit package. First, install gentoolkit:
Code Listing 3.2: Installing gentoolkit
Now run equery with the uses argument to view the USE flags of a
certain package. For instance, for the gnumeric package:
Code Listing 3.3: Using equery to view used USE flags
# equery --nocolor uses =gnumeric-1.6.3 -a
[ Searching for packages matching =gnumeric-1.6.3... ]
[ Colour Code : set unset ]
[ Legend : Left column (U) - USE flags from make.conf ]
[ : Right column (I) - USE flags packages was installed with ]
[ Found these USE variables for app-office/gnumeric-1.6.3 ]
- - debug : Enable extra debug codepaths, like asserts and extra output.
If you want to get meaningful backtraces see
http://www.gentoo.org/proj/en/qa/backtraces.xml .
+ + gnome : Adds GNOME support
+ + python : Adds support/bindings for the Python language
- - static : !!do not set this during bootstrap!! Causes binaries to be
statically linked instead of dynamically
3.a. Portage Features
Portage has several additional features that makes your Gentoo experience even
better. Many of these features rely on certain software tools that improve
performance, reliability, security, ...
To enable or disable certain Portage features you need to edit
/etc/portage/make.conf's FEATURES variable which contains
the various feature keywords, separated by white space. In several cases you
will also need to install the additional tool on which the feature relies.
Not all features that Portage supports are listed here. For a full overview,
please consult the make.conf man page:
Code Listing 1.1: Consulting the make.conf man page
$ man make.conf
To find out what FEATURES are default set, run emerge --info and search
for the FEATURES variable or grep it out:
Code Listing 1.2: Finding out the FEATURES that are already set
$ emerge --info | grep FEATURES
3.b. Distributed Compiling
Using distcc
distcc is a program to distribute compilations across several, not
necessarily identical, machines on a network. The distcc client sends all
necessary information to the available distcc servers (running distccd)
so they can compile pieces of source code for the client. The net result is a
faster compilation time.
You can find more information about distcc (and how to have it work
with Gentoo) in our Gentoo Distcc
Installing distcc
Distcc ships with a graphical monitor to monitor tasks that your computer is
sending away for compilation. If you use Gnome then put 'gnome' in your USE
variable. However, if you don't use Gnome and would still like to have the
monitor then you should put 'gtk' in your USE variable.
Code Listing 2.1: Installing distcc
# emerge distcc
Activating Portage Support
Add distcc to the FEATURES variable inside /etc/portage/make.conf.
Next, edit the MAKEOPTS variable to your liking. A known guideline is to fill in
"-jX" with X the number of CPUs that run distccd (including the current
host) plus one, but you might have better results with other numbers.
Now run distcc-config and enter the list of available distcc servers. For
a simple example we assume that the available DistCC servers are 192.168.1.102
(the current host), 192.168.1.103 and 192.168.1.104 (two "remote" hosts):
Code Listing 2.2: Configuring distcc to use three available distcc servers
# distcc-config --set-hosts "192.168.1.102 192.168.1.103 192.168.1.104"
Don't forget to run the distccd daemon as well:
Code Listing 2.3: Starting the distccd daemons
# rc-update add distccd default
# /etc/init.d/distccd start
3.c. Caching Compilation
About ccache
ccache is a fast compiler cache. When you compile a program, it will
cache intermediate results so that, whenever you recompile the same program, the
compilation time is greatly reduced. The first time you run ccache, it will be
much slower than a normal compilation. Subsequent recompiles should be faster.
ccache is only helpful if you will be recompiling the same application many
times; thus it's mostly only useful for software developers.
If you are interested in the ins and outs of ccache, please visit the
ccache homepage.
ccache is known to cause numerous compilation failures. Sometimes ccache
will retain stale code objects or corrupted files, which can lead to packages
that cannot be emerged. If this happens (if you receive errors like "File not
recognized: File truncated"), try recompiling the application with ccache
disabled (FEATURES="-ccache" in /etc/portage/make.conf)
before reporting a bug. Unless you are doing development work, do not
enable ccache.
Installing ccache
To install ccache, run emerge ccache:
Code Listing 3.1: Installing ccache
# emerge ccache
Open /etc/portage/make.conf and add ccache to the FEATURES
variable. Next, add a new variable called CCACHE_SIZE and set it to "2G":
Code Listing 3.2: Editing CCACHE_SIZE in /etc/portage/make.conf
To check if ccache functions, ask ccache to provide you with its statistics.
Because Portage uses a different ccache home directory, you need to set the
CCACHE_DIR variable as well:
Code Listing 3.3: Viewing ccache statistics
# CCACHE_DIR="/var/tmp/ccache" ccache -s
The /var/tmp/ccache location is Portage' default ccache home
directory; if you want to alter this setting you can set the CCACHE_DIR
variable in /etc/portage/make.conf.
However, if you would run ccache, it would use the default location of
${HOME}/.ccache, which is why you needed to set the
CCACHE_DIR variable when asking for the (Portage) ccache statistics.
Using ccache for non-Portage C Compiling
If you would like to use ccache for non-Portage compilations, add
/usr/lib/ccache/bin to the beginning of your PATH variable (before
/usr/bin). This can be accomplished by editing
.bash_profile in your user's home directory. Using
.bash_profile is one way to define PATH variables.
Code Listing 3.4: Editing .bash_profile
3.d. Binary Package Support
Creating Prebuilt Packages
Portage supports the installation of prebuilt packages. Even though Gentoo does
not provide prebuilt packages by itself Portage
can be made fully aware of prebuilt packages.
To create a prebuilt package you can use quickpkg if the package is
already installed on your system, or emerge with the --buildpkg or
--buildpkgonly options.
If you want Portage to create prebuilt packages of every single package you
install, add buildpkg to the FEATURES variable.
More extended support for creating prebuilt package sets can be obtained with
catalyst. For more information on catalyst please read the Catalyst Frequently Asked
Installing Prebuilt Packages
Although Gentoo doesn't provide one, you can create a central repository where
you store prebuilt packages. If you want to use this repository, you need to
make Portage aware of it by having the PORTAGE_BINHOST variable point to
it. For instance, if the prebuilt packages are on ftp://buildhost/gentoo:
Code Listing 4.1: Setting PORTAGE_BINHOST in /etc/portage/make.conf
When you want to install a prebuilt package, add the --getbinpkg option
to the emerge command alongside of the --usepkg option. The former tells
emerge to download the prebuilt package from the previously defined server
while the latter asks emerge to try to install the prebuilt package first before
fetching the sources and compiling it.
For instance, to install gnumeric with prebuilt packages:
Code Listing 4.2: Installing the gnumeric prebuilt package
# emerge --usepkg --getbinpkg gnumeric
More information about emerge's prebuilt package options can be found in the
emerge man page:
Code Listing 4.3: Reading the emerge man page
3.e. Fetching Files
Parallel fetch
When you are emerging a series of packages, Portage can fetch the source files
for the next package in the list even while it is compiling another package,
thus shortening compile times. To make use of this capability, add
"parallel-fetch" to your FEATURES. Note that this is on by default, so you
shouldn't need to specifically enable it.
When Portage is run as root, FEATURES="userfetch" will allow Portage to drop
root privileges while fetching package sources. This is a small security
3.f. Pulling Validated Portage Tree Snapshots
As an administrator, you can opt to only update your local Portage tree with a
cryptographically validated Portage tree snapshot as released by the Gentoo
infrastructure. This ensures that no rogue rsync mirror is adding unwanted code
or packages in the tree you are downloading.
To configure Portage, first create a truststore in which you download and accept
the keys of the Gentoo Infrastructure responsible for signing the Portage tree
snapshots. Of course, if you want to, you can validate this GPG key as per the
proper guidelines
(like checking the key fingerprint). You can find the list of GPG keys used by
the release engineering team on their project page.
Code Listing 6.1: Creating a truststore for Portage
# mkdir -p /etc/portage/gpg
# chmod 0700 /etc/portage/gpg
(... Substitute the keys with those mentioned on the release engineering site ...)
# gpg --homedir /etc/portage/gpg --keyserver subkeys.pgp.net --recv-keys 0xDB6B8C1F96D8BF6D
# gpg --homedir /etc/portage/gpg --edit-key 0xDB6B8C1F96D8BF6D trust
Next, edit /etc/portage/make.conf and enable support for validating
the signed Portage tree snapshots (using FEATURES="webrsync-gpg") and
disabling updating the Portage tree using the regular emerge --sync
Code Listing 6.2: Updating make.conf
Code Listing 6.3: Updating repos.conf
# Make sure sync-type and sync-uri are commented out
# sync-type = rsync
# sync-uri = ...
That's it. Next time you run emerge-webrsync, only the snapshots with
a valid signature will be expanded on your file system.
4.a. Runlevels
Booting your System
When you boot your system, you will notice lots of text floating by. If you pay
close attention, you will notice this text is the same every time you reboot
your system. The sequence of all these actions is called the boot
sequence and is (more or less) statically defined.
First, your boot loader will load the kernel image you have defined in the
boot loader configuration into memory after which it tells the CPU to run the
kernel. When the kernel is loaded and run, it initializes all kernel-specific
structures and tasks and starts the init process.
This process then makes sure that all filesystems (defined in
/etc/fstab) are mounted and ready to be used. Then it executes
several scripts located in /etc/init.d, which will start the
services you need in order to have a successfully booted system.
Finally, when all scripts are executed, init activates the terminals
(in most cases just the virtual consoles which are hidden beneath Alt-F1,
Alt-F2, etc.) attaching a special process called agetty to it.
This process will then make sure you are able to log on through these terminals
by running login.
Init Scripts
Now init doesn't just execute the scripts in /etc/init.d
randomly. Even more, it doesn't run all scripts in /etc/init.d,
only the scripts it is told to execute. It decides which scripts to execute by
looking into /etc/runlevels.
First, init runs all scripts from /etc/init.d that have
symbolic links inside /etc/runlevels/boot. Usually, it will
start the scripts in alphabetical order, but some scripts have dependency
information in them, telling the system that another script must be run before
they can be started.
When all /etc/runlevels/boot referenced scripts are executed,
init continues with running the scripts that have a symbolic link to them
in /etc/runlevels/default. Again, it will use the alphabetical
order to decide what script to run first, unless a script has dependency
information in it, in which case the order is changed to provide a valid
start-up sequence.
How Init Works
Of course init doesn't decide all that by itself. It needs a
configuration file that specifies what actions need to be taken. This
configuration file is /etc/inittab.
If you remember the boot sequence we have just described, you will remember
that init's first action is to mount all filesystems. This is defined in
the following line from /etc/inittab:
Code Listing 1.1: The system initialisation line in /etc/inittab
si::sysinit:/sbin/rc sysinit
This line tells init that it must run /sbin/rc sysinit to
initialize the system. The /sbin/rc script takes care of the
initialisation, so you might say that init doesn't do much -- it
delegates the task of initialising the system to another process.
Second, init executed all scripts that had symbolic links in
/etc/runlevels/boot. This is defined in the following line:
Code Listing 1.2: The system initialisation, continued
rc::bootwait:/sbin/rc boot
Again the rc script performs the necessary tasks. Note that the option
given to rc (boot) is the same as the subdirectory of
/etc/runlevels that is used.
Now init checks its configuration file to see what runlevel it
should run. To decide this, it reads the following line from
Code Listing 1.3: The initdefault line
In this case (which the majority of Gentoo users will use), the runlevel
id is 3. Using this information, init checks what it must run to start
runlevel 3:
Code Listing 1.4: The runlevel definitions
l0:0:wait:/sbin/rc shutdown
l1:S1:wait:/sbin/rc single
l2:2:wait:/sbin/rc nonetwork
l3:3:wait:/sbin/rc default
l4:4:wait:/sbin/rc default
l5:5:wait:/sbin/rc default
l6:6:wait:/sbin/rc reboot
The line that defines level 3, again, uses the rc script to start the
services (now with argument default). Again note that the argument of
rc is the same as the subdirectory from /etc/runlevels.
When rc has finished, init decides what virtual consoles it should
activate and what commands need to be run at each console:
Code Listing 1.5: The virtual consoles definition
c1:12345:respawn:/sbin/agetty 38400 tty1 linux
c2:12345:respawn:/sbin/agetty 38400 tty2 linux
c3:12345:respawn:/sbin/agetty 38400 tty3 linux
c4:12345:respawn:/sbin/agetty 38400 tty4 linux
c5:12345:respawn:/sbin/agetty 38400 tty5 linux
c6:12345:respawn:/sbin/agetty 38400 tty6 linux
What is a runlevel?
You have seen that init uses a numbering scheme to decide what
runlevel it should activate. A runlevel is a state in which
your system is running and contains a collection of scripts (runlevel scripts or
initscripts) that must be executed when you enter or leave a runlevel.
In Gentoo, there are seven runlevels defined: three internal runlevels, and four
user-defined runlevels. The internal runlevels are called sysinit,
shutdown and reboot and do exactly what their names imply:
initialize the system, powering off the system and rebooting the system.
The user-defined runlevels are those with an accompanying
/etc/runlevels subdirectory: boot,
default, nonetwork and single. The
boot runlevel starts all system-necessary services which all other
runlevels use. The remaining three runlevels differ in what services they start:
default is used for day-to-day operations, nonetwork
is used in case no network connectivity is required, and single is
used when you need to fix the system.
Working with the Init Scripts
The scripts that the rc process starts are called init scripts.
Each script in /etc/init.d can be executed with the arguments
start, stop, restart, zap,
status, ineed, iuse, needsme, usesme or
To start, stop or restart a service (and all depending services), start,
stop and restart should be used:
Code Listing 1.6: Starting Postfix
# /etc/init.d/postfix start
Only the services that need the given service are stopped or restarted.
The other depending services (those that use the service but don't need
it) are left untouched.
If you want to stop a service, but not the services that depend on it, you can
use the --nodeps argument together with the stop command:
Code Listing 1.7: Stopping Postfix but keep the depending services running
# /etc/init.d/postfix --nodeps stop
If you want to see what status a service has (started, stopped, ...) you
can use the status argument:
Code Listing 1.8: Status information for postfix
# /etc/init.d/postfix status
If the status information tells you that the service is running, but you know
that it is not, then you can reset the status information to "stopped" with the
zap argument:
Code Listing 1.9: Resetting status information for postfix
# /etc/init.d/postfix zap
To also ask what dependencies the service has, you can use iuse or
ineed. With ineed you can see the services that are really
necessary for the correct functioning of the service. iuse on the other
hand shows the services that can be used by the service, but are not necessary
for the correct functioning.
Code Listing 1.10: Requesting a list of all necessary services on which Postfix depends
# /etc/init.d/postfix ineed
Similarly, you can ask what services require the service (needsme) or can
use it (usesme):
Code Listing 1.11: Requesting a list of all services that require Postfix
# /etc/init.d/postfix needsme
Finally, you can ask what dependencies the service requires that are missing:
Code Listing 1.12: Requesting a list of missing dependencies for Postfix
# /etc/init.d/postfix broken
4.b. Working with rc-update
What is rc-update?
Gentoo's init system uses a dependency-tree to decide what service needs to be
started first. As this is a tedious task that we wouldn't want our users to
have to do manually, we have created tools that ease the administration of the
runlevels and init scripts.
With rc-update you can add and remove init scripts to a runlevel. The
rc-update tool will then automatically ask the depscan.sh script
to rebuild the dependency tree.
Adding and Removing Services
You have already added init scripts to the "default" runlevel during the
installation of Gentoo. At that time you might not have had a clue what the
"default" is for, but now you should. The rc-update script requires a
second argument that defines the action: add, del or show.
To add or remove an init script, just give rc-update the add or
del argument, followed by the init script and the runlevel. For instance:
Code Listing 2.1: Removing Postfix from the default runlevel
# rc-update del postfix default
The rc-update -v show command will show all the available init scripts and
list at which runlevels they will execute:
Code Listing 2.2: Receiving init script information
# rc-update -v show
You can also run rc-update show (without -v) to just view enabled
init scripts and their runlevels.
4.c. Configuring Services
Why the Need for Extra Configuration?
Init scripts can be quite complex. It is therefore not really desirable to
have the users edit the init script directly, as it would make it more
error-prone. It is however important to be able to configure such a service. For
instance, you might want to give more options to the service itself.
A second reason to have this configuration outside the init script is to be
able to update the init scripts without the fear that your configuration
changes will be undone.
The /etc/conf.d Directory
Gentoo provides an easy way to configure such a service: every init script that
can be configured has a file in /etc/conf.d. For instance, the
apache2 initscript (called /etc/init.d/apache2) has a
configuration file called /etc/conf.d/apache2, which can contain
the options you want to give to the Apache 2 server when it is started:
Code Listing 3.1: Variable defined in /etc/conf.d/apache2
Such a configuration file contains variables and variables alone (just like
/etc/portage/make.conf), making it very easy to configure services.
It also allows us to provide more information about the variables (as comments).
4.d. Writing Init Scripts
Do I Have To?
No, writing an init script is usually not necessary as Gentoo provides
ready-to-use init scripts for all provided services. However, you might have
installed a service without using Portage, in which case you will most likely
have to create an init script.
Do not use the init script provided by the service if it isn't explicitly
written for Gentoo: Gentoo's init scripts are not compatible with the init
scripts used by other distributions!
The basic layout of an init script is shown below.
Code Listing 4.1: Basic layout of an init script
depend() {
(Dependency information)
start() {
(Commands necessary to start the service)
stop() {
(Commands necessary to stop the service)
Any init script requires the start() function to be defined. All
other sections are optional.
There are two dependency-alike settings you can define that influence the
start-up or sequencing of init scripts: use and need. Next to
these two, there are also two order-influencing methods called before and
after. These last two are no dependencies per se - they do not make the
original init script fail if the selected one isn't scheduled to start (or fails
to start).
It should be clear from the above that need is the only "true" dependency
setting as it affects if the script will be started or not. All the others are
merely pointers towards the init system to clarify in which order scripts can be
(or should be) launched.
Now, if you look at many of Gentoo's available init scripts, you will notice
that some have dependencies on things that are no init scripts. These "things"
we call virtuals.
A virtual dependency is a dependency that a service provides, but that is
not provided solely by that service. Your init script can depend on a system
logger, but there are many system loggers available (metalogd, syslog-ng,
sysklogd, ...). As you cannot need every single one of them (no sensible
system has all these system loggers installed and running) we made sure that
all these services provide a virtual dependency.
Let us take a look at the dependency information for the postfix service.
Code Listing 4.2: Dependency information for Postfix
depend() {
need net
use logger dns
provide mta
As you can see, the postfix service:
Controlling the Order
As we described in the previous section, you can tell the init system what order
it should use for starting (or stopping) scripts. This ordering is handled both
through the dependency settings use and need, but also through the
order settings before and after. As we have described these
earlier already, let's take a look at the Portmap service as an example of such
init script.
Code Listing 4.3: The depend() function in the Portmap service
depend() {
need net
before inetd
before xinetd
You can also use the "*" glob to catch all services in the same runlevel,
although this isn't advisable.
Code Listing 4.4: Running an init script as first script in the runlevel
depend() {
before *
If your service must write to local disks, it should need localmount. If
it places anything in /var/run such as a pidfile, then it should
start after bootmisc:
Code Listing 4.5: Example depend() function
depend() {
need localmount
after bootmisc
Standard Functions
Next to the depend() functionality, you also need to define the
start() function. This one contains all the commands necessary to
initialize your service. It is advisable to use the ebegin and
eend functions to inform the user about what is happening:
Code Listing 4.6: Example start() function
start() {
if [ "${RC_CMD}" = "restart" ];
# Do something in case a restart requires more than stop, start
ebegin "Starting my_service"
start-stop-daemon --start --exec /path/to/my_service \
--pidfile /path/to/my_pidfile
eend $?
Both --exec and --pidfile should be used in start and stop
functions. If the service does not create a pidfile, then use
--make-pidfile if possible, though you should test this to be sure.
Otherwise, don't use pidfiles. You can also add --quiet to the
start-stop-daemon options, but this is not recommended unless the
service is extremely verbose. Using --quiet may hinder debugging if the
service fails to start.
Another notable setting used in the above example is to check the contents of
the RC_CMD variable. Unlike the previous init script system, the newer
openrc system does not support script-specific restart functionality.
Instead, the script needs to check the contents of the RC_CMD variable
to see if a function (be it start() or stop()) is called as part
of a restart or not.
Make sure that --exec actually calls a service and not just a shell
script that launches services and exits -- that's what the init script is
supposed to do.
If you need more examples of the start() function, please read the
source code of the available init scripts in your /etc/init.d
Another function you can define is stop(). You are not obliged to define
this function though! Our init system is intelligent enough to fill in this
function by itself if you use start-stop-daemon.
Here is an example of a stop() function:
Code Listing 4.7: Example stop() function
stop() {
ebegin "Stopping my_service"
start-stop-daemon --stop --exec /path/to/my_service \
--pidfile /path/to/my_pidfile
eend $?
If your service runs some other script (for example, bash, python, or perl),
and this script later changes names (for example, foo.py to foo),
then you will need to add --name to start-stop-daemon. You must
specify the name that your script will be changed to. In this example, a
service starts foo.py, which changes names to foo:
Code Listing 4.8: A service that starts the foo script
start() {
ebegin "Starting my_script"
start-stop-daemon --start --exec /path/to/my_script \
--pidfile /path/to/my_pidfile --name foo
eend $?
start-stop-daemon has an excellent man page available if you need more
Code Listing 4.9: Getting the man page for start-stop-daemon
$ man start-stop-daemon
Gentoo's init script syntax is based on the POSIX Shell so you are
free to use sh-compatible constructs inside your init script. Keep other
constructs, like bash-specific ones, out of the init scripts to ensure that the
scripts remain functional regardless of the change Gentoo might do on its init
Adding Custom Options
If you want your init script to support more options than the ones we have
already encountered, you should add the option to the extra_commands
variable, and create a function with the same name as the option. For instance,
to support an option called restartdelay:
Code Listing 4.10: Supporting the restartdelay option
restartdelay() {
sleep 3 # Wait 3 seconds before starting again
The function restart() cannot be overridden in openrc!
Service Configuration Variables
You don't have to do anything to support a configuration file in
/etc/conf.d: if your init script is executed, the following files
are automatically sourced (i.e. the variables are available to use):
Also, if your init script provides a virtual dependency (such as net),
the file associated with that dependency (such as /etc/conf.d/net)
will be sourced too.
4.e. Changing the Runlevel Behaviour
Who might benefit from this?
Many laptop users know the situation: at home you need to start net.eth0
while you don't want to start net.eth0 while you're on the road (as
there is no network available). With Gentoo you can alter the runlevel behaviour
to your own will.
For instance you can create a second "default" runlevel which you can boot that
has other init scripts assigned to it. You can then select at boottime what
default runlevel you want to use.
Using softlevel
First of all, create the runlevel directory for your second "default" runlevel.
As an example we create the offline runlevel:
Code Listing 5.1: Creating a runlevel directory
# mkdir /etc/runlevels/offline
Add the necessary init scripts to the newly created runlevels. For instance, if
you want to have an exact copy of your current default runlevel but
without net.eth0:
Code Listing 5.2: Adding the necessary init scripts
(Copy all services from default runlevel to offline runlevel)
# cd /etc/runlevels/default
# for service in *; do rc-update add $service offline; done
(Remove unwanted service from offline runlevel)
# rc-update del net.eth0 offline
(Display active services for offline runlevel)
# rc-update show offline
(Partial sample Output)
acpid | offline
domainname | offline
local | offline
net.eth0 |
Even though net.eth0 has been removed from the offline runlevel,
udev might want to attempt to start any devices it detects and launch the
appropriate services, a functionality that is called hotplugging. By
default, Gentoo does not enable hotplugging.
If you do want to enable hotplugging, but only for a selected set of scripts,
use the rc_hotplug variable in /etc/rc.conf:
Code Listing 5.3: Disabling device initiated services in /etc/rc.conf
# Allow net.wlan as well as any other service, except those matching net.*
# to be hotplugged
rc_hotplug="net.wlan !net.*"
For more information on device initiated services, please see the comments
inside /etc/rc.conf.
Now edit your bootloader configuration and add a new entry for the
offline runlevel. For instance, in /boot/grub/grub.conf:
Code Listing 5.4: Adding an entry for the offline runlevel
title Gentoo Linux Offline Usage
root (hd0,0)
kernel (hd0,0)/kernel-2.4.25 root=/dev/hda3 softlevel=offline
Voilà, you're all set now. If you boot your system and select the newly added
entry at boot, the offline runlevel will be used instead of the
default one.
Using bootlevel
Using bootlevel is completely analogous to softlevel. The only
difference here is that you define a second "boot" runlevel instead of a second
"default" runlevel.
5.a. Environment Variables?
What they are
An environment variable is a named object that contains information used by one
or more applications. Many users (and especially those new to Linux) find this
a bit weird or unmanageable. However, this is a mistake: by using environment
variables one can easily change a configuration setting for one or more
Important Examples
The following table lists a number of variables used by a Linux system and
describes their use. Example values are presented after the table.
Below you will find an example definition of all these variables:
Code Listing 1.1: Example definitions
CONFIG_PROTECT="/usr/X11R6/lib/X11/xkb /opt/tomcat/conf \
/usr/kde/3.1/share/config /usr/share/texmf/tex/generic/config/ \
/usr/share/texmf/tex/platex/config/ /usr/share/config"
5.b. Defining Variables Globally
The /etc/env.d Directory
To centralise the definitions of these variables, Gentoo introduced the
/etc/env.d directory. Inside this directory you will find a number
of files, such as 00basic, 05gcc, etc. which contain
the variables needed by the application mentioned in their name.
For instance, when you installed gcc, a file called 05gcc
was created by the ebuild which contains the definitions of the following
Code Listing 2.1: /etc/env.d/05gcc
Other distributions tell you to change or add such environment variable
definitions in /etc/profile or other locations. Gentoo on the other
hand makes it easy for you (and for Portage) to maintain and manage the
environment variables without having to pay attention to the numerous files that
can contain environment variables.
For instance, when gcc is updated, the /etc/env.d/05gcc file
is updated too without requesting any user-interaction.
This not only benefits Portage, but also you, as user. Occasionally you might
be asked to set a certain environment variable system-wide. As an example we
take the http_proxy variable. Instead of messing about with
/etc/profile, you can now just create a file
(/etc/env.d/99local) and enter your definition(s) in it:
Code Listing 2.2: /etc/env.d/99local
By using the same file for all your variables, you have a quick overview on the
variables you have defined yourself.
The env-update Script
Several files in /etc/env.d define the PATH variable. This
is not a mistake: when you run env-update, it will append the several
definitions before it updates the environment variables, thereby making it easy
for packages (or users) to add their own environment variable settings without
interfering with the already existing values.
The env-update script will append the values in the alphabetical order
of the /etc/env.d files. The file names must begin with two
decimal digits.
Code Listing 2.3: Update order used by env-update
00basic 99kde-env 99local
The concatenation of variables does not always happen, only with the following
variables: ADA_INCLUDE_PATH, ADA_OBJECTS_PATH, CLASSPATH,
PKG_CONFIG_PATH and PYTHONPATH.
For all other variables the latest defined value (in alphabetical order of the
files in /etc/env.d) is used.
You can add more variables into this list of concatenate-variables by adding the
variable name to either COLON_SEPARATED or SPACE_SEPARATED
variables (also inside an env.d file).
When you run env-update, the script will create all environment variables
and place them in /etc/profile.env (which is used by
/etc/profile). It will also extract the information from the
LDPATH variable and use that to create /etc/ld.so.conf.
After this, it will run ldconfig to recreate the
/etc/ld.so.cache file used by the dynamical linker.
If you want to notice the effect of env-update immediately after you run
it, execute the following command to update your environment. Users who have
installed Gentoo themselves will probably remember this from the installation
Code Listing 2.4: Updating the environment
The above command only updates the variables in your current terminal,
new consoles, and their children. Thus, if you are working in X11, you
will need to either type source /etc/profile in every new terminal you
open or restart X so that all new terminals source the new variables. If you
use a login manager, become root and type /etc/init.d/xdm restart. If
not, you will need to logout and log back in for X to spawn children with the
new variable values.
You cannot use shell variables when defining other variables. This means things
like FOO="$BAR" (where $BAR is another variable) are forbidden.
5.c. Defining Variables Locally
User Specific
You do not always want to define an environment variable globally. For instance,
you might want to add /home/my_user/bin and the current working
directory (the directory you are in) to the PATH variable
but don't want all other users on your system to have that in their PATH
too. If you want to define an environment variable locally, you should use
~/.bashrc or ~/.bash_profile:
Code Listing 3.1: Extending PATH for local usage in ~/.bashrc
(A colon followed by no directory is treated as the current working directory)
When you relogin, your PATH variable will be updated.
Session Specific
Sometimes even stricter definitions are requested. You might want to be able to
use binaries from a temporary directory you created without using the path to
the binaries themselves or editing ~/.bashrc for the short time
you need it.
In this case, you can just define the PATH variable in your current
session by using the export command. As long as you don't log out, the
PATH variable will be using the temporary settings.
Code Listing 3.2: Defining a session-specific environment variable
# export PATH="${PATH}:/home/my_user/tmp/usr/bin"
1.a. Portage Files
Configuration Directives
Portage comes with a default configuration stored in
/usr/share/portage/config/make.globals. When you take a look at it, you'll notice that
all Portage configuration is handled through variables. What variables Portage
listens to and what they mean are described later.
Since many configuration directives differ between architectures, Portage also
has default configuration files which are part of your profile. Your profile is
pointed to by the /etc/portage/make.profile symlink; Portage'
configurations are set in the make.defaults files of your profile
and all parent profiles. We'll explain more about profiles
and the /etc/portage/make.profile directory later on.
If you're planning on changing a configuration variable, don't alter
/usr/share/portage/config/make.globals or make.defaults. Instead use
/etc/portage/make.conf which has precedence over the previous
files. You'll also find a /usr/share/portage/config/make.conf.example.
As the name implies, this is merely an example file - Portage does not read
in this file.
You can also define a Portage configuration variable as an environment variable,
but we don't recommend this.
Profile-Specific Information
We've already encountered the /etc/portage/make.profile directory.
Well, this isn't exactly a directory but a symbolic link to a profile, by
default one inside /usr/portage/profiles although you can create
your own profiles elsewhere and point to them. The profile this symlink points
to is the profile to which your system adheres.
A profile contains architecture-specific information for Portage, such as a
list of packages that belong to the system corresponding with that profile,
a list of packages that don't work (or are masked-out) for that profile, etc.
User-Specific Configuration
When you need to override Portage's behaviour regarding the installation of
software, you will end up editing files within /etc/portage. You
are highly recommended to use files within /etc/portage and
highly discouraged to override the behaviour through environment
Within /etc/portage you can create the following files:
These don't have to be files; they can also be directories that contain one file
per package. More information about the /etc/portage directory and
a full list of possible files you can create can be found in the Portage man
Code Listing 1.1: Reading the Portage man page
$ man portage
Changing Portage File & Directory Locations
The previously mentioned configuration files cannot be stored elsewhere -
Portage will always look for those configuration files at those exact locations.
However, Portage uses many other locations for various purposes: build
directory, source code storage, Portage tree location, ...
All these purposes have well-known default locations but can be altered to your
own taste through /etc/portage/make.conf. The rest of this chapter
explains what special-purpose locations Portage uses and how to alter their
placement on your filesystem.
This document isn't meant to be used as a reference though. If you need 100%
coverage, please consult the Portage and make.conf man pages:
Code Listing 1.2: Reading the Portage and make.conf man pages
$ man portage
$ man make.conf
1.b. Storing Files
The Portage Tree
The Portage tree default location is /usr/portage. This is defined
by the PORTDIR variable. When you store the Portage tree elsewhere (by altering
this variable), don't forget to change the /etc/portage/make.profile
symbolic link accordingly.
If you alter the PORTDIR variable, you might want to alter the following
variables as well since they will not notice the PORTDIR change. This is due to
how Portage handles variables: PKGDIR, DISTDIR, RPMDIR.
Prebuilt Binaries
Even though Portage doesn't use prebuilt binaries by default, it has extensive
support for them. When you ask Portage to work with prebuilt packages, it will
look for them in /usr/portage/packages. This location is defined by
the PKGDIR variable.
Source Code
Application source code is stored in /usr/portage/distfiles by
default. This location is defined by the DISTDIR variable.
Portage Database
Portage stores the state of your system (what packages are installed, what files
belong to which package, ...) in /var/db/pkg. Do not alter
these files manually! It might break Portage's knowledge of your system.
Portage Cache
The Portage cache (with modification times, virtuals, dependency tree
information, ...) is stored in /var/cache/edb. This location really
is a cache: you can clean it if you are not running any portage-related
application at that moment.
1.c. Building Software
Temporary Portage Files
Portage's temporary files are stored in /var/tmp by default. This
is defined by the PORTAGE_TMPDIR variable.
If you alter the PORTAGE_TMPDIR variable, you might want to alter the following
variables as well since they will not notice the PORTAGE_TMPDIR change. This
is due to how Portage handles variables: BUILD_PREFIX.
Building Directory
Portage creates specific build directories for each package it emerges inside
/var/tmp/portage. This location is defined by the BUILD_PREFIX
Live Filesystem Location
By default Portage installs all files on the current filesystem
(/), but you can change this by setting the ROOT environment
variable. This is useful when you want to create new build images.
1.d. Logging Features
Ebuild Logging
Portage can create per-ebuild logfiles, but only when the PORT_LOGDIR variable
is set to a location that is writable by Portage (the portage user). By default
this variable is unset. If you don't set PORT_LOGDIR, then you won't receive
any build logs with the current logging system, though you may receive some
logs from the new elog. If you do have PORT_LOGDIR defined and you use
elog, you will receive build logs and any logs saved by elog, as explained
Portage offers fine-grained control over logging through the use of
If you used enotice with Portage-2.0.*, you must completely remove
enotice, as it is incompatible with elog.
2.a. Portage Configuration
As noted previously, Portage is configurable through many variables which
you should define in /etc/portage/make.conf or one of the subdirectories
of /etc/portage. Please refer to the make.conf and
portage man pages for more and complete information:
Code Listing 1.1: Reading the man pages
$ man make.conf
$ man portage
2.b. Build-specific Options
Configure and Compiler Options
When Portage builds applications, it passes the contents of the following
variables to the compiler and configure script:
The USE variable is also used during configure and compilations but has been
explained in great detail in previous chapters.
Merge Options
When Portage has merged a newer version of a certain software title, it will
remove the obsoleted files of the older version from your system. Portage gives
the user a 5 second delay before unmerging the older version. These 5 seconds
are defined by the CLEAN_DELAY variable.
You can tell emerge to use certain options every time it is run by
setting EMERGE_DEFAULT_OPTS. Some useful options would be --ask, --verbose,
--tree, and so on.
2.c. Configuration File Protection
Portage's Protected Locations
Portage overwrites files provided by newer versions of a software title if the
files aren't stored in a protected location. These protected locations
are defined by the CONFIG_PROTECT variable and are generally configuration file
locations. The directory listing is space-delimited.
A file that would be written in such a protected location is renamed and the
user is warned about the presence of a newer version of the (presumable)
configuration file.
You can find out about the current CONFIG_PROTECT setting from the emerge
--info output:
Code Listing 3.1: Getting the CONFIG_PROTECT setting
$ emerge --info | grep 'CONFIG_PROTECT='
More information about Portage's Configuration File Protection is available
in the CONFIGURATION FILES section of the emerge manpage:
Code Listing 3.2: More information about Configuration File Protection
Excluding Directories
To 'unprotect' certain subdirectories of protected locations you can use the
CONFIG_PROTECT_MASK variable.
2.d. Download Options
Server Locations
When the requested information or data is not available on your system, Portage
will retrieve it from the Internet. The server locations for the various
information and data channels are defined by the following variables:
A third setting involves the location of the rsync server which you use when you
update your Portage tree. This is defined in the /etc/portage/repos.conf
file (or a file inside that directory if it is defined as a directory):
The GENTOO_MIRRORS, sync-type and sync-uri variables can be set automatically through the
mirrorselect application. You need to emerge mirrorselect first
before you can use it. For more information, see mirrorselect's online
Code Listing 4.1: More information about mirrorselect
# mirrorselect --help
If your environment requires you to use a proxy server, you can use the
http_proxy, ftp_proxy and RSYNC_PROXY variables to declare a proxy server.
Fetch Commands
When Portage needs to fetch source code, it uses wget by default. You
can change this through the FETCHCOMMAND variable.
Portage is able to resume partially downloaded source code. It uses wget
by default, but this can be altered through the RESUMECOMMAND variable.
Make sure that your FETCHCOMMAND and RESUMECOMMAND stores the source code in the
correct location. Inside the variables you should use \${URI} and \${DISTDIR} to
point to the source code location and distfiles location respectively.
You can also define protocol-specific handlers with FETCHCOMMAND_HTTP,
FETCHCOMMAND_FTP, RESUMECOMMAND_HTTP, RESUMECOMMAND_FTP, and so on.
Rsync Settings
You cannot alter the rsync command used by Portage to update the Portage tree,
but you can set some variables related to the rsync command:
For more information on these options and others, please read man
2.e. Gentoo Configuration
Branch Selection
You can change your default branch with the ACCEPT_KEYWORDS variable. It
defaults to your architecture's stable branch. More information on Gentoo's
branches can be found in the next chapter.
Portage Features
You can activate certain Portage features through the FEATURES variable. The
Portage Features have been discussed in previous chapters, such as Portage Features.
2.f. Portage Behaviour
Resource Management
With the PORTAGE_NICENESS variable you can augment or reduce the nice value
Portage runs with. The PORTAGE_NICENESS value is added to the current
nice value.
For more information about nice values, see the nice man page:
Code Listing 6.1: More information about nice
$ man nice
Output Behaviour
The NOCOLOR, which defaults to "false", defines if Portage should disable the
use of coloured output.
3.a. Using One Branch
The Stable Branch
The ACCEPT_KEYWORDS variable defines what software branch you use on your
system. It defaults to the stable software branch for your architecture, for
instance x86.
We recommend that you only use the stable branch. However, if you don't care
about stability this much and you want to help out Gentoo by submitting
bugreports to http://bugs.gentoo.org, read on.
The Testing Branch
If you want to use more recent software, you can consider using the testing
branch instead. To have Portage use the testing branch, add a ~ in front of your
The testing branch is exactly what it says - Testing. If a package is in
testing, it means that the developers feel that it is functional but has not
been thoroughly tested. You could very well be the first to discover a bug in
the package in which case you could file a bugreport to let the developers know about
Beware though, you might notice stability issues, imperfect package handling
(for instance wrong/missing dependencies), too frequent updates (resulting in
lots of building) or broken packages. If you do not know how Gentoo works and
how to solve problems, we recommend that you stick with the stable and tested
For example, to select the testing branch for the x86 architecture, edit
/etc/portage/make.conf and set:
Code Listing 1.1: Setting the ACCEPT_KEYWORDS variable
If you update your system now, you will find out that lots of packages
will be updated. Mind you though: when you have updated your system to use the
testing branch there is usually no easy way back to the stable, official branch
(except for using backups of course).
3.b. Mixing Stable with Testing
The package.accept_keywords location
You can ask Portage to allow the testing branch for particular packages but use
the stable branch for the rest of the system. To achieve this, add the package
category and name you want to use the testing branch of in
/etc/portage/package.accept_keywords. You can also create a
directory (with the same name) and list the package in the files under that
directory. For instance, to use the testing branch for gnumeric:
Code Listing 2.1: /etc/portage/package.accept_keywords setting for gnumeric
Test Particular Versions
If you want to use a specific software version from the testing branch but you
don't want Portage to use the testing branch for subsequent versions, you can
add in the version in the package.accept_keywords location. In this
case you must use the = operator. You can also enter a version range
using the <=, <, > or >= operators.
In any case, if you add version information, you must use an operator. If
you leave out version information, you cannot use an operator.
In the following example we ask Portage to accept gnumeric-1.2.13:
Code Listing 2.2: Enabling a particular gnumeric test version
3.c. Using Masked Packages
The package.unmask location
The Gentoo developers do not support the use of this location. Please
exercise due caution when doing so. Support requests related to
package.unmask and/or package.mask will not be answered. You have
been warned.
When a package has been masked by the Gentoo developers and you still want to
use it despite the reason mentioned in the package.mask file
(situated in /usr/portage/profiles by default), add the
desired version (usually this will be the exact same line from
profiles) in the /etc/portage/package.unmask file
(or in a file in that directory if it is a directory).
For instance, if =net-mail/hotwayd-0.8 is masked, you can unmask it by
adding the exact same line in the package.unmask location:
Code Listing 3.1: /etc/portage/package.unmask
If an entry in /usr/portage/profiles/package.mask contains a range
of package versions, you will need to unmask only the version(s) you actually
want. Please read the previous section to learn how
to specify versions in package.unmask.
The package.mask location
When you don't want Portage to take a certain package or a specific version of a
package into account you can mask it yourself by adding an appropriate line to
the /etc/portage/package.mask location (either in that file or
in a file in this directory).
For instance, if you don't want Portage to install newer kernel sources than
gentoo-sources-220.127.116.11, you add the following line at the
package.mask location:
Code Listing 3.2: /etc/portage/package.mask example
4.a. dispatch-conf
dispatch-conf is a tool that aids in merging the
._cfg0000_<name> files. ._cfg0000_<name>
files are generated by Portage when it wants to overwrite a file in a directory
protected by the CONFIG_PROTECT variable.
With dispatch-conf, you are able to merge updates to your configuration
files while keeping track of all changes. dispatch-conf stores the
differences between the configuration files as patches or by using the RCS
revision system. This means that if you make a mistake when updating a config
file, you can revert to the previous version of your config file at any time.
When using dispatch-conf, you can ask to keep the configuration file
as-is, use the new configuration file, edit the current one or merge the changes
interactively. dispatch-conf also has some nice additional features:
Make certain you edit /etc/dispatch-conf.conf first and create the
directory referenced by the archive-dir variable.
Code Listing 1.1: Running dispatch-conf
# dispatch-conf
When running dispatch-conf, you'll be taken through each changed config
file, one at a time. Press u to update (replace) the current config file
with the new one and continue to the next file. Press z to zap (delete)
the new config file and continue to the next file. Once all config files have
been taken care of, dispatch-conf will exit. You can also press q
to exit any time.
For more information, check out the dispatch-conf man page. It tells you
how to interactively merge current and new config files, edit new config files,
examine differences between files, and more.
Code Listing 1.2: Reading the dispatch-conf man page
$ man dispatch-conf
4.b. etc-update
You can also use etc-update to merge config files. It's not as simple to
use as dispatch-conf, nor as featureful, but it does provide an
interactive merging setup and can also auto-merge trivial changes.
However, unlike dispatch-conf, etc-update does not preserve
the old versions of your config files. Once you update the file, the old version
is gone forever! So be very careful, as using etc-update is
significantly less safe than using dispatch-conf.
Code Listing 2.1: Running etc-update
# etc-update
After merging the straightforward changes, you will be prompted with a list of
protected files that have an update waiting. At the bottom you are greeted by
the possible options:
Code Listing 2.2: etc-update options
Please select a file to edit by entering the corresponding number.
(-1 to exit) (-3 to auto merge all remaining files)
(-5 to auto-merge AND not use 'mv -i'):
If you enter -1, etc-update will exit and discontinue any further
changes. If you enter -3 or -5, all listed configuration
files will be overwritten with the newer versions. It is therefore very
important to first select the configuration files that should not be
automatically updated. This is simply a matter of entering the number listed to
the left of that configuration file.
As an example, we select the configuration file /etc/pear.conf:
Code Listing 2.3: Updating a specific configuration file
Beginning of differences between /etc/pear.conf and /etc/._cfg0000_pear.conf
End of differences between /etc/pear.conf and /etc/._cfg0000_pear.conf
1) Replace original with update
2) Delete update, keeping original as is
3) Interactively merge original with update
4) Show differences again
You can now see the differences between the two files. If you believe that the
updated configuration file can be used without problems, enter 1. If you
believe that the updated configuration file isn't necessary, or doesn't provide
any new or useful information, enter 2. If you want to interactively
update your current configuration file, enter 3.
There is no point in further elaborating the interactive merging here. For
completeness sake, we will list the possible commands you can use while you are
interactively merging the two files. You are greeted with two lines (the
original one, and the proposed new one) and a prompt at which you can enter one
of the following commands:
Code Listing 2.4: Commands available for the interactive merging
ed: Edit then use both versions, each decorated with a header.
eb: Edit then use both versions.
el: Edit then use the left version.
er: Edit then use the right version.
e: Edit a new version.
l: Use the left version.
r: Use the right version.
s: Silently include common lines.
v: Verbosely include common lines.
q: Quit.
When you have finished updating the important configuration files, you can now
automatically update all the other configuration files. etc-update will
exit if it doesn't find any more updateable configuration files.
4.c. quickpkg
With quickpkg you can create archives of the packages that are already
merged on your system. These archives can be used as prebuilt packages. Running
quickpkg is straightforward: just add the names of the packages you want
to archive.
For instance, to archive curl, orage, and procps:
Code Listing 3.1: Example quickpkg usage
# quickpkg curl orage procps
The prebuilt packages will be stored in $PKGDIR
(/usr/portage/packages/ by default). These packages are placed in
5.a. Using a Portage Tree Subset
Excluding Packages/Categories
You can selectively update certain categories/packages and ignore the other
categories/packages. We achieve this by having rsync exclude
categories/packages during the emerge --sync step.
You need to define the name of the file that contains the exclude patterns in
the PORTAGE_RSYNC_EXTRA_OPTS variable in your /etc/portage/make.conf.
Code Listing 1.1: Defining the exclude file in /etc/portage/make.conf
Code Listing 1.2: Excluding all games in /etc/portage/rsync_excludes
Note however that this may lead to dependency issues since new, allowed packages
might depend on new but excluded packages.
5.b. Adding Unofficial Ebuilds
Defining a Portage Overlay Directory
You can ask Portage to use ebuilds that are not officially available through the
Portage tree. Create a new directory (for instance
/usr/local/portage) in which you store the 3rd-party ebuilds. Use
the same directory structure as the official Portage tree!
Then define PORTDIR_OVERLAY in /etc/portage/make.conf and have it
point to the previously defined directory. When you use Portage now, it will
take those ebuilds into account as well without removing/overwriting those
ebuilds the next time you run emerge --sync.
Working with Several Overlays
For the powerusers who develop on several overlays, test packages before they
hit the Portage tree or just want to use unofficial ebuilds from various
sources, the app-portage/layman package brings you
layman, a tool to help you keep the overlay repositories up to date.
First install and configure layman as shown in the Overlays Users' Guide, and add your
desired repositories with layman -a <overlay-name>.
Suppose you have two repositories called java (for the in-development
java ebuilds) and entapps (for the applications developed in-house for
your enterprise). You can update those repositories with the following
Code Listing 2.1: Using layman to update all repositories
# layman -S
For more information on working with overlays, please read man layman and
the layman/overlay users'
5.c. Non-Portage Maintained Software
Using Portage with Self-Maintained Software
In some cases you want to configure, install and maintain software yourself
without having Portage automate the process for you, even though Portage
can provide the software titles. Known cases are kernel sources and nvidia
drivers. You can configure Portage so it knows that a certain package is
manually installed on your system. This process is called injecting and
supported by Portage through the
/etc/portage/profile/package.provided file.
For instance, if you want to inform Portage about
gentoo-sources-126.96.36.199 which you've installed manually, add the
following line to /etc/portage/profile/package.provided:
Code Listing 3.1: Example line for package.provided
6.a. Introduction
For most users, the information received thus far is sufficient for all their
Linux operations. But Portage is capable of much more; many of its features are
for advanced users or only applicable in specific corner cases. Still, that
would not be an excuse not to document them.
Of course, with lots of flexibility comes a huge list of potential cases. It
will not be possible to document them all here. Instead, we hope to focus on
some generic issues which you can then bend to fit your own needs. If you have
need for more specific tweaks and tips, you might find them on the Gentoo Wiki instead.
Most, if not all of these additional features can be easily found by digging
through the manual pages that portage provides:
Code Listing 1.1: Reading up on portage man pages
Finally, know that these are advanced features which, if not worked with
correctly, can make debugging and troubleshooting very difficult. Make sure you
mention these if you think you hit a bug and want to open a bugreport.
6.b. Per-Package Environment Variables
Using /etc/portage/env
By default, package builds will use the environment variables defined in
/etc/portage/make.conf, such as CFLAGS, MAKEOPTS
and more. In some cases though, you might want to provide different variables
for specific packages. To do so, Portage supports the use of
/etc/portage/env and /etc/portage/package.env.
The /etc/portage/package.env file contains the list of packages for
which you want deviating variables as well as a specific identifier that tells
Portage which changes you want. The identifier name you pick yourself, Portage
will look for the variables in the /etc/portage/env/<identifier>
Example: Using debugging for specific packages
As an example, we enable debugging for the media-video/mplayer
First of all, we set the debugging variables in a file called
/etc/portage/env/debug-cflags. The name is arbitrarily chosen, but
of course reflects the reason of the deviation to make it more obvious later why
a deviation was put in.
Code Listing 2.1: /etc/portage/env/debug-cflags content
CFLAGS="-O2 -ggdb -pipe"
FEATURES="${FEATURES} nostrip"
Next, we tag the media-video/mplayer package to use this content:
Code Listing 2.2: /etc/portage/package.env content
media-video/mplayer debug-cflags
6.c. Hooking In the Emerge Process
Using /etc/portage/bashrc and affiliated files
When Portage works with ebuilds, it uses a bash environment in which it calls
the various build functions (like src_prepare, src_configure, pkg_postinst,
etc.). But Portage also allows you to set up a bash environment yourself.
The advantage of using your own bash environment is that you can hook in the
emerge process during each step it performs. This can be done for every emerge
(through /etc/portage/bashrc) or by using per-package environments
(through /etc/portage/env as discussed earlier).
To hook in the process, the bash environment can listen to the variables
EBUILD_PHASE, CATEGORY as well as the variables that are always
available during ebuild development (such as P, PF, ...). Based on
the values of these variables, you can then execute additional steps.
Example: Updating File Databases
In this example, we'll use /etc/portage/bashrc to call some file
database applications to ensure their databases are up to date with the system.
The applications used in the example are aide (an intrusion detection
tool) and updatedb (to use with locate), but these are meant as
examples. Do not consider this as a HOWTO for AIDE ;-)
To use /etc/portage/bashrc for this case, we need to "hook" in the
postrm (after removal of files) and postinst (after installation
of files) functions, because that is when the files on the file system have been
Code Listing 3.1: Example /etc/portage/bashrc
if [ "${EBUILD_PHASE}" == "postinst" ] || [ "${EBUILD_PHASE}" == "postrm" ];
echo ":: Calling aide --update to update its database";
aide --update;
echo ":: Calling updatedb to update its database";
6.d. Executing Tasks After --sync
The /etc/portage/postsync.d location
Until now we've talked about hooking into the ebuild processes. However, Portage
also has another important function: updating the Portage tree. In order to run
tasks after updating the Portage tree, put a script inside
/etc/portage/postsync.d and make sure it is marked as executable.
Example: Running eix-update
If you didn't use eix-sync to update the tree, you can still have its
database updated after running emerge --sync (or emerge-webrsync)
by putting a symlink to /usr/bin/eix called eix-update
in /etc/portage/postsync.d.
Code Listing 4.1: Running eix-update after a sync operation
# ln -s /usr/bin/eix /etc/portage/postsync.d/eix-update
If you rather use a different name, you will need to make a script that calls
/usr/bin/eix-update instead. The eix binary looks at how it has
been called to find out which function it has to execute. If you put in a
symlink to eix that isn't called eix-update, it will not run
6.e. Overriding Profile Settings
The /etc/portage/profile location
By default, Gentoo uses the settings contained in the profile pointed to by
/etc/portage/make.profile (a symbolic link to the right profile
directory). These profiles define both specific settings as well as inherit
settings from other profiles (through their parent file).
By using /etc/portage/profile, you can override profile settings
such as packages (what packages are considered to be part of the
system set), forced use flags and more.
Example: Adding nfs-utils to the System Set
If you use NFS-based file systems for rather critical file systems, you might
want to have net-fs/nfs-utils "protected" as a system package,
causing Portage to heavily warn you if it would be deleted.
To accomplish that, we add the package to
/etc/portage/profile/packages, prepended with a *:
Code Listing 5.1: /etc/portage/profile/packages content
6.f. Applying Non-Standard Patches
Using epatch_user
To manage several ebuilds in a similar manner, ebuild developers use
eclasses (sort-of shell libraries) that define commonly used functions.
One of these eclasses is eutils.eclass which offers an interesting
function called epatch_user.
The epatch_user function applies source code patches that are found in
whatever directory is found first. Sadly, not all ebuilds automatically call
this function so just putting your patch in this location might not always work.
Luckily, with the information provided above, you can call this function by
hooking into, for instance, the prepare phase. The function can be called
as many times as you like - it will only apply the patches once.
Example: Applying Patches to Firefox
The www-client/firefox package is one of the few that already call
epatch_user from within the ebuild, so you do not need to override
anything specific.
If you need to patch firefox (for instance because a developer provided you with
a patch and asked you to check if it fixes the bug you reported), put the patch in
/etc/portage/patches/www-client/firefox (probably best to use the
full name, including version so that the patch does not interfere with later
versions) and rebuild firefox.
1.a. Getting started
This document assumes that you have correctly configured your kernel, its
modules for your hardware and you know the interface name of your hardware.
We also assume that you are configuring eth0, but it could also be
eno0, ens1, wlan0, enp1s0 etc.
To get started configuring your network card, you need to tell the Gentoo RC
system about it. This is done by creating a symbolic link from
net.lo to net.eth0 (or whatever the network interface
name is on your system) in /etc/init.d.
Code Listing 1.1: Symlinking net.eth0 to net.lo
# cd /etc/init.d
# ln -s net.lo net.eth0
Gentoo's RC system now knows about that interface. It also needs to know how
to configure the new interface. All the network interfaces are configured in
/etc/conf.d/net. Below is a sample configuration for DHCP and
static addresses.
Code Listing 1.2: Examples for /etc/conf.d/net
# For DHCP
# For static IP using CIDR notation
routes_eth0="default via 192.168.0.1"
dns_servers_eth0="192.168.0.1 188.8.131.52"
# For static IP using netmask notation
config_eth0="192.168.0.7 netmask 255.255.255.0"
routes_eth0="default via 192.168.0.1"
dns_servers_eth0="192.168.0.1 188.8.131.52"
If you do not specify a configuration for your interface then DHCP is assumed.
CIDR stands for Classless InterDomain Routing. Originally, IPv4 addresses were
classified as A, B, or C. The early classification system did not envision the
massive popularity of the Internet, and is in danger of running out of new
unique addresses. CIDR is an addressing scheme that allows one IP address to
designate many IP addresses. A CIDR IP address looks like a normal IP address
except that it ends with a slash followed by a number; for example,
192.168.0.0/16. CIDR is described in RFC 1519.
Now that we have configured our interface, we can start and stop it using the
following commands:
Code Listing 1.3: Starting and stopping network scripts
# /etc/init.d/net.eth0 start
# /etc/init.d/net.eth0 stop
When troubleshooting networking, take a look at /var/log/rc.log.
Unless you have rc_logger="NO" set in /etc/rc.conf, you
will find information on the boot activity stored in that log file.
Now that you have successfully started and stopped your network interface, you
may wish to get it to start when Gentoo boots. Here's how to do this. The last
"rc" command instructs Gentoo to start any scripts in the current runlevel
that have not yet been started.
Code Listing 1.4: Configuring a network interface to load at boot time
# rc-update add net.eth0 default
# rc
2.a. Advanced Configuration
The config_eth0 variable is the heart of an interface configuration. It's
a high level instruction list for configuring the interface (eth0 in this
case). Each command in the instruction list is performed sequentially. The
interface is deemed OK if at least one command works.
Here's a list of built-in instructions.
If a command fails, you can specify a fallback command. The fallback has to
match the config structure exactly.
You can chain these commands together. Here are some real world examples.
Code Listing 1.1: Configuration examples
# Adding three IPv4 addresses
# Adding an IPv4 address and two IPv6 addresses
# Keep our kernel assigned address, unless the interface goes
# down so assign another via DHCP. If DHCP fails then add a
# static address determined by APIPA
When using the ifconfig module and adding more than one address,
interface aliases are created for each extra address. So with the above two
examples you will get interfaces eth0, eth0:1 and eth0:2.
You cannot do anything special with these interfaces as the kernel and other
programs will just treat eth0:1 and eth0:2 as eth0.
The fallback order is important! If we did not specify the null option
then the apipa command would only be run if the noop command
APIPA and DHCP are discussed later.
2.b. Network Dependencies
Init scripts in /etc/init.d can depend on a specific network
interface or just net. All network interfaces in Gentoo's init system provide
what is called net.
If, in /etc/rc.conf, rc_depend_strict="YES" is set, then all
network interfaces that provide net must be active before a dependency on "net"
is assumed to be met. In other words, if you have a net.eth0 and
net.eth1 and an init script depends on "net", then both must be
On the other hand, if rc_depend_strict="NO" is set, then the "net"
dependency is marked as resolved the moment at least one network interface is
brought up.
But what about net.br0 depending on net.eth0 and
net.eth1? net.eth1 may be a wireless or PPP device
that needs configuration before it can be added to the bridge. This cannot be
done in /etc/init.d/net.br0 as that's a symbolic link to
The answer is defining an rc_need_ setting in
Code Listing 2.1: net.br0 dependency in /etc/conf.d/net
rc_need_br0="net.eth0 net.eth1"
That alone, however, is not sufficient. Gentoo's networking init scripts use a
virtual dependency called net to inform the system when networking is
available. Clearly, in the above case, networking should only be marked as
available when net.br0 is up, not when the others are. So we need
to tell that in /etc/conf.d/net as well:
Code Listing 2.2: Updating virtual dependencies and provisions for networking
For a more detailed discussion about dependency, consult the section Writing Init Scripts in the Gentoo
Handbook. More information about /etc/rc.conf is available as
comments within that file.
2.c. Variable names and values
Variable names are dynamic. They normally follow the structure of
variable_${interface|mac|essid|apmac}. For example, the variable
dhcpcd_eth0 holds the value for dhcpcd options for eth0 and
dhcpcd_essid holds the value for dhcpcd options when any interface
connects to the ESSID "essid".
However, there is no hard and fast rule that states interface names must be
ethx. In fact, many wireless interfaces have names like wlanx, rax as well as
ethx. Also, some user defined interfaces such as bridges can be given any name,
such as foo. To make life more interesting, wireless Access Points can have
names with non alpha-numeric characters in them - this is important because
you can configure networking parameters per ESSID.
The downside of all this is that Gentoo uses bash variables for networking -
and bash cannot use anything outside of English alpha-numerics. To get around
this limitation we change every character that is not an English alpha-numeric
into a _ character.
Another downside of bash is the content of variables - some characters need to
be escaped. This can be achived by placing the \ character in front of
the character that needs to be escaped. The following list of characters needs
to be escaped in this way: ", ' and \.
In this example we use wireless ESSID as they can contain the widest scope
of characters. We shall use the ESSID My "\ NET:
Code Listing 3.1: variable name example
(This does work, but the domain is invalid)
dns_domain_My____NET="My \"\\ NET"
(The above sets the dns domain to My "\ NET when a wireless card
connects to an AP whose ESSID is My "\ NET)
2.d. Network Interface Naming
How It Works
Network interface names are not chosen arbitrarily: the Linux kernel and the
device manager (most systems have udev as their device manager although others
are available as well) choose the interface name through a fixed set of rules.
When an interface card is detected on a system, the Linux kernel gathers the
necessary data about this card. This includes:
Based on this information, the device manager decides how to name the interface
on the system. By default, it uses the first hit of the first three parameters
above (ID_NET_NAME_ONBOARD, _SLOT or _PATH).
For instance, if ID_NET_NAME_ONBOARD is found and set to eno1, then
the interface will be called eno1.
If you know your interface name, you can see the values of the provided
parameters using udevadm:
Code Listing 4.1: Reading the network interface card information
# udevadm test-builtin net_id /sys/class/net/enp3s0 2>/dev/null
ID_OUI_FROM_DATABASE=Quanta Computer Inc.
As the first (and actually only) hit of the top three parameters is the
ID_NET_NAME_PATH one, its value is used as the interface name. If none of
the parameters is found, then the system reverts back to the kernel-provided
naming (eth0, eth1, etc.)
Using the Old-style Kernel Naming
Before this change, network interface cards were named by the Linux kernel
itself, depending on the order that drivers are loaded (amongst other, possibly
more obscure reasons). This behavior can still be enabled by setting the
net.ifnames=0 boot option in the boot loader.
Another way of disabling this behavior (and thus reverting back to the
kernel-provided naming) is to create an empty udev rule named
80-net-name-slot.rules which will then override the default
provided one (with the same name) that is responsible for taking care of network
interface naming.
Code Listing 4.2: Overriding the network naming scheme
# ln -s /dev/null /etc/udev/rules.d/80-net-name-slot.rules
Using your Own Names
The entire idea behind the change in naming is not to confuse people, but to
make changing the names easier. Suppose you have two interfaces that are
otherwise called eth0 and eth1. One is meant to access the network through a
wire, the other one is for wireless access. With the support for interface
naming, you can have these called lan0 (wired) and wifi0 (wireless - it is best
to avoid using the previously well-known names like eth* and wlan* as those can
still collide with your suggested names).
All you need to do is to find out what the parameters are for the cards and then
use this information to set up your own naming rule:
Code Listing 4.3: Setting the lan0 name for the current eth0 interface
# udevadm test-builtin net_id /sys/class/net/eth0 2>/dev/null
ID_OUI_FROM_DATABASE=Quanta Computer Inc.
# vim /etc/udev/rules.d/76-net-name-use-custom.rules
# First one uses MAC information
SUBSYSTEM=="net", ACTION=="add", ENV{ID_NET_NAME_MAC}=="enxc80aa9429d76", NAME="lan0"
# Second one uses ID_NET_NAME_PATH information
SUBSYSTEM=="net", ACTION=="add", ENV{ID_NET_NAME_PATH}=="enp3s0", NAME="wifi0"
Because the rules are triggered before the default one (rules are triggered in
alphanumerical order, so 70 comes before 80) the names provided in the rule file
will be used instead of the default ones. The number granted to the file should
be between 76 and 79 (the environment variables are defined by a rule start
starts with 75 and the fallback naming is done in a rule numbered 80).
3.a. Network Modules
We now support modular networking scripts, which means we can easily add support
for new interface types and configuration modules while keeping compatibility
with existing ones.
Modules load by default if the package they need is installed. If you specify a
module here that doesn't have its package installed then you get an error
stating which package you need to install. Ideally, you only use the modules
setting when you have two or more packages installed that supply the same
service and you need to prefer one over the other.
All settings discussed here are stored in /etc/conf.d/net unless
otherwise specified.
Code Listing 1.1: Module preference
# Prefer ifconfig over iproute2
# You can also specify other modules for an interface
# In this case we prefer pump over dhcpcd
# You can also specify which modules not to use - for example you may be
# using a supplicant or linux-wlan-ng to control wireless configuration but
# you still want to configure network settings per ESSID associated with.
3.b. Interface Handlers
We provide two interface handlers presently: ifconfig and
iproute2. You need one of these to do any kind of network configuration.
ifconfig is installed by default (the net-tools package is part of
the system profile). iproute2 is a more powerful and flexible package,
but it's not included by default.
Code Listing 2.1: To install iproute2
# emerge sys-apps/iproute2
# To prefer ifconfig over iproute2 if both are installed as openrc prefers
# to use iproute2 then
As both ifconfig and iproute2 do very similar things we allow
their basic configuration to work with each other. For example both the below
code snippet work regardless of which module you are using.
Code Listing 2.2: ifconfig and iproute2 examples
config_eth0="192.168.0.2 netmask 255.255.255.0"
# We can also specify broadcast
config_eth0="192.168.0.2/24 brd 192.168.0.255"
config_eth0="192.168.0.2 netmask 255.255.255.0 broadcast 192.168.0.255"
3.c. DHCP
DHCP is a means of obtaining network information (IP address, DNS servers,
Gateway, etc) from a DHCP server. This means that if there is a DHCP server
running on the network, you just have to tell each client to use DHCP and it
sets up the network all by itself. Of course, you will have to configure for
other things like wireless, PPP or other things if required before you can use
DHCP can be provided by dhclient, dhcpcd, or pump. Each
DHCP module has its pros and cons - here's a quick run down.
If you have more than one DHCP client installed, you need to specify which one
to use - otherwise we default to dhcpcd if available.
To send specific options to the DHCP module, use module_eth0="..."
(change module to the DHCP module you're using - i.e. dhcpcd_eth0).
We try and make DHCP relatively agnostic - as such we support the following
commands using the dhcp_eth0 variable. The default is not to set any of
Code Listing 3.1: Sample DHCP configuration in /etc/conf.d/net
# Only needed if you have more than one DHCP module installed
dhcpcd_eth0="-t 10" # Timeout after 10 seconds
dhcp_eth0="release nodns nontp nonis" # Only get an address
dhcpcd and pump send the current hostname to the
DHCP server by default so you don't need to specify this anymore.
3.d. ADSL with PPPoE/PPPoA
First we need to install the ADSL software.
Code Listing 4.1: Install the ppp package
# emerge net-dialup/ppp
Second, create the PPP net script and the net script for the ethernet interface
to be used by PPP:
Code Listing 4.2: Creating the PPP and ethernet scripts
# ln -s /etc/init.d/net.lo /etc/init.d/net.ppp0
# ln -s /etc/init.d/net.lo /etc/init.d/net.eth0
Be sure to set rc_depend_strict to "YES" in /etc/rc.conf.
Now we need to configure /etc/conf.d/net.
Code Listing 4.3: A basic PPPoE setup
config_eth0=null (Specify your ethernet interface)
link_ppp0="eth0" (Specify your ethernet interface)
holdoff 3
child-timeout 60
lcp-echo-interval 15
lcp-echo-failure 3
noaccomp noccp nobsdcomp nodeflate nopcomp novj novjccomp"
You can also set your password in /etc/ppp/pap-secrets.
Code Listing 4.4: Sample /etc/ppp/pap-secrets
# The * is important
"username" * "password"
If you use PPPoE with a USB modem you'll need to emerge br2684ctl. Please
read /usr/portage/net-dialup/speedtouch-usb/files/README for
information on how to properly configure it.
Please carefully read the section on ADSL and PPP in
/usr/share/doc/netifrc-*/net.example.bz2. It contains many
more detailed explanations of all the settings your particular PPP setup will
likely need.
3.e. APIPA (Automatic Private IP Addressing)
APIPA tries to find a free address in the range 169.254.0.0-169.254.255.255 by
arping a random address in that range on the interface. If no reply is found
then we assign that address to the interface.
This is only useful for LANs where there is no DHCP server and you don't connect
directly to the internet and all other computers use APIPA.
For APIPA support, emerge net-misc/iputils or net-analyzer/arping.
Code Listing 5.1: APIPA configuration in /etc/conf.d/net
# Try DHCP first - if that fails then fallback to APIPA
# Just use APIPA
3.f. Bonding
For link bonding/trunking emerge net-misc/ifenslave.
Bonding is used to increase network bandwidth. If you have two network cards
going to the same network, you can bond them together so your applications see
just one interface but they really use both network cards.
First, clear the configuration of the participating interfaces:
Code Listing 6.1: Clearing interface configuration in /etc/conf.d/net
Next, define the bonding between the interfaces:
Code Listing 6.2: Define the bonding
slaves_bond0="eth0 eth1 eth2"
Remove the net.eth* services from the runlevels, create a
net.bond0 one and add that one to the correct runlevel.
3.g. Bridging (802.1d support)
For bridging support emerge net-misc/bridge-utils.
Bridging is used to join networks together. For example, you may have a server
that connects to the internet via an ADSL modem and a wireless access card to
enable other computers to connect to the internet via the ADSL modem. You could
create a bridge to join the two interfaces together.
Code Listing 7.1: Bridge configuration in /etc/conf.d/net
# Configure the bridge - "man brctl" for more details
brctl_br0="setfd 0
sethello 2
stp on"
# To add ports to bridge br0
bridge_br0="eth0 eth1"
# You need to configure the ports to null values so dhcp does not get started
# Finally give the bridge an address - you could use DHCP as well
# Depend on eth0 and eth1 as they may require extra configuration
rc_need_br0="net.eth0 net.eth1"
For using some bridge setups, you may need to consult the variable name documentation.
3.h. MAC Address
If you need to, you can change the MAC address of your interfaces through
the network configuration file too.
Code Listing 8.1: MAC Address change example
# To set the MAC address of the interface
# To randomize the last 3 bytes only
# To randomize between the same physical type of connection (e.g. fibre,
# copper, wireless) , all vendors
# To randomize between any physical type of connection (e.g. fibre, copper,
# wireless) , all vendors
# Full randomization - WARNING: some MAC addresses generated by this may
# NOT act as expected
3.i. Tunnelling
You don't need to emerge anything for tunnelling as the interface handler can do
it for you.
Code Listing 9.1: Tunnelling configuration in /etc/conf.d/net
# For GRE tunnels
iptunnel_vpn0="mode gre remote 126.96.36.199 key 0xffffffff ttl 255"
# For IPIP tunnels
iptunnel_vpn0="mode ipip remote 220.127.116.11 ttl 255"
# To configure the interface
config_vpn0="192.168.0.2 peer 192.168.1.1"
3.j. VLAN (802.1q support)
For VLAN support, emerge net-misc/vconfig. Also make sure that you use
iproute2 as configuration module rather than ifconfig.
Virtual LAN is a group of network devices that behave as if they were connected
to a single network segment - even though they may not be. VLAN members can only
see members of the same VLAN even though they may share the same physical
To configure VLANs, first specify the VLAN numbers in
/etc/conf.d/net like so:
Code Listing 10.1: Specifying VLAN numbers
vlans_eth0="1 2"
Next, configure the interface for each VLAN:
Code Listing 10.2: Interface configuration for each VLAN
config_eth0_1="172.16.3.1 netmask 255.255.254.0"
routes_eth0_1="default via 172.16.3.254"
config_eth0_2="172.16.2.1 netmask 255.255.254.0"
routes_eth0_2="default via 172.16.2.254"
VLAN-specific configurations are handled by vconfig like so:
Code Listing 10.3: Configuring the VLANs
vlan1_ingress="2:6 3:5"
For using some VLAN setups, you may need to consult the variable name documentation.
4.a. Introduction
Wireless networking on Linux is usually pretty straightforward. There are two
ways of configuring wifi: graphical clients, or the command line.
The easiest way is to use a graphical client once you've installed a
desktop environment. Most graphical clients,
such as wicd and NetworkManager, are
pretty self-explanatory. They offer a handy point-and-click interface that gets
you on a network in just a few seconds.
wicd offers a command line utility in addition to the main
graphical interface. You can get it by emerging wicd with the
ncurses USE flag set. This wicd-curses utility is particularly
useful for folks who don't use a gtk-based desktop environment, but still want
an easy command line tool that doesn't require hand-editing configuration
However, if you don't want to use a graphical client, then you can configure
wifi on the command line by editing a few configuration files. This takes a bit
more time to setup, but it also requires the fewest packages to download and
install. Since the graphical clients are mostly self-explanatory (with helpful
screenshots at their homepages), we'll focus on the command line alternatives.
You can setup wireless networking on the command line by installing
wireless-tools or wpa_supplicant. The important thing to remember
is that you configure wireless networks on a global basis and not an interface
wpa_supplicant is the best choice. For a list of supported drivers, read the wpa_supplicant
wireless-tools supports nearly all cards and drivers, but it cannot
connect to WPA-only Access Points. If your networks only offer WEP encryption or
are completely open, you may prefer the simplicity of wireless-tools.
The linux-wlan-ng driver is not supported by baselayout at this time.
This is because linux-wlan-ng have its own setup and configuration which
is completely different to everyone else's. The linux-wlan-ng developers
are rumoured to be changing their setup over to wireless-tools, so when
this happens you may use linux-wlan-ng with baselayout.
Some wireless cards are deactivated by default. To activate them, please consult
your hardware documentation. Some of these cards can be unblocked using the
rfkill application. If that is the case, use "rfkill list" to see the available
cards and "rfkill unblock <index>" to activate the wireless functionality.
If not, you might need to unblock the wireless card through a button, switch
or special key combination on your laptop.
4.b. WPA Supplicant
WPA Supplicant is a
package that allows you to connect to WPA enabled access points.
Code Listing 2.1: Install wpa_supplicant
# emerge net-wireless/wpa_supplicant
You have to have CONFIG_PACKET enabled in your kernel for
wpa_supplicant to work. Try running grep CONFIG_PACKET
/usr/src/linux/.config to see if you have it enabled in your kernel.
Depending on your USE flags, wpa_supplicant can install a graphical
interface written in Qt4, which will integrate nicely with KDE. To get it, run
echo "net-wireless/wpa_supplicant qt4" >> /etc/portage/package.use as
root before emerging wpa_supplicant.
Now we have to configure /etc/conf.d/net to so that we prefer
wpa_supplicant over wireless-tools (if both are installed,
wireless-tools is the default).
Code Listing 2.2: configure /etc/conf.d/net for wpa_supplicant
# Prefer wpa_supplicant over wireless-tools
# It's important that we tell wpa_supplicant which driver we should
# be using as it's not very good at guessing yet
If you're using the host-ap driver you will need to put the card in Managed
mode before it can be used with wpa_supplicant correctly. You can use
iwconfig_eth0="mode managed" to achieve this in
That was simple, wasn't it? However, we still have to configure
wpa_supplicant itself which is a bit more tricky depending on how secure
the Access Points are that you are trying to connect to. The below example is
taken and simplified from
which ships with wpa_supplicant.
Code Listing 2.3: An example /etc/wpa_supplicant/wpa_supplicant.conf
# The below line not be changed otherwise we refuse to work
# Ensure that only root can read the WPA configuration
# Let wpa_supplicant take care of scanning and AP selection
# Simple case: WPA-PSK, PSK as an ASCII passphrase, allow all valid ciphers
psk="very secret passphrase"
# The higher the priority the sooner we are matched
# Same as previous, but request SSID-specific scanning (for APs that reject
# broadcast SSID)
ssid="second ssid"
psk="very secret passphrase"
# Only WPA-PSK is used. Any valid cipher combination is accepted
pairwise=CCMP TKIP
group=CCMP TKIP WEP104 WEP40
# Plaintext connection (no WPA, no IEEE 802.1X)
# Shared WEP key connection (no WPA, no IEEE 802.1X)
# Keys in quotes are ASCII keys
# Keys specified without quotes are hex keys
# Shared WEP key connection (no WPA, no IEEE 802.1X) using Shared Key
# IEEE 802.11 authentication
# IBSS/ad-hoc network with WPA-None/TKIP
ssid="test adhoc"
psk="secret passphrase"
4.c. Wireless Tools
Initial setup and Managed Mode
Tools provide a generic way to configure basic wireless interfaces up to
the WEP security level. While WEP is a weak security method it's also the most
Wireless Tools configuration is controlled by a few main variables. The sample
configuration file below should describe all you need. One thing to bear in mind
is that no configuration means "connect to the strongest unencrypted Access
Point" - we will always try and connect you to something.
Code Listing 3.1: Install wireless-tools
# emerge net-wireless/wireless-tools
Although you can store your wireless settings in
/etc/conf.d/wireless this guide recommends you store them in
You will need to consult the variable name documentation.
Code Listing 3.2: sample iwconfig setup in /etc/conf.d/net
# Prefer iwconfig over wpa_supplicant
# Configure WEP keys for Access Points called ESSID1 and ESSID2
# You may configure up to 4 WEP keys, but only 1 can be active at
# any time so we supply a default index of [1] to set key [1] and then
# again afterwards to change the active key to [1]
# We do this incase you define other ESSID's to use WEP keys other than 1
# Prefixing the key with s: means it's an ASCII key, otherwise a HEX key
# enc open specified open security (most secure)
# enc restricted specified restricted security (least secure)
key_ESSID1="[1] s:yourkeyhere key [1] enc open"
key_ESSID2="[1] aaaa-bbbb-cccc-dd key [1] enc restricted"
# The below only work when we scan for available Access Points
# Sometimes more than one Access Point is visible so we need to
# define a preferred order to connect in
preferred_aps="'ESSID1' 'ESSID2'"
Fine tune Access Point Selection
You can add some extra options to fine-tune your Access Point selection, but
these are not normally required.
You can decide whether we only connect to preferred Access Points or not. By
default if everything configured has failed and we can connect to an unencrypted
Access Point then we will. This can be controlled by the associate_order
variable. Here's a table of values and how they control this.
Finally we have some blacklist_aps and unique_ap selection.
blacklist_aps works in a similar way to preferred_aps.
unique_ap is a yes or no value that says if a second
wireless interface can connect to the same Access Point as the first interface.
Code Listing 3.3: blacklist_aps and unique_ap example
# Sometimes you never want to connect to certain access points
blacklist_aps="'ESSID3' 'ESSID4'"
# If you have more than one wireless card, you can say if you want
# to allow each card to associate with the same Access Point or not
# Values are "yes" and "no"
# Default is "yes"
Ad-Hoc and Master Modes
If you want to set yourself up as an Ad-Hoc node if you fail to connect to any
Access Point in managed mode, you can do that too.
Code Listing 3.4: fallback to ad-hoc mode
adhoc_essid_eth0="This Adhoc Node"
What about connecting to Ad-Hoc networks or running in Master mode to become an
Access Point? Here's a configuration just for that! You may need to specify WEP
keys as shown above.
Code Listing 3.5: sample ad-hoc/master configuration
# Set the mode - can be managed (default), ad-hoc or master
# Not all drivers support all modes
# Set the ESSID of the interface
# In managed mode, this forces the interface to try and connect to the
# specified ESSID and nothing else
essid_eth0="This Adhoc Node"
# We use channel 3 if you don't specify one
The below is taken verbatim from the BSD wavelan documentation found at the NetBSD
documentation. There are 14 channels possible; We are told that channels
1-11 are legal for North America, channels 1-13 for most of Europe, channels
10-13 for France, and only channel 14 for Japan. If in doubt, please refer to
the documentation that came with your card or access point. Make sure that the
channel you select is the same channel your access point (or the other card in
an ad-hoc network) is on. The default for cards sold in North America and most
of Europe is 3; the default for cards sold in France is 11, and the default for
cards sold in Japan is 14.
Troubleshooting Wireless Tools
There are some more variables you can use to help get your wireless up and
running due to driver or environment problems. Here's a table of other things
you can try.
4.d. Defining network configuration per ESSID
Sometimes, you need a static IP when you connect to ESSID1 and you need
DHCP when you connect to ESSID2. In fact, most module variables can be
defined per ESSID. Here's how we do this.
These work if you're using WPA Supplicant or Wireless Tools.
Code Listing 4.1: override network settings per ESSID
config_ESSID1="192.168.0.3/24 brd 192.168.0.255"
routes_ESSID1="default via 192.168.0.1"
fallback_route_ESSID2="default via 192.168.3.1"
# We can define nameservers and other things too
# NOTE: DHCP will override these unless it's told not to
dns_servers_ESSID1="192.168.0.1 192.168.0.2"
dns_search_domains_ESSID1="search.this.domain search.that.domain"
# You override by the MAC address of the Access Point
# This handy if you goto different locations that have the same ESSID
dhcpcd_001122334455="-t 10"
dns_servers_001122334455="192.168.0.1 192.168.0.2"
5.a. Standard function hooks
Four functions can be defined in /etc/conf.d/net which will be
called surrounding the start/stop operations. The functions are
called with the interface name first so that one function can control multiple
The return values for the preup() and predown() functions should
be 0 (success) to indicate that configuration or deconfiguration of the
interface can continue. If preup() returns a non-zero value, then
interface configuration will be aborted. If predown() returns a non-zero
value, then the interface will not be allowed to continue deconfiguration.
The return values for the postup() and postdown() functions are
ignored since there's nothing to do if they indicate failure.
${IFACE} is set to the interface being brought up/down. ${IFVAR}
is ${IFACE} converted to variable name bash allows.
Code Listing 1.1: pre/post up/down function examples in /etc/conf.d/net
preup() {
# Test for link on the interface prior to bringing it up. This
# only works on some network adapters and requires the ethtool
# package to be installed.
if ethtool ${IFACE} | grep -q 'Link detected: no'; then
ewarn "No link on ${IFACE}, aborting configuration"
return 1
# Remember to return 0 on success
return 0
predown() {
# The default in the script is to test for NFS root and disallow
# downing interfaces in that case. Note that if you specify a
# predown() function you will override that logic. Here it is, in
# case you still want it...
if is_net_fs /; then
eerror "root filesystem is network mounted -- can't stop ${IFACE}"
return 1
# Remember to return 0 on success
return 0
postup() {
# This function could be used, for example, to register with a
# dynamic DNS service. Another possibility would be to
# send/receive mail once the interface is brought up.
return 0
postdown() {
# This function is mostly here for completeness... I haven't
# thought of anything nifty to do with it yet ;-)
return 0
For more information on writing your own functions, please read
5.b. Wireless Tools function hooks
This will not work with WPA Supplicant - but the ${ESSID} and
${ESSIDVAR} variables are available in the postup() function.
Two functions can be defined in /etc/conf.d/net which will be
called surrounding the associate function. The functions are called with the
interface name first so that one function can control multiple adapters.
The return values for the preassociate() function should be 0 (success)
to indicate that configuration or deconfiguration of the interface can continue.
If preassociate() returns a non-zero value, then interface configuration
will be aborted.
The return value for the postassociate() function is ignored since
there's nothing to do if it indicates failure.
${ESSID} is set to the exact ESSID of the AP you're connecting to.
${ESSIDVAR} is ${ESSID} converted to a variable name bash allows.
Code Listing 2.1: pre/post association functions in /etc/conf.d/net
preassociate() {
# The below adds two configuration variables leap_user_ESSID
# and leap_pass_ESSID. When they are both configured for the ESSID
# being connected to then we run the CISCO LEAP script
local user pass
eval user=\"\$\{leap_user_${ESSIDVAR}\}\"
eval pass=\"\$\{leap_pass_${ESSIDVAR}\}\"
if [[ -n ${user} && -n ${pass} ]]; then
if [[ ! -x /opt/cisco/bin/leapscript ]]; then
eend "For LEAP support, please emerge net-misc/cisco-aironet-client-utils"
return 1
einfo "Waiting for LEAP Authentication on \"${ESSID//\\\\//}\""
if /opt/cisco/bin/leapscript ${user} ${pass} | grep -q 'Login incorrect'; then
ewarn "Login Failed for ${user}"
return 1
return 0
postassociate() {
# This function is mostly here for completeness... I haven't
# thought of anything nifty to do with it yet ;-)
return 0
${ESSID} and ${ESSIDVAR} are unavailable in predown() and
postdown() functions.
6.a. Network Management
If you and your computer are always on the move, you may not always have an
ethernet cable or plugged in or an access point available. Also, you may want
networking to automatically work when an ethernet cable is plugged in or an
access point is found.
Here you can find some tools that help you manage this.
This document only talks about ifplugd, but there are alternatives such
as netplug. netplug is a lightweight alternative to
ifplugd, but it relies on your kernel network drivers working correctly,
and many drivers do not.
6.b. ifplugd
ifplugd is a
daemon that starts and stops interfaces when an ethernet cable is inserted or
removed. It can also manage detecting association to Access Points or when new
ones come in range.
Code Listing 2.1: Installing ifplugd
# emerge sys-apps/ifplugd
Configuration for ifplugd is fairly straightforward too. The configuration file
is held in /etc/conf.d/net. Run man ifplugd for details on
the available variables. Also, see
/usr/share/doc/netifrc-*/net.example.bz2 for more examples.
Code Listing 2.2: Sample ifplug configuration
(Replace eth0 with the interface to be monitored)
(To monitor a wireless interface)
In addition to managing multiple network connections, you may want to add a tool
that makes it easy to work with multiple DNS servers and configurations. This is
very handy when you receive your IP address via DHCP. Simply emerge
Code Listing 2.3: Installing openresolv
# emerge openresolv
See man resolvconf to learn more about its features.
The contents of this document, unless otherwise expressly stated, are licensed under the CC-BY-SA-2.5 license. The Gentoo Name and Logo Usage Guidelines apply.
Page updated January 23, 2014
This is the Gentoo Handbook, an effort to centralize Gentoo/Linux information.
This handbook contains the installation instructions for an Internet-based
installation on AMD64 systems and parts about working with Gentoo and Portage.
Sven Vermeulen
Grant Goodyear
Roy Marples
Daniel Robbins
Chris Houser
Jerry Alexandratos
Seemant Kulleen
Gentoo x86 Developer
Tavis Ormandy
Gentoo Alpha Developer
Jason Huebel
Gentoo AMD64 Developer
Guy Martin
Gentoo HPPA developer
Pieter Van den Abeele
Gentoo PPC developer
Joe Kallar
Gentoo SPARC developer
John P. Davis
EditorPierre-Henri JondotEditor
Eric Stockbridge
Rajiv Manglani
Jungmin Seo
Stoyan Zhekov
Jared Hudson
Colin Morey
Jorge Paulo
Carl Anderson
Jon Portnoy
Zack Gilburd
Jack Morgan
Benny Chuang
Joshua Kinard
Tobias Scherbaum
Xavier Neys
Joshua Saddler
Gerald J. Normandin Jr.
Donnie Berkholz
Ken Nowack
Lars Weiler
Donate to support our development efforts.
Your browser does not support iframes.