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8. Configuring your System
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 mountpoints 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.)
/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 first field shows the partition described (the path to the device
The second field shows the mountpoint at which the partition should be
The third field shows the filesystem used by the partition
The fourth field shows the mountoptions used by mount when it
wants to mount the partition. As every filesystem has its own mountoptions,
you are encouraged to read the mount man page (man mount) for a full
listing. Multiple mountoptions are comma-separated.
The fifth field is used by dump to determine if the partition needs to
be dumped or not. You can generally leave this as 0 (zero).
The sixth field is used by fsck to determine the order in which
filesystems should be checked if the system wasn't shut down properly.
The root filesystem should have 1 while the rest should have 2
(or 0 if a filesystem check isn't necessary).
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
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 HPPA 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 1 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 1 2
/dev/sda3 none swap sw 0 0
/dev/sda4 / ext3 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).
Double-check your /etc/fstab, save and quit to continue.
8.b. Networking Information
Hostname, 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.
We use these values in the next examples. First we set the hostname:
Code Listing 2.1: Setting the hostname
# nano -w /etc/conf.d/hostname
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.
Code Listing 2.2: Setting the domainname
# nano -w /etc/conf.d/net
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
For more information on configuring DNS and NIS, please read the examples
provided in /etc/conf.d/net.example. Also, you may want to emerge
resolvconf-gentoo 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 and does not require any further configuration.
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
Code Listing 2.4: Opening /etc/conf.d/net for editing
# nano -w /etc/conf.d/net
You will see the following file:
Code Listing 2.5: Default /etc/conf.d/net
# This blank configuration will automatically use DHCP for any net.*
# scripts in /etc/init.d. To create a more complete configuration,
# please review /etc/conf.d/net.example and save your configuration
# in /etc/conf.d/net (this file :]!).
To enter your own IP address, netmask and gateway, you need
to set both config_eth0 and routes_eth0:
Code Listing 2.6: 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 and add specific DHCP options, define config_eth0 and
Code Listing 2.7: Automatically obtaining an IP address for eth0
config_eth0=( "dhcp" )
dhcp_eth0="nodns nontp nonis"
Please read /etc/conf.d/net.example for a list of all available
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
Code Listing 2.8: Adding net.eth0 to the default runlevel
# rc-update add net.eth0 default
If you have several network interfaces, you need to create the appropriate
net.eth1, net.eth2 etc. initscripts for those. You can
use ln to do this:
Code Listing 2.9: Creating extra initscripts
# cd /etc/init.d
# ln -s net.lo net.eth1
# rc-update add net.eth1 default
Writing Down Network Information
You now need to inform Linux about your network. This is defined in
/etc/hosts and helps in resolving hostnames 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 2.10: Opening /etc/hosts
# nano -w /etc/hosts
Code Listing 2.11: Filling in the networking information
127.0.0.1 tux.homenetwork tux localhost
192.168.0.5 jenny.homenetwork jenny
192.168.0.6 benny.homenetwork benny
Save and exit the editor to continue.
8.c. System Information
First we set the root password by typing:
Code Listing 3.1: Setting the root password
If you want root to be able to log on through the serial console, add
tts/0 to /etc/securetty:
Code Listing 3.2: Adding tts/0 to /etc/securetty
# echo "tts/0" >> /etc/securetty
Gentoo uses /etc/rc.conf for general, system-wide configuration.
Open up /etc/rc.conf and enjoy all the comments in that file :)
Code Listing 3.3: Opening /etc/rc.conf
# nano -w /etc/rc.conf
When you're finished configuring /etc/rc.conf, save and exit.
As you can see, this file is well commented to help you set up the necessary
configuration variables. You can configure your system to use unicode and
define your default editor and your display manager (like gdm or kdm).
Gentoo uses /etc/conf.d/keymaps to handle keyboard configuration.
Edit it to configure your keyboard.
Code Listing 3.4: 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/clock to set clock options. Edit it
according to your needs.
Code Listing 3.5: Opening /etc/conf.d/clock
# nano -w /etc/conf.d/clock
If your hardware clock is not using UTC, you need to add CLOCK="local" to
the file. Otherwise you will notice some clock skew.
You should define the timezone that you previously copied to
/etc/localtime so that further upgrades of the
sys-libs/timezone-data package can update /etc/localtime
automatically. For instance, if you used the GMT timezone, you would add
When you're finished configuring /etc/conf.d/clock, save and
Please continue with Installing Necessary System
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