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8. Configuring your System

Content:

Filesystem Information

Networking Information

System Information

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 first field shows the partition described (the path to the device file)

The second field shows the mount point at which the partition should be mounted

The third field shows the filesystem used by the partition

The fourth field shows the mount options used by mount when it wants to mount the

partition. As every filesystem has its own mount options, you are encouraged to read the

mount man page (man mount) for a full listing. Multiple mount options 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).

Important: 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 x86 partitioning example, /boot is usually the /dev/sda1 partition, with ext2 as

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Updated July 19, 2010

Summary: You need to

edit some important

configuration files. In this

chapter you receive an

overview of these files and

an explanation on how to

proceed.

Sven Vermeulen

Author

Grant Goodyear

Author

Roy Marples

Author

Daniel Robbins

Author

Chris Houser

Author

Jerry Alexandratos

Author

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

Editor

Pierre-Henri Jondot

Editor

Eric Stockbridge

Editor

Gentoo Linux Documentation -- Configuring your System http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=1&chap=8

1 of 5 8/22/2010 12:34 AM

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/sda1 /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/sda1 /boot ext2 defaults,noatime 1 2/dev/sda2 none swap sw 0 0

/dev/sda3 / ext3 noatime 0 1

/dev/cdrom /mnt/cdrom auto noauto,user 0 0

proc /proc proc defaults 0 0shm /dev/shm tmpfs nodev,nosuid,noexec 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

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)HOSTNAME="tux"

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

(Set the dns_domain variable to your domain name)

dns_domain_lo="homenetwork"

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Note: If you choose not to set a domainname, you can get rid of the "This is hostname.(none)" messages atyour 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


(Set the nis_domain variable to your NIS domain name)nis_domain_lo="my-nisdomain"

Note: 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 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.

Note: More detailed information about networking, including advanced topics like bonding, bridging, 802.1QVLANs 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

/etc/conf.d/net.example.

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


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, define config_eth0:


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Code Listing 2.7: Automatically obtaining an IP address for eth0

config_eth0=( "dhcp" )

Please read /etc/conf.d/net.example 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 2.8: 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 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 2.10: Opening /etc/hosts

# nano -w /etc/hosts

Code Listing 2.11: 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 2.12: Installing pcmciautils

# emerge pcmciautils


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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 for general, system-wide configuration. Open up /etc/rc.conf and

enjoy all the comments in that file :)

Code Listing 3.2: 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 3.3: 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 exit.

Gentoo uses /etc/conf.d/clock to set clock options. Edit it according to your needs.

Code Listing 3.4: 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 TIMEZONE="GMT"

When you're finished configuring /etc/conf.d/clock, save and exit.

Please continue with Installing Necessary System Tools.

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Copyright 2001-2010 Gentoo Foundation, Inc. Questions, Comments? Contact us.


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