D.3. Installing Debian GNU/Linux from a Unix/Linux System

This section explains how to install Debian GNU/Linux from an existing Unix or Linux system, without using the menu-driven installer as explained in the rest of the manual. This “cross-install” HOWTO has been requested by users switching to Debian GNU/Linux from Red Hat, Mandrake, and SUSE. In this section some familiarity with entering *nix commands and navigating the file system is assumed. In this section, $ symbolizes a command to be entered in the user's current system, while # refers to a command entered in the Debian chroot.

Once you've got the new Debian system configured to your preference, you can migrate your existing user data (if any) to it, and keep on rolling. This is therefore a “zero downtime” Debian GNU/Linux install. It's also a clever way for dealing with hardware that otherwise doesn't play friendly with various boot or installation media.

D.3.1. Getting Started

With your current *nix partitioning tools, repartition the hard drive as needed, creating at least one filesystem plus swap. You need around 350MB of space available for a console only install, or about 1GB if you plan to install X (more if you intend to install desktop environments like GNOME or KDE).

Next, create file systems on the partitions. For example, to create an ext3 file system on partition /dev/hda6 (that's our example root partition):

# mke2fs -j /dev/hda6

To create an ext2 file system instead, omit -j.

Initialize and activate swap (substitute the partition number for your intended Debian swap partition):

# mkswap /dev/hda5
# sync; sync; sync
# swapon /dev/hda5

Mount one partition as /mnt/debinst (the installation point, to be the root (/) filesystem on your new system). The mount point name is strictly arbitrary, it is referenced later below.

# mkdir /mnt/debinst
# mount /dev/hda6 /mnt/debinst

Note

If you want to have parts of the filesystem (e.g. /usr) mounted on separate partitions, you will need to create and mount these directories manually before proceding with the next stage.

D.3.2. Install debootstrap

The utility used by the Debian installer, and recognized as the official way to install a Debian base system, is debootstrap. It uses wget and ar, but otherwise depends only on /bin/sh and basic Unix/Linux tools[19]. Install wget and ar if they aren't already on your current system, then download and install debootstrap.

Or, you can use the following procedure to install it manually. Make a work folder for extracting the .deb into:

# mkdir work
# cd work

The debootstrap binary is located in the Debian archive (be sure to select the proper file for your architecture). Download the debootstrap .deb from the pool, copy the package to the work folder, and extract the files from it. You will need to have root privileges to install the files.

# ar -x debootstrap_0.X.X_all.deb
# cd /
# zcat /full-path-to-work/work/data.tar.gz | tar xv

D.3.3. Run debootstrap

debootstrap can download the needed files directly from the archive when you run it. You can substitute any Debian archive mirror for http.us.debian.org/debian in the command example below, preferably a mirror close to you network-wise. Mirrors are listed at http://www.debian.org/misc/README.mirrors.

If you have a etch Debian GNU/Linux CD mounted at /cdrom, you could substitute a file URL instead of the http URL: file:/cdrom/debian/

Substitute one of the following for ARCH in the debootstrap command: alpha, amd64, arm, hppa, i386, ia64, m68k, mips, mipsel, powerpc, s390, or sparc.

# /usr/sbin/debootstrap --arch ARCH etch \
     /mnt/debinst http://ftp.us.debian.org/debian

D.3.4. Configure The Base System

Now you've got a real Debian system, though rather lean, on disk. chroot into it:

# LANG=C chroot /mnt/debinst /bin/bash

After chrooting you may need to set the terminal definition to be compatible with the Debian base system, for example:

# export TERM=xterm-color

D.3.4.1. Mount Partitions

You need to create /etc/fstab.

# editor /etc/fstab

Here is a sample you can modify to suit:

# /etc/fstab: static file system information.
#
# file system    mount point   type    options                  dump pass
/dev/XXX         /             ext3    defaults                 0    1
/dev/XXX         /boot         ext3    ro,nosuid,nodev          0    2

/dev/XXX         none          swap    sw                       0    0
proc             /proc         proc    defaults                 0    0

/dev/fd0         /media/floppy auto    noauto,rw,sync,user,exec 0    0
/dev/cdrom       /media/cdrom  iso9660 noauto,ro,user,exec      0    0

/dev/XXX         /tmp          ext3    rw,nosuid,nodev          0    2
/dev/XXX         /var          ext3    rw,nosuid,nodev          0    2
/dev/XXX         /usr          ext3    rw,nodev                 0    2
/dev/XXX         /home         ext3    rw,nosuid,nodev          0    2

Use mount -a to mount all the file systems you have specified in your /etc/fstab, or, to mount file systems individually, use:

# mount /path   # e.g.: mount /usr

Current Debian systems have mountpoints for removable media under /media, but keep compatibility symlinks in /. Create these as as needed, for example:

# cd /media
# mkdir cdrom0
# ln -s cdrom0 cdrom
# cd /
# ln -s media/cdrom

You can mount the proc file system multiple times and to arbitrary locations, though /proc is customary. If you didn't use mount -a, be sure to mount proc before continuing:

# mount -t proc proc /proc

The command ls /proc should now show a non-empty directory. Should this fail, you may be able to mount proc from outside the chroot:

# mount -t proc proc /mnt/debinst/proc

D.3.4.2. Setting Timezone

An option in the file /etc/default/rcS determines whether the system will interpret the hardware clock as being set to UTC or local time. The following command allow you to set that and choose your timezone.

# editor /etc/default/rcS
# tzconfig

D.3.4.3. Configure Networking

To configure networking, edit /etc/network/interfaces, /etc/resolv.conf, /etc/hostname and /etc/hosts.

# editor /etc/network/interfaces

Here are some simple examples from /usr/share/doc/ifupdown/examples:

######################################################################
# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)
# See the interfaces(5) manpage for information on what options are
# available.
######################################################################

# We always want the loopback interface.
#
auto lo
iface lo inet loopback

# To use dhcp:
#
# auto eth0
# iface eth0 inet dhcp

# An example static IP setup: (broadcast and gateway are optional)
#
# auto eth0
# iface eth0 inet static
#     address 192.168.0.42
#     network 192.168.0.0
#     netmask 255.255.255.0
#     broadcast 192.168.0.255
#     gateway 192.168.0.1

Enter your nameserver(s) and search directives in /etc/resolv.conf:

# editor /etc/resolv.conf

A simple example /etc/resolv.conf:

search hqdom.local
nameserver 10.1.1.36
nameserver 192.168.9.100

Enter your system's host name (2 to 63 characters):

# echo DebianHostName > /etc/hostname

And a basic /etc/hosts with IPv6 support:

127.0.0.1 localhost DebianHostName

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

If you have multiple network cards, you should arrange the names of driver modules in the /etc/modules file into the desired order. Then during boot, each card will be associated with the interface name (eth0, eth1, etc.) that you expect.

D.3.4.4. Configure Apt

Debootstrap will have created a very basic /etc/apt/sources.list that will allow installing additional packages. However, you may want to add some additional sources, for example for source packages and security updates:

deb-src http://ftp.us.debian.org/debian etch main

deb http://security.debian.org/ etch/updates main
deb-src http://security.debian.org/ etch/updates main

Make sure to run aptitude update after you have made changes to the sources list.

D.3.4.5. Configure Locales and Keyboard

To configure your locale settings to use a language other than English, install the locales support package and configure it. Currently the use of UTF-8 locales is recommended.

# aptitude install locales
# dpkg-reconfigure locales

To configure your keyboard (if needed):

# aptitude install console-data
# dpkg-reconfigure console-data

Note that the keyboard cannot be set while in the chroot, but will be configured for the next reboot.

D.3.5. Install a Kernel

If you intend to boot this system, you probably want a Linux kernel and a boot loader. Identify available pre-packaged kernels with:

# apt-cache search linux-image

If you intend to use a pre-packaged kernel, you may want to create the configuration file /etc/kernel-img.conf before you do so. Here's an example file:

# Kernel image management overrides
# See kernel-img.conf(5) for details
do_symlinks = yes
relative_links = yes
do_bootloader = yes
do_bootfloppy = no
do_initrd = yes
link_in_boot = no

For detailed information about this file and the various options, consult its man page which will be available after installing the kernel-package package. We recommend that you check that the values are appropriate for your system.

Then install the kernel package of your choice using its package name.

# aptitude install linux-image-2.6.18-arch-etc

If you did not create a /etc/kernel-img.conf before installing a pre-packaged kernel, you may be asked some questions during its installation that refer to it.

D.3.6. Set up the Boot Loader

To make your Debian GNU/Linux system bootable, set up your boot loader to load the installed kernel with your new root partition. Note that debootstrap does not install a boot loader, though you can use aptitude inside your Debian chroot to do so.

D.3.7. Finishing touches

As mentioned earlier, the installed system will be very basic. If you would like to make the system a bit more mature, there is an easy method to install all packages with “standard” priority:

# tasksel install standard

Of course, you can also just use aptitude to install packages individually.

After the installation there will be a lot of downloaded packages in /var/cache/apt/archives/. You can free up some diskspace by running:

# aptitude clean



[19] These include the GNU core utilities and commands like sed, grep, tar and gzip.