This section explains how to install Ubuntu from an existing
Unix or Linux system, without using the ncurses-based, menu-driven
installer as explained in the rest of the manual. This "cross-install"
HOWTO has been requested by users switching to Ubuntu from
Debian GNU/Linux, 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 Ubuntu chroot.
Once you've got the new Ubuntu 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" Ubuntu install. It's also a clever way for dealing with hardware that otherwise doesn't play friendly with various boot or installation media.
With your current *nix partitioning tools, repartition the hard drive as needed, creating at least one filesystem plus swap. You need at least 400MB of space available for a minimal server install, or at least 2GB if you plan to install the Ubuntu desktop.
To create file systems on your 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 Ubuntu swap partition):
# mkswap /dev/hda5 # sync; sync; sync # swapon /dev/hda5
Mount one partition as /mnt/ubuntu (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/ubuntu # mount /dev/hda6 /mnt/ubuntu
The tool that the Ubuntu installer uses, which is recognized as the
official way to install an Ubuntu base system, is
debootstrap. It uses wget and
ar, but otherwise depends only on
/bin/sh. Install wget and
ar if they aren't already on your current system,
then download and install debootstrap.
If you have an rpm-based system, you can use alien to convert the .deb into .rpm.
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 Ubuntu 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 binary files from it. You will need to have root privileges to install the binaries.
# tar -xf debootstrap_0.X.X_arch.deb # cd / # zcat /full-path-to-work/work/data.tar.gz | tar xv
debootstrap can download the needed files directly
from the archive when you run it. You can substitute any Ubuntu
archive mirror for archive.ubuntu.com/ubuntu in
the command example below, preferably a mirror close to you
network-wise. Mirrors are listed at
http://wiki.ubuntu.com/Archive.
If you have an Ubuntu breezy CD mounted at
/cdrom, you could substitute a file URL instead
of the http URL: file:/cdrom/ubuntu/
Substitute one of the following for ARCH
in the debootstrap command:
amd64,
i386,
ia64, or
powerpc.
# /usr/sbin/debootstrap --arch ARCH breezy \
/mnt/debinst http://http.us.debian.org/debian
Now you've got a real Ubuntu system, though rather lean, on disk. Chroot into it:
# chroot /mnt/ubuntu /bin/bash
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 / ext2 defaults 0 0 /dev/XXX /boot ext2 ro,nosuid,nodev 0 2 /dev/XXX none swap sw 0 0 proc /proc proc defaults 0 0 sys /sys sysfs defaults 0 0 /dev/fd0 /mnt/floppy auto noauto,rw,sync,user,exec 0 0 /dev/cdrom /mnt/cdrom iso9660 noauto,ro,user,exec 0 0 /dev/XXX /tmp ext2 rw,nosuid,nodev 0 2 /dev/XXX /var ext2 rw,nosuid,nodev 0 2 /dev/XXX /usr ext2 rw,nodev 0 2 /dev/XXX /home ext2 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
You can mount the proc and sysfs file systems multiple times and to arbitrary
locations, though /proc and /sys respectively are customary. If you didn't use
mount -a, be sure to mount proc and sysfs before
continuing:
# mount -t proc proc /proc # mount -t sysfs sysfs /sys
To configure networking, edit
/etc/network/interfaces,
/etc/resolv.conf, and
/etc/hostname.
# 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 /etc/resolv.conf:
search hqdom.local\000 nameserver 10.1.1.36 nameserver 192.168.9.100
Enter your system's host name (2 to 63 characters):
# echo UbuntuHostName > /etc/hostname
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.
Set your timezone, add a normal user, and choose your apt sources by running
# /usr/sbin/base-config new
To configure your locale settings to use a language other than English, install the locales support package and configure it:
# apt-get install locales # dpkg-reconfigure locales
NOTE: Apt must be configured before, ie. during the base-config phase. Before using locales with character sets other than ASCII or latin1, please consult the appropriate localization HOWTO.
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
Then install your choice using its package name.
# apt-get install linux-image-2.X.X-arch-etc
To make your Ubuntu 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 apt-get inside your Ubuntu chroot to do so.
At this point, you probably want to reboot into your new Ubuntu system to make sure it all works. Once you've done that, log in as the user you created in Section C.4.4.4, “Configure Timezone, Users, and APT”, and run:
$ sudo aptitude -y install ubuntu-standard ubuntu-desktop
You will need to enter your password to authorise sudo to run as root.
aptitude will now get on with installing the packages that make up the Ubuntu desktop, which will take a while. When it's finished, you should be presented with a graphical login prompt. The installation is now complete, so go ahead and log in.