## D.3. Disk Space Needed 

A minimal server installation of focal requires 400MB of disk space. 

## D.4. Installing Ubuntu from a Unix/Linux System 

This section explains how to install Ubuntu 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 Ubuntu from Debian, Red Hat, Mandriva, 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. 

Note: As this is a mostly manual procedure, you should bear in mind that you will need to do a lot of basic configuration of the system yourself, which will also require more knowledge of Ubuntu and of Linux in general than performing a regular installation. You cannot expect this procedure to result in a system that is identical to a system from a regular installation. You should also keep in mind that this procedure only gives the basic steps to set up a system. Additional installation and/or configuration steps may be needed. In general, this method of installation is not recommended for casual or first time users. 

## D.4.1. Getting Started 

With your current *nix partitioning tools, repartition the hard drive as needed, creating at least one filesystem plus swap. You need around 506MB of space available for a console only install. 

Next, create file systems on the partitions. For example, to create an ext3 file system on partition /dev/sda6 (that’s our example root partition): 

# mke2fs -j /dev/ sda6 

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/ sda5 # sync # swapon /dev/ sda5 

Note: Instead of using a dedicated swap partition, you may omit the swap partition setup here and later just use a swap file instead. 

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. 

