First off, you will want to build images on a KVM capable machine. If not, you will be missing out on the hardware acceleration and your install will take forever!

virt-install

This is a command line tool written in python that will allow you to specify the layout of a guest, and do an installation of that guest.

Since the man page for this program contains most information you would want to know, I will keep this section short with just an example and a few quick notes.

The below example will create a 10GB sparse backing file, and start the installation from the ISO image specified in the --cdrom option. The disk is specified as having a bus type of virtio, this is only available if your distro has virtio drivers available. As of SL5.3 (RHEL5.3) the virtio drivers have been backported as well as all necessary software to support virtio(lvm2, etc) upgraded to enable you to use virtio. If you are using SL5.2 or less you must remove the bus=virtio option.

virt-install --connect qemu:///system \
    --os-type linux \
    --os-variant rhel5 \
    --name sl53 \
    --ram 256 \
    --disk path=/home/mvliet/sl53-pvm.img,bus=virtio,size=10,sparse=true \
    --cdrom /home/mvliet/SL.53.031809.DVD.i386.disc1.iso

The example below will create a 10GB guest image and start a net based install of fedora10. To achieve a truly text-only install, the --nographics option is used in combination with the --extra-args option. The provided arguments for the --extra-args option are specific to the Anaconda installer and inform it to enable a serial console for the installation process. Since the default behavior of virt-install is to connect to the guest console, you will immediately be connected to the serial console you told Anaconda to create. This method will also work for RedHat based distros (rhel, centos, scientific linux, etc.) as they will all use Anaconda.

sudo virt-install --connect qemu:///system \
    --os-type linux \
    --name fedora2 \
    --ram 512 \
    --disk path=/home/mvliet/fedora.img,bus=virtio,size=10,sparse=true \
    --location http://download.fedoraproject.org/pub/fedora/linux/releases/10/Fedora/i386/os/ \
    --nographics \
    --extra-args="serial console=tty0 console=ttyS0,115200"

The following example will create a 5GB guest image and start a net based install of ubuntu 10.10. Once again the --nographics option will be used.

sudo virt-install --connect qemu:///system --name maverick --disk path=/tmp/maverick.img --file-size=5 --ram=512 --accelerate --network=bridge:virbr0 --location http://ftp.ubuntu.com/ubuntu/dists/maverick/main/installer-i386/ --nographics --extra-args="console=ttyS0"

(Note: I seem to have more luck creating guests while using net installs as opposed to iso files. Here are some common locations:

Fedora: http://download.fedoraproject.org/pub/fedora/linux/releases/13/Fedora/i386/os/ Change "13" to the Fedora release, and "i386" to x86_64 for a 64 bit guest. 
Debian: http://ftp.us.debian.org/debian/dists/stable/main/installer-i386/ Change "us" to your country code (for faster access to a local mirror), and "i386" to amd64 for a 64 bit guest. 
Ubuntu: http://ftp.ubuntu.com/ubuntu/dists/maverick/main/installer-i386/ Change "maverick" to the name of the version of Ubuntu to install, and "i386" to amd64 for a 64 bit guest.

NOTES:

• The --accelerate option used in previous versions of this document is now depreciated in new versions of virt-install.
• the --cdrom option can point to an actual drive (ie, /dev/hdc), or a iso file on your local machine.
• use --location for a remote file (ftp, http, etc.).
• ram is specified in MB, disk size is specified in GB.
• the --disk option may be of more use to you the --file.

virt-manager

One of the features of virt-manager is the ability to create new guests by using a nice GUI. There are some features you will not have access to with this approach, but the majority of features you need will be there.

virt-clone

This is another command line program that will take an existing guest image and create a copy of it. Assignment of new UUIDs and network MACs is easily handeled here.

-- MattVliet - 04 Mar 2009