There is quite a good walkthrough here. Essentially the tool you're wanting to use is virt-install, which you should already have if you have installed everything needed for QEMU-KVM. Here's the most relevant section.
6. Creating a new Guest VM using virt-install
virt-install tool is used to create the VM. This tool can be used in
both interactive or non-interactive mode.
In the following example, I passed all the required values to create
an VM as command line parameters to the virt-install command.
# virt-install \
-n myRHELVM1 \
--description "Test VM with RHEL 6" \
--disk path=/var/lib/libvirt/images/myRHELVM1.img,bus=virtio,size=10 \
--graphics none \
--cdrom /var/rhel-server-6.5-x86_64-dvd.iso \
In the above virt-install command the parameters have the following meaning:
n: Name of your virtual machine
description: Some valid description about your VM.
For example: Application server, database server, web server, etc.
os-type: OS type can be Linux, Solaris, Unix or Windows.
os-variant: Distribution type for the above os-type. For example, for linux, it can be rhel6, centos6, ubuntu14, suse11, fedora6 , etc.
For windows, this can be win2k, win2k8, win8, win7
ram: Memory for the VM in MB
vcpu: Total number of virtual CPUs for the VM.
disk path=/var/lib/libvirt/images/myRHELVM1.img,bus=virtio,size=10: Path where the VM image files is stored. Size in GB. In this example,
this VM image file is 10GB.
graphics none: This instructs virt-install to use a text console on VM serial port instead of graphical VNC window. If you have the
xmanager set up, then you can ignore this parameter.
cdrom: Indicates the location of installation image. You can specify the NFS or http installation location (instead of –-cdrom). For
network bridge:br0: This example uses bridged adapter br0. It is also possible to create your own network on any specific port instead of bridged adapter.
If you want to use the NAT then use something like
below for the network parameter with the virtual network name known as
VMnetwork1. All the network configuration files are located under
/etc/libvirt/qemu/networks/ for the virtual machines. For example: