Install a guest:

Create the image:

cd /data2tb/virtualmachines
qemu-img create -f qcow2 ./name.qcow2 8G

Install a guest:

virt-install --name kaitain --ram 1024 --disk path=/data2tb/virtualmachines/kaitain.img,size=100 --vcpus 1 --os-type linux --os-variant ubuntu16.04 --network bridge=br1 --cdrom /data1tb/ISO/ubuntu-16.04.3-server-amd64.iso

Use osinfo-query os to find the available variants.