Hooks are useful tools for managing your QEMU/Libvirt VMs. Details can be found at its website.
After you setting up hooks script for the QEMU guest in the file /etc/libvirt/hoos/qemu, you have to restart the livbvertd.service to make it take effect, via sudo systemctl restart libvirtd.service. This can be painful when you have multiple VMs to manage and configure. Therefore the libvirt-hooks management tool come to rescure.