There's a lot of useful command-line tooling for KVM- and QEMU-based virt. Here's a small selection of them:

• virsh — This[1] is libvirt's shell interface; and gives you access to the rich set of libvirt APIs.

• virt-builder — Use this for rapidly building minimal or customized virtual machines; it's greatly flexible; check out its man page[2]. And here's[3] a quick example that connects both virt-builder and virsh together.

• virt-install — Use this if you don't like the default build of the template images from virt-builder; it lets you create "headless" servers via 'kickstart' and Linux OS trees from the command-line.

• guestfish and libguestfs suite[4] — This rich set of tools help you in a variety of use-cases: repairing your broken disk images, editing, cloning, debugging disk images, and more. It has saved my behind a lot of times.

• qemu-img[5] – This Swiss Army knife lets you powerfully manipulate disk images (QCOW2, raw, et al) offline. Example operations include: create images, backing chains, offline snapshots, disk image merging, ability to convert disk images from one format to another, and more.

[1] https://libvirt.org/manpages/virsh.html

[2] https://libguestfs.org/virt-builder.1.html

[3] https://developer.fedoraproject.org/tools/virt-builder/about...

[4] http://libguestfs.org/

[5] https://qemu.readthedocs.io/en/latest/tools/qemu-img.html