Create a QEMU/KVM Virtual Machine from the Command Line

Gregg

July 15, 2023

You can use a combination of command line tools to create and configure a virtual machine. Here we will use few tools from the QEMU and libvirt packages to do this.

Use QEMU to create a 15GB QCOW disk image:

$ qemu-img create -f qcow2 /home/user/KVM/CentOS-Stream-9.qcow2 15G Formatting '/home/user/KVM/CentOS-Stream-9.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=16106127360 lazy_refcounts=off refcount_bits=16

Start the installation:

$ sudo virt-install --name=CentOS-Stream-9 --vcpus=1 --memory=1024 --location=/home/user/Downloads/CentOS-Stream-9-20230704.1-x86_64-boot.iso --os-variant=centos8 --network bridge:virbr0 --disk path=/home/user/KVM/CentOS-Stream-9.qcow2 --disk size=15 Password: WARNING Requested memory 1024 MiB is less than the recommended 1536 MiB for OS centos8 Starting install... Retrieving 'vmlinuz' | 0 B 00:00:00 ... Retrieving 'initrd.img' | 0 B 00:00:00 ... Allocating 'CentOS-Stream-9.qcow2' | 2.5 MB 00:00:03 ... WARNING Overriding memory to 3072 MiB needed for centos8 network install. Creating domain... | 0 B 00:00:00 Running graphical console command: virt-viewer --connect qemu:///system --wait CentOS-Stream-9

Once this gets to this point another window should open up by the virt-viewer application (which you should install if you didn’t already) and you can complete the installation and reboot. You’ll use the same virt-viewer window to use the shell or desktop (depending upon the distro you installed).

When you are done and close the virt-viewer GUI you can find the VM in the running state using virsh:

$ sudo virsh list --all Password: Id Name State ------------------------------------ 5 CentOS-Stream-9 running - slackware-current shut off

Then you can shut it down:

$ sudo virsh shutdown 5 Password: Domain '5' is being shutdown $ sudo virsh list --all Password: Id Name State ------------------------------------ - CentOS-Stream-9 shut off - slackware-current shut off

Optionally, you can delete the VM domain and the QCOW file using the undefine parameter:

$ sudo virsh undefine --domain CentOS-Stream-9 --remove-all-storage Password: Domain 'CentOS-Stream-9' has been undefined Volume 'vda'(/home/user/KVM/CentOS-Stream-9.qcow2) removed.