How to manage virtual machines using virsh

virsh is a powerful command-line tool included in libvirt that allows you to manage virtual machines and associated resources in KVM.
Through virsh, you can create, start, stop, modify, and monitor domains (virtual machines), as well as manage networks, volumes, and storage pools.

1. Domain (Virtual Machine) Management

Command	Description
`virsh list --all`	Lists all virtual machines, both active and inactive.
`virsh start vm_name`	Starts a previously defined virtual machine.
`virsh shutdown vm_name`	Shuts down a virtual machine gracefully.
`virsh destroy vm_name`	Stops a virtual machine immediately (similar to forcefully powering it off).
`virsh suspend vm_name`	Suspends the execution of a virtual machine.
`virsh resume vm_name`	Resumes a suspended machine.
`virsh reboot vm_name`	Reboots the virtual machine.
`virsh reset vm_name`	Resets a virtual machine as if the physical reset button was pressed.
`virsh autostart vm_name`	Enables automatic startup of the VM when the host boots.
`virsh dominfo vm_name`	Shows detailed information about the VM (state, UUID, CPU, memory, etc.).
`virsh dumpxml vm_name`	Shows the complete XML definition of the VM.
`virsh edit vm_name`	Opens the VM’s XML definition in an editor for modification.
`virsh undefine vm_name`	Removes the VM definition without deleting its disk.
`virsh domrename old_name new_name`	Changes the name of a virtual machine.

2. Information and Monitoring

Command	Description
`virsh domstate vm_name`	Shows the current state of a VM (`running`, `shut off`, etc.).
`virsh domstats vm_name`	Shows real-time CPU, network, and disk statistics.
`virsh domblklist vm_name`	Lists block devices (disks) associated with a VM.
`virsh domblkinfo vm_name vda`	Shows detailed information about a virtual disk.
`virsh domiflist vm_name`	Shows network interfaces connected to the VM.
`virsh domifaddr vm_name`	Shows IP addresses assigned to the VM’s network interfaces.
`virsh cpu-stats vm_name`	Shows detailed CPU usage statistics for the VM.
`virsh dommemstat vm_name`	Shows memory usage statistics for a VM.
`virsh console vm_name`	Connects to the virtual machine’s text console.
`virsh vncdisplay vm_name`	Shows the VNC port assigned to the VM for graphical access.

3. Storage

Command	Description
`virsh pool-list`	Lists all storage pools.
`virsh pool-info pool_name`	Shows detailed information about a pool.
`virsh pool-start pool_name`	Starts a storage pool.
`virsh pool-destroy pool_name`	Stops a storage pool.
`virsh pool-undefine pool_name`	Removes the pool definition.
`virsh vol-list pool_name`	Lists volumes (disks) within a pool.
`virsh vol-info --pool pool_name vol_name`	Shows information about a volume.
`virsh vol-create-as pool_name vol_name 20G --format qcow2`	Creates a new 20 GB volume in QCOW2 format.
`virsh vol-delete --pool pool_name vol_name`	Deletes a volume from a pool.
`virsh vol-clone --pool pool_name source_vol new_vol`	Clones an existing volume.

4. Virtual Networks

Command	Description
`virsh net-list --all`	Lists all virtual networks, both active and inactive.
`virsh net-info net_name`	Shows detailed information about a network.
`virsh net-start net_name`	Starts a virtual network.
`virsh net-destroy net_name`	Stops a virtual network.
`virsh net-autostart net_name`	Enables automatic startup of a network.
`virsh net-edit net_name`	Edits the XML configuration of a network.
`virsh net-dumpxml net_name`	Shows the XML definition of a network.
`virsh net-update net_name`	Updates network parameters without needing to restart it.
`virsh net-dhcp-leases net_name`	Shows IP addresses delivered by DHCP on a network.

5. Snapshots and Backups

Command	Description
`virsh snapshot-list vm_name`	Lists available snapshots for a VM.
`virsh snapshot-create-as vm_name snapshot_name "Description"`	Creates a snapshot with name and description.
`virsh snapshot-revert vm_name snapshot_name`	Reverts the VM to the state saved in a snapshot.
`virsh snapshot-delete vm_name snapshot_name`	Deletes a specific snapshot.
`virsh backup-begin vm_name --target /backup/`	Initiates a backup of the VM’s disks.
`virsh backup-dumpxml vm_name`	Shows XML information about an ongoing backup task.

6. Migration and State Saving

Command	Description
`virsh save vm_name /ruta/estado.save`	Saves the current state of a VM to a file.
`virsh restore /ruta/estado.save`	Restores a VM from a saved file.
`virsh migrate --live vm_name qemu+ssh://host_destino/system`	Migrates a running VM to another host via SSH.

7. Host and Hypervisor Information

Command	Description
`virsh nodeinfo`	Shows information about the host’s CPU, memory, and architecture.
`virsh capabilities`	Shows the hypervisor’s capabilities (CPU, virtualization, etc.).
`virsh domcapabilities`	Shows capabilities supported by VMs.
`virsh version`	Shows the version of libvirt and the hypervisor.
`virsh hostname`	Shows the hostname running libvirt.
`virsh uri`	Shows the connection URI to the hypervisor.

8. Additional Tips

To run commands without privileges, you can use --connect qemu:///session or adding your user to the group kvm and libvirt.
If managing system VMs, use sudo virsh --connect qemu:///system.
Use virsh help <section> to see all available commands in a group (for example, virsh help domain).
All changes made via virsh edit are saved directly to the configuration XML files in /etc/libvirt/qemu/.

Francisco Javier Cruces Doval