Virsh can be used to create, pause, restart, and shutdown domains. In addition, virsh can be used to list current domains available in your Virtualization hypervisor platform.

Virsh interacts with Libvirt which is a library aimed at providing a long-term stable C API. It currently supports Xen, QEMU, KVM, LXC, OpenVZ, VirtualBox and VMware ESX.

In this virsh commands cheatsheet, I’ll show you most used virsh commands to manage Guest Virtual Machines running on KVM or Xen Hypervisor.

The basic structure of most virsh usage is:

''$ virsh [OPTION]... <command> <domain> [ARG]...''

This is the first item on our virsh commands cheatsheet. This displays the host node information and the machines that support the virtualization process.

''$ **sudo virsh nodeinfo ** CPU model:   x86_64
CPU(s):              8
CPU frequency:       2200 MHz
CPU socket(s):       1
Core(s) per socket:  4
Thread(s) per core:  2
NUMA cell(s):        1
Memory size:         12238908 KiB''

To get the value for the –os-variant run the following command: $ osinfo-query os === Virsh list all domains === To list both inactive and active domains, use the command: $ sudo virsh list –all Id Name State —- - admin shut off - cloudstack shut off - hyperv shut off - ipa shut off - katello shut off - node1 shut off - node2 shut off - node3 shut off - server1 shut off - server2 shut off - test shut off - ubuntu14.04 shut off - win12k shut off - xen shut off - zenoss shut off === List only active domains === To list only active domains with virsh command, use: $ sudo virsh list Id Name State —————————————————- === Virsh rename domain === Syntax: virsh domrename currentname newname List available domains # virsh list –all Id Name State —- 4 centos-8.2 running

# virsh domrename centos-8.2 apacheserver01 Domain successfully renamed We’ve changed the name of the domain from centos-8.2 to apacheserver01 ==== Virsh change domain boot disk ==== Edit the domain by passing its name: # virsh edit domain Scroll down until <devices> section and modify values for the line below: <source file=/> Example

''<source file='/var/lib/libvirt/images/**apacheserver01**.**qcow2**'/>
''

</file>
===   Virsh start vm   ===

''This is an example on how to use virsh command to start a guest virtual machine. We’re going to start ''test domain displayed above: <code>''$ **sudo virsh start test** Domain test started $ **sudo virsh list ** Id Name State —————————————————- 3 test running

=== Virsh autostart vm ===

To set a vm to start automatically on system startup, do:

<code>
''$ **sudo virsh autostart test** Domain test marked as autostarted

$ **sudo virsh dominfo test  ** Id:   9
Name:           test
UUID:           a943ed42-ba62-4270-a41d-7f81e793d754
OS Type:        hvm
State:          running
CPU(s):         2
CPU time:       144.6s
Max memory:     2048 KiB
Used memory:    2048 KiB
Persistent:     yes
Autostart:      enable
Managed save:   no
Security model: none
Security DOI:   0''

Keep an eye on the option Autostart: enable. === Virsh autostart disable === To disable autostart feature for a vm: $ virsh autostart –disable test Domain test unmarked as autostarted $ virsh dominfo test Id: - Name: test UUID: a943ed42-ba62-4270-a41d-7f81e793d754 OS Type: hvm State: shut off CPU(s): 2 Max memory: 2048 KiB Used memory: 2048 KiB Persistent: yes Autostart: disable Managed save: no Security model: none Security DOI: 0 === Virsh stop vm, virsh shutdown vm === To shutdown a running vm gracefully use: $ sudo virsh shutdown test Domain test is being shutdown $ sudo virsh list Id Name State —————————————————- === Virsh force shutdown vm === You can do a forceful shutdown of active domain using the command: $ sudo virsh destroy test === Virsh stop all running vms === In case you would like to shutdown all running domains, just issue the command below: $ for i in `sudo virsh list | grep running | awk '{print $2}'` do sudo virsh shutdown $i

done === Virsh reboot vm === To restart a vm named test, the command used is: sudo virsh reboot test === Virsh remove vm === To cleanly remove a vm including its storage columes, use the commands shown below. The domain test should be replaced with the actual domain to be removed. sudo virsh destroy test 2> /dev/null sudo virsh undefine test sudo virsh pool-refresh default sudo virsh vol-delete –pool default test.qcow2 In this example, storage volume is named /var/lib/libvirt/images/test.qcow2 You can also use undefine with–remove-all-storage option: virsh undefine test –remove-all-storage === Virsh create a vm === If you would like to create a new virtual machine with virsh, the relevant command to use is virt-install. This is crucial and can’t miss on virsh commands cheatsheet arsenal. The example below will install a new operating system from CentOS 7 ISO Image. sudo virt-install \ –name centos7 \ –description GESHI_QUOTTest VM with CentOS 7GESHI_QUOT \ –ram=1024 \ –vcpus=2 \ –os-type=Linux \ –os-variant=rhel7 \ –disk path=/var/lib/libvirt/images/centos7.qcow2,bus=virtio,size=10 \ –graphics none \ –location $HOME/iso/CentOS-7-x86_64-Everything-1611.iso \ –network bridge:virbr0 \ –console pty,target_type=serial -x 'console=ttyS0,115200n8 serial' === Virsh connect to vm console === To connect to the guest console, use the command: $ sudo virsh console test This will return a fail message if an active console session exists for the provided domain. To solve this run: $ sudo virsh console test –force === Virsh edit vm xml file === To edit a vm xml file, use: $ sudo EDITOR=vim $ virsh edit test To use nano text editor $ sudo EDITOR=nano $ virsh edit test === Virsh suspend vm, virsh resume vm === To suspend a guest called testwith virsh command, run: $ sudo virsh suspend test Domain test suspended NOTE: When a domain is in a suspended state, it still consumes system RAM. Disk and network I/O will not occur while the guest is suspended. === Resuming a guest vm: === To restore a suspended guest with virsh using the resume option: $ sudo virsh resume test Domain test resumed === Virsh save vm === To save the current state of a vm to a file using the virsh command : The syntax is: $ sudo virsh save test test.saved Domain test saved to test.save $ ls -l test.save -rw——- 1 root root 328645215 Mar 18 01:35 test.saved === Restoring a saved vm === To restore saved vm from the file: $ sudo virsh restore test.save Domain restored from test.save

$ sudo virsh list Id Name State —- 7 test running

==== Virsh Manage Volumes ==== Here we’ll cover how to create a storage volume , attach it to a vm , detach it from a vm and how to delete a volume. === Virsh create volume === To create a 2GB volume named test_vol2 on the default storage pool, use: $ sudo virsh vol-create-as default test_vol2.qcow2 2G Vol test_vol2.qcow2 created

$ sudo du -sh /var/lib/libvirt/images/test_vol2.qcow2 2.0G/var/lib/libvirt/images/test_vol2.qcow2 * default: Is the pool name. * test_vol2: This is the name of the volume. * 2G: This is the storage capacity of the volume. List volumes sudo virsh vol-list –pool default sudo virsh vol-list –pool images === Virsh attach a volume to vm === To attach created volume above to vm test, run: $ sudo virsh attach-disk –domain test \ –source /var/lib/libvirt/images/test_vol2.qcow2 \ –persistent –target vdb * –persistent : Make live change persistent * –target vdb : Target of a disk device You can confirm that the volume was added to the vm as a block device /dev/vdb $ ssh test Last login: Fri Mar 17 19:30:54 2017 from gateway [root@test ~]# [root@test ~]# lsblk –output NAME,SIZE,TYPE NAME SIZE TYPE sr0 1024M rom vda 10G disk ├─vda1 1G part └─vda2 9G part

''├─cl_test-root    8G lvm
  └─cl_test-swap    1G lvm
  vdb                 2G disk

Example showing how to create and attach secondary virtual disk: <code> export VM=test-vm sudo qemu-img create -f qcow2 /var/lib/libvirt/images/${VM}-disk2.qcow2 20g

sudo virsh attach-disk \

1. -source /var/lib/libvirt/images/${VM}-disk2.qcow2 \
2. -target vdb \
3. -persistent \
4. -subdriver qcow2 \
5. -driver qemu \
6. -type disk </code> === Virsh detach volume on vm === To detach above volume test_vol2 from the vm test: <code> $ sudo virsh detach-disk –domain test –persistent –live –target vdb

Disk detached successfully

$ ssh test Last login: Sat Mar 18 01:52:33 2017 from gateway [root@test ~]# [root@test ~]# lsblk –output NAME,SIZE,TYPE NAME SIZE TYPE sr0 1024M rom vda 10G disk ├─vda1 1G part └─vda2 9G part ├─cl_test-root 8G lvm └─cl_test-swap 1G lvm [root@test ~]# </code> You can indeed confirm from this output that the device /dev/vdb has been detached Please note that you can directly grow disk image for the vm using qemu-img command, this will look something like this: <code> $ sudo qemu-img resize /var/lib/libvirt/images/test.qcow2 +1G </code> The main shortcoming of above command is that you cannot resize an image which has snapshots. === Virsh delete volume === List storage pools: <code> $ sudo virsh pool-list Name State Autostart

default active yes </code> To delete volume with virsh command, use: <code> # List volumes $ sudo virsh vol-list –pool default

$ sudo virsh vol-delete test_vol2.qcow2 –pool default Vol test_vol2.qcow2 deleted

$ sudo virsh pool-refresh default Pool default refreshed

$ sudo virsh vol-list default Name Path

admin.qcow2 /var/lib/libvirt/images/admin.qcow2 cloudstack.qcow2 /var/lib/libvirt/images/cloudstack.qcow2 ipa.qcow2 /var/lib/libvirt/images/ipa.qcow2 katello.qcow2 /var/lib/libvirt/images/katello.qcow2 node1.qcow2 /var/lib/libvirt/images/node1.qcow2 node2.qcow2 /var/lib/libvirt/images/node2.qcow2 node3.qcow2 /var/lib/libvirt/images/node3.qcow2 test.qcow2 /var/lib/libvirt/images/test.qcow2 ubuntu14.04.qcow2 /var/lib/libvirt/images/ubuntu14.04.qcow2 zenoss.qcow2 /var/lib/libvirt/images/zenoss.qcow2 </code> ==== Virsh Manage Snapshots ==== In this second last section of managing kvm guest machines with virsh command, we’ll have a look at managing VM snapshots. === Virsh Create Snapshot for a vm === Let’s create a snapshot for our test vm. <code> $ sudo virsh snapshot-create-as –domain test \ –name "test_vm_snapshot1" \ –description "test vm snapshot 1-working"

Domain snapshot test_vm_snapshot1 created </code> === Virsh list Snapshots for a vm === To list available snapshots for a vm, use: <code> $ sudo virsh snapshot-list test Name Creation Time State

1489689679           2017-03-16 21:41:19 +0300 shutoff
test_fresh           2017-03-16 22:11:48 +0300 shutoff
test_vm_snapshot1    2017-03-18 02:15:58 +0300 running''

</code>

To retrieve more information about a domain, use:

''$ **sudo virsh snapshot-info --domain test --snapshotname test_vm_snapshot1**
Name:   test_vm_snapshot1
Domain:         test
Current:        yes
State:          running
Location:       internal
Parent:         test_fresh
Children:       0
Descendants:    0
Metadata:       yes''

Here we’ll create another snapshot called test_vm_snapshot2, then revert to snapshot test_vm_snapshot1

''$ sudo virsh snapshot-create-as \
--domain test --name "test_vm_snapshot2" \
--description "test vm snapshot 2-working"

Domain snapshot test_vm_snapshot2 created''

Let’s revert the snapshot we created before:

''$ **sudo virsh snapshot-list test**
 Name   Creation Time             State
 ------------------------------------------------------------
  1489689679           2017-03-16 21:41:19 +0300 shutoff
  test_fresh           2017-03-16 22:11:48 +0300 shutoff
  test_vm_snapshot1    2017-03-18 02:15:58 +0300 running
  test_vm_snapshot2    2017-03-18 02:23:29 +0300 running

$ **sudo virsh snapshot-revert --domain test  --snapshotname test_vm_snapshot1  --running**''

Let’s delete the two snapshots we created:

''$ **sudo  virsh snapshot-delete --domain test --snapshotname  test_vm_snapshot2**
Domain snapshot test_vm_snapshot2 deleted

$ **sudo  virsh snapshot-delete --domain test --snapshotname  test_vm_snapshot1**
Domain snapshot test_vm_snapshot1 deleted

$ sudo virsh snapshot-list test
 Name   Creation Time             State
 ------------------------------------------------------------
  1489689679           2017-03-16 21:41:19 +0300 shutoff
  test_fresh           2017-03-16 22:11:48 +0300 shutoff''

Domain with devices to clone must be paused or shutoff. So let’s shut it down:

''$ **sudo virsh destroy test**
Domain test destroyed''

Then clone a vm, do it as shown below:

''$ sudo virt-clone --connect qemu:///system \
--original test \
--name test_clone \
--file /var/lib/libvirt/images/test_clone.qcow2

Allocating 'test_clone.qcow2'   |  10 GB  00:00:06

Clone 'test_clone' created successfully.

$ **sudo virsh dominfo test_clone**
Id:   -
Name:           test_clone
UUID:           be0621fd-51b5-4d2b-a05c-ce76e59baafa
OS Type:        hvm
State:          shut off
CPU(s):         1
Max memory:     1048576 KiB
Used memory:    1048576 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: none
Security DOI:   0''


</file>

==== Virsh manage VM vcpus ====

This virsh commands cheatsheet section covers how to add additional virtual cpus to a virtual machine:
<code>


''$ sudo virsh setvcpus --domain test --maximum 2 --config
$ sudo virsh setvcpus --domain test --count 2 --config
$ sudo virsh shutdown test
$ sudo virsh start test''

Confirm that the number of vcpu has changed, the previous was 1, the current value is 2:

''$ **virsh dominfo test**
Id:   -
Name:           test
UUID:           a943ed42-ba62-4270-a41d-7f81e793d754
OS Type:        hvm
State:          shut off
CPU(s):         2
Max memory:     1048576 KiB
Used memory:    1048576 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: none
Security DOI:   0''

Also on virsh commands cheatsheet is managing RAM with virsh. To adjust the total ram used by the guest operating system, the following commands are used:

''**# In MB
**sudo virsh setmaxmem test 2048 --config
sudo virsh setmem test 2048 --config
sudo virsh shutdown test
sudo virsh start test

**# Same in GB
**sudo virsh setmaxmem test 16G --config
sudo virsh setmem test 16G --config
sudo virsh shutdown test
sudo virsh start test''

Check domain info to confirm the current RAM allocated to the VM.

''$ **virsh dominfo test  **
Id:             9
Name:           test
UUID:           a943ed42-ba62-4270-a41d-7f81e793d754
OS Type:        hvm
State:          running
CPU(s):         2
CPU time:       70.7s
Max memory:     2048 KiB
Used memory:    2048 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: none
Security DOI:   0''

Notice that the current ram allocated to the VM is 2048

You can mount a virtual disk on KVM for offline administration. For this, we have a ready article which you can reference from the link below:

How to mount VM virtual disk on KVM hypervisor

To ls a directory on a running VM, you need the libguestfs-tools installed.

The run:

''# **virt-ls -l -d <domain>  <directory>**''

E.g

''# **virsh list**
 Id Name State
----------------------------------------------------
 10 allot_netxplorer_01 running
 19 sg-ve-01 running

# **virt-ls -l -d allot_netxplorer_01 /root**
total 28
dr-xr-x---. 2 root root 135 Mar 22 14:26 .
dr-xr-xr-x. 17 root root 224 Mar 21 10:37 ..
-rw-------. 1 root root 385 Mar 22 14:26 .bash_history
-rw-r--r--. 1 root root 18 Dec 29 2013 .bash_logout
-rw-r--r--. 1 root root 176 Dec 29 2013 .bash_profile
-rw-r--r--. 1 root root 176 Dec 29 2013 .bashrc
-rw-r--r--. 1 root root 100 Dec 29 2013 .cshrc
-rw-r--r--. 1 root root 129 Dec 29 2013 .tcshrc
-rw-------. 1 root root 1447 Mar 21 10:38 anaconda-ks.cfg''


</file>

Common options are:

<code>//-R |--recursive//
  --> Recursive listing
//-h |--human-readable//
  --> Human-readable sizes in output
//-d |--domain guest //
 --> Add disks from libvirt guest
//-l |--long //
 --> Long listing

You can as well cat a file without doing ssh to the VM or accessing it via the console. You need the libguestfs tools installed on the hypervisor for this to work.

''$ sudo virt-cat -d <domain>  <file_path>
$ **sudo virt-cat -d sg-ve-01 /etc/redhat-release**
CentOS Linux release 7.1.1503 (Core)

$ **sudo dufo virt-cat -d sg-ve-01 /etc/redhat-release> check_os**
$ **cat check_os **
CentOS Linux release 7.1.1503 (Core)''


</file>

===== Edit a file in a virtual machine =====

After installing libguestfs-tools on the hypervisor, use the **virsh-edit** command:

<code>''# virt-edit -d sg-ve-01 /etc/hosts''

Use the virt-df command:

''$ **sudo virt-df -d sg-ve-01 **
Filesystem 1K-blocks Used Available Use%sg-ve-01:/dev/sda1 20469760 3954792 16514968 20%
sg-ve-01:/dev/sda2 27739924 173828 27566096 1%''

''$ **sudo virt-filesystems -l -d sg-ve-01**
Name Type VFS Label Size Parent
/dev/sda1 filesystem xfs - 20971520000 -
/dev/sda2 filesystem xfs - 28419555328 -

$ **sudo virt-filesystems -l -h -d sg-ve-01**
Name Type VFS Label Size Parent
/dev/sda1 filesystem xfs - 20G -
/dev/sda2 filesystem xfs - 26G -

$ **sudo virt-filesystems -l -h -d sg-ve-01 --partitions**
Name   Type    MBR Size Parent
/dev/sda1 partition 83 20G /dev/sda
/dev/sda2 partition 83 26G /dev/sda
/dev/sda3 partition 82 4.0G /dev/sda

$ **sudo virt-filesystems -d sg-ve-01 --all --long --uuid -h**
Name Type VFS Label MBR Size Parent UUID
/dev/sda1 filesystem xfs - - 20G - 97074514-612e-4d1c-8433-935dbb3ec775
/dev/sda2 filesystem xfs - - 26G - 8cc9e0cd-282d-46a4-9a37-069dfb93c4f2
/dev/sda3 filesystem swap - - 4.0G - ad7dcd49-fe1a-4938-8600-f7299a59c57a
/dev/sda1 partition - - 83 20G /dev/sda -
/dev/sda2 partition - - 83 26G /dev/sda -
/dev/sda3 partition - - 82 4.0G /dev/sda -
/dev/sda device - - - 100G - -''


</file>

===== Show stats of virtualized domains =====

Use virt-top to display stats of virtualized domains. You can filter by CPU, RAM e.t.c and save the output to a CSV file.

<code>''$ virt-top
$ sudo virt-top --csv file.csv''


</file>

You can also send debug and error messages to a filename. To send error messages to syslog you can do:

<code>''$ sudo virt-top --debug>(logger -t virt-top)''

“virt-log” is a command line tool to display the log files from the named virtual machine (or disk image). This tool understands and displays both plain text log files (eg. /var/log/messages) and binary formats such as the systemd journal.

''$ sudo virt-log -d <domain> | less
$ sudo virt-log -d <domain> | grep 'dhclient.*bound''