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Chapter 20. Managing Guest Virtual Machines with virsh
virshis a command-line interface tool for managing guest virtual machines, and works as the primary means of controlling virtualization on Red Hat Enterprise Linux 7. The
virshcommand-line tool is built on the libvirt management API, and can be used to create, deploy, and manage guest virtual machines. The
virshutility is ideal for creating virtualization administration scripts, and users without root privileges can use it in read-only mode. The
virshpackage is installed with
yumas part of the libvirt-client package.
For installation instructions, see Section 2.2.1, “Installing Virtualization Packages Manually”. For a general introduction of virsh, including a practical demonstration, see the Virtualization Getting Started Guide The remaining sections of this chapter cover the
virshcommand set in a logical order based on usage.
Note that when using the help or when reading the man pages, the term 'domain' will be used instead of the term guest virtual machine. This is the term used by libvirt. In cases where the screen output is displayed and the word 'domain' is used, it will not be switched to guest or guest virtual machine. In all examples, the guest virtual machine 'guest1' will be used. You should replace this with the name of your guest virtual machine in all cases. When creating a name for a guest virtual machine you should use a short easy to remember integer (0,1,2...), a text string name, or in all cases you can also use the virtual machine's full UUID.
It is important to note which user you are using. If you create a guest virtual machine using one user, you will not be able to retrieve information about it using another user. This is especially important when you create a virtual machine in virt-manager. The default user is root in that case unless otherwise specified. Should you have a case where you cannot list the virtual machine using the
virsh list --allcommand, it is most likely due to you running the command using a different user than you used to create the virtual machine. See Important for more information.
20.1. Guest Virtual Machine States and Types
virshcommands are affected by the state of the guest virtual machine:
- Transient - A transient guest does not survive reboot.
- Persistent - A persistent guest virtual machine survives reboot and lasts until it is deleted.
During the life cycle of a virtual machine, libvirt will classify the guest as any of the following states:
- Undefined - This is a guest virtual machine that has not been defined or created. As such, libvirt is unaware of any guest in this state and will not report about guest virtual machines in this state.
- Shut off - This is a guest virtual machine which is defined, but is not running. Only persistent guests can be considered shut off. As such, when a transient guest virtual machine is put into this state, it ceases to exist.
- Running - The guest virtual machine in this state has been defined and is currently working. This state can be used with both persistent and transient guest virtual machines.
- Paused - The guest virtual machine's execution on the hypervisor has been suspended, or its state has been temporarily stored until it is resumed. Guest virtual machines in this state are not aware they have been suspended and do not notice that time has passed when they are resumed.
- Saved - This state is similar to the paused state, however the guest virtual machine's configuration is saved to persistent storage. Any guest virtual machine in this state is not aware it is paused and does not notice that time has passed once it has been restored.