How to identify that Linux is running as a Virtual Machine?

For troubleshooting or in scripts you might want to identify if you Linux is running as a Virtual Machine. If you work with puppet you might be familiar with facter which provides the facts "is_virtual" (true or false) and "virtual" (Virtualization type).

There is another handy tool called virt-what that is available in Fedora (13+), Red Hat Enterprise Linux (5.7+ and 6.1+), Debian, Ubuntu, ArchLinux and Gentoo, and it can be compiled from source on just about any Linux.

virt-what is a shell script which can be used to detect if the program is running in a virtual machine. The program prints out a list of facts about the virtual machine, derived from heuristics. One fact is printed per line.

Example 1: Ubuntu 12.04.5 LTS, running on ESXi 5.5:

root@mail01:~# virt-what
vmware

In that case, the system is running on a VMware based Hypervisor (ESXi/Workstation/Fusion)

If there is no output and the script exits with code 0 the systen is either running on bare-metal or the hypervizor cannot be detected.

Example 2: Raspbian GNU/Linux 7 running on Raspberry Pi:

root@raspberrypi:~# virt-what
root@raspberrypi:~# echo $?
0

In scripts virt-what can also be handy when you want a functions to be only executed when the system is running as a virtual machine. This little snippet can be used to run your code only when the virtual machine is running on a VMware based hypervisor:

/usr/sbin/virt-what | grep 'vmware' &> /dev/null
if [ $? == 0 ]; then
  echo "VMware detected"
  #do something
fi

The script can detect the following hypervisor types:

• hyperv: Microsoft Hyper-V
• ibm_systemz: IBM SystemZ
• ibm_systemz-zvm: z/VM guest in a LPAR on an IBM SystemZ
• linux_vserver: Linux VServer container
• kvm: KVM hypervisor
• openvz: OpenVZ/Virtuozzo
• parallels: Parallels Desktop/Parallels Server
• powervm_lx86: IBM PowerVM Lx86 Linux/x86 emulator
• qemu: QEMU software emulation
• uml: User-Mode Linux (UML) guest
• virtage: Hitachi Virtualization Manager (HVM)
• virtualbox: VirtualBox guest.
• virtualpc: Microsoft VirtualPC
• vmware: VMware ESXi/Workstation/Fusion
• xen: Xen hypervisor
• xen-dom0: Xen privileged domain
• xen-domU: Xen paravirtualized guest domain
• xen-hvm: Xen guest fully virtualized (HVM)
• virt: Unspecified Virtualization