sys-is-vm

#!/bin/sh -u
# sys-is-vm (part of ossobv/vcutil) // wdoekes/2021 // Public Domain
#
# Quick and dirty script that guesses whether we're a virtual machine.
#
# Return value 0 (success) means VM, return value 1 (failure) means hardware.
#
# Note that it only detects Xen/QEMU/KVM based VMs. For LXC containers it
# will guess that you're on (the host) hardware.
#
test -t 2; QUIET=$?  # silent if stderr is not a tty

chassis=$(cat /sys/class/dmi/id/chassis_vendor)
test "$chassis" = "QEMU" -o "$chassis" = "Xen"; chassis_is_not_vm=$?

test $QUIET = 1 && exit $chassis_is_not_vm  # 0=is_vm, 1=is_not_vm

cpu_model=$(sed -ne '/^model name/{s/^[^:]*:[[:blank:]]*//p;q}' /proc/cpuinfo)
test "$cpu_model" = "Common KVM processor"; cpu_is_not_vm=$?

if test $cpu_is_not_vm = 0 -a $chassis_is_not_vm = 1; then
    echo "WARNING: CPU looks like VM, but chassis does not" >&2
fi

is_vm_str=$(test $chassis_is_not_vm = 0 && echo true || echo false)
echo "chassis:    $chassis  [/sys/class/dmi/id/chassis_vendor]" >&2
echo "cpu:        $cpu_model  [/proc/cpuinfo]" >&2
echo "sys-is-vm:  $is_vm_str" >&2
exit $chassis_is_not_vm  # 0=is_vm, 1=is_not_vm