code:

require 'rubygems'
require 'rbvmomi'

@server = "vsphere.domain"
@datacenter = "vspheredcname"
@user = "v_user"
@pass = "v_pass"
@vm_user = "root"
@vm_pass = "rootpass"

@vim = VIM.connect(:host => @server, :user => @user, :password => @pass, :insecure => true)
#puts "Connected"

@dc = @vim.serviceInstance.find_datacenter(@datacenter) or abort "datacenter not found"
#puts "DC: #{@dc}"

def find_vm(folder)
  folder.childEntity.each do |x|
    name, junk = x.to_s.split('(')
    case name
    when "Folder"
      find_vm(x)
    when "VirtualMachine"
      if (x.name == @vmname)
        return x
      end
    else
      puts "# Unrecognized Entity " + x.to_s
    end
  end
  return nil
end

vm = find_vm(@dc.vmFolder) or abort "VM Not found. Aborting."

attempts = 1
retries = 15

while vm.guest.toolsStatus != "toolsOk" && attempts <= retries
  puts "Waiting for vmware tools to respond... (#{attempts}/#{retries})"
  sleep 10
  attempts += 1
end
if attempts >= retries
  puts "Timed out! VMWare Tools never responded."
  exit 1
end

@om = @vim.serviceInstance.RetrieveServiceContent().guestOperationsManager
@pm = @om.processManager

def remote_exec(vm,cmd)
  bin, args = cmd.split(" ",2)
  auth = RbVmomi::VIM::NamePasswordAuthentication(:interactiveSession => false, :username => @vm_user, :password => @vm_pass)
  spec = RbVmomi::VIM::GuestProgramSpec(:programPath => bin, :arguments => args)
  pid = @pm.StartProgramInGuest(:vm => vm, :auth => auth, :spec => spec)
  while @pm.ListProcessesInGuest(:vm => vm, :auth => auth, :pids => [ pid.to_s ])[0].exitCode == nil
    sleep 0.5
  end
  return @pm.ListProcessesInGuest(:vm => vm, :auth => auth, :pids => [ pid.to_s ])[0].exitCode
end

remote_exec(vm,"ls -la")