A section of my .profile which puts the running VM count into the prompt.

gistfile1.sh

function parse_vagrant_vms {
  # Use sed to strip out the whitespace, can't seem to get wc to give nice formatting standalone
  # Thanks to @pkqk for showing me the speedy 'VBoxManage' command
  local vm_count=$(VBoxManage list runningvms | wc -l | sed 's/^ *//; s/; */;/g')
  # I use curly braces to mean vm count, edit to taste
  if [ $vm_count -eq 1 ]; then
    echo "{${vm_count}vm}"
  fi
  if [ $vm_count -gt 1 ]; then
    echo "{${vm_count}vms}"
  fi
}

# In my true profile, there's a lot more in PS1 than this, but I've edited for brevity
export PS1="\$(parse_vagrant_vms)\n\$ "