Available commands about probes:

probe-create name [-p period] [-o output]* [-target target]* [-i indicator]* [-start]
  default period is 10 seconds
  at least one output and one indicator must be defined
  if a target is provided, it overrides the indicators' targets
  -start will start the probe at once.

probe-change name [-p period] [-o output]* [-target target]* [-i indicator]*
  All parameters but the name may be omitted if they do not change.
  If the probe is running, it will be suspended before changed and restarted after.

probe-remove name

probe-start name

probe-stop name

probe-list [probe]
  if no -n option, the list of probes is printed.
