selection-only

Selection: per and only

'only' => array('sshd', 'cron') makes the default selection "only these elements": of all the systemd services of a Linux, two are watched by default.

How to read it

• The collector still returns every service it sees: the poller keeps only those the selection names. The administrator adds others on the probe, by name or by pattern (nginx*).
• ignore and only never go together.
• text.match($line, '([^ ]+).service +[^ ]+ +([^ ]+)'): the name of the service in the first group, its active state in the second. A line that does not match is skipped.
• watch.expect raises on any state but active.

To adapt it

• On a distribution where SSH runs as ssh, write ssh in the list, or a pattern ssh*.