The purpose of this script is to check the devices mentioned in /online_dir/online.xml:

$ --help
usage: [-h] [-t TAGS]

Create proxies to all devices in /online_dir/online.xml
and evaluate their state()

optional arguments:
  -h, --help  show this help message and exit
  -t TAGS     tags matching online.xml tags

    check all devices in /online_dir/online.xml and
    display a statistic of the tags. -t expert
    check all devices in /online_dir/online.xml having the expert tag -t expert,user
    ... having the expert and the user tag

A device not replying to state() is considered offline. Device states() ALARM and FAULT are reported. All other states are considered OK.