Create a new daemon that sends out alarm notifications upon customised trigger conditions

[HouzuoGuo]

The new daemon collects configuration input on alarm name, methods of notification (telephone, SMS, email, satellite, or any combination), and trigger conditions such as:

• Disk usage on / (built-in)
• Free memory (built-in)
• Shell script that normally exits with status 0 (customised input)

Then, the daemon runs in background and periodically checks the trigger conditions, interval of which is also customised by configuration input.

Consecutive failures in trigger conditions will not cause more notifications to be delivered, however, when trigger conditions are no longer present, notifications will tell that alarm conditions are no longer triggered.

For example:

An alarm called "disk usage threshold exceeded" is configured to send notification via telephone call, SMS, and email, the alarm checks disk usage on / at 3 minutes interval and triggers when the usage exceeds 95%.