在nagios的几个触发参数里会有w、d、u、f这样的调用方式。具体每个字母代表的意思如下：

 1host_notification_options：
 2d = notify on DOWN host states,
 3u = notify on UNREACHABLE host states
 4r = notify on host recoveries (UP states)
 5f = notify when the host starts and stops flapping
 6s = send notifications when host or service scheduled downtime starts and ends
 7n (none) as an option, the contact will not receive any type of host notifications.
 8service_notification_options:
 9w = notify on WARNING service states
10u = notify on UNKNOWN service states
11c = notify on CRITICAL service states
12r = notify on service recoveries (OK states)
13f = notify when the service starts and stops flapping
14n (none) as an option, the contact will not receive any type of service notifications.
15常用的设置
16host_notification_options：d,u,r
17service_notification_options:w,u,c,r