Synopsis:
   on [#][<mode>]timer_hour [<serial#>] [-|^]<match> { <action> }

Description:
   This hook is triggered whenever the specified time (or time glob pattern)
   matches the current time.  The time is in the following format:

      Format         Description                                          
      hh:mm          0 <= hh <= 23, 0 <= mm <= 59

Parameters:
   $0    current time 

Examples:
   To inform the user of the time once per hour on the hour:
      on ^timer "%:00*" {
         echo *** The time is not $Z
         beep
      }

See Also:
   set(4) clock_24hour

