Check timespan which may cross day boundary - powershell

Question

I have a monitoring script which is executed every 5 minutes by task scheduler. If the script determines there is a problem, an alert condition is raised and a notification email is sent. The script then terminates. All well and good.
I want to define some 'quiet hours' during which time, monitoring still takes place on schedule, but notifications are suppressed. These hours will cross the midnight boundary.
I could do this with something like this:
$quietHoursStart = "22:00"
$quietHoursEnd = "06:00"
$timeNow = Get-Date
if ( $timeNow -lt (Get-Date $quietHoursStart ) -and
$timeNow -gt (Get-Date $quietHoursEnd ) ) {
Send-NotificationEmail
}
That's fine, but if I ever re-define the quiet hours range so that it does not cross the midnight boundary (e.g. 00:00 -> 06:00) , then the notification will always fail since the if condition can never be true.
If could add additional tests to see if the range crosses midnight, then have two separate checks to see if current time is 'quiet', but I feel there should be a more elegant solution.
The values for the quiet hours start/end are actually pulled in from an XML config file but for the sake of clarity, the example above uses simple definitions.
EDIT: To clarify; the script must run every 5 minutes, regardless of quiet hours, since it records a log of problems found. Changing the schedule will not achieve this.

Answer 1

Add comparison between $quietHoursStart and $quietHoursEnd to check is given interval cross midnight or not.
$quietHoursStart = "22:00"
$quietHoursEnd = "06:00"
$timeNow = Get-Date
$TimeOfDay = $timeNow.TimeOfDay
$IsQuietHours = if ( $quietHoursStart -le $quietHoursEnd ) {
$TimeOfDay -ge $quietHoursStart -and $TimeOfDay -lt $quietHoursEnd
} else {
$TimeOfDay -ge $quietHoursStart -or $TimeOfDay -lt $quietHoursEnd
}
if ( !$IsQuietHours ) {
Send-NotificationEmail
}

Answer 2

Alain O'Dea's link really does address your need quite well, but from a scripting focused stance I think a better way to approach this (script wise, his link to scheduling the task is probably better) would be to define a starting time, and then a duration. So you want it to start at 10PM and go until 6AM? That's an 8 hour duration. Also, I would test to see if it is in your quiet time, and then invert it with -Not (I use the alias !)Try something like this:
$quietHoursStart = "22:00"
$quietHoursDuration = 8
$timeNow = Get-Date
if (! ($timeNow -gt (Get-Date $quietHoursStart ) -and $timeNow -lt (Get-Date $quietHoursStart ).AddHours($quietHoursDuration)) ) {
Send-NotificationEmail
}