How to Calculate Time Differences for Scheduled Restarts in PowerShell?

Remember that `Restart-Computer` has its quirks. If you need to schedule it effectively, consider using scheduled tasks instead or `shutdown.exe` directly. This might help avoid all the back-and-forth with time spans. Also, you can use a complete datetime string for clarity, like `New-TimeSpan -End ([datetime]"06-02-2025 23:00")`. This way, you sidestep any locale issues.

You should definitely use `New-TimeSpan` with actual datetime values. Instead of just specifying the target time like `New-TimeSpan -Start 10PM -End 1AM`, define the specific date too, like `New-TimeSpan -Start ('06/01/2025 5PM') -End ('06/02/2025 1AM')`. This way, it knows to calculate the time correctly between the two moments without going negative.

A simple fix is to check if the target time is less than the current time and add a day if so. You can do this by comparing the two datetime objects. If the target is earlier or the same as the current time, then just add 24 hours to it before calculating the difference!

You could set up a function to handle this. Just grab the current time with `Get-Date`, compare it to your target time, and if it's less, add a day. Here's a quick example:

```powershell
function New-ForwardTimeSpan {
param ([DateTime]$TargetTime)
$CurrentTime = Get-Date
if ($TargetTime -le $CurrentTime) {
$TargetTime = $TargetTime.AddDays(1)
}
return New-TimeSpan -Start $CurrentTime -End $TargetTime
}
```
This should help you get the right number of seconds you're looking for! Let me know how it works out for you.

You could simplify this by creating a scheduled task that triggers your restart at the specified time. This way, you don’t have to deal with all the complexities of time calculations, and it can save you from needing a script running constantly.