Review and use the If construct in Windows PowerShell scripts

Completed

You can use the If construct in Windows PowerShell to make decisions. You also can use it to evaluate data you've queried or user input. For example, you could have an If statement that displays a warning if available disk space is low.

The If construct uses the following syntax:

If ($freeSpace -le 5GB) {
   Write-Host "Free disk space is less than 5 GB"
} ElseIf ($freeSpace -le 10GB) {
   Write-Host "Free disk space is less than 10 GB"
} Else {
   Write-Host "Free disk space is more than 10 GB"
}

In the previous example, the condition $freeSpace -le 5GB is evaluated first. If this condition is true, the script block in the braces is run, and no further processing happens in the If construct. In this case, a message indicating that there's less than 5 GB of free disk space is displayed.

If the first condition isn't true, the condition $freeSpace -le 10GB that's defined for ElseIf is evaluated. If this condition is true, the script block in the braces is run, and no further processing happens in the If construct. In this example, there's a single ElseIf, but you can have multiple ElseIf statements or none.

If all conditions aren't true, then the script block for Else is run. Else is optional.

Note

When you're making multiple decisions based on a single variable, using multiple ElseIf script blocks rather than nesting multiple If statements is preferred.