I helped someone on a forum recently that needed to determine if a path existed or not. Providing the path did exist, they would need to perform an action. The problem wasn’t what to do (in the end), it was determining if the path existed (to begin with). Here’s a rough draft of their code:

$Path = 'C:\Scripts\TestFolder'

If ($Path) {
    Remove-Item -Path $Path
}

If you’ve been doing this a little while, then it’s quite easy to spot the problem with the “logic” used in the example above. The If statement’s condition is only evaluating if $Path has a value (if it contains something). The fact that the value may, or may not, be a path, and whether or not it exists (if it is a path), is not being evaluated. I recommended they use the Test-Path cmdlet, to ensure the value stored in $Path, was a path, and that it existed.

$Path = 'C:\Scripts\TestFolder'

If (Test-Path -Path $Path) {
    Remove-Item -Path $Path
}

There are times when all you will want to know is if a variable contains a value. As an example, we can use a variable to record if a specific process is running (at the time the variable is created), and take action depending on if it is, or isn’t.

The example below checks for a process called pn (Programmer’s Notepad) and stores the results in the $PNProcess variable. We can then check and determine if $PNProcess has been set, or assigned a value, and make a determination of what to do based on the results. Since we’re only looking to see if our variable contains a value, then this is a perfectly suitable solution.

$PNProcess = Get-Process -ProcessName pn -ErrorAction SilentlyContinue

If ($PNProcess) {
    Write-Output -Verbose "Programmer's Notepad is running."
} Else {
    Write-Output -Verbose "Programmer's Notepad is not running."
}

Note: While I would normally wrap a string in single quotes, double quotes are being used because single quotes will not work when there’s a single quote in the string.