使用变量后，PowerShell命令失败

Question

I'm trying to run a command to gather use profiles with certain requirements, here's my code:

#$numberOfDays = 30
#$numberOfDays

$profileStructsToRemove = Get-CimInstance Win32_UserProfile | 
    Where-Object {$_.LastUseTime -lt $(Get-Date).Date.AddDays(-$numberOfDays) } |
    Where-Object {$_.LocalPath.ToUpper() -ne 'C:\USERS\ADMINISTRATOR'} |
    Where-Object {$_.LocalPath.ToUpper() -ne 'C:\USERS\SOME_PROFILE_TO_KEEP'} |
    Where-Object {$_.LocalPath.ToUpper() -ne 'C:\USERS\PUBLIC'}

$profileStructsToRemove #print

I use the $numberOfDays variable to determine the number of days subtracted from today's date that I want to use as the filter. Right now it's commented out, and the command succeeds, although since $numberOfDays isn't defined I assume it's using a null value? I'm not really sure but it works that way...

However, when I assign $numberOfDays to 30, it fails to populate the variable $profileStructsToRemove with ANYTHING at all. It just utterly fails. I could really use some input on why this is happenening.

1. How is the command working when $numberOfDays isn't defined? Is it just a null value, or treating it as 0 for the AddDays function?
2. Why is this command failing once $numberOfDays is assigned a value?

Answer 1

gms0ulman's helpful answer answers question #1 well (converting $null to an [int] yields 0 ).

As for question #2:

At least on Windows 10 on a non-domain machine, the .LastUseTime property seemingly always returns the current date and time , which (a) makes it useless and (b) explains why you didn't see any results.

You could try to check the .LastDownloadTime instead, if that field has a value in your case - I presume it would only have a value if the profiles are roaming profiles.

---

For reference, here's the full list of available time stamps:
LastAttemptedProfileDownloadTime , LastAttemptedProfileUploadTime , LastBackgroundRegistryUploadTime , LastDownloadTime , LastUploadTime , LastUseTime .

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As for how to optimize the code in your question in general:

• PowerShell string operators are case-insensitive by default, so there's no need for .toUpper() .

• You could combine your multiple Where-Object calls into a single one, and you can use
  -notin with an array of paths on the RHS, instead of using -ne with individual paths.

To put it all together (PSv3+; keeping in mind that comparing against .LastUsedTime may be pointless):

$profileStructsToRemove = Get-CimInstance win32_userprofile | Where-Object {
    $_.LastUseTime -lt $(Get-Date).Date.AddDays(-$numberOfDays) -and
      $_.LocalPath -notin 'C:\USERS\ADMINISTRATOR',
                          'C:\USERS\SOME_PROFILE_TO_KEEP',
                          'C:\USERS\PUBLIC'
}

Answer 2

1. Yes, it's null, which added zero days. This is fine - you can test with:

    $(Get-Date).Date.AddDays($null) 

2. Are you sure there are profiles that match that data? Check the data when $numberOfDays is null to confirm.