%systemdrive% in Powershell

I was just trying to write a script to manage IIS logs. I was able to get the log directory, but it comes back as  %SystemDrive%\inetpub\logs\LogFiles

Reading between the lines from a couple of posts, I found that I can use $env:SystemDrive in place of %SystemDrive%

So I can do something like this:
Import-Module WebAdministration
$website = Get-Website | Where-Object {$_.name -eq 'SharePoint - 443'}
$logfileDirectory = $website.logFile.directory -replace '%SystemDrive%', $env:SystemDrive
...


0x80070002 when adding web part using Powershell

I was adding a webpart using this powershell:
$webpart = New-Object Microsoft.SharePoint.WebPartPages.SilverlightWebPart
$wpm = $web.GetLimitedWebPartManager($page.Uri.OriginalString, "Shared")
$wpm.AddWebPart($webpart, 'Header', 0)

... and got this error:

Exception calling "AddWebPart" with "3" argument(s): "<nativehr>0x80070002</nativehr><nativestack></nativestack>"
At line:1 char:16
+ $wpm.AddWebPart <<<< ($webpart, 'Header', 0)
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException


It turns out that my $page was the wrong one which was not checked out nor editable at the time.

Listing a page's web part zones

I have been trying to figure out a way to list all of a page's web part zones. There is not much documentation out there on this. Here's what I have been able to figure out. It is for a publishing web, but the procedure should be pretty much the same.

$myweburl
$mylayouttitle
$web = Get-SPWeb $myweburl
$pWeb = [Microsoft.SharePoint.Publishing.PublishingWeb]::GetPublishingWeb($web)
$layout = $pWeb.GetAvailablePageLayouts() | Where-Object {$_.Title -eq $mylayouttitle}
$layout.ListItem.Properties['vti_cachedzones']


And to list the webparts on a page:
$pageurl
$wpm = $web.GetLimitedWebPartManager($pageurl, 'Shared'
$wpm.WebParts | Format-Table -AutoSize WebBrowsableObject, ZoneId, ZoneIndex


There's also a post Determine which webpartzones are on a webpartpage that uses reflection to get at a private member however I have not gotten it to work.