Save XML file after changes in powershell

Question

I've parsed the XML file and I have these strings. So, I need to replace the GUID "{87440A4C-1FE4-412E-80C3-74E4F97A31B4}" with a new GUID "{BBB7C1EB-B0B0-40F3-B1D0-1F28111C5806}". How can I save XML after these changes?

Strings which I parsed:

C:\ProgramData\Program {87440A4C-1FE4-412E-80C3-74E4F97A31B4}\Extensions\Signal Integrity  
C:\ProgramData\Program {87440A4C-1FE4-412E-80C3-74E4F97A31B4}\Extensions\Vcs_SVN_Unicode 
C:\ProgramData\Program {87440A4C-1FE4-412E-80C3-74E4F97A31B4}\Extensions\Mixed Simulation 
C:\ProgramData\Program {87440A4C-1FE4-412E-80C3-74E4F97A31B4}\Extensions\SIMetrix

$fileName = "C:\temp\Extensions\ExtensionsRegistry.xml"
$xml = [System.Xml.XmlDocument](Get-Content $fileName)

$Xml.Extensions.Item.Path.ForEach{ $_ -replace 'Program  {87440A4C-1FE4-412E-80C3-74E4F97A31B4}', "Program {BBB7C1EB-B0B0-40F3-B1D0-1F28111C5806}"}

$Xml.Save($fileName)

Answer 1

• The -replace operator doesn't modify its LHS in place, it returns a modified copy of the LHS.

• If the Path elements only have text content, using PowerShell's adaptation of the XML via dot notation returns just that text itself, not the element objects, so you cannot modify the elements that way.

Therefore, you must enumerate the Path elements differently and assign the result of the
-replace operations back to their .InnerText property:

$xml.Extensions.Item.ChildNodes.Where({ $_.Name -eq 'Path' }).ForEach({ 
  $_.InnerText = $_.InnerText -replace 'Program  {87440A4C-1FE4-412E-80C3-74E4F97A31B4}', 'Program {BBB7C1EB-B0B0-40F3-B1D0-1F28111C5806}'
})

Answer 2

Pipe the output to a file, via Set-Content.