Powershell scriptlet to allow dedicated Excel instances

Excel Assoc new instance.ps1

$ErrorActionPreference = "Stop"

# https://blogs.technet.microsoft.com/heyscriptingguy/2013/12/10/use-powershell-to-create-registry-keys/
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/set-itemproperty
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/set-item
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/remove-item
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/get-itempropertyvalue
# https://docs.microsoft.com/en-us/windows/desktop/shell/fa-verbs
# https://docs.microsoft.com/en-us/windows/desktop/shell/handlers
# https://docs.microsoft.com/en-us/windows/desktop/shell/fa-sample-scenarios
# http://www.angelfire.com/biz/rhaminisys/fileasoc.html
# https://social.technet.microsoft.com/wiki/contents/articles/4542.powershell-loops.aspx
# https://ss64.com/ps/syntax-arrays.html
# https://docs.microsoft.com/fr-fr/powershell/module/Microsoft.PowerShell.Utility/write-host
# https://stackoverflow.com/questions/9948517/how-to-stop-a-powershell-script-on-the-first-error
# https://www.powershellgallery.com/packages/PSLDAPQueryLogging/1.0/Content/Private%5CGet-RegValue.ps1

# https://stackoverflow.com/questions/18000757/regex-match-any-string-powershell
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/get-childitem?view=powershell-6
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/test-path?view=powershell-6
# https://stackoverflow.com/questions/13466698/find-values-in-registry-subkeys-and-delete-them
# https://stackoverflow.com/questions/11474449/get-childitem-trying-to-get-the-registry-entry-from-current-working-directory
# https://www.itprotoday.com/powershell/powershell-basics-filtering-objects
# https://stackoverflow.com/questions/14406315/how-to-get-an-objects-propertys-value-by-property-name-in-powershell
# https://stackoverflow.com/questions/11471519/how-to-get-registrykey-name-alone-instead-of-full-registry-keypath

(Get-ChildItem HKLM:\Software\Classes\ -Name) -match '^Excel\..*' | ForEach-Object {
	$open_path = "HKLM:\Software\Classes\${_}\shell\Open"
	if (Test-Path "${open_path}\command") {
		$current_command = Get-ItemPropertyValue -Path "${open_path}\command" -Name '(Default)'
		if ($current_command -match "\\excel\.exe.+/dde$") {
			$new_command = $current_command -Replace '/dde$','"%1"'
			Write-Output "${_}: Backuping keys (command, ddeexec)"
			Rename-Item -Path "${open_path}\ddeexec" -NewName 'ddeexec.backup'
			Rename-Item -Path "${open_path}\command" -NewName 'command.backup'

			Write-Output "${_}: Writing new command"
			New-Item -Path "${open_path}\command" -Value $new_command | Out-Null
		}
	}
}

#Get-ItemPropertyValue -Path "HKLM:\Software\Classes\$_\shell\Open\command" -Name '(Default)'
#}

#Get-Item HKLM:\Software\Classes\Excel.* | % { $_.Name } 
#Get-Item HKLM:\Software\Classes\Excel.* | ForEach-Object {
#	Get-ItemPropertyValue -Path "HKLM:\Software\Classes\$_.Name\shell\Open\command" -Name '(Default)'
#}

#Set-Item -Path "HKLM:\Software\Classes\${class}\shell\Open\command" -value '"C:\Program Files\Microsoft Office\Office14\EXCEL.EXE" "%1"'
#New-Item -Path "HKLM:\Software\Classes\${class}\shell\Open\command" -value '"C:\Program Files\Microsoft Office\Office14\EXCEL.EXE" "%1"' >$null

Excel Rollback new instance.ps1

$ErrorActionPreference = "Stop"

(Get-ChildItem HKLM:\Software\Classes\ -Name) -match '^Excel\..*' | ForEach-Object {
	$open_path = "HKLM:\Software\Classes\${_}\shell\Open"
	# If there's a full backup, then restore
	if ((Test-Path "${open_path}\command.backup") -And (Test-Path "${open_path}\ddeexec.backup")) {
		Write-Output "${_}: Deleting new command"
		Remove-Item "${open_path}\command"
	
		Write-Output "${_}: Restoring keys (command, ddeexec)"
		Rename-Item -Path "${open_path}\ddeexec.backup" -NewName 'ddeexec'
		Rename-Item -Path "${open_path}\command.backup" -NewName 'command'
	}
}