A script which can export Windows classic event logs (Application, System, Security) to an evtx file

EventLogBackup.ps1

# Followed this article: https://www.thomasmaurer.ch/2011/05/powershell-how-to-export-windows-eventlogs-with-powershell/
[CmdletBinding()]
param (
    [Parameter(Mandatory=$false)]
    [ValidateSet('Application','HardwareEvents','Security','System','Windows PowerShell')]
    [string] $LogFileName = 'Application'
)

$exportFileName = Join-Path -Path $ENV:TEMP -ChildPath ($ENV:COMPUTERNAME + '_' + $logFileName + "_" + "$(Get-Date -f yyyyMMdd).evtx")
$logFile = Get-WmiObject -Class Win32_NTEventlogFile | Where-Object {$_.LogFileName -eq $LogFileName}
if ($logFile) {
    $null = $logFile.BackupEventLog($exportFileName)
    if (Test-Path -Path $exportFileName -PathType Leaf) {
        Write-Host "Please attach file [$exportFileName] to case."
    }
    else {
        Write-Warning "Unable to export events to [$exportFileName]."
    }
}
else {
    Write-Warning "Unable to retrieve a reference to the [$LogFileName] event log."
}