Compress/Zip IIS Logs using Powershell

In my short search for a script which can compress IIS log files i couldn’t find any solution (written in powershell). So i made my one myself. The script compresses all .log files located in the sub directories of $LogDir and files newer than 5 days are skipped. The script uses the zip functionality present in windows so no external programs are needed. The script was tested on Windows 2008 Server R2.

$LogDir = "D:\Logs"

function Zip-Logs
{
    foreach($Dir in Get-ChildItem $LogDir | ?{ $_.PSIsContainer } )
    {
        foreach ($file in Get-ChildItem -Filter *.log $Dir.FullName)
        {
            $TimeSpan = New-TimeSpan ($file.LastWriteTime) (Get-Date)
            $filename = $file.FullName + ".zip"

            if ($TimeSpan.TotalDays -gt 5)
            {
                #Create Zip
                New-Zip -zipfilename $filename
                #Add file
                $file | Add-Zip -zipfilename $filename
                #Delete the uncompressed file
                $file.Delete()
            }
        }
    }
}

function Add-Zip
{
	param([string]$zipfilename)

	if(-not (test-path($zipfilename)))
	{
		set-content $zipfilename ("PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
		(dir $zipfilename).IsReadOnly = $false	
	}

	$shellApplication = new-object -com shell.application
	$zipPackage = $shellApplication.NameSpace($zipfilename)

	foreach($file in $input) 
	{ 
        $zipPackage.CopyHere($file.FullName)

        #This waits for the zip operation to finish
        while($zipPackage.Items().Item($file.Name) -Eq $null)
        {
            start-sleep -m 10
        }
	}
}

function New-Zip
{
	param([string]$zipfilename)
	set-content $zipfilename ("PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
	(dir $zipfilename).IsReadOnly = $false
}

Zip-Logs