current SCCM-based uninstaller

Uninstall-SysAid.ps1

 <#
 This checks for non-current copies of SysAid & uninstalls them.

 FILES:
    Uninstall-SysAid.ps1
        This file.  Must be run with execution policy bypassed:
        powershell.exe -executionpolicy bypass -file .\Uninstall-SysAid.ps1
    SysAidAgentx64.msi
        This is the "install" file.  We're using it with uninstall
        switches to remove existing copies of SysAid.
    SysAidWorker.exe
        This is the reference file of the current properly installed
        version of SysAid.  If a new version of SysAid comes out, just
        replace this file with the newest one.
   

 #>

# Function to convert version number to decimal
function Get-VersionAsDec {
    param($VersionInfo,[switch]$FileVersion)

    $digits = 6

    If ($FileVersion){$iVersionNumber = $VersionInfo.FileVersion}
    Else{$iVersionNumber = $VersionInfo.ProductVersion}

    $rVersionDec = ''

    ForEach ($versionPart in ($iVersionNumber -split '\.')){
        $lessDigits = $digits - $versionPart.Length
        For ($i = 0 ; $i -lt $lessDigits ; $i++){
            $versionPart = '0' + $versionPart
        }
        $rVersionDec = $rVersionDec + [string]$versionPart
    }
    $rVersionDec = [decimal]($rVersionDec.TrimStart('0'))
    Return $rVersionDec
}

# Clear error variable
$error.clear()

# MSI install verification info
$productName = 'sysaid'
$productCode = '{FC5E1D1D-6D3F-4844-A937-567D589F655E}'

# File names
$msiName = 'SysAidAgentx64.msi'
$currentExecFileName = 'SysAidWorker.exe'
$badSysAidFolderUNC = 'C:\Program Files\SysAid (x86)\'
$sysAidFolderUNC = 'C:\Program Files\SysAid\'
$sysAidEXEUNC = 'C:\Program Files\SysAid\SysAidWorker.exe'

# Normalize installer name
$msiUninstaller = Get-Item ('.\' + $msiName) -Force | Select -ExpandProperty FullName

# Get example EXE information
$currentVerEXE = Get-Item ('.\' + $currentExecFileName) -Force

　
If (-not $error){

    # Set failure variable
    $uninstallNeeded = $false

    # Test to make sure there wasn't a previous x86 install
        $badSysAidExists = Get-Item $badSysAidFolderUNC -Force -ErrorAction Ignore
        If ($badSysAidExists){$uninstallNeeded = $true}

    # Test to see if there is an existing install folder
    If (-not $uninstallNeeded){
        $sysAidFolder = Get-Item $sysAidFolderUNC -Force -ErrorAction Ignore

        If (-not $sysAidFolder){$uninstallNeeded = $true}
        Else{
            $sysAidInstalledEXE = Get-Item $sysAidEXEUNC -Force -ErrorAction Ignore
            If(-not $sysAidInstalledEXE){$uninstallNeeded = $true}
            Else{
                # Compare version numbers
                $refVer = Get-VersionAsDec ($currentVerEXE.VersionInfo)
                $insVer = Get-VersionAsDec ($sysAidInstalledEXE.VersionInfo)

                If ($insVer -lt $refVer){$uninstallNeeded = $true}
            }
        }
    }

　
    # If evidence of any old installs found, run uninstaller (or if no evidence)
    If ($uninstallNeeded){

        # Call uninstall method (MSI)
        $cmdCommand = (
            ('/x ' + $msiUninstaller),
            '/qn',
            '/norestart'
        )
        #Start-Process -FilePath 'MSIEXEC.EXE' -ArgumentList $cmdCommand -NoNewWindow -Wait
        Write-Verbose 'Call uninstaller.'

        # Verify we can't find application
        $uninstallFailed = (
            Get-Item $sysAidEXEUNC -Force -ErrorAction Ignore |
            Where {
                (Get-VersionAsDec $_.VersionInfo) -lt (Get-VersionAsDec $currentVerEXE.VersionInfo)
            } -ErrorAction Ignore
        )
    }
}

　
# If $installSuccessful isn't empty, report success, otherwise failure
If ((-not $uninstallFailed) -and (-not $error)){
    # Must write something (anything) to host
    Write-Host ('Success!')
    Exit 0
}
Else{
    # this condition returns a failure
    Clear-Host
    Exit 0
}