Get List of installed Programs on Windows via Powershell

windows-get-list-of-installed-programs.ps1

function Get-InstalledApps {
    param (
        [Parameter(ValueFromPipeline=$true)]
	    [string[]]$comps = $env:COMPUTERNAME
    )

    foreach ($comp in $comps) {
        $keys = '','\Wow6432Node'
        foreach ($key in $keys) {
            $apps = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine',$comp).OpenSubKey("SOFTWARE$key\Microsoft\Windows\CurrentVersion\Uninstall").GetSubKeyNames()
            foreach ($app in $apps) {
                $program = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine',$comp).OpenSubKey("SOFTWARE$key\Microsoft\Windows\CurrentVersion\Uninstall\$app")
                $name = $program.GetValue('DisplayName')
                if ($name) {
                    New-Object PSObject -Property @{
                        'DisplayName'     = $name
                        'DisplayVersion'  = $program.GetValue('DisplayVersion')
                        'Publisher'       = $program.GetValue('Publisher')
                        'InstallDate'     = $program.GetValue('InstallDate')
                        'UninstallString' = $program.GetValue('UninstallString')
                    }
                }
            }
        }
    }
}

$apps = get-installedapps

# write-output $apps

$apps = get-installedapps
$is_installed = $apps | ?{ $_.DisplayName -eq "<APP TO FIND>" }

if ($is_installed.Length -eq 0) {
    write-output "not installed"
} else {
    write-output "already installed"
}