PowerShell Invoke-WebRequest, how to automatically use original file name?

Question

How can I use Invoke-WebRequest to download a file but automatically make the file name the same as if I downloaded via browser? I haven't found a way to make -OutFile work without manually specifying the file name. I'm fine with this involving a few other lines of code.

A good solution will:

• Work even if the file name isn't in the request URL. For example, the URL to download the Visual Studio x64 Remote Debugging Tools is http://go.microsoft.com/fwlink/?LinkId=393217 but it downloads the file rtools_setup_x64.exe.
• Not save the whole file to memory before writing to disk, unless that's what Invoke-WebRequest already does even with the -OutFile parameter (?)

Thanks!

Answer 1

For the example given you're going to need to get the redirected URL, which includes the file name to be downloaded. You can use the following function to do so:

Function Get-RedirectedUrl {

    Param (
        [Parameter(Mandatory=$true)]
        [String]$URL
    )

    $request = [System.Net.WebRequest]::Create($url)
    $request.AllowAutoRedirect=$false
    $response=$request.GetResponse()

    If ($response.StatusCode -eq "Found")
    {
        $response.GetResponseHeader("Location")
    }
}

Then it's a matter of parsing the file name from the end of the responding URL (GetFileName from System.IO.Path will do that):

$FileName = [System.IO.Path]::GetFileName((Get-RedirectedUrl "http://go.microsoft.com/fwlink/?LinkId=393217"))

That will leave $FileName = rtools_setup_x64.exe and you should be able to download your file from there.