Download Multiple Files from http using Powershell with proper names

If you do the web request before you decide on file name you should be able to get the expanded path (otherwise you would have to make two web requests, one to get the extended path and one to download the file).

When I tried this, I found that the BaseResponse property of the Microsoft.PowerShell.Commands.HtmlWebResponseObject returned by the Invoke-WebRequest cmdlet had a ResponseUri property which was the extended path we are looking for.

If you get the correct response, just save the file using the name from the extended path, something like the following (this sample code does not look at HTTP response codes or similar, but expects everything to go well):

function Save-TinyUrlFile
{
    PARAM (
        $TinyUrl,
        $DestinationFolder
    )

    $response = Invoke-WebRequest -Uri $TinyUrl
    $filename = [System.IO.Path]::GetFileName($response.BaseResponse.ResponseUri.OriginalString)
    $filepath = [System.IO.Path]::Combine($DestinationFolder, $filename)
    try
    {
        $filestream = [System.IO.File]::Create($filepath)
        $response.RawContentStream.WriteTo($filestream)
        $filestream.Close()
    }
    finally
    {
        if ($filestream)
        {
            $filestream.Dispose();
        }
    }
}

This method could be called using something like the following, given that the $HOME\Documents\Temp folder exists:

Save-TinyUrlFile -TinyUrl http://tinyurl.com/ojt3lgz -DestinationFolder $HOME\Documents\Temp

On my computer, that saves a file called robots.txt, taken from a github repository, to my computer.

If you want to download many files at the same time, you could let PowerShell make this happen for you. Either use PowerShell workflows parallel functionality or simply start a Job for each url. Here's a sample on how you could do it using PowerShell Jobs:

Get-Content files.txt | Foreach {
    Start-Job {
        function Save-TinyUrlFile
        {
            PARAM (
                $TinyUrl,
                $DestinationFolder
            )

            $response = Invoke-WebRequest -Uri $TinyUrl
            $filename = [System.IO.Path]::GetFileName($response.BaseResponse.ResponseUri.OriginalString)
            $filepath = [System.IO.Path]::Combine($DestinationFolder, $filename)
            try
            {
                $filestream = [System.IO.File]::Create($filepath)
                $response.RawContentStream.WriteTo($filestream)
                $filestream.Close()
            }
            finally
            {
                if ($filestream)
                {
                    $filestream.Dispose();
                }
            }
        }

        Save-TinyUrlFile -TinyUrl $args[0] -DestinationFolder $args[1]
    } -ArgumentList $_, "$HOME\documents\temp"
}