How do I check the filehash of a file thats online in PowerShell?-CodePudding

So well, I am making a pull request to Chris Titus Tech's Ultimate Windows Toolkit, and I wanna make something that checks if it's updated. But when I try running:

Get-FileHash -Algorithm SHA256 https://raw.githubusercontent.com/fgclue/etcher/master/desktop.ini

It just says:

Get-FileHash: Cannot find drive. A drive with the name 'https' does not exist. And I want to make it look something like this:

$hash = Get-FileHash -Algorithm SHA256 URL
$chash = Get-FileHash -Algorithm SHA256 win10debloat.ps1

if ($hash -ne $chash){
     Write-Host "There is an update!"
     Write-Host "Update?"
     $Opt = Read-Host "Choice"     
     if (Opt -ne y){
          exit
     }
     if (Opt -ne yn){
          Start-Process "https://github.com/ChrisTitusTech/win10script/"
          Write-Host Please download the new version and close this windows.
     }
}

CodePudding user response：

I'm not totally sure what actually you want to compare but here is how you can test if what you have is up to date without downloading anything, in this case I believe you need to use IO.MemoryStream to get the hash of the remote file.

There is likely a better way to do it, also note, this code is using UTF8 Encoding with a BOM for getting the remote file bytes, you need to make sure the encoding is correct, i.e.: if you need UTF8 no BOM, use [System.Text.UTF8Encoding]::new().GetBytes(...) instead.

$uri = 'https://raw.githubusercontent.com/fgclue/etcher/master/desktop.ini'
$theHashIHave = Get-FileHash myfilehere.ext -Algorithm SHA256

try {
    $content = Invoke-RestMethod $uri
    $memstream = [System.IO.MemoryStream]::new(
        [System.Text.Encoding]::UTF8.GetBytes($content)
    )
    $thisFileHash = Get-FileHash -InputStream $memstream -Algorithm SHA256
    if($theHashIhave.Hash -eq $thisFileHash.Hash) {
        "all good"
    }
    else {
        "should update here"
    }
}
finally {
    $memstream.foreach('Dispose')
}