Or, in this case, how to make a file not readonly in powershell. It took me a while to get this working and this is my best effort. In fact, this particular example recurses a whole folder and makes all files not readonly

$readonly = [System.IO.FileAttributes]::ReadOnly
get-childitem . -recurse | foreach { if ($_.Attributes -band $readonly -eq $readonly) { $_.Attributes -= $readonly.value__ } }

I did try to set the IsReadOnly property but Powershell throws a wobbly at that. If anybody knows a neater way of doing this I'd love to know.