Question

If I try to access this system variable from the Run… dialog, Windows tells me the directory doesn’t exist. Some system variables, like %SYSTEMROOT% and %USERPROFILE%, do work. Consequently, if I try to use a supposedly nonexistent variable like %DEFAULTUSERPROFILE% or %PROFILESFOLDER% in C#, I get nothing in return. Is there something special I need to do to get access to these variables?

Answer 1

My suggestion is to retreive that value directly from the registry – in case you can’t expand it:

public static string GetDefaultUserProfilePath() {
    string path = System.Environment.GetEnvironmentVariable("DEFAULTUSERPROFILE") ?? string.Empty;
    if (path.Length == 0) {
        using (Microsoft.Win32.RegistryKey key = Microsoft.Win32.Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList")) {
            path = (string)key.GetValue("Default", string.Empty);
        }
    }
    return path;
}