Retrieve UPN from .NET Core

retrieveupn.cs

var procStartInfo = new System.Diagnostics.ProcessStartInfo("cmd", "/c whoami /upn");
procStartInfo.RedirectStandardOutput = true;
procStartInfo.UseShellExecute = false;
procStartInfo.CreateNoWindow = true;
System.Diagnostics.Process proc = new System.Diagnostics.Process();
proc.StartInfo = procStartInfo;
proc.Start();
string result = proc.StandardOutput.ReadToEnd();
var email = result.Trim();