detect root using id command

salt/common/tools/sbin/so-status

@@ -170,7 +170,8 @@ def main():
   if "-h" in options or "--help" in options or "-?" in options:
     showUsage(options, None)
 
-  if os.environ["USER"] != "root":
+  proc = subprocess.run(['id', '-u'], stdout=subprocess.PIPE, encoding="utf-8")
+  if proc.stdout.strip() != "0":
     fail("This program must be run as root")
   
   console = Console()