diff --git a/Util.py b/Util.py
index 908a1bd..188e615 100644
--- a/Util.py
+++ b/Util.py
@@ -63,21 +63,25 @@ def executeCommand(command):
     return result
 
 
-def executeCommandOn(target_machine_fqdn, strCommand, remote_user=None):
+def executeCommandOn(target_machine_fqdn, command, user=None):
     """
     execute command on a local or remote machine (using ssh then)
-    :param str remote_user: 
+    :param str user: if not None, the user that should be used to execute the command (instead of the current user)
     """
     print("comparing %s and %s" % (getHostName(), target_machine_fqdn.split('.')[0]))
     if getHostName() == target_machine_fqdn.split('.')[0]:
-        return executeCommand(strCommand)
+        if user is not None:
+            # su -c "ls -l /tmp" graffy
+            return executeCommand("su -c '%s' %s" % (command, user))
+        else:
+            return executeCommand(command)
     else:
-        if not remote_user is None:
-            target = '%s@%s' % (remote_user, target_machine_fqdn)
+        if user is not None:
+            target = '%s@%s' % (user, target_machine_fqdn)
         else:
             target = target_machine_fqdn
         
-        return executeProgram(['ssh', target, "%s" % strCommand])
+        return executeProgram(['ssh', target, "%s" % command])
 
 
 def getUpsStatus():