Rename file

[balala]

i tried sth very similar last night with 2 variables, but i used OnChangeAction instead of FinishAction.

Unfortunately you can't use an OnChangeAction option for such a thing, because the rename command doesn't return anything when executed. Otherwise you could, but due to this "silence" of the command, you can't. FinishAction on the other hand is executed whenever the plugin measure is ran.