While running executable modules are locked in a manner that you can't edit them. Accessible for reading, but not for writing. This means that in order to modify them you must wait till they are done, start a new process to do a modifications and do what ever you want (if you have enough rights). Ability to do that without additional module (take this conditionally) improves security of an application and makes it more portable. For example, script in this post deletes itself (compiled or not) a