How can i do that? Is it safe? Why is it disabled by default?

Thanks
/Richard

++
ie: the program to write to other users
--

Richard, you must have hit a button to start a new thread because the text of your message is not connected to anything and contains no clue as to what question you are asking. Try again please.

How can i do that? Is it safe? Why is it disabled by default?

Thanks
/Richard

++
ie: the program to write to other users
--

Still not clear as there is no single program to write to other users. If YOU are a superuser (root or having those privileges) you can write to basically anything. Therefore I assume you are a normal user and, yes, you are normally prevented from writing to other users' files and folders UNLESS that user or root has changed permission settings to open the permissions to you, a group you are a member of, or for everyone. But there is, and should not be, any way for you to change those permissions.

If you are referring to a specific program which allows a non superuser to write to other peoples files, it must be a very special purpose program which you have not named. As to whether it is safe would depend on what it was designed to do or any security holes it might have which coiuld allow it to be abused.