On a Linux environment sometimes I need to run a script as root which will add/modify serveral files on my fs.

Basically I'd like to know exactly which files are modified and how WITHOUT opening the script and trying to guess the code.

I was thinking about using something like unionfs: the main fs would be accessible in readonly mode and all changes are written on a file used as a partition and "mounted" in write mode.

Are there other ways to achieve the same goal (i.e. other than unionfs)?