Monitor which folder has used the disk storage I got a mac air with only 256 GB storage.  Some apps must be using the storage and after deleting and moving everything I can (down to relocate mail and dropbox to external disk using symbolic links and their own folder), the storage is still kept on dropping. It lost quite quickly down to 0.01G per 15 minutes. Looking using du df or visual is hard to spot so far.

Is there any way (shell script etc.) to monitor which folder is increasing in size over time? (Space approach)

If that is not possible, how about a script to monitor any directories that have been modified in the last 15 minutes? (Time approach)

Many advice I found is only on one folder or one layer e.g. home/* but not the whole directory structure.  Possibly to have a way to spot out an offending directory?
I like omni disk sweeper to see where my space is going. Link: https://www.omnigroup.com/applications/omnidisksweeper/

To see which folders have changed in the last 15 minutes, run this from a command-line: $ find / -type d -cmin -15