manjaro – How do I create a script to run certain sets of commands automatically on a periodic interval?

I noticed that my root partition experience a jump in the usage size by about 2 GB within the last 24 hours. I don’t install anything during this time. The only thing unusual I did was opening 50 pdf files simultaneously using Okular. Now I am left to figure out where in the / directory the sudden large-size files were created, which I decided not to pursue this time. Instead, to anticipate similar events in the future (it has happened twice by now), I want to create a script that runs automatically on a regular basis, e.g. at 09:00 PM GMT+4 everyday. This script prints the output of sudo du -sh /*, sudo du -sh /var/*, sudo du -sh /var/cache/*, sudo du -sh /var/cache/*, and sudo du -sh /usr/* (these are the places I suspected where the aforementioned large files were created) to a file store in ~/Document/mylog. Every print is preceded by the current date and time, and rolls at 30 days, meaning, the output file contains the last 30 days. My computer runs on Manjaro Linux.