How to monitor a complete directory tree for changes in Linux?

I’ve done something similar using the inotifywait tool:

#!/bin/bash
while true; do

inotifywait -e modify,create,delete -r /path/to/your/dir && \
<some command to execute when a file event is recorded>

done

This will setup recursive directory watches on the entire tree and allow you to execute a command when something changes. If you just want to view the changes, you can add the -m flag to put it into monitor mode.