# Install the inotifywait package, on Fedora:
$ sudo dnf install inotify-tool

# Run inotify-wait on a loop
while true; do inotifywait -e modify -r <folder to watch>; < curstom ; commands> ; done

# eg: recompile a progam when a file is changed:
while true; do inotifywait -e modify -r sources/; make clean; make;done