Can continuously loop over the file, examine the md5 hash for changes.
Run the script if it has changed.
https://stackoverflow.com/questions/6475252/bash-script-watch-folder-execute-command
daemon() {
chsum1=""
while [[ true ]]
do
chsum2=`find src/ -type f -exec md5 {} \;`
if [[ $chsum1 != $chsum2 ]] ; then
if [ -n "$chsum1" ]; then
compile
fi
chsum1=$chsum2
fi
sleep 2
done
}