Toil is a very simple program that waits for any of the files given as arguments to change. It works as a very limited replacement for tools like inotifywait, but using file monitoring code heavily based on GNU tail's -F mode to ensure it works when, for example, checking a file over a network share where the inotify interface isn't available.

You'll need make and a C compiler, at which point you should just be able to run:

make
sudo make install