OS X FSEvents

Detects when a file changed. Tested in OS X 10.9 (Mavericks) and OS X 10.10 (Yosemite).

Compile the C version with:

gcc -framework CoreServices main.c -o main_c

Compile the C++ version with:

gcc -framework CoreServices -lstdc++ main.cpp -o main_cpp

Execute the C version with:

./main_c /path/to/listen

Execute the C++ version with:

./main_cpp /path/to/listen

Differences between C & C++ versions

There is no difference, both work in the same way.