Caffeinated Bitstream

Bits, bytes, and words.

File event notifications in Mac OS

While using Mac OS, I've been missing the handy Linux inotifywait utility—it's a simple program to use the Linux inotify facility to wait on certain file events. I sometimes write scripts that use inotifywait to automatically launch programs when files are changed. For instance, I can have a script automatically compile a program whenever I save the source file in the editor.

It turns out that Mac OS and other recent BSD operating systems have a similar kernel facility called kqueue, and it was really easy to whip up a small program to block until an event occurs on a file. My filewait program is linked below, and can be used in scripts such as this one:

# wait for the file to change...
while filewait magnumopus.tex; do
    # compile the file
    sleep 0.2
    pdflatex magnumopus.tex


  • filewait.c - My simple program to pause until a file event occurs.