Discarding output with "> /dev/null" is something that is universal. It is used everywhere from startup scripts to working on the command line. There are over 140 instances in /etc alone (on FreeBSD).
But have you ever wondered how it works? How does the kernel know that /dev/null is special and not just any normal file? And where in the kernel do the writes eventually disappear? Then this talk is for you! Join me on a journey through the kernel.
This talk is targeted at people unfamiliar with kernel internals and would like to get a high-level overview on what is hiding behind such a common operation. We will look at the OpenBSD kernel, but if time permits we will also check out the differences to FreeBSD, namely that in OpenBSD /dev/null is a real inode on your harddrive, while in FreeBSD it is (usually) on the virtual devfs(4) filesystem.