A Look at the Filesystem Hierarchy Standard 3.0
It was big news when the 3.0 kernel was released at the end of July, but as luck would have it, another fundamental piece of your average distribution is about to bump its own version number up to 3.0 as well: the filesystem hierarchy standard (FHS). If you're not sure exactly what that means or why you should care, don't worry. It's the distros that implement the FHS — when it goes well, all you know is that your system runs smoothly. But that doesn't mean there's nothing important hidden away in this new release.
The What Now?
The FHS defines the basic structure of a Unix-like operating system — what the directories are, what types of files and data belong in each, and so on. This is important for application developers (so that they know to create temporary files in /tmp/ rather than in the user's home directory, for instance), but it is also important for system administrators. Not only does FHS specify where the directories go, but it specifies important properties like which directories must be mounted read-only (critical for security) and which must be available at boot time (so that vital directories are on local disks not NFS mounts that won't be available early in the boot sequence).