/joh'liks/ n.,adj. 386BSD
PORTING UNIX TO THE 386: A PRACTICAL APPROACH
William & Lynne Jolitz
A number of additional directorys are present in the root to handle a variety of other purposes, but these are more to do with full operation of the system beyond the initial root filesystem.
Other Directories: /lib, /mnt, /usr, /root, and /sys
Finally, we have a group of files that don't fit any of the above categories. /lib contains object libraries and runtime start-off routines to allow C and other languages to run on the system. /usr is an empty directory used as a mount point to attach a much larger filesystem to -- one that contains everything else not on the root in the way of utilities, object libraries, include files, documentation, and system source. /mnt, also an empty directory, is used as a mount point for optional filesystems to be attached to when needed. /root contains the home directory for the superuser account (root), keeping it separate from the actual root directory of the system. /sys is our sole example here of a symbolic link -- a file type that provides a shortcut within the filesystem to another location in the filesystem tree. In this case, /sys hides a reference to /usr/src/sys, so when the filesystem associated with /usr is mounted, a reference to a file like "/sys/i386/i386/locore.s" is satisfied with a reference to the file "/usr/src/sys/i386/i386/locore.s".