Mounts a synthfs filesystem, which is a simple mapping of memory into the filesystem hierarchy (i.e., the contents of a synthfs filesystem are contained in memory). While creation of files in the filesystem is prevented (in fact, you may cause the system to hang after attempting to create files), directory hierarchies are allowed. This could be used to set up transient mount points for other volumes on, for example, read-only media with a shortage of spare directories to serve as mount points (like an installation CD).
Take -o options as listed in the mount manpage.
The directory on which the filesystem is mounted.