How do I figure out which file system a given file/directory is located on?(For example, I would like to know if the file/directory is a temporary file in RAM, or if it's stored on disk. And what mount point it corresponds to, if any. Etc.)
What file system is my file on?
filesystems;files;mount
df <path> should do what you want on nearly all systems.  It displays the file system and the mount point, along with the space usage statistics.