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Unlike mount, automount does not consult the file /etc/vfstab for a list of resources to mount automatically. Rather, it consults a series of maps. These maps enable the automounter to locate the appropriate NFS file server, the exported filesystem, and the mount options for the requested resource.
The automounter mounts everything under the directory /tmp_mnt by default and provides a symbolic link from the requested mount point to the actual mount point under /tmp_mnt. For instance, if a user wants to mount a remote directory src under /usr/src, the actual mount point will be /tmp_mnt/usr/src, and /usr/src will be a symbolic link to that location.
When the automount daemon is called, it serves each mount point in the maps and makes the kernel believe that the mount has taken place. The daemon sleeps until a request is made to access the corresponding resource. In the mount state, the daemon intercepts the request, mounts the remote resource, creates a symbolic link between the requested mount point and the actual mount point under /tmp_mnt, passes the symbolic link to the kernel, and steps aside.
When a predetermined amount of time has passed with the link not being touched (five minutes by default), the daemon unmounts the resource and resumes its previous position.
Using the automounter requires the creation of map files (see ``Preparing the automounter maps'') prior to using the automount command (see ``Invoking the automounter'').