System Administration Guide: Devices and File Systems

How File System Commands Determine the File System Type

The generic file system commands determine the file system type by following this sequence:

  1. From the -F option, if supplied.

  2. By matching a special device with an entry in the /etc/vfstab file (if the special device is supplied). For example, fsck first looks for a match against the fsck device field. If no match is found, the command then checks the special device field.

  3. By using the default specified in the /etc/default/fs file for local file systems and in the /etc/dfs/fstypes file for remote file systems.