UFS snapshot A backing store image (fancy term for an image used as a backup) of a file system at a given point in time.
umask A value that modifies the default permissions on a newly created file or directory, resulting in the file or directory's real permission structure.
Universal Disk Format (UDF) The file system used for DVD-ROMs.
UNIX File System (UFS) The standard hard disk-based file system used in Solaris (and most of the rest of the UNIX world).
unmount To make a file system unavailable for use.
User ID (UID) A number that uniquely identifies a user on the computer.
username A character string that uniquely identifies a user on the computer. Users log in by using their username and a password.
user profile A set of files run during the login process that configures the user's working environment.