Mac OS X Tiger in a Nutshell

Differences Between HFS+ and UFS

Here are the most noticeable differences between the HFS+ and UFS file formats:

• UFS is case-sensitive in its file path interpretation, while standard HFS+ is not. The paths /tmp/foo, /tmp/Foo, and /TMP/FOO all point to the same location on an HFS+ system but to three different ones on a UFS filesystem. However, using Mac OS X Server 10.3 and higher, you can format case-sensitive HFS+ volumes, and these volumes will maintain case-sensitivity when mounted on a Mac OS X client system.

  Tip

  Some software from the UFS world might assert case-sensitivity despite HFS+’s permissiveness. The Tab-completion feature of the bash or zsh shell command lines, for example, is case-sensitive, even if the filesystem they’re working with is not.

• UFS uses slashes (/) as its path separator, while HFS+ uses colons (:). However, various Mac OS X applications accept slash-using path notation no matter the underlying filesystem format. The Finder’s Go → Go To Folder (Shift--G) command lets you type a path to travel to that point on the computer’s filesystem. On the other hand, the Finder’s Get Info window displays the real, colon-based path of the selected Finder object if it’s on an HFS+ system.

  The two filesystems have a different concept of “root ,” or what the path / or : means, respectively. A UFS system’s root directory is the top level of some designated disk volume, while ...