2.6 Case sensitivity of the VFAT file system

The VFAT file system is able to remember the case of the filenames. However, filenames which differ only in case are not allowed to coexist in the same directory. For example if you store a file called LongFileName on a VFAT file system, mdir shows this file as LongFileName, and not as Longfilename. However, if you then try to add LongFilename to the same directory, it is refused, because case is ignored for clash checks.

The VFAT file system allows to store the case of a filename in the attribute byte, if all letters of the filename are the same case, and if all letters of the extension are the same case too. Mtools uses this information when displaying the files, and also to generate the Unix filename when mcopying to a Unix directory. This may have unexpected results when applied to files written using an pre-7.0 version of DOS: Indeed, the old style filenames map to all upper case. This is different from the behavior of the old version of mtools which used to generate lower case Unix filenames.