DOCUMENT:Q100625 23-NOV-1993 [W_NT] TITLE :Filenames are Case Sensitive on NTFS Volumes PRODUCT :Windows NT PROD/VER:3.10 OPER/SYS:WINDOWS KEYWORDS: ---------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT operating system, version 3.1 - Microsoft Windows NT Advanced Server, version 3.1 ---------------------------------------------------------------------- As part of the requirements for POSIX compliance, the Windows NT File System (NTFS) provides a case-sensitive file and directory naming convention. Even though NTFS and the POSIX subsystem each handle case-sensitivity well, 16-bit Windows-based, MS-DOS-based, OS/2-based, and Win32-based applications do not. In NTFS, you can create unique file names, stored in the same directory, that differ only in case. For example, the following filenames can coexist in one directory on an NTFS volume: CASE.TXT case.txt case.TXT However, if you attempt to open one of these files in a Win32 application, such as Notepad, you would only have access to one of the files, regardless of the case of the filename you type in the Open File dialog box. Other inconsistencies also exist. The Windows NT Command Prompt and File Manager correctly display the names of the files. However, normal commands, such as COPY, fail when you attempt to access one or more filenames that differ only in case. NTFS supports two slightly different modes of operation that can be selected by the subsystem of the application interacting with NTFS. The first is fully case sensitive and demands that file names supplied by the application match the names stored on disk including case if the file on disk is to be selected. The second mode of operation is case preserving but not case sensitive. This means that applications can select files on the disk even if the supplied name differs in case from the name stored on the disk. Note that both modes preserve the case used to create the files. The difference in behavior noted here applies only when an application needs to locate an existing file. POSIX takes advantage of the full case sensitive mode, while MS-DOS, WOW, and Win32 subsystems use the case insensitive mode. Additional reference words: 3.10 filsys KBCategory: KBSubCategory: filsys ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 1993.