The following rules apply to creating DOS file names and directories. Windows 9.x/NT/2000/Me and Windows XP support long file names (LFNs). LFNs can be up to 255 characters long. Although these new operating systems support LFNs, they still allow backward compatibility with the 8.3 naming structure associated with DOS by creating an associated 8.3 file name for each newly created file. LFNs are divided into 12-byte sections that allow the use of up to 255 characters, as shown below: The following basic rules allow applications to create and process valid names for files and directories, regardless of file system: In MS-DOS, file names are not case-sensitive and are limited to eight characters and possibly to a period and three additional characters. Emacs knows enough about these limitations to handle filenames for other operating systems. For example, the start points `.` in file names are not valid in MS-DOS, so Emacs transparently converts them to `_`; Therefore, your default initialization file (see The Emacs Initialization File) is called on MS-DOS _emacs. Excess characters before or after the period are usually ignored by MS-DOS itself. So when you call the LongFileName.EvenLongerExtension file, you get longfile.eve in the background, but Emacs still displays the long filename in the fashion line.
Otherwise, it is up to you to specify the file names that are valid under MS-DOS. The seamless conversion described above only works with the file names embedded in Emacs. Note: This list is not exhaustive. It is designed to help you avoid common errors in file names. If you have any questions or need help, don`t hesitate to cmshelp@mtu.edu. For Windows API functions that manipulate files, file names can often be relative to the current directory, while some APIs require a full path. A file name is relative to the current directory if it does not begin with one of the following options: All file systems follow the same general naming conventions for a single file: a base file name and an optional extension, separated by a period. However, each file system, such as NTFS, CDFS, EXFAT, UDFS, FAT, and FAT32, can have specific and different rules for forming each component in the path to a directory or file. Note that a directory is simply a file with a special attribute that calls it a directory, but must follow the same naming rules as a normal file.
Because the term directory simply refers to a specific file type with respect to the file system, some reference documents use the general term file to include both directory concepts and data files as such. For this reason, unless otherwise specified, any naming or usage rules or examples in a file must also apply to a directory. The term path refers to one or more directories, backslashes, and optionally a volume name. For more information, see Paths. On many file systems, a file name contains a tilde (~) in each component of the name that is too long to comply with 8.3 naming rules. Use any character in the current code page for a name, including Unicode characters and extended characters (128–255), except for the following: Specific characters (? * , ; = + | [ ] / ) are illegal and may not be used. Each component of a path is also limited by the maximum length specified for a particular file system. In general, these rules fall into two categories: short and long. Note that directory names are stored by the file system as a special file type, but file naming rules also apply to directory names. In summary, a path is simply the string representation of the hierarchy between all directories that exist for a particular file or directory name.
Do not use the following reserved names for a file name: In DOS, the ATTRIB command can be used to modify the attributes of a file on the command line. For example, to change the attributes of the MSDOS system file.SYS from a read-only/hidden file, type the following command at the DOS command prompt: With multi-user support through Terminal Services and virtual machines, it has also become necessary to virtualize the root device system-wide in the Win32 namespace. This was achieved by adding the symbolic link named “GLOBALROOT” to the Win32 namespace, which you can see in the “Global??” subdirectory of the previously discussed WinObj browser tool and which you can access via the “?GLOBALROOT” path. This prefix ensures that the following path is in the true root path of System Object Manager and not in a session-dependent path. For backward compatibility with legacy applications (on DOS and Windows 3.1), an 8.3 file name is automatically generated for each LFN, which can still be used to rename, delete, or open the file. The 8.3 file name can be retrieved using the GetShortPathName function of Kernel32.dll. VFAT, a variant of FAT with an extended directory format, was introduced in Windows 95 and Windows NT 3.5. It allowed mixed case of long Unicode (LFN) filenames in addition to classic 8.3 names. Data is accessed from disks, devices, and network shares using file I/O APIs. Files and directories, as well as namespaces, are part of the path concept, which is a string representation that specifies where to retrieve data, whether it comes from a disk, device, or network connection for a particular operation. DOS files are stored in directories or subdirectories. In today`s Windows world, directories are called folders.
In DOS, there are certain rules for creating and naming files and directories. All file systems supported by Windows use the concept of files and directories to access data stored on a disk or device. Windows developers working with Windows file and device I/O APIs need to understand the different rules, conventions, and restrictions of file and directory names. This command removes the read-only and hidden attributes associated with the file. You can then read and delete the file. Please do not remove MSDOS until you are certified.SYS you are certified. You can add the attributes to MSDOS .SYS run the following command at the DOS command prompt: The following PC Guide Web site contains an excellent page that describes LFNs: www.pcguide.com/ref/hdd/file/fatLong-c.html The prefix and conventions of the Win32 namespace are summarized in this and the following section with descriptions of how to use them. Note that these samples are intended for use with Windows API functions, and not all of them necessarily work with Windows shell applications such as Windows Explorer.
For this reason, there is a wider range of possible paths than is typically available for Windows shell applications, and Windows applications that take advantage of them can be developed using these namespace conventions. File naming rules – A file name consists of two parts of the principal name and extension. 8.3 The file naming convention is used, i.e. ,. However, special characters cannot be used in the file name such as /: *? ” | On newer file systems such as NTFS, exFAT, UDFS, and FAT32, Windows stores long file names on disk in Unicode, which means that the original long file name is always preserved. This is true even if a long file name contains extended characters, regardless of which code page is active on disk during a read or write operation. There are two main categories of namespace conventions used in Windows APIs, commonly referred to as NT namespaces and Win32 namespaces. The NT namespace was designed as the lowest namespace on which other subsystems and namespaces could exist, including the Win32 subsystem, and thus the Win32 namespaces.
POSIX is another example of a subsystem in Windows built on the NT namespace. Early versions of Windows also defined several predefined or reserved names for specific devices such as communication ports (serial and parallel) and the default display console as part of the current NT device namespace, and are still supported in current versions of Windows for backward compatibility. Relative paths can combine both types of samples, for example, “C:. tmp.txt”. This is useful because if the system keeps track of the current drive with that drive`s current directory, it also tracks the current directories in each of the different drive letters (if your system has several), regardless of the drive identifier set as the current drive. The path to a specified file consists of one or more components separated by a special character (backslash), each component usually being a directory name or a file name, but with some notable exceptions, which are explained below. For the system`s interpretation of a path, it is often crucial to know what the beginning or prefix of the path looks like. This prefix determines the namespace used by the path and, in addition, which special characters are used in which location in the path, including the last character.
Some file systems, such as NTFS, support linked files and directories that also follow file naming conventions and rules, just like a normal file or directory. For more information, see In-Hard Links and Junctions and Reparse Points and File Operations. Here we learn the directory structure and naming rules for a file in the DOS operating system. Submitted by IncludeHelp on December 10, 2020 To request 8.3 file names, long file names, or the full path of a file from the system, consider the following options: In editions of Windows earlier than Windows 10, version 1607, the maximum length of a path is MAX_PATH, which is set to 260 characters.