Filename
Encyclopedia
The filename is metadata
about a file
; a string
used to uniquely identify a file
stored on the file system
. Different file systems impose different restrictions on length and allowed characters on filenames.
A filename includes one or more of these components:
To refer to a file on a remote computer filesystem ( host, server) some utilities use the remote computer name or address to prefix the filename.
, NTFS
, and VMS
systems, allow a filename extension
that consists of one or more characters following the last period in the filename, dividing the filename into two parts: the basename (the primary filename) and an extension used by some applications to indicate the file type. Multiple output files created by an application use the same basename and various extensions. For example a compiler might use the extension
, store filenames as upper-case regardless of the case used to create them. For example "MyName" and "myname" would be stored as "MYNAME". A directory could not contain a file with the name "MyName" and another file with the name "myname". Any variation of case can be used to refer to the file (ex: "MYname"). These file systems are called "case-insensitive".
Some filesystems prohibit lower case letters.
Some file systems store filenames as specified when the files is created meaning files MyName and myname would be valid names for different files concurrently in the same directory. Those file systems are called "case-sensitive". Some of these filesystems include a parameter specified when the filesystem which allows references to files regardless of the case. For example a file named "FirstFile" can be referenced as "firstFile", "firstfile", etc.
Not all file systems in Unix-like systems are case-sensitive; by default, HFS+ in Mac OS X
is case-insensitive, and SMB
servers usually provide case-insensitive behavior (even when the underlying file system is case-sensitive, for example Samba
on most Unix-like systems), SMB client file systems provide case-insensitive behavior. File system case sensitivity
is a considerable challenge for software such as Samba and Wine
, which must interoperate efficiently with both systems that treat uppercase and lowercase files as different and systems that treat them the same.
s from appearing in filenames. In Unix-like file systems the null character
, as that is the end-of-string indicator and the path separator
Some file system utilities prohibit some particular characters from appearing in filenames:
Note 1: While they are allowed in Unix file and folder names, most Unix shell
s require certain characters such as spaces, <, >, |, \, and sometimes :, , &, ;, #, as well as wildcards such as ? and *, to be quoted or escaped
:
In Windows utilities the space and the period are not allowed as the final character of a filename. The period is allowed as the first character, but certain Windows applications, such as Windows Explorer
, forbid creating or renaming such files (despite this convention being used in Unix-like systems to describe hidden files and directories). Among workarounds are using different explorer applications or saving a file with the desired filename from within an application .
Some file systems on a given operating system (especially file systems originally implemented on other operating systems), and particular applications on that operating system, may apply further restrictions and interpretations. See comparison of file systems
for more details on restrictions.
In Unix-like systems, MS-DOS, and Windows, the filenames "." and ".." have special meanings (current and parent directory respectively).
In addition, in Windows and DOS utilities, some words might also be reserved and can not be used as filenames. For example, DOS
Device file:
CON, PRN, AUX, CLOCK$, NUL
COM0, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9
LPT0, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9.
Systems that have these restrictions cause incompatibilities with some other filesystems. For example, Windows will fail to handle, or raise error reports for, these legal UNIX filenames: aux.c, q"uote"s.txt, or NUL.txt.
NTFS filenames that are used internally include:
$Mft, $MftMirr, $LogFile, $Volume, $AttrDef, $Bitmap, $Boot, $BadClus, $Secure,
$Upcase, $Extend, $Quota, $ObjId and $Reparse
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
about a file
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
; a string
String (computer science)
In formal languages, which are used in mathematical logic and theoretical computer science, a string is a finite sequence of symbols that are chosen from a set or alphabet....
used to uniquely identify a file
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
stored on the file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
. Different file systems impose different restrictions on length and allowed characters on filenames.
A filename includes one or more of these components:
- directory (or path) – directory tree (e.g., /usr/bin, \TEMP, [USR.LIB.SRC], etc.)
- file – base name of the file
- type (format or extension) – indicates the content type of the file (e.g., .txt, .exe, .COM, etc.)
- version – revision or generation number of the file
To refer to a file on a remote computer filesystem ( host, server) some utilities use the remote computer name or address to prefix the filename.
Length Restrictions
Some filesystems restrict the length of filenames to 11, 14, 31, 44 or 255 charactersFilename extensions
Many file systems, including FATFile Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
, NTFS
NTFS
NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7....
, and VMS
VMS
- Communication and transportation :* Voice Mail System, automated telephone messaging* Video Messaging Service , video messaging for 3G handsets* VMS MobiFone, one of the largest mobile phone operators in Vietnam...
systems, allow a filename extension
Filename extension
A filename extension is a suffix to the name of a computer file applied to indicate the encoding of its contents or usage....
that consists of one or more characters following the last period in the filename, dividing the filename into two parts: the basename (the primary filename) and an extension used by some applications to indicate the file type. Multiple output files created by an application use the same basename and various extensions. For example a compiler might use the extension
FOR for the source input file, OBJ for the object output and LST for the listing. Although there are some common extensions they are arbitrary and a different application might use REL and RPT. On filesystems that do not segregate the extension, files will often have a longer extension such as html.Uniqueness
Within a single directory, filenames must be unique. Since the filename syntax also applies for directories, it is not possible to create a file and directory entries with the same name in a single directory. Multiple files in different directories may have the same name.Case: upper, lower, preservation
Some filesystems, such as FATFile Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
, store filenames as upper-case regardless of the case used to create them. For example "MyName" and "myname" would be stored as "MYNAME". A directory could not contain a file with the name "MyName" and another file with the name "myname". Any variation of case can be used to refer to the file (ex: "MYname"). These file systems are called "case-insensitive".
Some filesystems prohibit lower case letters.
Some file systems store filenames as specified when the files is created meaning files MyName and myname would be valid names for different files concurrently in the same directory. Those file systems are called "case-sensitive". Some of these filesystems include a parameter specified when the filesystem which allows references to files regardless of the case. For example a file named "FirstFile" can be referenced as "firstFile", "firstfile", etc.
Not all file systems in Unix-like systems are case-sensitive; by default, HFS+ in Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
is case-insensitive, and SMB
Server Message Block
In computer networking, Server Message Block , also known as Common Internet File System operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an...
servers usually provide case-insensitive behavior (even when the underlying file system is case-sensitive, for example Samba
Samba (software)
Samba is a free software re-implementation, originally developed by Andrew Tridgell, of the SMB/CIFS networking protocol. As of version 3, Samba provides file and print services for various Microsoft Windows clients and can integrate with a Windows Server domain, either as a Primary Domain...
on most Unix-like systems), SMB client file systems provide case-insensitive behavior. File system case sensitivity
Case sensitivity
Text sometimes exhibits case sensitivity; that is, words can differ in meaning based on differing use of uppercase and lowercase letters. Words with capital letters do not always have the same meaning when written with lowercase letters....
is a considerable challenge for software such as Samba and Wine
Wine (software)
Wine is a free software application that aims to allow computer programs written for Microsoft Windows to run on Unix-like operating systems. Wine also provides a software library, known as Winelib, against which developers can compile Windows applications to help port them to Unix-like...
, which must interoperate efficiently with both systems that treat uppercase and lowercase files as different and systems that treat them the same.
Reserved characters and words
Many file system utilities prohibit control characterControl character
In computing and telecommunication, a control character or non-printing character is a code point in a character set, that does not in itself represent a written symbol.It is in-band signaling in the context of character encoding....
s from appearing in filenames. In Unix-like file systems the null character
Null character
The null character , abbreviated NUL, is a control character with the value zero.It is present in many character sets, including ISO/IEC 646 , the C0 control code, the Universal Character Set , and EBCDIC...
, as that is the end-of-string indicator and the path separator
/ are prohibited.Some file system utilities prohibit some particular characters from appearing in filenames:
| Character | Name | Reason |
|---|---|---|
/ |
slash Slash (punctuation) The slash is a sign used as a punctuation mark and for various other purposes. It is now often called a forward slash , and many other alternative names.-History:... |
used as a path name component separator in Unix-like, Windows, and Amiga systems. (The MS-DOS command.com shell would consume it as a switch character, but Windows itself always accepts it as a separator.) |
\ |
backslash Backslash The backslash is a typographical mark used mainly in computing. It was first introduced to computers in 1960 by Bob Bemer. Sometimes called a reverse solidus or a slosh, it is the mirror image of the common slash.... |
Also used as a path name component separator in MS-DOS, OS/2 and Windows (where there are few differences between slash and backslash); allowed in Unix filenames, see Note 1 |
? |
question mark Question mark The question mark , is a punctuation mark that replaces the full stop at the end of an interrogative sentence in English and many other languages. The question mark is not used for indirect questions... |
used as a wildcard in Unix, Windows and AmigaOS AmigaOS AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000... ; marks a single character. Allowed in Unix filenames, see Note 1 |
% |
percent Percent sign The percent sign is the symbol used to indicate a percentage .Related signs include the permille sign ‰ and the permyriad sign , which indicate that a number is divided by one thousand or ten thousand respectively... |
used as a wildcard in RT-11 RT-11 RT-11 was a small, single-user real-time operating system for the Digital Equipment Corporation PDP-11 family of 16-bit computers... ; marks a single character. |
* |
asterisk Asterisk An asterisk is a typographical symbol or glyph. It is so called because it resembles a conventional image of a star. Computer scientists and mathematicians often pronounce it as star... or star |
used as a wildcard in Unix, MS-DOS, RT-11, VMS and Windows. Marks any sequence of characters (Unix, Windows, later versions of MS-DOS) or any sequence of characters in either the basename or extension (thus "*.*" in early versions of MS-DOS means "all files". Allowed in Unix filenames, see note 1 |
: |
colon Colon (punctuation) The colon is a punctuation mark consisting of two equally sized dots centered on the same vertical line.-Usage:A colon informs the reader that what follows the mark proves, explains, or lists elements of what preceded the mark.... |
used to determine the mount point / drive on Windows; used to determine the virtual device or physical device such as a drive on AmigaOS, RT-11 RT-11 RT-11 was a small, single-user real-time operating system for the Digital Equipment Corporation PDP-11 family of 16-bit computers... and VMS; used as a pathname separator in classic Mac OS Mac OS Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface... . Doubled after a name on VMS, indicates the DECnet nodename (equivalent to a NetBIOS (Windows networking) hostname preceded by "\\".) |
|
vertical bar Vertical bar The vertical bar is a character with various uses in mathematics, where it can be used to represent absolute value, among others; in computing and programming and in general typography, as a divider not unlike the interpunct... or pipe |
designates software pipelining Pipeline (Unix) In Unix-like computer operating systems , a pipeline is the original software pipeline: a set of processes chained by their standard streams, so that the output of each process feeds directly as input to the next one. Each connection is implemented by an anonymous pipe... in Unix and Windows; allowed in Unix filenames, see Note 1 |
" |
quote Quotation mark Quotation marks or inverted commas are punctuation marks at the beginning and end of a quotation, direct speech, literal title or name. Quotation marks can also be used to indicate a different meaning of a word or phrase than the one typically associated with it and are often used to express irony... |
used to mark beginning and end of filenames containing spaces in Windows, see Note 1 |
< |
less than | used to redirect input, allowed in Unix filenames, see Note 1 |
> |
greater than | used to redirect output, allowed in Unix filenames, see Note 1 |
. |
period Full stop A full stop is the punctuation mark commonly placed at the end of sentences. In American English, the term used for this punctuation is period. In the 21st century, it is often also called a dot by young people... or dot |
allowed but the last occurrence will be interpreted to be the extension separator in VMS, MS-DOS and Windows. In other OSes, usually considered as part of the filename, and more than one period (full stop) may be allowed. |
Note 1: While they are allowed in Unix file and folder names, most Unix shell
Unix shell
A Unix shell is a command-line interpreter or shell that provides a traditional user interface for the Unix operating system and for Unix-like systems...
s require certain characters such as spaces, <, >, |, \, and sometimes :, , &, ;, #, as well as wildcards such as ? and *, to be quoted or escaped
Escape character
In computing and telecommunication, an escape character is a character which invokes an alternative interpretation on subsequent characters in a character sequence. An escape character is a particular case of metacharacters...
:
five\ and\ six\ (example of escaping)
'five and six or "five and six (examples of quoting) In Windows utilities the space and the period are not allowed as the final character of a filename. The period is allowed as the first character, but certain Windows applications, such as Windows Explorer
Windows Explorer
This article is about the Windows file system browser. For the similarly named web browser, see Internet ExplorerWindows Explorer is a file manager application that is included with releases of the Microsoft Windows operating system from Windows 95 onwards. It provides a graphical user interface...
, forbid creating or renaming such files (despite this convention being used in Unix-like systems to describe hidden files and directories). Among workarounds are using different explorer applications or saving a file with the desired filename from within an application .
Some file systems on a given operating system (especially file systems originally implemented on other operating systems), and particular applications on that operating system, may apply further restrictions and interpretations. See comparison of file systems
Comparison of file systems
-General information:-Limits:-Metadata:-Features:-Allocation and layout policies:-Supporting operating systems:-See also:* Comparison of archive formats* Comparison of file archivers* List of archive formats* List of file archivers...
for more details on restrictions.
In Unix-like systems, MS-DOS, and Windows, the filenames "." and ".." have special meanings (current and parent directory respectively).
In addition, in Windows and DOS utilities, some words might also be reserved and can not be used as filenames. For example, DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
Device file:
CON, PRN, AUX, CLOCK$, NUL
COM0, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9
LPT0, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9.
Systems that have these restrictions cause incompatibilities with some other filesystems. For example, Windows will fail to handle, or raise error reports for, these legal UNIX filenames: aux.c, q"uote"s.txt, or NUL.txt.
NTFS filenames that are used internally include:
$Mft, $MftMirr, $LogFile, $Volume, $AttrDef, $Bitmap, $Boot, $BadClus, $Secure,
$Upcase, $Extend, $Quota, $ObjId and $Reparse
Comparison of filename limitations
| System | Alphabetic Case Sensitivity | Allowed Character Set | Reserved Characters | Reserved Words | Maximum Length | Comments |
|---|---|---|---|---|---|---|
| MS-DOS MS-DOS MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating... FAT File Allocation Table File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of... |
case-insensitive case-destruction | any 8-bit set | x00-x1F SPACE DEL " * / : < > ? \ > | Devicesnames like: AUX COM1 … COM9 CON LPT1 … LPT9 NUL PRN | 11 | Maximum 8 character base name limit and 3 character extension; see 8.3 filename |
| Win95 VFAT File Allocation Table File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of... |
case-insensitive | any 8-bit set | |\?*<":>+[]/ control characters | 255 | ||
| FAT32 File Allocation Table File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of... |
case-insensitive | Unicode Unicode Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems... , using UTF-16 encoding |
|\?*<":>+[]/ control characters | 255 | ||
| NTFS NTFS NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7.... |
optional (case-preservation) | Unicode Unicode Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems... , using UTF-16 encoding |
/ null (i.e., 0x00) | Only in Root Directory: $AttrDef $BadClus $Bitmap $Boot $LogFile $MFT $MFTMirr pagefile.sys $Secure $UpCase $Volume $Extend $Extend\$ObjId $Extend\$Quota $Extend\$Reparse ($Extend is a directory) | 255 | forbids the use of characters in range 1-31 (0x01-0x1F) and characters " * : < > ? \ / |. NTFS allows each path component (directory or filename) to be 255 characters long. Windows forbids the use of the MS-DOS device names AUX, CLOCK$, COM1, …, COM9, CON, LPT1, …, LPT9, NUL and PRN, as well as these names with any extension (for example, AUX.txt), except when using Long UNC paths (ex. \\.\C:\nul.txt or \\?\D:\aux\con). (CLOCK$ may be used if an extension is provided.) The Win32 API strips trailing space and period (full-stop) characters from filenames, except when UNC paths are used. These restrictions only apply to Windows; Linux NTFS allows the use of the " * : < > ? \ | characters. |
| OS/2 HPFS | case-insensitive case-preservation | any 8-bit set | |\?*<":>/ | 254 | ||
| Mac OS Mac OS Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface... HFS Hierarchical File System Hierarchical File System is a file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs... |
case-insensitive case-preservation | any 8-bit set | : | 255 | old versions of Finder are limited to 31 characters | |
| Mac OS Mac OS Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface... HFS+ HFS Plus HFS Plus or HFS+ is a file system developed by Apple Inc. to replace their Hierarchical File System as the primary file system used in Macintosh computers . It is also one of the formats used by the iPod digital music player... |
optional (case-preservation) | any 8-bit set | : on disk, in classic Mac OS, and at the Carbon Carbon (API) Carbon is one of Apple Inc.'s procedural application programming interfaces for the Macintosh operating system. It provides C programming language access to Macintosh system services... layer in Mac OS X; / at the Unix layer in Mac OS X |
255 | Mac OS 8.1 - Mac OS X | |
| most UNIX Unix Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna... file systems |
case-sensitive case-preservation | any 8-bit set | / null | 255 | a leading . indicates that ls and file managers will not show the file by default |
|
| zOS | other than $ # @ - x'C0' | 44 | first character must be alphabetic or national ($, #, @) "Qualified" contains . after every 8 characters or fewer. |
|||
| early UNIX Unix Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna... (AT&T AT&T AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services... ) |
case-sensitive case-preservation | any 8-bit set | / | 14 | a leading . indicates a "hidden" file | |
| POSIX POSIX POSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems... "Fully portable filenames" |
case-sensitive case-preservation | A–Z a–z 0–9 . _ - | / null | Filenames to avoid include: a.out, core, .profile, .history, .cshrc | 14 | hyphen must not be first character |
| ISO 9660 ISO 9660 ISO 9660, also referred to as CDFS by some hardware and software providers, is a file system standard published by the International Organization for Standardization for optical disc media.... |
case-insensitive | A–Z 0–9 _ . | "close to 180"(Level 2) or 200(Level 3) | Used on CDs; 8 directory levels max (for Level 1, not level 2,3) | ||
| AmigaOS AmigaOS AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000... |
case-insensitive case-preservation | any 8-bit set | : / " | 107 | dos.library | |
| Amiga OFS Amiga Old File System On the Amiga, the Old File System was the filesystem for Amiga OS before the Amiga Fast File System. Even though it used 512-byte blocks, it reserved the first small portion of each block for metadata, leaving an actual data block capacity of 488 bytes per block... |
case-insensitive case-preservation | any 8-bit set | : / " | 30 | Original File System 1985 | |
| Amiga FFS Amiga Fast File System The Amiga Fast File System is a file system used on the Amiga personal computer. The previous Amiga filesystem upon the release of FFS became known as Amiga Old File System . OFS, while fine on floppy disk, soon proved too slow to keep up with era hard drives... |
case-insensitive case-preservation | any 8-bit set | : / " | 30 | Fast File System 1988 | |
| Amiga PFS Professional File System The Professional File System is a filesystem originally developed commercially for the Amiga, it is now distributed on Aminet with a 4-clause BSD license. PFS tends to perform very well, due to the simplicity of design. Compatible successor of Ami-FileSafe.... |
case-insensitive case-preservation | any 8-bit set | : / " | 255 | Professional File System 1993 | |
| Amiga SFS Smart File System The Smart File System is a journaling filesystem used on Amiga computers. It is designed for performance, scalability and integrity... |
case-insensitive case-preservation | any 8-bit set | : / " | 32,000 | Smart File System 1998 | |
| Amiga FFS2 | case-insensitive case-preservation | any 8-bit set | : / " | 107 | Fast File System 2 2002 | |
| BeOS BeOS BeOS is an operating system for personal computers which began development by Be Inc. in 1991. It was first written to run on BeBox hardware. BeOS was optimized for digital media work and was written to take advantage of modern hardware facilities such as symmetric multiprocessing by utilizing... BFS Be File System The Be File System is the native file system for the BeOS.... |
case-sensitive | Unicode Unicode Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems... , using UTF-8 UTF-8 UTF-8 is a multibyte character encoding for Unicode. Like UTF-16 and UTF-32, UTF-8 can represent every character in the Unicode character set. Unlike them, it is backward-compatible with ASCII and avoids the complications of endianness and byte order marks... encoding |
/ | 255 | ||
| DEC Digital Equipment Corporation Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s... PDP-11 PDP-11 The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years... RT-11 RT-11 RT-11 was a small, single-user real-time operating system for the Digital Equipment Corporation PDP-11 family of 16-bit computers... |
case-insensitive | RADIX-50 RADIX-50 RADIX-50, commonly called Rad-50 or RAD50, is a character encoding created by Digital Equipment Corporation for use on their DECsystem, PDP, and VAX computers... |
6 + 3 | Flat filesystem with no subdirs. A full "file specification" includes device, filename and extension (file type) in the format: dev:filnam.ext. | ||
| DEC Digital Equipment Corporation Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s... VAX VAX VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs... VMS OpenVMS OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase... |
case-insensitive | A–Z 0–9 $ - _ | 32 per component; earlier 9 per component; latterly, 255 for a filename and 32 for an extension. | a full "file specification" includes nodename, diskname, directory/ies, filename, extension and version in the format: OURNODE::MYDISK:[THISDIR.THATDIR]FILENAME.EXTENSION;2 Directories can only go 8 levels deep. | ||
| Commodore 64 Commodore 64 The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595... |
case-sensitive case-preservation | any 8-bit set | :, = | $ | 16 | length depends on the drive, usually 16 |
See also
- File systemFile systemA file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
- Fully qualified file nameFully qualified file nameThe term fully qualified file name means a file on a computer whose exact name is completely specified such that it is unambiguous and cannot be mistaken for any other file on that system. It is somewhat equivalent on the Internet to a URL specifying the full name of the computer and the entire...
- Long filenameLong filenameLong filenames , are Microsoft's way of implementing filenames longer than the 8.3 filename, or short-filename, naming scheme used in Microsoft DOS in their modern FAT and NTFS filesystems. Because these filenames can be longer than an 8.3 filename, they can be more descriptive...
- Path (computing)Path (computing)A path, the general form of a filename or of a directory name, specifies a unique location in a file system. A path points to a file system location by following the directory tree hierarchy expressed in a string of characters in which path components, separated by a delimiting character, represent...
- Symbolic linkSymbolic linkIn computing, a symbolic link is a special type of file that contains a reference to another file or directory in the form of an absolute or relative path and that affects pathname resolution. Symbolic links were already present by 1978 in mini-computer operating systems from DEC and Data...
- Uniform Resource IdentifierUniform Resource IdentifierIn computing, a uniform resource identifier is a string of characters used to identify a name or a resource on the Internet. Such identification enables interaction with representations of the resource over a network using specific protocols...
(URI) - Uniform Resource LocatorUniform Resource LocatorIn computing, a uniform resource locator or universal resource locator is a specific character string that constitutes a reference to an Internet resource....
(URL)