The process of filename mangling, in computing

Computing

Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...

, involves a re-writing of the file name for compatibility at the operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 level. It occurs when a filename

Filename

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:...

 on a filesystem appears in a form incompatible with the operating system accessing it. Such mangling occurs, for example, on computer network

Computer network

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

s when a Windows

Microsoft Windows

Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 machine attempts to access a file on a 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...

 server and that file has a filename which includes characters not valid in Windows.

Examples

• Unix file names can contain 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....
  
  s or 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....
  
  es, whereas Windows interprets such characters in other ways. Accordingly, software could mangle the Unix file "Notes: 11-04-03" as "Notes_ 11-04-03" to enable Windows software to remotely access the file.

• Other Unix-like
  Unix-like
  A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
  
   systems, such as Samba on Unix, use different mangling systems to map long filenames to DOS-compatible filenames (although Samba administrators can configure this behavior in the config file).

• Probably the best-known example of name mangling occurs on 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...
  
   file systems on versions of Windows from Windows 95
  Windows 95
  Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft, and was a significant progression from the company's previous Windows products...
  
   onwards. The VFAT specification allows Long File Names (LFNs). For backwards-compatibility with 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...
  
   and older Windows software, which recognizes filenames of a maximum of 11 characters in length with 8.3
  8.3
  An 8.3 filename is a filename convention used by old versions of DOS, versions of Microsoft Windows prior to Windows 95, and Windows NT 3.51. It is also used in modern Microsoft operating systems as an alternate filename to the long filename for compatibility with legacy programs. The filename...
  
   format (i.e.: an eight-letter filename, a dot and a three-letter extension), files with LFNs get stored on disk in 8.3 format, with the long file name stored elsewhere on the disk. Normally, when using compatible Windows programs which use standard Windows methods of reading the disk, the I/O
  Input/output
  In computing, input/output, or I/O, refers to the communication between an information processing system , and the outside world, possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it...
  
   subsystem returns the long filename to the program — however, if an old DOS application or an old Windows application tries to address the file, it will use the older, 8.3-only APIs, or work at a lower level and perform its own disk access, which results in the return of an 8.3 filename. In this case, the filenames become mangled by taking the first six non-space characters in the filename and adding a tilde
  Tilde
  The tilde is a grapheme with several uses. The name of the character comes from Portuguese and Spanish, from the Latin titulus meaning "title" or "superscription", though the term "tilde" has evolved and now has a different meaning in linguistics....
  
   (~) and then a number to ensure the uniqueness of the 8.3 filename on the disk. Thus this mangling scheme can turn (for example) "Program Files" into "PROGRA~1". This tradition continues today when people use DOSBox
  DOSBox
  DOSBox is emulator software that emulates an IBM PC compatible computer running MS-DOS. It is intended especially for use with old PC games. DOSBox is free software....
  
   to play classic DOS games or use Windows 3.1 in conjunction to play Win16 games on 64-bit Windows.
• 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...
  
  replaces instances of ":" in filenames with a "/". This is because prior versions of Mac OS used the ":" character internally as a path separator.