Directory (file systems)
Encyclopedia
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...

, a folder, directory, catalog, or drawer, is a virtual container originally derived from an earlier Object-oriented programming
Object-oriented programming
Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...

 concept by the same name within a digital 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...

, in which groups of computer 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...

s and other folders can be kept and organized.

A typical file system may contain thousands (or even hundreds of thousands) of folders. Files are kept organized by storing related files in the same folder. The folder can also be referred to as the root. A folder contained inside another folder is called a subfolder, subdirectory, or child of that folder. Together, the folders form a hierarchy
Hierarchy
A hierarchy is an arrangement of items in which the items are represented as being "above," "below," or "at the same level as" one another...

, or tree structure.

Overview

Historically, and even on some modern embedded devices, the file systems either have no support for folders at all or only have a flat directory structure
Directory structure
In computing, a directory structure is the way an operating system's file system and its files are displayed to the user. Files are typically displayed in a Hierarchical tree structure.-File names and extensions:...

, meaning subfolders are not allowed; there is only a group of top-level folders each containing files. The first popular fully general hierarchical file system was that of Multics
Multics
Multics was an influential early time-sharing operating system. The project was started in 1964 in Cambridge, Massachusetts...

. This type of file system was an early research interest of Dennis Ritchie
Dennis Ritchie
Dennis MacAlistair Ritchie , was an American computer scientist who "helped shape the digital era." He created the C programming language and, with long-time colleague Ken Thompson, the UNIX operating system...

.

Most modern 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, especially Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

, have a standard folder structure defined by the Filesystem Hierarchy Standard
Filesystem Hierarchy Standard
The Filesystem Hierarchy Standard defines the main directories and their contents in Linux operating systems. For the most part, it is a formalization and extension of the traditional BSD filesystem hierarchy....

.

In many 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...

s, programs have an associated working directory
Working directory
In computing, the working directory of a process is a directory of a hierarchical file system, if any, dynamically associated with each process. When the process refers to a file using a simple file name or relative path , the reference is interpreted relative to the current working directory of...

 in which they execute. Typically file names accessed by the program are assumed to reside within this folder if the file names are not specified with an explicit folder name.

Some operating systems restrict a user's
Computer User
Computer User is a computer magazine originally founded in 1982, and which, after several owners and fundamental changes, is still in business today online as computeruser.com...

 access to only their home directory
Home directory
A Home directory is a file system directory on a multi-user operating system containing files for a given user of the system. The specifics of the home directory is defined by the operating system involved; for example, Windows systems between 2000 and 2003 keep home directories in a folder...

 or project folder, thus isolating their activities from all other users.

Unix systems treat folders as a type of file.

The folder metaphor

The name folder, presenting an analogy to the file folder
File folder
A file folder is a kind of folder that holds loose papers together for organization and protection. File folders usually consist of a sheet of heavy paper stock or other thin, but stiff, material which is folded in half, and are used to keep paper documents...

 used in offices, and used originally by Apple Lisa
Apple Lisa
The Apple Lisa—also known as the Lisa—is a :personal computer designed by Apple Computer, Inc. during the early 1980s....

, is used in almost all modern 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...

s' desktop environments. Folders are often depicted with icon
Computer icon
A computer icon is a pictogram displayed on a computer screen and used to navigate a computer system or mobile device. The icon itself is a small picture or symbol serving as a quick, intuitive representation of a software tool, function or a data file accessible on the system. It functions as an...

s which visually resemble physical file folders.

Strictly speaking, there is a difference between a directory which is a 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...

 concept, and the graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

 metaphor that is used to represent it (a folder). For example, Microsoft Windows uses the concept of special folders
Special Folders
On Microsoft Windows, a special folder is a folder which is presented to the user through an interface as an abstract concept, instead of an absolute folder path...

 to help present the contents of the computer to the user in a fairly consistent way that frees the user from having to deal with absolute directory paths, which can vary between versions of Windows, and between individual installations.

If one is referring to a container of documents, the term folder is more appropriate. The term directory refers to the way a structured list of document files and folders is stored on the computer. It is comparable to a telephone directory that contains lists of names, numbers and addresses and does not contain the actual documents themselves.

See also

  • Cd command
  • Chroot system call
    Chroot
    A chroot on Unix operating systems is an operation that changes the apparent root directory for the current running process and its children. A program that is run in such a modified environment cannot name files outside the designated directory tree. The term "chroot" may refer to the chroot...

  • Directory structure
    Directory structure
    In computing, a directory structure is the way an operating system's file system and its files are displayed to the user. Files are typically displayed in a Hierarchical tree structure.-File names and extensions:...

  • Dired
    Dired
    Dired is a visual directory editor, a computer program for editing file system directories. Dired runs on any Emacs platform. Its commands are generally more modal than most Emacs commands because Dired is a specialized major mode on its own...

  • 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:...

  • Mkdir command
    Mkdir
    The mkdir command in the Unix, DOS, OS/2 and Microsoft Windows operating systems is used to make a new directory. In DOS, OS/2 and Windows the command is often abbreviated to md.-Usage:Normal usage is as straightforward as follows:...


  • Pushd and popd commands
    Pushd and popd
    In computing, pushd and popd are commands in various Unix, DOS and Microsoft Windows command line interpreters such as Bash, cmd.exe, 4DOS/4NT and Windows PowerShell...

  • Root directory
    Root directory
    In computer file systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the root of a tree — the starting point where all branches originate.-Metaphor:...

  • Web directory
    Web directory
    A web directory or link directory is a directory on the World Wide Web. It specializes in linking to other web sites and categorizing those links....

  • Working directory
    Working directory
    In computing, the working directory of a process is a directory of a hierarchical file system, if any, dynamically associated with each process. When the process refers to a file using a simple file name or relative path , the reference is interpreted relative to the current working directory of...

  • Virtual folder
    Virtual folder
    In computing, a virtual folder generally denotes an organizing principle for files that is not dependent on location in a hierarchical directory tree...



External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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