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computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
, a command is a directive to a computer program to perform a specific task. It may be issued via a
command-line interface A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...
, such as a shell, or as input to a network service as part of a network protocol, or as an event in a
graphical user interface The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, ins ...
triggered by the user selecting an option in a
menu In a restaurant, the menu is a list of food and beverages offered to customers and the prices. A menu may be à la carte – which presents a list of options from which customers choose – or table d'hôte, in which case a pre-established seque ...
. Specifically, the term ''command'' is used in imperative computer languages. The name arises because statements in these languages are usually written in a manner similar to the
imperative mood The imperative mood is a grammatical mood that forms a command or request. The imperative mood is used to demand or require that an action be performed. It is usually found only in the present tense, second person. To form the imperative mood, ...
used in many
natural language In neuropsychology, linguistics, and philosophy of language, a natural language or ordinary language is any language that has evolved naturally in humans through use and repetition without conscious planning or premeditation. Natural languages ...
s. If one views a statement in an imperative language as being like a sentence in a natural language, then a command is generally like a verb in such a language. Many programs allow specially formatted arguments, known as flags or options, which modify the default behaviour of the program, while further arguments may provide objects, such as files, to act on. As an analogy to a natural language, the flags are adverbs, while the other arguments are
object Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an ...
s.


Examples

Here are some commands given to a command-line interpreter ( Unix shell). The following command changes the user's working position in the directory tree to the directory ''/home/pete''. The utility program is '' cd'' and the argument is ''/home/pete'': cd /home/pete The following command prints the text ''Hello World'' on the standard output stream, which, in this case, just prints the text on the screen. The program name is echo and the argument is "Hello World". The quotes are used to prevent ''Hello'' and ''World'' being treated as separate tokens: echo "Hello World" The following commands are equivalent. They list files in the directory ''/bin''. The program is '' ls'', having three flags (''l'', ''t'', ''r''), and the argument is the directory '' /bin'': ls -l -t -r /bin ls -ltr /bin The following command displays the contents of the files ''ch1.txt'' and ''ch2.txt''. The program name is '' cat'', having two file name arguments: cat ch1.txt ch2.txt Here are some commands for the
DOS DOS is shorthand for the MS-DOS and IBM PC DOS family of operating systems. DOS may also refer to: Computing * Data over signalling (DoS), multiplexing data onto a signalling channel * Denial-of-service attack (DoS), an attack on a communicat ...
,
OS/2 OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 r ...
and
Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...
command prompt Command Prompt, also known as cmd.exe or cmd, is the default command-line interpreter for the OS/2, eComStation, ArcaOS, Microsoft Windows (Windows NT family and Windows CE family), and ReactOS operating systems. On Windows CE .NET 4.2, ...
processor. The following command displays the contents of the file ''readme.txt''. The program name is '' type'' and the argument is ''readme.txt''. type readme.txt The following command lists the contents of the current directory. The program name is '' dir'', and ''Q'' is a flag requesting that the owner of each file also be listed. dir /Q


See also

*
Gesture recognition Gesture recognition is a topic in computer science and language technology with the goal of interpreting human gestures via mathematical algorithms. It is a subdiscipline of computer vision. Gestures can originate from any bodily motion or sta ...
* List of Unix commands * List of DOS commands *
Formal grammar In formal language theory, a grammar (when the context is not given, often called a formal grammar for clarity) describes how to form strings from a language's alphabet that are valid according to the language's syntax. A grammar does not describe ...


References


External links


command
from FOLDOC
Windows Commands , Microsoft Docs
{{Windows commands User interfaces Computing terminology