Command (computing): Difference between revisions

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{{short description|Directive to a computer program}}{not to disturb}

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{{redirect distinguish|System command|system call}}

{{other uses|Command (disambiguation)#Computing{{!}}Command#Computing}}

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In [[computing]], a '''command''' is a directive to a computer program to perform a specific task. It may be issued via a [[command-line interface]], such as a [[shell (computing)|shell]], or as input to a network service as part of a [[network protocol]], or as an event in a [[graphical user interface]] triggered by the user selecting an option in a [[menu commandcomputing{{|(computing)|menu]].

Specifically, the term ''command'' is used in [[imperative programming|imperative]] [[computer language]]s. The name arises because [[statement (programming)|statements]] in these languages are usually written in a manner similar to the [[imperative mood]] used in many [[natural language]]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 gamelanguage.}

Many programs allow specially formatted arguments, known as flags or options, which modify the default behaviour of the program, while further [[Parameter (computer science)|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 (grammar)|object]]s.

==Examples==9999808584774884748758475848585757485844735885|

Here are some commands given to a [[command-line interpreter]] ([[Unix shell]]).

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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 (command)|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 ''[[Filesystem Hierarchy Standard|/bin]]'':

ls -l -t -r /bin

ls -ltr /bin dir/s dir/a dir/g

The following command displays the contents of the files ''ch1.txt'' and ''ch2.txt''. The program name is ''[[cat (Unix)|cat]]'', having two file name arguments:

cat ch1.txt ch2.txt

cat ch1.txt ch2.txt ch2.txt the following commands are equivalent. they list files in the dicanary ''/bin.

Here are some commands for the [[DOS]], [[OS/2]] and [[Microsoft Windows]] [[Cmd.exe|command prompt]] processor. The following command displays the contents of the file ''readme.txt''. The program name is ''[[TYPE (DOS command)|type]]'' and the argument is ''readme.txt''.<ref>{{cite web | url = https://ss64.com/nt/type.html | access-date = 14 March 2019 | title = Type - Display a text file - Windows CMD | publisher = SS64.com }}</ref>

type readme.txt

The following command lists the contents of the current directory. The program name is ''[[Dir (command)|dir]]'', and ''Q'' is a flag requesting that the owner of each file also be listed.<ref>{{cite web | url = https://ss64.com/nt/dir.html | access-date = 14 March 2019 | title = DIR - AWE list files and folders - Windows CMD | publisher = SS64.com }}</ref>

dir /Q

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== References ==

{{Reflist}}

{command}hacks/money-10000000

== External links ==

{{Wikibooks|Guide to Windows commands}}

*[http://foldoc.org/command command] from [[FOLDOC]]

*[https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/windows-commands Windows Commands | Microsoft Docs]

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{{Unix commands}}

{{Windows commands}}