Editing Cmd.exe

{{short description|Shell for Windows NT and other operating systems}}
{{distinguish|COMMAND.COM}}
{{Other uses|CMD (disambiguation){{!}}CMD}}
{{Redirect|Command Prompt|the concept|Command prompt}}
{{Lowercase title}}
{{use mdy dates|date=January 2024}}
{{Infobox software
| name = Command Prompt (cmd.exe)
| logo = Command prompt icon (windows).png
| logo_size = 48px
| screenshot = 
| screenshot_size = 100px
| caption = Command Prompt in [[Windows 11]]
| developer = [[Microsoft]], [[IBM]], ReactOS contributors
| released = {{Start date and age|1987|12}}
| other_names = Windows Command Processor
| replaces = [[COMMAND.COM]]
| operating system = {{Plainlist|
* [[Windows NT]] family
* [[Windows CE]] family
* [[OS/2]]
* [[eComStation]]
* [[ArcaOS]]
* [[ReactOS]]}}
| platform = [[IA-32]], [[x86-64]], [[ARM architecture|ARM]] (and historically [[DEC Alpha]], [[MIPS architecture|MIPS]], [[PowerPC]], and [[Itanium]])
| genre = [[Command-line interpreter]]
}}
'''cmd.exe''', a.k.a. '''Command Prompt''', is a [[shell (computing)|shell]] [[computer program|program]] on later versions of [[Windows]] ([[Windows NT|NT]] and [[Windows CE|CE]] families), [[OS/2]],<ref>{{Cite web|url=http://www.tavi.co.uk/os2pages/cmd.html|title=Notes on using the default OS/2 command processor (CMD.EXE)|website=www.tavi.co.uk}}</ref>, [[eComStation]], [[ArcaOS]], and [[ReactOS]]<ref name="ReactOS" />. In some versions of Windows ([[Windows CE .NET 4.2|CE .NET 4.2]],<ref>{{Cite web|url=https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ms879823(v%3dmsdn.10)|title=Command Processor Shell (Windows CE .NET 4.2)|website=Microsoft Docs |date=June 30, 2006 |url-status=live |archive-url=https://web.archive.org/web/20220831154120/https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ms879823(v%3dmsdn.10) |archive-date=August 31, 2022}}</ref> [[Windows CE 5.0|CE 5.0]]<ref>{{Cite web|url=https://docs.microsoft.com/en-us/previous-versions/windows/embedded/aa453925(v%3dmsdn.10)|title=Command Processor Shell (Windows CE 5.0)|website=Microsoft Docs |date=September 14, 2012 |url-status=live |archive-url=https://web.archive.org/web/20220828195757/https://docs.microsoft.com/en-us/previous-versions/windows/embedded/aa453925(v%3dmsdn.10) |archive-date=August 28, 2022}}</ref> and [[Windows Embedded CE 6.0|Embedded CE 6.0]]<ref>{{Cite web|url=https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee499728(v%3dwinembedded.60)|title=Command Processor Shell (Windows Embedded CE 6.0)|website=Microsoft Docs |date=2012 |url-status=live |archive-url=https://web.archive.org/web/20220905191436/https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee499728(v%3dwinembedded.60) |archive-date=September 5, 2022}}</ref>) it is referred to as the '''Command Processor Shell'''. Implementation differs between operating systems, but with significant consistency of behavior and available commands.

Older, related operating systems, [[DOS]] and [[Windows 9x]], provided {{mono|[[COMMAND.COM]]}} as the shell. {{mono|cmd.exe}} replaced {{mono|COMMAND.COM}} in the Windows product line with the introduction of NT. Current versions of Windows include [[PowerShell]] as an alternative shell that runs side-by-side with {{mono|cmd.exe}}.

The initial version of {{mono|cmd.exe}} for Windows NT was developed by Therese Stowell.<ref name="Zachary_1994">{{Cite book |title=Showstopper! The Breakneck Race to Create Windows NT and the Next Generation at Microsoft |author-first=G. Pascal |author-last=Zachary |date=1994 |publisher=[[Free Press (publisher)|The Free Press]] |isbn=0-02-935671-7 |url-access=registration |url=https://archive.org/details/showstopperbreak00zach}}</ref> [[Windows CE 2.11]] was the first embedded Windows release to support a console and a Windows CE version of {{mono|cmd.exe}}.<ref>{{Cite book|author=Douglas McConnaughey Boling|year=2001|title=Programming Microsoft Windows CE|edition=2nd|publisher=[[Microsoft Press]]|isbn=978-0735614437}}</ref> The ReactOS implementation of {{mono|cmd.exe}} is derived from FreeCOM, the [[FreeDOS]] command line interpreter.<ref name="ReactOS" />

==Use==

===Desktop integration===
In Windows, the shell is presented in the [[Windows Desktop|desktop]] via [[Windows Terminal]] or on older versions via [[Windows Console]].

===Concurrent piping===
In OS/2 and Windows, the shell supports [[Pipeline (Unix)|pipes]] to allow both sides of a pipeline to run concurrently. As a result, it is possible to redirect the [[standard error stream]]. In contrast, {{mono|COMMAND.COM}} uses temporary files, and runs the two sides serially, one after the other.

===Command separator===
Multiple commands can be included in a single line using the command separator {{code|&}} or {{code|&&}}.<ref name="docs.microsoft.com">{{Cite web|url=https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/cmd|title=cmd|website=Microsoft Learn |date=September 12, 2023 |url-status=live |archive-url=https://web.archive.org/web/20231121065635/https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/cmd |archive-date=November 21, 2023}}</ref> 

With the {{code|&}} separator, a subsequent command is executed even if the previous command indicates an error.<ref>{{Cite web|title=Command Redirection, Pipes - Windows CMD - SS64.com|url=https://ss64.com/nt/syntax-redirection.html|access-date=2021-09-23|website=ss64.com}}</ref> In the following example, each of the three commands is executed, one after the other, and regardless of their result code.

<syntaxhighlight lang="doscon">
>CommandA & CommandB & CommandC
</syntaxhighlight>

With the {{code|&&}} separator, a command must complete successfully for the subsequent command to execute. In the following example, {{code|CommandB}} only executes if {{code|CommandA}} completes successfully, and {{code|CommandC}} only executes if {{code|CommandB}} also completes successfully. 

<syntaxhighlight lang="doscon">
>CommandA && CommandB && CommandC
</syntaxhighlight>

===Command line limit===
The shell limits the length of a command line which includes entered text, individual [[environment variable]]s that are inherited by other [[process (computing)|processes]], and all environment variable expansions<ref>[https://support.microsoft.com/en-us/help/830473/command-prompt-cmd-exe-command-line-string-limitation Command prompt (Cmd.exe) command-line string limitation]</ref> On [[Windows XP]] and later, the maximum length is 8191 (2<sup>13</sup>-1) characters. On earlier versions, such as [[Windows 2000]] or [[Windows NT 4.0]], the maximum length is 2047 (2<sup>11</sup>-1) characters.

===Escaping special characters===
The shell reserves the following characters as [[special character|special]]:<ref name="docs.microsoft.com"/> <code>&<>[]{}^=;!'+,`~</code> and [[whitespace character|whitespace]]. In some cases, an argument that contains such characters must be enclosed in double quotes to escape from the special character handling. For example:

<syntaxhighlight lang="doscon">>echo me & you
me
'you' is not recognized as an internal or external command,
operable program or batch file.

>echo "me & you"
"me & you"
</syntaxhighlight>

==Internal commands==

The following sections list [[Shell builtin|internal]] [[command (computing)|commands]] for implementations of the shell on various operating systems.

===OS/2===
[[File:Microsoft OS 2 Version 1.3 cmd.exe OS 2 Window 640x373.png|thumb|{{mono|cmd.exe}} running in '''OS/2 Window''' on OS/2 version 1.3]]

Internal commands in OS/2:<ref>{{Cite book|title=Microsoft Operating System/2 User's Reference|date=1987|publisher=[[Microsoft]]|url=http://www.os2museum.com/wp/wp-content/uploads/2011/12/1987-Oct-OS2-1.0-Users_Reference.pdf}}</ref>

{{Div col|colwidth=6em}}
* [[break (command)|break]]
* [[chcp (command)|chcp]]
* [[cd (command)|cd]]
* [[cd (command)|chdir]]
* [[cls (command)|cls]]
* [[copy (command)|copy]]
* [[date (command)|date]]
* [[del (command)|del]]
* detach
* [[dir (command)|dir]]
* [[dpath]]
* [[echo (command)|echo]]
* [[del (command)|erase]]
* [[exit (command)|exit]]
* [[FOR (DOS command)|for]]
* [[GOTO (DOS command)|goto]]
* [[IF (DOS command)|if]]
* [[mkdir|md]]
* [[mkdir]]
* [[path (command)|path]]
* [[pause (command)|pause]]
* [[prompt (command)|prompt]]
* [[rmdir|rd]]
* [[rem (command)|rem]]
* [[ren (command)|ren]]
* [[ren (command)|rename]]
* [[rmdir]]
* [[set (command)|set]]
* [[shift (command)|shift]]
* [[start (command)|start]]
* [[TIME (command)|time]]
* [[TYPE (DOS command)|type]]
* [[ver (command)|ver]]
* [[verify (command)|verify]]
* [[vol (command)|vol]]
{{Div col end}}

===Windows NT family===
[[File:Windows11Terminal uk.png|thumb|{{mono|cmd.exe}} running in '''Windows Terminal''' on Ukrainian [[Windows 11]]]]

Internal commands in Windows NT and later:<ref>{{Cite book|author-last=Hill|author-first=Tim|title=Windows NT Shell Scripting|date=1998|publisher=[[Macmillan Inc.|Macmillan Technical Publishing]]|isbn=978-1578700479|url-access=registration|url=https://archive.org/details/windowsntshellsc0000hill}}</ref>

{{Div col|colwidth=6em}}
* assoc
* [[break (command)|break]]
* [[call (command)|call]]
* [[cd (command)|cd]]
* [[cd (command)|chdir]]
* [[cls (command)|cls]]
* color
* [[copy (command)|copy]]
* [[date (command)|date]]
* [[del (command)|del]]
* [[dir (command)|dir]]
* [[dpath]]
* [[echo (command)|echo]]
* endlocal
* [[del (command)|erase]]
* [[exit (command)|exit]]
* [[FOR (DOS command)|for]]
* [[ftype]]
* [[GOTO (DOS command)|goto]]
* [[help (command)|help]]
* [[IF (DOS command)|if]]
* keys
* [[mkdir|md]]
* [[mkdir]]
* [[mklink]]
* [[move (command)|move]]
* [[path (command)|path]]
* [[pause (command)|pause]]
* [[pushd and popd|popd]]
* [[prompt (command)|prompt]]
* [[pushd and popd|pushd]]
* [[rmdir|rd]]
* [[rem (command)|rem]]
* [[ren (command)|ren]]
* [[ren (command)|rename]]
* [[rmdir]]
* [[set (command)|set]]
* setlocal
* [[shift (command)|shift]]
* [[start (command)|start]]
* [[TIME (command)|time]]
* [[title (command)|title]]
* [[TYPE (DOS command)|type]]
* [[ver (command)|ver]]
* [[verify (command)|verify]]
* [[vol (command)|vol]]
{{Div col end}}

===Windows CE===
[[File:Microsoft Windows CE Version 3.0 (Build 126) cmd.exe Command Prompt 800x574.png|thumb|Pocket CMD v 3.0 (cmd.exe) on [[Windows CE 3.0]]]]

Internal commands in Windows CE .NET 4.2,<ref>{{Cite web|url=https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ms879786(v=msdn.10)|title=Command Processor Commands (Windows CE .NET 4.2)|website=Microsoft Docs |date=June 30, 2006 |url-status=live |archive-url=https://web.archive.org/web/20220831154120/https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ms879786(v=msdn.10) |archive-date=August 31, 2022}}</ref> Windows CE 5.0<ref>{{Cite web|url=https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ms907227(v=msdn.10)|title=Command Processor Commands (Windows CE 5.0)|website=Microsoft Docs |date=September 14, 2012 |url-status=live |archive-url=https://web.archive.org/web/20220831150618/https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ms907227(v=msdn.10) |archive-date=August 31, 2022}}</ref> and Windows Embedded CE 6.0:<ref>{{Cite web|url=https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee505427(v=winembedded.60)|title=Command Processor Commands (Windows Embedded CE 6.0)|website=Microsoft Docs |date=January 5, 2012 |url-status=live |archive-url=https://web.archive.org/web/20220906020659/https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee505427(v=winembedded.60) |archive-date=September 6, 2022}}</ref>

{{Div col|colwidth=6em}}
* [[attrib]]
* call
* cd
* chdir
* cls
* copy
* date
* del
* dir
* echo
* erase
* exit
* goto
* [[help (command)|help]]
* if
* md
* mkdir
* move
* path
* pause
* prompt
* [[pwd]]
* rd
* rem
* ren
* rename
* rmdir
* set
* shift
* start
* time
* title
* type
{{Div col end}}

The {{mono|[[net (command)|net]]}} command is available as an external command.

===ReactOS===
[[File:ReactOS-0.4.13 cmd.exe Command Prompt 667x434.png|thumb|{{mono|cmd.exe}} on ReactOS]]

Internal commands in ReactOS:<ref name="ReactOS">{{Cite web|url=https://github.com/reactos/reactos |title=reactos/reactos |website=GitHub |date=December 4, 2021}}</ref>

{{Div col|colwidth=6em}}
* ?
* [[alias (command)|alias]]
* assoc
* [[beep (command)|beep]]
* call
* cd
* chdir
* [[choice (command)|choice]]
* cls
* color
* copy
* ctty
* date
* del
* delete
* delay
* dir
* dirs
* echo
* echos
* {{not a typo|echoerr}}
* {{not a typo|echoserr}}
* endlocal
* erase
* exit
* for
* free
* goto
* [[history (command)|history]]
* if
* memory
* md
* mkdir
* mklink
* move
* path
* pause
* popd
* prompt
* pushd
* rd
* rmdir
* rem
* ren
* rename
* replace
* screen
* set
* setlocal
* shift
* start
* time
* timer
* title
* type
* ver
* verify
* vol
{{Div col end}}

==Comparison with COMMAND.COM==
On Windows, {{mono|cmd.exe}} provides various [[user experience]] enhancments as compared to {{mono|COMMAND.COM}}, including:

* More detailed error reporting for malformed commands than the generic {{mono|COMMAND.COM}} "[[Bad command or file name]]". In OS/2, errors are reported in the chosen language of the system, their text being taken from the system message files. The <code>[[help (command)|HELP]]</code> command can then be issued with the error message number to obtain further information.
* Supports using of arrow keys to scroll through command history. With {{mono|COMMAND.COM}}, this functionality was only available in [[DR DOS]]; via [[HISTORY (CONFIG.SYS directive)|HISTORY]]) and later via an external component called {{mono|[[DOSKEY]]}}.
* Adds [[Command-line completion#Rotating completion|rotating command-line completion]] for file and folder paths, where the user can cycle through results for the prefix using the {{keypress|[[tab key|tab]]}}, and {{keypress|[[Shift key|Shift]]|Tab}} for reverse direction.
* Treats the [[caret]] character ({{mono|^}}) as the [[escape character]]; the character following it is to be taken literally. There are special characters in {{mono|cmd.exe}} and {{mono|COMMAND.COM}} that are meant to alter the behavior of the command line processor. The caret character forces the command line processor to interpret them literally.
* Supports delayed variable expansion with {{code|SETLOCAL EnableDelayedExpansion}}, allowing values of variables to be calculated at runtime instead of during parsing of script before execution (Windows 2000 and later), fixing DOS idioms that made using [[control structures]] hard and complex.<ref name="Delay"/> The extensions can be disabled, providing a stricter compatibility mode.
* The {{mono|COMMAND.COM}} <code>[[DELTREE]]</code> command was merged into the <code>[[RMDIR|rd]]</code> command via the {{code|/S}} [[Switch (command line)|switch]].
* {{code|SetLocal}} and {{code|EndLocal}} commands limit the scope of changes to the environment. Changes made to the command line environment after {{code|SetLocal}} are local to the [[batch file]]. {{code|EndLocal}} restores the previous settings.<ref name="SetLocal"/>
* The {{code|call}} command allows subroutines within batch file. The {{mono|COMMAND.COM}} {{code|CALL}} command only supports calling external batch files.
* File name parser extensions to the {{code|set}} command are comparable with [[C shell]].{{Explain|reason=|date=October 2015}}
* The {{code|set}} command can perform [[Expression Evaluation|expression evaluation]].
* An expansion of the <code>[[For loop|for]]</code> command supports parsing files and arbitrary sets in addition to file names.
* The new <code>[[PUSHD|pushd]]</code> and <code>[[POPD|popd]]</code> commands provide access past navigated paths similar to forward and back buttons in a web browser or [[File Explorer]].
* The conditional {{code|if}} command can perform [[Case sensitivity|case-insensitive]] comparisons and numeric equality and inequality comparisons in addition to case-sensitive string comparisons. This was available in DR-DOS, but not in [[PC DOS]] or [[MS-DOS]].

==See also==
* {{Annotated link|Comparison of command shells}}
* {{Annotated link|List of DOS commands}}

==References==
{{Reflist|refs=
<!-- <ref name="Zachary_1994">{{Cite book |title=Showstopper! The Breakneck Race to Create Windows NT and the Next Generation at Microsoft |author-first=G. Pascal |author-last=Zachary |date=1994 |publisher=[[Free Press (publisher)|The Free Press]] |isbn=0-02-935671-7 |url-access=registration |url=https://archive.org/details/showstopperbreak00zach}}</ref> -->
<ref name="Delay">{{Cite web |title=Windows 2000 delayed environment variable expansion |work=Windows IT Pro |url=http://windowsitpro.com/windows/jsi-tip-3240-windows-2000-delayed-environment-variable-expansion |access-date=2015-07-13 |archive-url=https://web.archive.org/web/20150713131827/http://windowsitpro.com/windows/jsi-tip-3240-windows-2000-delayed-environment-variable-expansion |archive-date=2015-07-13 |url-status=dead}}</ref>
<ref name="SetLocal">{{Cite web |title=Setlocal |work=[[Microsoft TechNet|TechNet]] |date=September 11, 2009 |publisher=[[Microsoft]] |url=https://technet.microsoft.com/en-us/library/bb491001.aspx |access-date=2015-01-13}}</ref>
}}

==Further reading==
* {{Cite book|author1=David Moskowitz|author2=David Kerr|year=1994|title=OS/2 2.11 Unleashed|edition=2nd|publisher=[[Sams Publishing]]|isbn=978-0672304453|ref=none}}
* {{Cite book|first=William R.|last=Stanek|year=2008|title=Windows Command-Line Administrator's Pocket Consultant|edition=2nd|publisher=[[Microsoft Press]]|isbn=978-0735622623|ref=none}}

==External links==
{{Commons category|Windows Command Prompt}}
{{Wikibooks|Windows Batch Scripting}}

* {{Cite web|url=https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/windows-commands|title=Command-line reference A-Z|date=April 26, 2023 |publisher=[[Microsoft]]}}
* {{Cite web |url=http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/cmd.mspx |title=Cmd |publisher=[[Microsoft]] |work=Microsoft Windows XP Product Documentation |access-date=2006-05-24 |archive-url=https://web.archive.org/web/20110902070525/http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/cmd.mspx |archive-date=2011-09-02 |url-status=dead}}
* {{Cite web |url=http://windows.microsoft.com/en-us/windows/command-prompt-faq#1TC=windows-7 |title=Command Prompt: frequently asked questions |publisher=[[Microsoft]] |work=windows Help |access-date=2015-04-20 |archive-url=https://web.archive.org/web/20150422041137/http://windows.microsoft.com/en-us/windows/command-prompt-faq#1TC=windows-7 |archive-date=2015-04-22 |url-status=dead}}
* {{Cite web |url=https://ss64.com/nt/ |title=An A–Z Index of the Windows CMD command line |publisher=SS64.com}}
* {{Cite web |url=https://windowscmd.com/ |title=Windows CMD.com – Hub of Windows Commands |publisher=windowscmd.com |access-date=2022-01-04 |archive-date=2022-01-11 |archive-url=https://web.archive.org/web/20220111180551/https://windowscmd.com/ |url-status=dead }}
* [https://www.colorconsole.de/console/en/index.htm  Most important CMD commands in Windows - colorconsole.de] 

{{Microsoft Windows components}}
{{Windows commands}}

[[Category:Command shells]]
[[Category:OS/2 command shells]]
[[Category:Windows command shells]]
[[Category:OS/2 commands]]
[[Category:OS/2 files]]
[[Category:Windows commands]]
[[Category:Windows files]]
[[Category:Windows components]]