, also known as Command Prompt or Windows Command Processor, is a shell program on later versions of Windows (NT and CE families), OS/2, eComStation, ArcaOS, and ReactOS. CE 5.0 and Embedded CE 6.0) 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 as the shell. replaced 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 .

The initial version of for Windows NT was developed by Therese Stowell. Windows CE 2.11 was the first embedded Windows release to support a console and a Windows CE version of . The ReactOS implementation of is derived from FreeCOM, the FreeDOS command line interpreter.

With the separator, a subsequent command is executed even if the previous command indicates an error. In the following example, each of the three commands is executed, one after the other, and regardless of their exit code.

<syntaxhighlight lang="doscon">

>CommandA & CommandB & CommandC

</syntaxhighlight>

With the separator, a command must succeed, i.e. yield the exit code 0, for the subsequent command to execute. In the following example, only executes if completes successfully, and only executes if also completes successfully.

<syntaxhighlight lang="doscon">

>CommandA && CommandB && CommandC

</syntaxhighlight>

With the <code>||</code> separator, a command must fail, i.e. yield an exit code not equal 0, for the subsequent command to execute. In the following example, executes if fails, and executes if succeeds.

<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 variables that are inherited by other processes, and all environment variable expansions 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:

  • break
  • chcp
  • cd
  • chdir
  • cls
  • copy
  • date
  • del
  • detach
  • dir
  • dpath
  • echo
  • erase
  • exit
  • for
  • goto
  • if
  • md
  • mkdir
  • path
  • pause
  • prompt
  • rd
  • rem
  • ren
  • rename
  • rmdir
  • set
  • shift
  • start
  • time
  • type
  • ver
  • verify
  • vol

Windows NT family

thumb| running in Windows Terminal on Ukrainian [[Windows 11]]

Internal commands in Windows NT and later:

  • assoc
  • break
  • call
  • cd
  • chdir
  • cls
  • color
  • copy
  • date
  • del
  • dir
  • dpath
  • echo
  • endlocal
  • erase
  • exit
  • for
  • ftype
  • goto
  • if
  • keys
  • md
  • mkdir
  • mklink
  • move
  • path
  • pause
  • popd
  • prompt
  • pushd
  • rd
  • rem
  • ren
  • rename
  • rmdir
  • set
  • setlocal
  • shift
  • start
  • time
  • title
  • type
  • ver
  • verify
  • vol

Windows CE

thumb|Pocket CMD v 3.0 (cmd.exe) on [[Windows CE 3.0]]

Internal commands in Windows CE .NET 4.2, Windows CE 5.0 and Windows Embedded CE 6.0:

  • attrib
  • call
  • cd
  • chdir
  • cls
  • copy
  • date
  • del
  • dir
  • echo
  • erase
  • exit
  • goto
  • help
  • if
  • md
  • mkdir
  • move
  • path
  • pause
  • prompt
  • pwd
  • rd
  • rem
  • ren
  • rename
  • rmdir
  • set
  • shift
  • start
  • time
  • title
  • type

The command is available as an external command.

ReactOS

thumb| on ReactOS

Internal commands in ReactOS:

  • ?
  • alias
  • assoc
  • beep
  • call
  • cd
  • chdir
  • choice
  • cls
  • color
  • copy
  • ctty
  • date
  • del
  • delete
  • delay
  • dir
  • dirs
  • echo
  • echos
  • endlocal
  • erase
  • exit
  • for
  • free
  • goto
  • 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

Comparison with COMMAND.COM

On Windows, provides various user experience enhancements as compared to , including:

  • More detailed error reporting for malformed commands than the generic "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</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 , this functionality was only available in DR DOS (via HISTORY) and later via an external component called .
  • Adds rotating command-line completion for file and folder paths, where the user can cycle through results for the prefix using the , and for reverse direction.
  • Treats the caret character () as the escape character; the character following it is to be taken literally. There are special characters in and 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 , 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. -->

Further reading

  • Most important CMD commands in Windows - colorconsole.de