Command Prompt (Windows)

Command Prompt
Other names
  • Windows Command Processor
  • cmd.exe
DevelopersMicrosoft, IBM, ReactOS contributors
ReleaseDecember 1987; 38 years ago (1987-12)
Operating system
PlatformIA-32, x86-64, ARM (and historically DEC Alpha, MIPS, PowerPC, and Itanium)
PredecessorCOMMAND.COM
TypeCommand-line interpreter

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. In some versions of Windows (CE .NET 4.2, 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 COMMAND.COM as the shell. Command Prompt (cmd.exe) replaced 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 Command Prompt.

The initial version of Command Prompt 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 Command Prompt. The ReactOS implementation of Command Prompt is derived from FreeCOM, the FreeDOS command line interpreter.

Use

Desktop integration

In Windows, the shell is presented in the desktop via Windows Terminal or on older versions via Windows Console.

Concurrent piping

In OS/2 and Windows, the shell supports 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, 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 separators &, && or ||.

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.

>CommandA & CommandB & CommandC

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

>CommandA && CommandB && CommandC

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

>CommandA || CommandB && CommandC

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 (213-1) characters. On earlier versions, such as Windows 2000 or Windows NT 4.0, the maximum length is 2047 (211-1) characters.

Escaping special characters

The shell reserves the following characters as special: &<>[]{}^=;!'+,`~ and 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:

>echo me & you
me
'you' is not recognized as an internal or external command,
operable program or batch file.

>echo "me & you"
"me & you"

Internal commands

The following sections list internal commands for implementations of the shell on various operating systems.

OS/2

cmd.exe running in OS/2 Window on OS/2 version 1.3

Internal commands in OS/2:

Windows NT family

cmd.exe running in Windows Terminal on Ukrainian Windows 11

Internal commands in Windows NT and later:

Windows CE

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 net command is available as an external command.

ReactOS

cmd.exe 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
  • echoerr
  • echoserr
  • 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, cmd.exe provides various user experience enhancements as compared to COMMAND.COM, including:

See also

References

  1. ↑ "Notes on using the default OS/2 command processor (CMD.EXE)". www.tavi.co.uk.
  2. 1 2 3 "reactos/reactos". GitHub. December 4, 2021.
  3. ↑ "Command Processor Shell (Windows CE .NET 4.2)". Microsoft Docs. June 30, 2006. Archived from the original on August 31, 2022.
  4. ↑ "Command Processor Shell (Windows CE 5.0)". Microsoft Docs. September 14, 2012. Archived from the original on August 28, 2022.
  5. ↑ "Command Processor Shell (Windows Embedded CE 6.0)". Microsoft Docs. 2012. Archived from the original on September 5, 2022.
  6. ↑ Zachary, G. Pascal (1994). Showstopper! The Breakneck Race to Create Windows NT and the Next Generation at Microsoft. The Free Press. ISBN 0-02-935671-7.
  7. ↑ Douglas McConnaughey Boling (2001). Programming Microsoft Windows CE (2nd ed.). Microsoft Press. ISBN 978-0735614437.
  8. 1 2 "cmd". Microsoft Learn. September 12, 2023. Archived from the original on November 21, 2023.
  9. ↑ "Command shell overview". Microsoft TechNet. Retrieved February 22, 2026.
  10. ↑ Command prompt (Cmd.exe) command-line string limitation
  11. ↑ Microsoft Operating System/2 User's Reference (PDF). Microsoft. 1987.
  12. ↑ Hill, Tim (1998). Windows NT Shell Scripting. Macmillan Technical Publishing. ISBN 978-1578700479.
  13. ↑ "Command Processor Commands (Windows CE .NET 4.2)". Microsoft Docs. June 30, 2006. Archived from the original on August 31, 2022.
  14. ↑ "Command Processor Commands (Windows CE 5.0)". Microsoft Docs. September 14, 2012. Archived from the original on August 31, 2022.
  15. ↑ "Command Processor Commands (Windows Embedded CE 6.0)". Microsoft Docs. January 5, 2012. Archived from the original on September 6, 2022.
  16. ↑ "Windows 2000 delayed environment variable expansion". Windows IT Pro. Archived from the original on July 13, 2015. Retrieved July 13, 2015.
  17. ↑ "Setlocal". TechNet. Microsoft. September 11, 2009. Retrieved January 13, 2015.

Further reading