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Cmd.exe

From Alfawiki
cmd.exe
Company typeCommand-line interpreter
IndustrySoftware
FounderTherese Stowell
ProductsCommand-line shell for Windows NT, Windows CE, OS/2, eComStation, ArcaOS, ReactOS

cmd.exe, often referred to as Command Prompt, serves as a command-line interpreter in later editions of Windows (notably within the Windows NT and Windows CE series), as well as in OS/2, eComStation, ArcaOS, and ReactOS. In certain Windows variants, including Windows CE .NET 4.2, Windows CE 5.0, and Windows Embedded CE 6.0, it is designated the Command Processor Shell. Despite differences in implementation across these platforms, its commands and functionalities remain predominantly uniform.

Earlier operating systems such as DOS and Windows 9x relied on as their command interpreter. The introduction of Windows NT marked the replacement of by . In addition to , contemporary Windows systems also offer PowerShell as a supplementary shell environment.

The original version of for Windows NT was created by Therese Stowell. The embedded Windows release, Windows CE 2.11, was the first to incorporate a console along with a Windows CE adaptation of . ReactOS’s iteration of is derived from FreeCOM, the command interpreter utilized by FreeDOS.

Desktop access

Within Windows, users launch the shell through the desktop interface, commonly via Windows Terminal, or on legacy versions, through the Windows Console application.

Simultaneous piping

On platforms like OS/2 and Windows, the shell supports pipes that execute both ends concurrently, allowing for redirection of the standard error stream. This contrasts with , which processes pipeline commands sequentially using temporary files.

Separating commands

It is possible to chain multiple commands on a single line using either or . When employing , all commands execute regardless of any errors encountered:

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

Conversely, with , each command executes only if the preceding command completes successfully:

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

Maximum command length

The shell imposes a maximum length on command lines—including both input text and expanded environment variables—capped at 8191 characters on Windows XP and subsequent versions, while earlier editions such as Windows 2000 and Windows NT 4.0 restrict this to 2047 characters.

Handling special characters

Certain characters are reserved within the shell environment: &<>[]{}^=;!'+,`~ along with whitespace. Arguments containing these symbols typically require enclosing in double quotes to prevent parsing errors:

<syntaxhighlight lang="doscon"> >echo me & you me 'you' is not recognized as an internal or external command

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

Internal commands

This segment enumerates the built-in commands available within various shell implementations across different operating systems.

OS/2

The following are internal commands supported in OS/2:

Windows NT series

The internal commands available in Windows NT and subsequent versions include:

Windows CE

The following internal commands are present 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, rmdir
  • rem
  • ren, rename
  • set
  • shift
  • start
  • time
  • title
  • type

The command functions as an external utility.

ReactOS

ReactOS supports the following internal commands:

  • ?
  • 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

Compared to , Windows' provides numerous improvements in user interaction, such as:

  • Enhanced error diagnostics for incorrect commands beyond the generic "Bad command or file name." OS/2 delivers error messages localized in the system language with explanations sourced from system files. The HELP function can be invoked with the error code for additional information.
  • Support for arrow keys to navigate through previous commands, a feature formerly limited to systems like DR DOS using HISTORY or third-party utilities.
  • Command-line completion cycles through file and directory names by utilizing the and keys.
  • The caret symbol () acts as an escape character, allowing literal interpretation of subsequent characters and improving command parsing.
  • Delayed variable expansion is enabled via , permitting variables to be evaluated during execution rather than at parse time—available from Windows 2000 onward—thus enhancing scripting flexibility.[1] This feature can be disabled to maintain strict backward compatibility.
  • . The functionality of the DELTREE command has been merged into rd with an additional switch.
  • . Commands like and confine environment variable modifications to the batch file's scope, restoring prior settings after completion.[2]
  • . The command supports invoking subroutines within batch scripts, whereas COMMAND.COM's CALL is limited to external batch files only.
  • . Extensions to the file name parser within resemble capabilities found in the C shell, enabling expression evaluation.
  • . The for command is capable of iterating over files and arbitrary sets beyond just file names.
  • . Newly introduced pushd and popd commands facilitate directory stack navigation similar to forward/backward browsing or the navigation features in File Explorer.
  • . The conditional command supports case-insensitive string comparisons along with numeric equality and inequality tests, extending functionality beyond earlier DOS implementations.

See also

Further reading

External links

  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Delay
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SetLocal
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