Cmd

Starts a new instance of the command interpreter, Cmd.exe. Used without parameters, cmd displays Windows XP version and copyright information.

Syntax

cmd [[{/c|/k}] [/s] [/q] [/d] [{/a|/u}] [/t:fg] [/e:{on|off}] [/f:{on|off}] [/v:{on|off}] string]

Parameters

/c : Carries out the command specified by string and then stops.

/k : Carries out the command specified by string and continues.

/s : Modifies the treatment of string after /c or /k.

/q : Turns the echo off.

/d : Disables execution of AutoRun commands.

/a : Creates American National Standards Institute (ANSI) output.

/u : Creates Unicode output.

/t:fg : Sets the foreground f and background g colors. The following tables lists valid hexadecimal digits that you can use as the values for f and g.

ValueColor

0

Black

1

Blue

2

Green

3

Aqua

4

Red

5

Purple

6

Yellow

7

White

8

Gray

9

Light blue

A

Light green

B

Light aqua

C

Light red

D

Light purple

E

Light yellow

F

Bright white

/e:on : Enables command extensions.

/e:off : Disables commands extensions.

/f:on : Enables file and directory name completion.

/f:off : Disables file and directory name completion.

/v:on : Enables delayed environment variable expansion.

/v:off : Disables delayed environment variable expansion.

string : Specifies the command you want to carry out.

/? : Displays help at the command prompt.

Remarks

Using multiple commands

You can use multiple commands separated by the command separator && for string, but you must enclose them in quotation marks (for example, "command&&command&&command").

Processing quotation marks

If you specify /c or /k, cmd processes the remainder of string and quotation marks are preserved only if all of the following conditions are met:

You do not use /s.

You use exactly one set of quotation marks.

You do not use any special characters within the quotation marks (for example: &<>( ) @ ^ |).

You use one or more white-space characters within the quotation marks.

The string within quotation marks is the name of an executable file.

If the previous conditions are not met, string is processed by examining the first character to verify whether or not it is an opening quotation mark. If the first character is an opening quotation mark, it is stripped along with the closing quotation mark. Any text following the closing quotation marks is preserved.

Executing registry subkeys

If you do not specify /d in string, Cmd.exe looks for the following registry subkeys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\AutoRun\REG_SZ 

HKEY_CURRENT_USER\Software\Microsoft\Command Processor\AutoRun REG_EXPAND_SZ

If either one or both registry subkeys are present, they are executed before all other variables.

 Caution

Incorrectly editing the registry may severely damage your system. Before making changes to the registry, you should back up any valued data on the computer.

Enabling and disabling command extensions

Command extensions are enabled by default in Windows XP. You can disable them for a particular process by using /e:off. You can enable or disable extensions for all cmd command-line options on a computer or user session by setting the following REG_DWORD values:

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\EnableExtensions\REG_DWORD 

HKEY_CURRENT_USER\Software\Microsoft\Command Processor\EnableExtensions\REG_DWORD 

Set the REG_DWORD value to either 0×1 (that is, enabled) or 0×0 (that is, disabled) in the registry by using Regedit.exe. User-specified settings take precedence over computer settings, and command-line options take precedence over registry settings.

 Caution

Incorrectly editing the registry may severely damage your system. Before making changes to the registry, you should back up any valued data on the computer.

When you enable command extensions, the following commands are affected:

assoc 

call 

chdir (cd)

color 

del (erase)

endlocal 

for 

ftype 

goto 

if 

mkdir (md)

popd 

prompt 

pushd 

set 

setlocal 

shift 

start (also includes changes to external command processes)

For more information about these commands, see Related Topics.

Enabling delayed environment variable expansion

If you enable delayed environment variable expansion, you can use the exclamation character to substitute the value of an environment variable at run time.

Enabling file and directory name completion

File and directory name completion is not enabled by default. You can enable or disable file name completion for a particular process of the cmd command with /f:{on|off}. You can enable or disable file and directory name completion for all processes of the cmd command on a computer or user logon session by setting the following REG_DWORD values:

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\CompletionChar\REG_DWORD 

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\PathCompletionChar\REG_DWORD 

HKEY_CURRENT_USER\Software\Microsoft\Command Processor\CompletionChar\REG_DWORD 

HKEY_CURRENT_USER\Software\Microsoft\Command Processor\PathCompletionChar\REG_DWORD 

To set the REG_DWORD value, run Regedit.exe and use the hexadecimal value of a control character for a particular function (for example, 0×9 is TAB and 0×08 is BACKSPACE). User-specified settings take precedence over computer settings, and command-line options take precedence over registry settings.

 Caution

Incorrectly editing the registry may severely damage your system. Before making changes to the registry, you should back up any valued data on the computer.

If you enable file and directory name completion by using /f:on, use CTRL+D for directory name completion and CTRL+F for file name completion. To disable a particular completion character in the registry, use the value for white space [0×20] because it is not a valid control character.

When you press CTRL+D or CTRL+F, cmd processes file and directory name completion. These key combination functions append a wildcard character to string (that is, if one is not present), build a list of paths that match, and then display the first matching path. If none of the paths match, the file and directory name completion function beeps and does not change the display. To move through the list of matching paths, press CTRL+D or CTRL+F repeatedly. To move through the list backwards, press the SHIFT key and CTRL+D or CTRL+F simultaneously. To discard the saved list of matching paths and generate a new list, edit string and press CTRL+D or CTRL+F. If you switch between CTRL+D and CTRL+F, the saved list of matching paths is discarded and a new list is generated. The only difference between the key combinations CTRL+D and CTRL+F is that CTRL+D only matches directory names and CTRL+F matches both file and directory names. If you use file and directory name completion on any of the built-in directory commands (that is, CD, MD, or RD), directory completion is assumed.

File and directory name completion correctly processes file names that contain white space or special characters if you place quotation marks around the matching path.

The following special characters require quotation marks: & < > [ ] { } ^ = ; ! ' + , ` ~ [white space]

If the information that you supply contains spaces, use quotation marks around the text (for example, "Computer Name").

If you process file and directory name completion from within string, any part of the [Path] to the right of the cursor is discarded (that is, at the point in string where the completion was processed).

Formatting legend

FormatMeaning

Italic

Information that the user must supply

Bold

Elements that the user must type exactly as shown

Ellipsis (...)

Parameter that can be repeated several times in a command line

Between brackets ([])

Optional items

Between braces ({}); choices separated by pipe (|). Example: {even|odd}

Set of choices from which the user must choose only one

Courier font

Code or program output

Assoc

Call

Chdir

Color

Del (erase)

Endlocal

For

Ftype

Goto

If

Mkdir

Popd

Prompt

Pushd

Set

Setlocal

Shift

Start

Command-line reference A-Z

Command shell overview



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