set


set

The set command manipulates environment variables from the command line.

TIP

figs/frog_climbingxp_tip.gif

Because the command prompt's environment is reset when its window is closed, the usefulness of set is fairly limited. To affect more permanent changes to environment variables, go to Control Panel System Advanced tab Environment variables.

Type set without options to display all the current environment variables, or use this syntax:

 set [   variable   [=[   string   ]]] set /p   variable   =[   promptstring   ] set /a   expression   

Type set with only a variable name (no equal sign or value) to display a list of all the variables whose prefix matches the name . The set options are:

Option

Description

variable

Specifies the variable name. If variable is specified by itself, its value is displayed. If variable is specified by itself with an equals sign, the variable is assigned an empty value and deleted. variable cannot contain spaces.

string

Specifies a series of characters to assign to variable . This can contain references to other variables by surrounding them with preceding and trailing percent signs ( % ).

/p

Specifies that variable will be assigned by text input from the user , rather than string.

promptstring

The text prompt to display when using the /p option.

/a

Specifies that expression is a numerical expression to be evaluated.

expression

When used with the /a option, expression is a collection of symbols, numbers , and variables arranged so that it can be evaluated by set. The following symbols are recognized (in decreasing order of precedence):

 () !~ */ +- << >> & ^  = *= /=  %= += -= &= ^= = <<= >>= 

Examples

 C:\>  set dummy=not much  C:\>  set dircmd=/s /o-s  C:\>  set path=%path%;c:\mystuff  C:\>  set prompt=$t>  C:\>  set /p dummy=Enter text here>  C:\>  set /a 7+(3*4)  

You can reference environment variables with other commands:

 C:\>  set workdir=C:\stuff\tim's draft  C:\>  cd %workdir%  

Table 6-1 shows most of Windows ' predefined variables.

Table 6-1. Predefined Windows variables

Variable

Description

ALLUSERSPROFILE

The location of the All Users folder, usually c:\Documents and Settings\All Users .

APPDATA

The location of the Application Data folder, usually c:\Documents and Settings\%USERNAME%\Application Data .

COMMONPROGRAMFILES

The location of the Common Files folder, usually c:\Program Files\Common Files .

COMPUTERNAME

The network name of the computer, set by going to Control Panel System Computer Name tab Change.

COMSPEC

The location of the command prompt application executable, c:\Windows\system32\cmd.exe by default.

COPYCMD

Whether the copy, move, and xcopy commands should prompt for confirmation before overwriting a file. The default value is /-y. To stop the warning messages, set COPYCMD to /y.

DIRCMD

Specifies the default options for the dir command. For example, setting DIRCMD to /p will cause dir to always pause after displaying a screenful of output.

HOMEDRIVE

The drive letter of the drive containing the current user's home directory, usually c: , used with HOMEPATH.

HOMEPATH

Along with HOMEDRIVE, the path of the current user's home directory, usually \Documents and Settings\%USERNAME% .

LOGONSERVER

The name of the computer as seen by other computers on your network, usually the same as COMPUTERNAME preceded by two backslashes.

OS

Used to identify the operating system to some applications; for Windows XP, OS is set to "Windows_NT." You may be able to "fool" an older program that is programmed not to run on an NT system by changing this variable temporarily.

PATH

The sequence of directories in which the command interpreter will look for commands to be interpreted. See "path," earlier in this chapter.

PATHEXT

The filename extensions (file types) Windows will look for in the directories listed in the path (see "path," earlier in this chapter). The default is .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH.

PROGRAMFILES

The location of the Program Files folder, usually c:\Program Files .

PROMPT

The format of the command-line prompt, usually $P$G. See "prompt," earlier in this chapter, for details.

SESSIONNAME

The name of the current command prompt session; usually "Console."

SYSTEMDRIVE

The drive letter of the drive containing Windows, usually c: .

SYSTEMROOT

The location of the Windows directory (or more specifically , the name of the folder in which the \Windows\System32 folder can be found), usually c:\windows .

TEMP and TMP

The location where many programs will store temporary files. TEMP and TMP are two different variables, but they should both have the same value. Usually set to C:\DOCUME~1\%USERNAME%\LOCALS~1\Temp (short name used to maintain compatibility with older DOS programs).

USERDOMAIN

The name of the domain to which the computer belongs (set by going to Control Panel System Computer Name Change). If no domain is specified, USERDOMAIN is the same as COMPUTERNAME.

USERNAME

The name of the current user.

USERPROFILE

The location of the current user's home directory, which should be the same as HOMEDRIVE plus HOMEPATH, usually c:\Documents and Settings\%USERNAME% .

WINDIR

The location of the Windows directory, usually c:\windows .



Windows XP Pocket Reference
Windows XP Pocket Reference
ISBN: 0596004257
EAN: 2147483647
Year: 2001
Pages: 154
Authors: David A. Karp

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net