• Using set with command extensions enabled
  
  When command extensions are enabled (the default) and you run set with a value, it displays all of the variables that begin with that value.
  
  
• Using special characters
  
  The characters <, >, |, &, ^ are special command shell characters, and they must be preceded by the escape character (^) or enclosed in quotation marks when used in String (for example, "StringContaining&Symbol"). If you use quotation marks to enclose a string that contains one of the special characters, the quotation marks are set as part of the environment variable value.
  
  
• Using environment variables
  
  Use environment variables to control the behavior of some batch files and programs and to control the way Windows and the MS-DOS subsystem appears and works. The set command is often used in the Autoexec.nt file to set environment variables.
  
  
• Displaying the current environment settings
  
  When you type the set command alone, the current environment settings are displayed. These settings usually include the COMSPEC and PATH environment variables, which are used to help find programs on disk. Two other environment variables used by Windows are PROMPT and DIRCMD.
  
  
• Using parameters
  
  When you specify values for Variable and String, the specified variable value is added to the environment and String is associated with that variable. If the variable already exists in the environment, the new string value replaces the old string value.
  
  If you specify only a variable and an equal sign (without String) for the set command, the String value associated with the variable is cleared (as if the variable is not there).
  
  
• Using /a
  
  The following table lists the operators supported for /a in descending order of precedence.
  
  

  Operator	Operation performed
  ( )	Grouping
  ! ~ -	Unary
  * / %	Arithmetic
  + -	Arithmetic
  << >>	Logical shift
  &	Bitwise AND
  ^	Bitwise exclusive OR
  |	Bitwise OR
  = *= /= %= += -= &= ^= |= <<= >>=	Assignment
  ,	Expression separator

  If you use logical (&& or ||) or modulus (%) operators, enclose the expression string in quotation marks. Any non-numeric strings in the expression are considered environment variable names, and their values are converted to numbers before they are processed. If you specify an environment variable name that is not defined in the current environment, a value of zero is allotted, which allows you to perform arithmetic with environment variable values without using the % to retrieve a value.
  
  If you run set /a from the command line outside of a command script, it displays the final value of the expression.
  
  Numeric values are decimal numbers unless prefixed by 0× for hexadecimal numbers or 0 for octal numbers. Therefore, 0×12 is the same as 18, which is the same as 022.
  
  
• Supporting delayed environment variable expansion
  
  Delayed environment variable expansion support is disabled by default, but you can enable or disable it by using cmd /v.
  
  
• Working with command extensions
  
  When command extensions are enabled (the default) and you run set alone, it displays all current environment variables. If you run set with a value, it displays the variables that match that value.
  
  
• Using set in batch files
  
  When creating batch files, you can use set to create variables, and then use them in the same way that you would use the numbered variables %0 through %9. You can also use the variables %0 through %9 as input for set.
  
  
• Calling a set variable from a batch file
  
  When you call a variable value from a batch file, enclose the value with percent signs (%). For example, if your batch program creates an environment variable named BAUD, you can use the string associated with BAUD as a replaceable parameter by typing %baud% at the command prompt.
  
  
• Using set at the Recovery Console
  
  The set command, with different parameters, is available from the Recovery Console.
  
  

To set an environment variable named TEST^1, type:

set testVar=test^^1

	Note
	The set command assigns everything that follows the equal sign (=) to the value of the variable. If you type:

set testVar="test^1"

To set an environment variable named TEST&1, type:

set testVar=test^&1

To set an environment variable named INCLUDE so that the string C:\Inc (the \Inc directory on drive C) is associated with it, type:

set include=c:\inc

You can then use the string C:\Inc in batch files by enclosing the name INCLUDE with percent signs (%). For example, you might include the following command in a batch file so that you can display the contents of the directory that is associated with the INCLUDE environment variable:

dir %include%

When this command is processed, the string C:\Inc replaces %include%.

You can also use set in a batch program that adds a new directory to the PATH environment variable. For example:

@echo off
rem ADDPATH.BAT adds a new directory
rem to the path environment variable.
set path=%1;%path%
set

To display a list of all of the environment variables that begin with the letter P, type:

set p 

	Note
	This command requires command extensions, which are enabled by default.