My IT blog

Understanding Windows XP's environment variables

Windows XP's environment variables control the behavior of batch files
and programs, and also control the way Windows XP and the MS-DOS
subsystem appears and works. Check out this list of environment
variables, along with their descriptions.

• ALLUSERSPROFILE: Lists the
  location of the All Users Profile.
• APPDATA: Lists the location where
  applications store data by default.
• CD: Lists the current directory
  string.
• CLIENTNAME: List the client's
  NETBIOS name when connected to terminal server session.
• CMDCMDLINE: Lists the command
  line used to start the current cmd.exe.
• CMDEXTVERSION: Lists the version
  number of the current Command Processor Extensions.
• CommonProgramFiles: Lists the path to the Common
  Files folder.
• COMPUTERNAME: Lists the name of
  the computer.
• COMSPEC: Lists the path to the
  command shell executable.
• DATE: Lists the current date.
• ERRORLEVEL: Lists the error code
  of the most recently used command.
• HOMEDRIVE: Lists the drive letter
  is connected to the user's home directory.
• HOMEPATH: Lists the full path of
  the user's home directory.
• HOMESHARE: Lists the network path
  to the user's shared home directory.
• LOGONSEVER: Lists the name of the
  domain controller that validated the current logon session.
• NUMBER_OF_PROCESSORS: Lists the
  number of processors installed on the computer.
• OS: Lists the name of the
  operating system. (Windows XP and Windows 2000 list the operating system as
  Windows_NT.)
• Path: Lists the search path for
  executable files.
• PATHEXT: Lists the file
  extensions that the operating system considers to be executable.
• PROCESSOR_ARCHITECTURE: Lists the
  processor's chip architecture.
• PROCESSOR_IDENTFIER: Lists the
  description of the processor.
• PROCESSOR_LEVEL: Lists the model
  number of the computer's processor.
• PROCESSOR_REVISION: Lists the
  revision number of the processor.
• ProgramFiles: Lists the path to the Program
  Files folder.
• PROMPT: Lists the command-prompt
  settings for the current interpreter.
• RANDOM: Lists a random decimal
  number between 0 and 32767.
• SESSIONNAME: Lists the connection
  and session names when connected to terminal server session.
• SYSTEMDRIVE: Lists the drive
  containing the Windows root directory.
• SYSTEMROOT: Lists the location of
  the Windows root directory.
• TEMP and TMP: List default
  temporary directories for applications that are
  available to users who are currently logged on.
• TIME: Lists the current time.
• USERDOMAIN: Lists the name of the
  domain that contains the user's account.
• USERNAME: Lists the name of the
  user currently logged on.
• USERPROFILE: Lists the location
  of the profile for the current user.
• WINDIR: Lists the location of the
  OS directory.