Environment Variables on Windows

Common predefined environment variables in Windows XP

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Variable	Typical value (may vary, depending on System)
% Allusersprofile %	C: \ Documents ents and Settings \ All Users
% Appdata %	C: \ Documents ents and Settings \{Username}\ Application Data
% Computername %	{Computername}
% Comspec %	C: \ windows \ system32 \ cmd.exe
% Homedrive %	C:
% Homepath %	\ Documents and Settings \{Username}
% PATH %	C: \ windows \ system32 \; C: \ WINDOWS \; c: \ windows \ system32 \ WBEM
% Pathext %	. Com;. EXE;. BAT;. CMD;. vbs;. VBE;. js;. WSF;. wsh
% ProgramFiles %	Directory containing program files, usually c: \ Program Files
% Prompt %	Code for current command prompt format. Code is usually $ p $ G
% Systemdrive %	The drive containing the Windows XP root directory, usually C:
% SystemRoot %	The Windows XP root directory, usually C: \ WINDOWS
% Temp % and % TMP %	C: \ release E ~ 1 \{Username}\ Locals ~ 1 \ Temp
% Username %	{Username}
% USERPROFILE %	C: \ Documents ents and Settings \{Username}
% WINDIR %	C: \ WINDOWS

 

Some Dynamic Environment Variables

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Variable	Value
% Date %	Current date in the format determined byDateCommand
% Time %	Current Time in the format determined byTimeCommand
% Cd %	Current Directory with its full path
% Errorlevel %	Number defining exit status of a previous command or program
% Random %	Random number between 0 and 32767

 

Common predefined environment variables in Windows Vista/7

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Variable	Typical value (may vary, depending on System)
% Allusersprofile %	C: \ programdata
% Appdata %	C: \ Users \(Username}\ Appdata \ roaming
% Commonprogramfiles %	C: \ Program Files \ common files
% Computername %	{Computername}
% Comspec %	C: \ windows \ system32 \ cmd.exe
% Homedrive %	C:
% Homepath %	\ Users \{Username}
% Localappdata %	C: \ Users \{Username}\ Appdata \ Local
% PATH %	Varies. schemdes c: \ windows \ system32 \; C: \ WINDOWS \; c: \ windows \ system32 \ WBEM
% Pathext %	. Com;. EXE;. BAT;. CMD;. vbs;. VBE;. js;. WSF;. wsh;. MSC
% Programdata %	C: \ programdata
% ProgramFiles %	Directory containing program files, usually c: \ Program Files
% ProgramFiles (x86) %	In 64-bit systems, directory containing 32-bit programs. Usually c: \ Program Files (x86)
% Prompt %	Code for current command prompt format. Code is usually $ p $ G
% Public %	C: \ Users \ public
% Systemdrive %	The drive containing the Windows XP root directory, usually C:
% SystemRoot %	The Windows XP root directory, usually C: \ WINDOWS
% Temp % and % TMP %	C: \ Users \{Username}\ Appdata \ Local \ Temp
% Username %	{Username}
% USERPROFILE %	C: \ Users \{Username}
% WINDIR %	C: \ WINDOWS

 

Source:

Environment variables in Windows XP

Http://vlaurie.com/computers2/Articles/environment.htm

Environment variables in Windows Vista and Windows 7

Http://vlaurie.com/computers2/Articles/environment-variables-windows-vista-7.htm