Environments Variables
Variable                 Type            Description
%ALLUSERSPROFILE%.       Local           Returns the location of the All Users Profile.
%APPDATA%                Local           Returns the location where applications store data by default.
%CD%                     Local           Returns the current directory string.
%CMDCMDLINE%             Local           Returns the exact command line used to start the current Cmd.exe.
%CMDEXTVERSION%          System          Returns the version number of the current Command Processor Extensions.
%COMPUTERNAME%           System          Returns the name of the computer.
%COMSPEC%                System          Returns the exact path to the command shell executable.
%DATE%                   System          Returns the current date. Uses the same format as the date /t command. Generated by Cmd.exe.
%ERRORLEVEL%             System          Returns the error code of the most recently used command. A non zero value usually indicates an error.
%HOMEDRIVE%              System          Returns which local workstation drive letter is connected to the user's home directory. Set based on the value of the home directory. The user's home directory is specified in Local Users and Groups.
%HOMEPATH%               System          Returns the full path of the user's home directory. Set based on the value of the home directory. The user's home directory is specified in Local Users and Groups.
%HOMESHARE%              System          Returns the network path to the user's shared home directory. Set based on the value of the home directory. The user's home directory is specified in Local Users and Groups.
%LOGONSEVER%.            Local           Returns the name of the domain controller that validated the current logon session.
%NUMBER_OF_PROCESSORS%   System          Specifies the number of processors installed on the computer.
%OS%                     System          Returns the operating system name. Windows 2000 displays the operating system as Windows_NT.
%PATH%                   System          Specifies the search path for executable files.
%PATHEXT%                System          Returns a list of the file extensions that the operating system considers to be executable.
%PROCESSOR_ARCHITECTURE% System          Returns the chip architecture of the processor. Values: x86, IA64.
%PROCESSOR_IDENTFIER%    System          Returns a description of the processor.
%PROCESSOR_LEVEL%        System          Returns the model number of the processor installed on the computer.
%PROCESSOR_REVISION%     System          Returns the revision number of the processor.
%PROMPT%                 Local           Returns the command prompt settings for the current interpreter. Generated by Cmd.exe.
%RANDOM%                 System          Returns a random decimal number between 0 and 32767. Generated by Cmd.exe.
%SYSTEMDRIVE%            System          Returns the drive containing the Windows XP root directory (that is, the system root).
%SYSTEMROOT%             System          Returns the location of the Windows XP root directory.
%TEMP% and %TMP%         System and User Returns the default temporary directories that are used by applications available to users who are currently logged on. Some applications require TEMP and others require TMP.
%TIME%                   System          Returns the current time. Uses the same format as the time /t command. Generated by Cmd.exe.
%USERDOMAIN%             Local           Returns the name of the domain that contains the user's account.
%USERNAME%               Local           Returns the name of the user who is currently logged on.
%USERPROFILE%.           Local           Returns the location of the profile for the current user.
%WINDIR%                 System          Returns the location of the operating system directory.
Reset Windows Update parameters
# Ouvrir un invité de commande en tant qu’administrateur
# Entrer chaque ligne, l’une après l’autre
net stop wuauserv
net stop cryptSvc
net stop bits
net stop msiserver
ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 catroot2.old
net start wuauserv
net start cryptSvc
net start bits
net start msiserver