Windows - Environment Variable


An environment variable is an operating system variable that use the hosted application to set application parameters.

They can be set on different scopes:

  1. for a shell thread with the set DOS command (ie for a specific process)
  2. for a specific user
  3. global for a system

How to manage an environment variable ?



  • System: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment
  • User: HKEY_CURRENT_USER\Environment


  • Start / Control Panel / (Performance and Maintenance for XP) / System
  • In the Advanced tab, click the Environment Variable button
  • You can enter a environment variable for:
  • a user session
  • of for the complete system (also known as a global environment variable)


Example: listing of the environment variable of the Outlook process (application) within Process explorer

See process environment variable

Built-in Environment variable

%PATH% list of directories where the OS search to find executable binary. See Os - (Search) Path Environment Variable
%temp% Temp Directory

Powered by ComboStrap