This step-by-step article describes how you can manage the environment variables in Windows XP. Environment variables are strings that contain information about the environment for the system, and the currently logged on user. Some software programs use the information to determine where to place files (such as temporary files). During installation, Windows XP Setup configures the default system variables, such as the path to the Windows files.
You must be an administrator to modify a system environment variable. System environment variables are defined by Windows and apply to all computer users. Changes to the system environment are written to the registry, and usually require a restart to become effective.
Any user can add, modify, or remove a user environment variable. These variables are established by Windows XP Setup, by some programs, and by users. The changes are written to the registry, and are usually effective immediately. However, after a change to user environment variables is made, any open software programs should be restarted to force them to read the new registry values. The common reason to add variables is to provide data that is required for variables that you want to use in scripts.
To view or change environment variables:
Right-click My Computer, and then click Properties.
Click the Advanced tab.
Click Environment variables.
Click one the following options, for either a user or a system variable:
Click New to add a new variable name and value.
Click an existing variable, and then click Edit to change its name or value.
Click an existing variable, and then click Delete to remove it.