When you assign a value to an environment variable using %ENV, the value is effective only for that session. After the program that sets the variable terminates, the value is no longer available. To create a persistent environment variable, you must set the value in the Registry . One way to do that is uses a program in the Windows resource kit.

Use the Setx resource kit utility. Setx is a powerful tool with which you can manage the environment variables in NT. This utility has three modes of operation: command line, Registry, and file. The command-line and Registry modes are the most common.

setx LOCATION DALLAS -m

The other option is to hack the registry .

The HKEY_LOCAL_MACHINE\SYSTEM\ CurrentControlSet\Control\ Session Manager\ Environment Registry key stores static system variables.