Environment variables.

[Dale Strickland-Clark]

You can't change the environment variables of your calling
environment. There is simply no mechanism in the OS.

When your program is called, it gets a copy of the calling program's
environment. You can change this copy all you like but when your
program ends, it is destroyed.

The only way to set environment variables so they persist is by
attacking the registry but then the new values don't get used until
you start a new command prompt window.
--
Dale Strickland-Clark
Riverhall Systems Ltd