To install environment variables, use the
Environment tag in a component:
<Environment Id='UpdatePath' Name='PATH' Action='set' Permanent='yes' System='yes' Part='last' Value='[INSTALLDIR]' />
Action attribute specifies what to do when the component is installed, its possible values are create, set and remove. The
Part attribute governs the way the new value is assigned: all replaces the previous value with the new one, first prepends it to the original value, last appends to it.
Permanent='yes' makes the environment variable stay when the product is removed, otherwise, it will be removed as well.
System specifies whether the environment variable should be added to the system or the user environment space. Make sure you use all-uppercase names.