New environment variables are set by creating the corresponding file in /env and writing the required value to that file. Similarly environment variables are destroyed (unset) by removing the corresponding file.

Processes sharing an `environment group' see the same files and contents; changes made by one process are seen by the others. A process can insulate itself from further changes using the FORKENV option to sys-pctl(2), which creates a new environment group that is a copy of the old, but further changes in each are independent. A new empty environment group is created by the NEWENV option to sys-pctl(2).