From QB64 Wiki
The ENVIRON statement is used in Windows to temporarily set or change an environmental string value.
- ENVIRON string_expression$
- The string expression must include the environmental parameter ID and the setting two ways:
- * Using an = : ENVIRON parameterID=setting
- * Using a space: ENVIRON parameterID setting
- If the parameter ID did not previously exist in the environmental string table, it is appended to the end of the table.
- If a parameter ID did exist, it is deleted and the new value is appended to end of the list.
- DOS discards any changes when your program ends so the program must set them when run!
- WARNING: The amount of space in a environmental table is limited and may create memory errors.