From QB64 Wiki
The ENVIRON statement is used in DOS/Windows to temporarily set or change an environmental string value.
- ENVIRON stringExpression$
- Not supported in QB64.
- The stringExpression$ must include the environmental parameter ID and the setting:
- Using an = sign: 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.