Sets the environment variable variable in the environment of processes launched from this launcher.
On UNIX, both the variable's name and value can be arbitrary byte strings, except that the variable's name cannot contain '='. On Windows, they should be in UTF-8.
| this | |
| variable |
the environment variable to set, must not contain '=' |
| value |
the new value for the variable |
| overwrite |
whether to change the variable if it already exists |