This built-in predicate deletes an environment variable from the environment of the current process. If the environment variable was successfully deleted then the predicate is exited, else it fails.
| Examples | |
| del_env('test'). | If the environment of the current process has no variable called 'test' then the predicate fails. |
| set_env('test', 'value'), del_env('test'). |
The variable 'test' is added to the environment, after that the variable 'test' is successfully deleted, the predicate is exited. |
| Exceptions | |
| The argument is a variable | an instantiation_error exception is thrown |
| The argument Arg is not an atom | a type_error(atom, Arg) exception is thrown |