| ENV | |
| --- | |
| Operator to read environment variables. | |
| Use the syntax ``$ENV{VAR}`` to read environment variable ``VAR``. | |
| To test whether an environment variable is defined, use the signature | |
| ``if(DEFINED ENV{<name>})`` of the :command:`if` command. | |
| See the :command:`set` and :command:`unset` commands to see how to | |
| write or remove environment variables. |