### ENV\{"varname"\} -- inspect the value of an environment variable - Returns the current value of the environment variable in the CGI (Common Gateway Interface) environment. This is the environment that the TWiki scripts run in on the web server. - **_Note:_** For security reasons, only those variables whose names match the regular expression in `{AccessibleENV}` in the **Security Settings/Miscellaneous** section of `configure` can be displayed. Any other variable will just be shown as an empty string, irrespective of its real value. - Example: `%ENV{MOD_PERL}%` displays as: - If a variable is undefined (as against being set to the empty string) it will be returned as `not set`. - Related: [[HTTP_HOST|Main/VarHTTPHOST]], [[REMOTE_ADDR|Main/VarREMOTEADDR]], [[REMOTE_PORT|Main/VarREMOTEPORT]], [[REMOTE_USER|Main/VarREMOTEUSER]]