The interpreter exposes a few global variables that can be used during execution. Nitrogen reserves all variables starting with a single underscore for interpreter provided values. Use of variables starting with a single underscore in user code is discouraged.
_FILE is the absolute path to the currently executing script.
_SEARCH_PATHS is an array containing the paths used for import search.
_SERVER is a map containing values given by a web server when using CGI or SCGI.
If a script is run in another way, _SERVER will be nil.