+However, if you receive the following message:
+
+bc. ARVADOS_API_HOST and ARVADOS_API_TOKEN need to be defined as environment variables
+
+Then follow the instructions for "getting an API token,":{{site.basedoc}}/user/reference/api-tokens.html and return to this document.
+
+The unique identifier represents your identity in the Arvados system and is similar to the concept of a pointer or a foreign key. You may de-reference (get the contents of) any identifier returned by the "arv" command using the @-h@ command line option. For example: