Tabcmd is a special utility for Tableau Server. It is a kind of client that can trigger Tableau Server and do lots of awesome and useful things. We just installed Tabcmd on our machine and connected Server. In addition, we've got a PDF from the Server. You may do many more actions with Tabcmd. This is a link with commands:
https://onlinehelp.tableau.com/current/server/en-us/tabcmd_cmd.htm
In a real-world scenario, Tabcmd is used for automation purposes and one script will include many commands, for example, you might refresh Tableau Extract first and then export a PDF of dashboards or generate Package Workbooks.