ITYM "caffeinate"

  DESCRIPTION
     caffeinate creates assertions to alter system sleep behavior.  If no
     assertion flags are specified, caffeinate creates an assertion to prevent
     idle sleep.  If a utility is specified, caffeinate creates the assertions
     on the utility's behalf, and those assertions will persist for the
     duration of the utility's execution. Otherwise, caffeinate creates the
     assertions directly, and those assertions will persist until caffeinate
     exits.