A bit of hack: file-only download command

hworker/control/cli.py

@@ -200,10 +200,18 @@ def complete_shell(self, text, line, begidx, endidx):
             return self.filtertext(globals(), prefix)
 
     def do_download(self, arg):
-        """Download all homeworks (do not parse if "only" parmeter is given)"""
+        """Download all homeworks
+
+        Download from single backend if backand name is given
+        Do not parse if "only" parmeter is given
+        """
         args = self.shplit(arg)
-        deliver.download_all()
-        if args != ["only"]:
+        back = set(args) - {"only"}
+        if back:
+            getattr(deliver, back.pop()).download_all()
+        else:
+            deliver.download_all()
+        if "only" not in args:
             make.parse_all_stored_homeworks()
 
     def complete_download(self, text, line, begidx, endidx):