diff --git a/src/python/jw/pkg/App.py b/src/python/jw/pkg/App.py
index 26ee7c42..35b71579 100644
--- a/src/python/jw/pkg/App.py
+++ b/src/python/jw/pkg/App.py
@@ -78,8 +78,7 @@ class App(Base):
     async def _run(self, args: argparse.Namespace) -> None:
 
         self.opt_debug = args.debug
-        if len(args.os):
-            self.opt_os = args.os[0]
+        self.opt_os = args.os
 
         if args.prefix is not None:
             self.projs_root = args.prefix
diff --git a/src/python/jw/pkg/build/Cmd.py b/src/python/jw/pkg/build/Cmd.py
index 8d45714e..0b8c19b3 100644
--- a/src/python/jw/pkg/build/Cmd.py
+++ b/src/python/jw/pkg/build/Cmd.py
@@ -5,54 +5,13 @@ from typing import Type, Union, TypeVar
 import inspect, abc, argparse
 from argparse import ArgumentParser
 
-class Cmd(abc.ABC): # export
+from ..lib.Cmd import Cmd as Base
+
+class Cmd(Base): # export
 
     def __init__(self, name: str, help: str) -> None:
+        super().__init__(name, help)
         from ..App import App
-        self.name = name
-        self.help = help
-        self.parent = None
-        self.children: list[Cmd] = []
-        self.child_classes: list[Type[Cmd]] = []
-        self.app: App|None = None
 
-    @abc.abstractmethod
-    def _run(self, args):
-        pass
-
-    def run(self, args):
+    async def run(self, args):
         return self._run(args)
-
-    def add_parser(self, parsers) -> ArgumentParser:
-        r = parsers.add_parser(self.name, help=self.help,
-            formatter_class=argparse.ArgumentDefaultsHelpFormatter)
-        r.set_defaults(func=self.run)
-        return r
-
-    def add_subcommands(self, cmd: Union[str, Type[Cmd], list[Type[Cmd]]]) -> None:
-        if isinstance(cmd, str):
-            import sys, re
-            sc = []
-            for name, obj in inspect.getmembers(sys.modules[self.__class__.__module__]):
-                if inspect.isclass(obj):
-                    if re.search(cmd, str(obj)):
-                        sc.append(obj)
-                        log.slog(log.DEBUG, f"Found subcommand {obj}")
-            self.add_subcommands(sc)
-            return
-        if isinstance(cmd, list):
-            for c in cmd:
-                self.add_subcommands(c)
-            return
-        self.child_classes.append(cmd)
-
-    # To be overridden by derived class in case the command does take arguments.
-    # Will be called from App base class constructor and set up the parser hierarchy
-    def add_arguments(self, parser: ArgumentParser) -> None:
-        pass
-
-    def conf_value(self, path, default=None):
-        ret = None if self.app is None else self.app.conf_value(path, default)
-        if ret is None and default is not None:
-            return default
-        return ret