diff --git a/bin/user/sdr.py b/bin/user/sdr.py
index 12c9976..d5e8db2 100644
--- a/bin/user/sdr.py
+++ b/bin/user/sdr.py
@@ -215,8 +215,9 @@ def __init__(self):
         self.stdout_reader = None
         self.stderr_queue = queue.Queue()
         self.stderr_reader = None
+        self.uses_shell = None
 
-    def startup(self, cmd, path=None, ld_library_path=None):
+    def startup(self, cmd, path=None, use_shell=None, ld_library_path=None):
         self._cmd = cmd
         loginf("startup process '%s'" % self._cmd)
         env = os.environ.copy()
@@ -225,7 +226,15 @@ def startup(self, cmd, path=None, ld_library_path=None):
         if ld_library_path:
             env['LD_LIBRARY_PATH'] = ld_library_path
         try:
-            self._process = subprocess.Popen(cmd.split(' '),
+            if use_shell:
+                self.uses_shell = True
+                self._process = subprocess.Popen(cmd,
+                                             shell=True,
+                                             env=env,
+                                             stdout=subprocess.PIPE,
+                                             stderr=subprocess.PIPE)
+            else:
+                self._process = subprocess.Popen(cmd.split(' '),
                                              env=env,
                                              stdout=subprocess.PIPE,
                                              stderr=subprocess.PIPE)
@@ -241,7 +250,20 @@ def startup(self, cmd, path=None, ld_library_path=None):
 
     def shutdown(self):
         loginf('shutdown process %s' % self._cmd)
-        self._process.kill()
+        logdbg('waiting for %s' % self.stdout_reader.getName())
+        self.stdout_reader.stop_running()
+        if self.uses_shell:
+            os.kill(self._process.pid, signal.SIGTERM)
+        self.stdout_reader.join(10.0)
+        if self.stdout_reader.isAlive():
+            loginf('timed out waiting for %s' % self.stdout_reader.getName())
+        self.stdout_reader = None
+        logdbg('waiting for %s' % self.stderr_reader.getName())
+        self.stderr_reader.stop_running()
+        self.stderr_reader.join(10.0)
+        if self.stderr_reader.isAlive():
+            loginf('timed out waiting for %s' % self.stderr_reader.getName())
+        self.stderr_reader = None
         logdbg("close stdout")
         self._process.stdout.close()
         logdbg("close stderr")
@@ -3279,10 +3301,11 @@ def __init__(self, **stn_dict):
         self._counter_values = dict()
         cmd = stn_dict.get('cmd', DEFAULT_CMD)
         path = stn_dict.get('path', None)
+        use_shell = stn_dict.get('use_shell', None)
         ld_library_path = stn_dict.get('ld_library_path', None)
         self._last_pkt = None # avoid duplicate sequential packets
         self._mgr = ProcManager()
-        self._mgr.startup(cmd, path, ld_library_path)
+        self._mgr.startup(cmd, path, use_shell, ld_library_path)
 
     def closePort(self):
         self._mgr.shutdown()