Command line entry point to list running notebook servers

IPython/html/notebookapp.py

@@ -214,6 +214,27 b' class NotebookWebApplication(web.Application):'
         return new_handlers
 
 
+class NbserverListApp(BaseIPythonApplication):
+    
+    description="List currently running notebook servers in this profile."
+    
+    flags = dict(
+        json=({'NbserverListApp': {'json': True}},
+              "Produce machine-readable JSON output."),
+    )
+    
+    json = Bool(False, config=True,
+          help="If True, each line of output will be a JSON object with the "
+                  "details from the server info file.")
+
+    def start(self):
+        if not self.json:
+            print("Currently running servers:")
+        for serverinfo in discover_running_servers(self.profile):
+            if self.json:
+                print(json.dumps(serverinfo))
+            else:
+                print(serverinfo['url'], "::", serverinfo['notebookdir'])
 
 #-----------------------------------------------------------------------------
 # Aliases and Flags
@@ -287,6 +308,10 b' class NotebookApp(BaseIPythonApplication):'
     flags = Dict(flags)
     aliases = Dict(aliases)
 
+    subcommands = dict(
+        list=(NbserverListApp, NbserverListApp.description.splitlines()[0]),
+    )
+
     kernel_argv = List(Unicode)
 
     def _log_level_default(self):
@@ -746,6 +771,9 b' class NotebookApp(BaseIPythonApplication):'
         
         This method takes no arguments so all configuration and initialization
         must be done prior to calling this method."""
+        if self.subapp is not None:
+            return self.subapp.start()
+
         info = self.log.info
         for line in self.notebook_info().split("\n"):
             info(line)
@@ -789,7 +817,7 b' class NotebookApp(BaseIPythonApplication):'
             self.remove_server_info_file()
 
 
-def discover_running_servers(profile='default'):
+def list_running_servers(profile='default'):
     """Iterate over the server info files of running notebook servers.
     
     Given a profile name, find nbserver-* files in the security directory of

IPython/html/tests/test_notebookapp.py

@@ -27,7 +27,7 b' def test_help_output():'
 def test_server_info_file():
     nbapp = notebookapp.NotebookApp(profile='nbserver_file_test')
     def get_servers():
-        return list(notebookapp.discover_running_servers(profile='nbserver_file_test'))
+        return list(notebookapp.list_running_servers(profile='nbserver_file_test'))
     nbapp.initialize(argv=[])
     nbapp.write_server_info_file()
     servers = get_servers()