[trac384] addressed two comments from jeremy

- only set a prompt if we have an interactive terminal
- be a bit less verbose on errors

in case of a socket error, only print that error, and not the extra (is it running?) message.
FailToLogin() exception is no longer printed (the methods that raise it already print the real error themselves)
Unexpected Exceptions are now printed *more* verbose, i.e. with a full stacktrace instead of just a message. If we want to 'expect' more error types (and only print a short message that speaks for itself, to look more userfriendly), we should add those explicitely, and not use 'except Exception'.

src/bin/bindctl/bindcmd.py

@@ -51,7 +51,6 @@ except ImportError:
     my_readline = sys.stdin.readline
 
 CSV_FILE_NAME = 'default_user.csv'
-FAIL_TO_CONNECT_WITH_CMDCTL = "Fail to connect with b10-cmdctl module, is it running?"
 CONFIG_MODULE_NAME = 'config'
 CONST_BINDCTL_HELP = """
 usage: <module name> <command name> [param1 = value1 [, param2 = value2]]
@@ -92,7 +91,10 @@ class BindCmdInterpreter(Cmd):
         Cmd.__init__(self)
         self.location = ""
         self.prompt_end = '> '
-        self.prompt = self.prompt_end
+        if sys.stdin.isatty():
+            self.prompt = self.prompt_end
+        else:
+            self.prompt = ""
         self.ruler = '-'
         self.modules = OrderedDict()
         self.add_module_info(ModuleInfo("help", desc = "Get help for bindctl"))
@@ -119,8 +121,8 @@ class BindCmdInterpreter(Cmd):
 
             self.cmdloop()
         except FailToLogin as err:
-            print(err)
-            print(FAIL_TO_CONNECT_WITH_CMDCTL)
+            # error already printed when this was raised, ignoring
+            pass
         except KeyboardInterrupt:
             print('\nExit from bindctl')
 
@@ -270,8 +272,10 @@ class BindCmdInterpreter(Cmd):
         return line 
 
     def postcmd(self, stop, line):
-        '''Update the prompt after every command'''
-        self.prompt = self.location + self.prompt_end
+        '''Update the prompt after every command, but only if we
+           have a tty as output'''
+        if sys.stdin.isatty():
+            self.prompt = self.location + self.prompt_end
         return stop
 
     def _prepare_module_commands(self, module_spec):
@@ -525,8 +529,7 @@ class BindCmdInterpreter(Cmd):
             self._validate_cmd(cmd)
             self._handle_cmd(cmd)
         except (IOError, http.client.HTTPException) as err:
-            print('Error!', err)
-            print(FAIL_TO_CONNECT_WITH_CMDCTL)
+            print('Error: ', err)
         except BindCtlException as err:
             print("Error! ", err)
             self._print_correct_usage(err)