[WIP] improve help message

base.py

@@ -487,12 +487,20 @@ class ServiceManager:
                 print(str(e))
 
     def do_help(self, *args):
+        options = {'ins': '<instance> ', 'optional_ins': '[instance] ', 'remark': '*', 'legend': ''}
+        wildcards = True
         if self.main_ins:
-            usage = self.USAGE.replace('<instance>', '[instance]') % (
-               '[instance] is empty or one of %s' % ', '.join(self.info))
+            if len(self.info) == 1:
+                for key in options:
+                    options[key] = ''
+                wildcards = False
+            else:
+                options['legend'] = '        [instance] is empty or one of %s\n' % ', '.join(self.info)
         else:
-            usage = self.USAGE % ('<instance> is one of %s' % ', '.join(self.info))
-        print(usage)
+            options['legend'] = '        <instance> is one of %s' % ', '.join(self.info)
+        if wildcards:
+            options['legend'] += "      * wildcards allowed, using '.' to replace 0 or more arbitrary characters in <instance>\n"
+        print(self.USAGE % options)
 
     def treat_args(self, argdict, unknown=(), extra=()):
         if unknown: