bin/trema in trema-0.5.1 vs bin/trema in trema-0.6.0

@@ -6,12 +6,10 @@
 require 'phut'
 require 'pio'
 require 'rake'
 require 'trema'
 
-ENV['GLI_DEBUG'] = 'true'
-
 # OpenFlow controller framework.
 module Trema
   # trema command.
   module App
     extend GLI::App
@@ -35,10 +33,13 @@
       c.switch :openflow13, default_value: false
 
       c.desc 'Overrides the default openflow channel port'
       c.flag [:p, :port]
 
+      c.desc 'Set logging level'
+      c.flag [:l, :logging_level], default_value: :info
+
       c.desc 'Location to put pid files'
       c.flag [:P, :pid_dir], default_value: Trema::DEFAULT_PID_DIR
       c.desc 'Location to put log files'
       c.flag [:L, :log_dir], default_value: Trema::DEFAULT_LOG_DIR
       c.desc 'Location to put socket files'
@@ -231,9 +232,23 @@
         end
       end
     end
 
     default_command :help
+
+    on_error do |e|
+      case e
+      when OptionParser::ParseError,
+        Trema::NoControllerDefined,
+        Trema::InvalidLoggingLevel,
+        Phut::OpenVswitch::AlreadyRunning,
+        GLI::UnknownCommandArgument
+        true
+      else
+        # show backtrace
+        fail e
+      end
+    end
 
     exit run(ARGV)
   end
 end