diff --git a/library/think/Console.php b/library/think/Console.php
index 5035958a..24b85134 100644
--- a/library/think/Console.php
+++ b/library/think/Console.php
@@ -740,7 +740,7 @@ class Console
 
     public static function addDefaultCommands(array $classnames)
     {
-        self::$defaultCommands[] = array_merge(self::$defaultCommands, $classnames);
+        self::$defaultCommands = array_merge(self::$defaultCommands, $classnames);
     }
 
     /**
diff --git a/library/think/console/output/Null.php b/library/think/console/output/Null.php
new file mode 100644
index 00000000..4e8f355c
--- /dev/null
+++ b/library/think/console/output/Null.php
@@ -0,0 +1,109 @@
+<?php
+// +----------------------------------------------------------------------
+// | ThinkPHP [ WE CAN DO IT JUST THINK ]
+// +----------------------------------------------------------------------
+// | Copyright (c) 2006~2015 http://thinkphp.cn All rights reserved.
+// +----------------------------------------------------------------------
+// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
+// +----------------------------------------------------------------------
+// | Author: yunwuxin <448901948@qq.com>
+// +----------------------------------------------------------------------
+
+namespace think\console\output;
+
+
+use think\console\Output;
+
+class Null extends Output
+{
+    /** @noinspection PhpMissingParentConstructorInspection */
+    public function __construct()
+    {
+        
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setFormatter(Formatter $formatter)
+    {
+        // do nothing
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getFormatter()
+    {
+        // to comply with the interface we must return a OutputFormatterInterface
+        return new Formatter();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setDecorated($decorated)
+    {
+        // do nothing
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function isDecorated()
+    {
+        return false;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setVerbosity($level)
+    {
+        // do nothing
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getVerbosity()
+    {
+        return self::VERBOSITY_QUIET;
+    }
+
+    public function isQuiet()
+    {
+        return true;
+    }
+
+    public function isVerbose()
+    {
+        return false;
+    }
+
+    public function isVeryVerbose()
+    {
+        return false;
+    }
+
+    public function isDebug()
+    {
+        return false;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function writeln($messages, $options = self::OUTPUT_NORMAL)
+    {
+        // do nothing
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function write($messages, $newline = false, $options = self::OUTPUT_NORMAL)
+    {
+        // do nothing
+    }
+}
\ No newline at end of file