jsch ssh服务器调用Linux命令或脚本的小问题

    public static boolean execshell(String command, String user, String passwd, String host) throws JSchException, IOException {  
        connect(user, passwd, host);
        BufferedReader reader = null;
        boolean flag = true;
        Channel channel = null;  
        String charset ="UTF-8";
        try {  
            //执行linux命令
            channel = session.openChannel("exec"); 
            ((ChannelExec) channel).setCommand(command);  
            ((ChannelExec) channel).setErrStream(System.err);  
            channel.connect(); 
            InputStream in = channel.getInputStream();
            reader = new BufferedReader(new InputStreamReader(in,
            Charset.forName(charset)));
            String buf = null;
            while ((buf = reader.readLine()) != null) {
            log.info(buf);
            }            
             }catch (Exception e) {
                 e.printStackTrace();
             }finally {   
                 reader.close();
                 channel.disconnect();  
                 session.disconnect();  
        }
        return flag;
    }