执行commands有问题

for (String command : commands) {
 if (command == null) {
 continue;
 }

```
 // donnot use os.writeBytes(commmand), avoid chinese charset error
 os.write(command.getBytes());
 os.writeBytes(COMMAND_LINE_END);
 os.flush();
 }
```

当传入的commands数组过大，os write将近64M的字节时会出现错误
