./arm _qt4.5_build 出现错误，求大神指导

本人按照《天嵌科技出品--Qt程序开发完全手册之24小时超级版本_V2.2_20100606》这本资料的第六章 建立QT4的平台一步步来的，遇到运行./arm _qt4.5_build ，出现以下错误，小弟已经在网上找了一晚上，没有找到答案，求大神解决，不胜感激啊:handshake
the build_arm directory is already !
the __install/arm directory is already !
Config Qt4.5 now, please wait ...
This is the Qt for Embedded Linux Open Source Edition.
Preparing build tree...
You are licensed to use this software under the terms of
the GNU Lesser General Public License (LGPL) version 2.1 or
the GNU General Public License (GPL) version 3.
Type '3' to view the GNU General Public License version 3.
Type 'L' to view the GNU Lesser General Public License version 2.1.
Type 'yes' to accept this license offer.
Type 'no' to decline this license offer.
Do you accept the terms of either license?
Creating qmake. Please wait...
gmake: Nothing to be done for `first'.
gmake: *** No targets specified and no makefile found.  Stop.

等了几天，大神都没出现，经过我几晚上的研究发现是因为我没有安装交叉编译器，真是伤不起啊，看资料还是得从头看啊。