for file in *; do mv $file `echo $file | sed 's/Tool/Down/g'`; done
sed -i "s/Tool/Down/g" `grep Tool -rl ~/project/temp/`
Ref:
http://hi.baidu.com/east_door/blog/item/66993518f3dac872dbb4bdf2.html
http://www.thingy-ma-jig.co.uk/blog/19-04-2008/how-batch-rename-files
http://www.admin99.net/read.php/108.htm
http://www.linux-wiki.cn/index.php/%E6%89%B9%E9%87%8F%E9%87%8D%E5%91%BD%E5%90%8D%E6%96%87%E4%BB%B6