How to get root privilege in recovery mode? I have copyed the 'su' command to /system in adb. but i cannot run the 'su', 'su' says: Permission denied.
Install the Superuser app from the Market and reboot.  Then try running su from adb with your device connected to your computer -- Superuser should pop up a notification on the phone asking if you want to allow it to run.  Then you can use it.  Note your phone must be rooted.