Ubuntu忘記root密碼

1. 按Esc鍵進入grub menu

2. 選擇recovery mode

3. 進入recovery menu，選擇root並按enter進入命令模式

4. 此時檔案系統為read-only，需要執行下列命令remount檔案系統有存取權限 At this stage you should have a read-only filesystem. You have to remount it with write permissions:

$ mount -rw -o remount /

5. 執行命令修改root密碼

$ passwd root

6. 參考來源
http://askubuntu.com/questions/24006/how-do-i-reset-a-lost-administrative-password