由於長久不用Air了，所以忘記了之前的root密碼，導致很多命令都無法執行，於是找到了這個解決方法（經本人在Mac os x 10.6.8下測試成功！），故來跟大家分享下。
開機，並迅速按住 Command + S組合鍵，進入命令行模式
輸入命令(有時可能要命令路徑不同，可參考屏幕上顯示的那兩行提示),檢查系統錯誤並修復
[plain] view plaincopy
/sbin/fsck -fy
輸入命令,使有權限更改系統配置
[html] view plaincopy
/sbin/mount -uw /
最后根據命令
[html] view plaincopy
passwd root
來更改密碼就ok啦！
然后 敲入 reboot 命令，重啟機器就完工啦！
以下是原文：
Change an Admin Password in Mac OS X Single User Mode
This is a multistep process but it’s easy to follow:
First you need to enter Single User Mode. Reboot the Mac and hold down Command+S at boot to enter into the command line.
You’ll see a note where Mac OS X tells you that you need to run two commands in order to make filesystem changes, this is necessary so let’s handle that first
The first command checks the Mac OS X filesystem for errors and fixes them, it can take a few minutes to run:
fsck -fy
The next command mounts the root Mac OS X drive as writable, allowing you to make changes to the filesystem:
mount -uw /
After the filesystem is mounted, you can reset any users password using the following command:
passwd username
You’ll need to enter the new password twice to reset and confirm the changes