解決Mac系統下"don't have permission to see its contents"問題

Mac Yosemite系統下插U盤上去，提示無法訪問，說我"don't have permission to see its contents"。憑什麼我自己的U盤我沒有權限訪問呢？

經過一番搜索，以下這個方法解決了問題，文末也解釋了每一步的含義。原始鏈接：https://discussions.apple.com/thread/2135793?start=0&tstart=0

*1. Open an application in your Utilities folder called Terminal.* 

This is the Unix part of Mac OS X that does not have a GUI (graphic user interface). Think of it like working in DOS (or BASIC), if you're as old as I am. It's also a bit like a word processing program, only much more powerful.

You type a command (_EXACTLY, character for character, space for space, as it is shown in the example_) and then hit ENTER or RETURN to execute the command. After the first ENTER/RETURN, you will probably have to enter your account password (or an administrator password if you're not logged in as such). 

You won't see any characters appear as you type your password, (the cursor remains in the same place) but continue typing it and then hit RETURN/ENTER.

2. In Terminal, CUT AND PASTE the following lines +one at a time+ (obviously replace "Volumename" with the name of your volume). Make SURE you include spaces where there are spaces. And those are ZEROS after "chflags" and "chown", not Oh's.  

Hit RETURN/ENTER after the "Volumename", and watch your HD's icon on your desktop after each command. In my case, the little padlock disappeared first, then my custom icon was restored, and then it was just blink blink every time after. But it works!!! REMEMBER, THIS FIRST PROCEDURE IS ONLY FOR VOLUMES WITH SINGLE-WORD NAMES:

*sudo chflags 0 /Volumes/Volumename* (don't type this part in Terminal. 
*sudo chown 0:80 /Volumes/Volumename*
*sudo chmod 775 /Volumes/Volumename*
*sudo chmod -N /Volumes/Volumename*

BUT if your volume's name includes one or more spaces like this: "My HD Backup", then you must write the command like this (Notice the spaces :

sudo chflags 0 /Volumes/firstname\ secondname\ thirdname\ fourthname\ fifth etc.
sudo chown 0:80 /Volumes/firstname\ secondname\ thirdname\ fourthname\ fifth etc.
sudo chmod 775 /Volumes/firstname\ secondname\ thirdname\ fourthname\ fifth etc.
sudo chmod -N /Volumes/firstname\ secondname\ thirdname\ fourthname\ fifth etc.

or like in my example:

Quote:
sudo chflags 0 /Volumes/My\ HD\ Backup
sudo chown 0:80 /Volumes/My\ HD\ Backup
sudo chmod 775 /Volumes/My\ HD\ Backup
sudo chmod -N /Volumes/My\ HD\ Backup 

That should do it! Hope it works for everyone with this problem. Thanks to "IEatApples" on MacRumors for the solution!

For anyone who cares, here's what another MacRumors user (angelwatt) said these commands actually do:

1. chflags 0 removes all flags from the file(s)
2. chown 0:80 ensures root:admin (owner:group) permissions so the system can access the files
3. chmod 775 adjusts file permissions so you and your group have read/write/execute permissions
4. chmod -N removes the ACL (Access Control Lists) from the named file(s)