Disable booting into single user mode

Posted on 2013-05-14
Medium Priority
Last Modified: 2013-05-15

I have a Macbook Pro (Snow Leopard 10.6.8) and would like to disable the ability to boot into single user mode by pressing Command+S when the system starts up (even if all other startup key combinations are disabled to achieve the desired result, it will do). Is there any way in which this can be done without adding a firmware password?

Had a look at the link given below but was unable to find the needed boot file. Moreover the link seems to be outdated.


Question by:N_Joshi
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LVL 53

Expert Comment

ID: 39166971
Haven't tried it, but here is one possibility:


Author Comment

ID: 39167141
Am unable to download the file from the link you have given so am now trying to follow the details from the below link to directly edit the boot file to disable single user mode if possible. Do let me know if i am on the right track and if so, how exactly i should edit the boot file (com.apple.Boot.plist). Thanks.
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LVL 32

Accepted Solution

serialband earned 1500 total points
ID: 39167185
From: http://hints.macworld.com/comment.php?mode=view&cid=98570

1. Log in as administrator
2. Open Terminal
3. cd /etc
4. sudo cp ttys ttys.old (backs up previous ttys config).
5. sudo pico ttys
6. Replace all occurrences of the word "secure" with "insecure" at any lines that do not begin with a "#"
7. Exit, saving changes.

And a different way for other versions.

Author Comment

ID: 39167604
There are two things which i need to mention here.

1. I contacted the apple service center and they told me that it is officially not possible to password protect "single user mode" on an intel based Mac. The ability to password protect "single user mode" without having to put a firmware password, is only possible on a Power PC, which i do not have.

Before i enter any commands in Terminal, I need to be sure that your method will not cause any booting problems.
LVL 32

Expert Comment

ID: 39167959
I can't guarantee that, as I have only ever used the Firmware password to protect the Mac.  I can only guess that it's technically possible to put a password on single user mode, since that's built on BSD.  Apple probably doesn't want you to do it, officially, because they want a "back door" into your system if you have to bring it to their "genius" bar for service.  Again, that's just another guess.

Author Comment

ID: 39168914
I understand the utility given below can be used to disable single user mode and moreover since it seems to be a more authentic approach, I first wish to try this out. I guess i will need to backup all the data first, incase there is a boot failure.


Author Comment

ID: 39169714
Sorry, but the rEFIt utility is unable to block Single user mode, but your link was very helpful. Thanks for the help.

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