VE3VLF
Level 1 (8 points)
Mac OS X

Q: Locked out of iMac after changing Sharing and Permissions of HD

Made a big mistake with the Sharing and Permissions of my iMac's internal HD.   I was experimenting with the Sharing and Permissions section of the HD's info panel while in the administrator's account.    In that section I changed the "everyone" name to "no access" but in doing so it froze up the machine.  Nothing was responding.  I tried to reboot but after the Apple logo and progress bar appeared briefly, the screen went blank. 

 

I tried to do a back up using Time Machine but when the time came to erase the HD and replace with the TM backup, I got an error message saying that the system was unable to erase the HD.  I tried going in using Safe Mode but it keeps sending me to the Recovery mode. 

 

I have a separate boot disk that I made in Carbon Copy Cloner that is at another location right now but that I can get and maybe I can boot from that and do a total erase of the internal HD and start over.  But is there anything I can do in the mean time?  It looks like that one setting has locked me completely out of the HD of the iMac. 

 

Thanks,

 

Ed

Posted on Sep 10, 2016 8:39 PM

by VE3VLF,Solvedanswer
VE3VLF VE3VLF
Level 1 (8 points)
Mac OS X
A:

To follow up, I tried something different. I used the Reinstall OS X option when the Utility pane was up.  My iMac then went through the process of downloading and reinstalling OS X.  After about 40 minutes, when it was all done, my machine came back with login, settings and data all in place.  I didn't even have to do a Time Machine reinstall of data.  Problem corrected.

 

Moral of the story is, don't play around with staring and permission to much!

Posted on Sep 11, 2016 6:29 AM

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Q: Locked out of iMac after changing Sharing and Permissions of HD

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  • by VE3VLF,Solvedanswer

    VE3VLF VE3VLF Sep 11, 2016 6:29 AM in response to VE3VLF
    Level 1 (8 points)
    Mac OS X
    Sep 11, 2016 6:29 AM in response to VE3VLF

    To follow up, I tried something different. I used the Reinstall OS X option when the Utility pane was up.  My iMac then went through the process of downloading and reinstalling OS X.  After about 40 minutes, when it was all done, my machine came back with login, settings and data all in place.  I didn't even have to do a Time Machine reinstall of data.  Problem corrected.

     

    Moral of the story is, don't play around with staring and permission to much!

  • by Barney-15E,

    Barney-15E Barney-15E Sep 11, 2016 6:43 AM in response to VE3VLF
    Level 8 (49,784 points)
    Mac OS X
    Sep 11, 2016 6:43 AM in response to VE3VLF

    Did you "Apply to Enclosed" or did you just change the permissions on the top level of the Hard drive?

    If the latter, you can boot into Single-user Mode and change the permissions back.

    Hold down cmd-s on restart. You will just get a bunch of text.

    When it is done booting, there will be instructions to check the disk and mount it for modifications. They are

    /sbin/fsck -fy

    /sbin/mount -uw /

    Do both but if you get a message that "***** FILE SYSTEM WAS MODIFIED *****" , run the fsck again until you get, "The Volume Macintosh HD appears OK." Then you can mount the drive.

     

    Now, run this command:

    chmod 755 /

    Note that in all of those, there is a space before the last "/".

    That / is the shortcut term for the hard drive.

  • by Barney-15E,

    Barney-15E Barney-15E Sep 11, 2016 6:44 AM in response to VE3VLF
    Level 8 (49,784 points)
    Mac OS X
    Sep 11, 2016 6:44 AM in response to VE3VLF

    VE3VLF wrote:

     

    To follow up, I tried something different. I used the Reinstall OS X option when the Utility pane was up.

    That would be the longer, but easier to understand method.

  • by VE3VLF,

    VE3VLF VE3VLF Sep 11, 2016 3:06 PM in response to Barney-15E
    Level 1 (8 points)
    Mac OS X
    Sep 11, 2016 3:06 PM in response to Barney-15E

    I believe I changed permissions on the top level of the hard drive.  Thanks for the information to change permissions back using the single-user mode, which I had not heard about before.  If this happens again (which I hope not!) I try this method. 

  • by Barney-15E,

    Barney-15E Barney-15E Sep 11, 2016 5:34 PM in response to VE3VLF
    Level 8 (49,784 points)
    Mac OS X
    Sep 11, 2016 5:34 PM in response to VE3VLF

    If you apply to enclosed, I think a reinstall is the only hope. However, I seem to remember they may have done something to prevent you from doing it.