how to clean install MacOS without Administrator PW

Discussion in 'Mac Basics and Help' started by Wiley1, Apr 5, 2018.

  1. Wiley1 macrumors member

    Wiley1

    Joined:
    Apr 5, 2018
    Location:
    Virginia, USA
    #1
    I have inherited an iMac with OS 10.6.8. It also has DeepFreeze installed and, of course, nobody knows the password. I know the only way to overcome this issue is to wipe the HD clean and reinstall the OS. But, I'd like to get it accomplished without cracking open the case.
    Command-R won't work because the OS is too old.
    I'm not able to create a bootable USB media on this machine because I don't have the Administrator PW.
    How do I wipe the HD clean and install a new OS (El Capitan?) without physical access to the HD?
     
  2. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #2
    You need to create a bootable USB with another Mac.
     
  3. Shadow Jolteon macrumors regular

    Shadow Jolteon

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    Feb 1, 2018
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    #3
    You could try using the instructions here to create a new admin account on the machine, then create the installer from there.

    If you're not able to access single-user mode for some reason, then you'll need to use another Mac to download the macOS installer and put it on a flash drive.
     
  4. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #4
    This is a better idea assuming it works with DeepFreeze
     
  5. Wiley1 thread starter macrumors member

    Wiley1

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    #5
    Everything works with DeepFreeze. That is, until you reboot. I was excited about the instructions until I saw the reboot instruction at the end. At that point, the new Admin account that we just created will be un-created unless it lives in NV ram somewhere. If it lives on the HD, it will be wiped out. That's what DF does.

    I'm confused about the procedure for creating a boot disk on another Mac. If the resulting boot image can be taken from one machine to another, why can't I go online somewhere and find a ready-made boot USB image?
     
  6. Shadow Jolteon macrumors regular

    Shadow Jolteon

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    #6
    Ah, yeah, sorry about that. I wasn't thinking about DeepFreeze resetting everything when I sent that.

    And the installers will work on any machine that is compatible with that version of macOS/OS X. If you can find a version of the installer somewhere online, that would probably work, but I certainly wouldn't recommend downloading it from unofficial sources.
     
  7. Wiley1 thread starter macrumors member

    Wiley1

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    #7
    I have folder named "Install OS El Capitan.app" that contains a folder named "Contents" that is full of files.
    Now, how do I create a bootable USB for this?
    Once I boot from the USB, will it allow me to wipe the drive before I install the OS?
     
  8. cruisin macrumors 6502a

    cruisin

    Joined:
    Apr 1, 2014
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    Canada
    #8
    You need access to a Mac with an admin password as you need sudo. If you have a virtual machine already installed (installing it would require a admin password), You could boot into it.

    If the installer is in the default Applications folder you use the Terminal command (assuming you just reformatted the USB drive and therefore it is labeled "Untitled"):
    Booting into the USB will definitely let you wipe the drive.
     
  9. Fishrrman, Apr 6, 2018
    Last edited: Apr 6, 2018

    Fishrrman macrumors P6

    Fishrrman

    Joined:
    Feb 20, 2009
    #9
    Boot from an external source. It could be a USB flashdrive installer, or it could be an external drive with a copy of the OS already set up and running on it.

    Erase the internal drive with Disk Utility.
    NUKE the internal drive BACK TO ZERO.
    WIPE IT OUT.
    (This assumes that DeepFreeze -- which I've never heard of -- will permit that. It's not firmware-based, is it?)

    Now, re-install "from scratch". Everything brand new.
     
  10. Wiley1 thread starter macrumors member

    Wiley1

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    #10
    OK. Did that:
    - found a MacBook, ran the Sudo command, created the boot USB
    - booted the iMac from USB, wiped the HD
    - I know it is wiped because, without the boot USB, all I get is a folder with a "?"
    - when I boot with the USB, I get to a 4 choice menu. Install OS X is the 2nd choice.
    - when I highlight Install OS X and click Continue, it flashes blue, but does nothing
    - when I close that window, it goes to a windows to choose Startup drive, but that is blank -- no startup drive
    - First Aid says there is nothing wrong with my 500GB SATA drive

    What did I do wrong? Is my boot USB no good?
     
  11. francisurquhart macrumors newbie

    Joined:
    Apr 9, 2018
    #11
    You're 99% of the way there. It sounds to me like you need to go into Disk Utility from the installer and format the drive.
     
  12. Wiley1 thread starter macrumors member

    Wiley1

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    #12
    I have that: 499 GB with 477 MB used, OS X Extended, non-bootable

    What else could be wrong?
     
  13. 960design macrumors 68030

    Joined:
    Apr 17, 2012
    Location:
    Destin, FL
    #13
    DeepFreeze is often used in commercial and educational environments where devices are not one to one for the life of the device. To swap control of the device a quick restore will enable DeepFreeze which will prebuild a base configuration profile to immediately get the device back up and working upon reboot, no configuration required by IT ( or as little as IT wants ).
     
  14. hallux macrumors 68030

    hallux

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    Apr 25, 2012
    #14
    What version of OS X are you trying to install? Specifically what model iMac are you working with (you can look up the serial number on https://checkcoverage.apple.com to find out). It may be that the iMac is too old for the OS you're trying to install, 10.6.8 may have been the limit.
     
  15. Wiley1 thread starter macrumors member

    Wiley1

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    #15
    I remember doing all that before I wiped the drive. I came to the conclusion that it would take High Sierra but, just to be safe, I decided to install El Capitan first. At this point, all I have is a blank HD, but I suppose I can find the serial name by clicking INFO. Will get back to you with the details.

    But, do you think I might have messed up the Sudo command in a way that would make the USB bootable but not executable? It did allow me to wipe the drive and format but now I'm at a dead end with no error messages.

    I actually copied the "Install OS X EL Capitan..." folder from a thumbdrive to the C:\download\ folder on a MacBook before using Terminal. The volume name of the target USB was "untitled". In this specific case, what would my Sudo command look like?
     
  16. cruisin macrumors 6502a

    cruisin

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    #16
    The command should be fine (or at least it has always worked for me). You can always try the command again or a different USB drive altogether in the unlikely event that something went wrong.

    Keep in mind that if it came with 10.6.8 and it is too old for booting to recovery (⌘+R) it might be limited to 10.6.8 at most.

    Frankly I am surprised that you found a directory that starts with C:

    To change the location for the command you need to know the login name of the account (not the same as the full name of the account) as the Downloads folder is under the account name (every account will have its own Downloads folder). So if the name is John Smith on the login screen the login is likely different (needs to be without spaces for a start). It could be johnsmith for example.

    You change the command in two places (assuming johnsmith):
    If you have problems discovering the login you can open Terminal and type pwd (for print working directory). By default it should be in the root folder of your account and should also give you what you need.

    Or just move it to Applications and continue as before.
     
  17. Wiley1 thread starter macrumors member

    Wiley1

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    #17
    Here is the info I pulled from the machine before I wiped the HD:
    Mac OS 10.6.8
    Model 11.2
    Year 2010
    CPU: i3
    SMC= 1.64f5​
    This should be OK for El Capitan, right?

    Ha, ha. You are correct. There is no "C:" (my DOS/Windows roots are showing.)

    I think I will try putting the files in the Application folder and running Sudo again.

    Does it matter if the files were downloaded on a different Mac than the one creating the boot USB?
     
  18. hallux macrumors 68030

    hallux

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    Apr 25, 2012
    #18
    No. I've downloaded the installers on my personal Mac and then copied to my work Mac to create drives for work.
     
  19. cruisin macrumors 6502a

    cruisin

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    Canada
    #19
    It will work for El Capitan and all the way up to the current (High Sierra).

    When you boot, did you go to the 4th option (Disk Utility) and wipe the whole drive? https://support.apple.com/en-ca/HT201314
     
  20. Wiley1 thread starter macrumors member

    Wiley1

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    #20
    I think there is something wrong with the content I downloaded and I can't remember where I got it.
    Now that I have access to a MacBook Pro, I decided to go to the App Store and download High Sierra. But, Apple won't allow me to do that because the machine I'm using is too old. Sheez, I just want to download. So, I guess I have to download El Capitan first. Once I get it installed on the iMac, I'll be able to download High Sierra and create another boot USB.

    Now I've hit another speed-bump. When I try to log into the App Store with the owner's password, it sends her a "code" and tells me I have append the code to her password. What a pain.

    Has anybody had any success with downloads from MacUpdate.com? It comes in a .DMG file, not an APP folder.
     
  21. Nermal Moderator

    Nermal

    Staff Member

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    New Zealand
    #21
    You should be able to create your own account and use that; you can "buy" El Captain from this page and associate it with your own account.

    The .dmg file on MacUpdate is probably an updater rather than a full installer.
     
  22. cruisin macrumors 6502a

    cruisin

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    Apr 1, 2014
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    Canada
    #22
    Once you have El Capitan you will simply be able to update directly to High Sierra. You can make a boot USB for future use, but it won't be necessary for the update.

    You should make your own account. Not only will it help with your current issue, but anytime you want to update to a newer macOS version you will need that account to get the newer version (unless you go to someone else each time).
     
  23. Wiley1 thread starter macrumors member

    Wiley1

    Joined:
    Apr 5, 2018
    Location:
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    #23
    Guys: This thing is killing me.
    I used a thing called DiskMaker_X_7 to create a bootable 16GB USB drive named "Mac OS High Sierra Install Disk"
    It seemed to boot OK, so I selected "Install MacOS"
    Now, when I boot the iMac (usb not inserted), all I get is a 4-choice menu: Restore a Time Machine Backup, Install MacOS, Get Help, and Disk Utility. If I choose Install MacOS, all it does is grey out the buttons and stay that way forever.
    So, I reboot and choose Disk Utility. I see two drives:
    1. OS X Base System, 1,28 GB used of 2.00 GB, physical, Disk1s1, MacOS Extended, files: 35,270, bootable: no
    2. Mac OS High Sierra Install Disk 10.13.2, 800 MB used of 500 GB, physical, Disk0s2, MacOS Extended (Journaled), writable: no, files: 1231, bootable: yes
    ---------------
    When I try to erase the Install Disk volume, it fails with "Couldn't unmount"

    Questions:
    What did I do wrong?
    How can I recover?
     
  24. DeltaMac macrumors G3

    DeltaMac

    Joined:
    Jul 30, 2003
    Location:
    Delaware
    #24
    Boot to your USB installer drive again.
    At the menu, open Disk Utility.
    in the View menu, select Show All Devices.
    You should see more items appear in the drive list.
    The top item should be the model number of the internal hard drive, like a manufacturer's part number. Choose that line...
    Choose the Erase button. It will provide a space to name the erased drive, so put something in there - whatever you like - I like "The Abyss" (some things seem to disappear in a dark hole - the abyss :cool: ), but whatever you like for a volume name. Choose Mac OS Extended (journaled) from the dropdown for Format, and then click the Erase button. Should complete in a few seconds, so you can quit Disk Utility, then continue on with Reinstall macOS. Choose the volume that you just created for a destination, and Continue.
    That should get you going. The install might take 30 minutes to an hour, then the new user setup, and you should be all set.
     
  25. hobowankenobi, May 10, 2018
    Last edited: May 10, 2018

    hobowankenobi macrumors 6502a

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    on the land line mr. smith.
    #25
    THIS: Choose Mac OS Extended (journaled)

    Any other option will cause problems, including but not limited to: not booting.

    Looks like it can run 10.13, although 10.12 may be best. Anything from 10.7 to 10.11 will get you rolling though.
     

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