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User profile for user: par4uk
par4uk Author
User level: Level 1
8 points

repair permissions in Big Sur on startup drive

suddenly I do not have permission to write to my startup drive in Big Sur 11.1.


iMac 27" 2TB fusion drive 2019 5K retina, Big Sur 11.1


machine/OS was OK a few hours ago. I have tried Disk Utility (does not work like a few years ago), I have restarted, I have just about exhausted my options.


I have tried to add my self in various ways to the permission list, no joy. I have tried to add administrators, no joy. System says R &W permission, but not me -- I even tried to grant everyone R&W permission. no joy. But I can start up my computer.


Don't know what to do (except use Time Machine).


Help, please. Phil Richardson


How

iMac 27″, macOS 11.1

Posted on Jan 19, 2021 5:19 AM

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User profile for user: Barney-15E
Barney-15E
User level: Level 10
116,620 points

Posted on Jan 19, 2021 7:48 PM

With an External, it is usually easiest just to check the ignore ownership check box in get info. If that is missing, it usually indicates that something has taken over control of that drive, like Time Machine

I just use Get Info or use chmod in the Terminal if it needs more capability than is provided in the info window.

BatChmod is a GUI for chmod, Doesn’t handle ACLs, except to delete them all, which may be useful. If you used file sharing with that drive, I suppose it is possible that you created an ACL that is restricting your permissions.


You can’t do anything to a time machine back up drive it’s locked down.


If the drive is formatted with a file system that doesn’t have permissions you can’t do anything to it and you shouldn’t need to, ExFAT or FAT32.

I am also seeing where the root level of an external seems to be unmodifiable. But, subfolder shouldn’t be a problem.

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User profile for user: Barney-15E
Barney-15E
User level: Level 10
116,620 points

Jan 19, 2021 7:48 PM in response to par4uk

With an External, it is usually easiest just to check the ignore ownership check box in get info. If that is missing, it usually indicates that something has taken over control of that drive, like Time Machine

I just use Get Info or use chmod in the Terminal if it needs more capability than is provided in the info window.

BatChmod is a GUI for chmod, Doesn’t handle ACLs, except to delete them all, which may be useful. If you used file sharing with that drive, I suppose it is possible that you created an ACL that is restricting your permissions.


You can’t do anything to a time machine back up drive it’s locked down.


If the drive is formatted with a file system that doesn’t have permissions you can’t do anything to it and you shouldn’t need to, ExFAT or FAT32.

I am also seeing where the root level of an external seems to be unmodifiable. But, subfolder shouldn’t be a problem.

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User profile for user: Barney-15E
Barney-15E
User level: Level 10
116,620 points

Jan 19, 2021 5:48 AM in response to par4uk

Where on the startup drive are you trying to write?

The vast majority of the startup drive is mounted read-only, so attempting to write to it will fail.

Your user should not have any permissions on the root level of the startup drive. That is not a problem that can be solved nor needs to be solved.


Do you have problems writing to your home folder?

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repair permissions in Big Sur on startup drive

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